0001666071-21-000029 | 10-K | XBRL Viewer

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Cover Page - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Cover Page - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2020	Feb. 28, 2021	Dec. 31, 2019	Jun. 28, 2019	Jan. 26, 2018
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-38386
Entity Registrant Name	CARDLYTICS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-3039436
Entity Address, Address Line One	675 Ponce de Leon Ave. NE, Ste 6000
Entity Address, City or Town	Atlanta
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30308
City Area Code	(888)
Local Phone Number	792-5802
Title of 12(b) Security	Common Stock
Trading Symbol	CDLX
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float				$ 1,800.0
Entity Common Stock, Shares Outstanding (in shares)		27,903,828
Common stock, par or stated value per share (in usd per share)	$ 0.0001		$ 0.0001		$ 0.0001
Entity Central Index Key	0001666071
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 293,239	$ 104,458
Restricted cash	110	129
Accounts receivable, net	81,249	81,452
Other receivables	5,306	3,908
Prepaid expenses and other assets	5,687	5,783
Total current assets	385,591	195,730
Long-term assets:
Property and equipment, net	13,865	14,290
Right-of-use assets under operating leases, net	10,764	0
Intangible assets, net	447	389
Capitalized software development costs, net	6,299	3,815
Deferred FI implementation costs, net	3,785	8,383
Other long-term assets, net	1,786	1,706
Total assets	422,537	224,313
Current liabilities:
Accounts payable	1,363	1,229
Accrued liabilities:
Accrued compensation	7,582	8,186
Accrued expenses	5,502	6,018
FI Share liability	37,457	41,956
Consumer Incentive liability	24,290	19,861
Deferred revenue	349	1,127
Current operating lease liabilities	4,718	0
Current finance lease liabilities	13	24
Total current liabilities	81,274	78,401
Long-term liabilities:
Convertible senior notes, net	174,011	0
Deferred liabilities	0	2,632
Long-term operating lease liabilities	9,381	0
Long-term finance lease liabilities	0	13
Other long-term liabilities	679	0
Liabilities	265,345	81,046
Stockholders’ equity:
Common stock, $0.0001 par value—100,000 shares authorized and 26,547 and 27,861 shares issued and outstanding as of December 31, 2019 and December 31, 2020, respectively	8	8
Additional paid-in capital	551,429	480,578
Accumulated other comprehensive income (loss)	(192)	1,312
Accumulated deficit	(394,053)	(338,631)
Total stockholders’ equity	157,192	143,267
Total liabilities and stockholders’ equity	$ 422,537	$ 224,313

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019	Jan. 26, 2018
Statement of Financial Position [Abstract]
Common stock, par or stated value per share (in usd per share)	$ 0.0001	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	100,000,000		100,000,000

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Revenue	$ 186,892	$ 210,430	$ 150,684
Costs and expenses:
FI Share and other third-party costs	109,308	118,080	85,371
Delivery costs	14,310	12,893	10,632
Sales and marketing expense	45,307	43,828	41,878
Research and development expense	17,532	11,699	16,210
General and administration expense	46,532	36,720	34,228
Depreciation and amortization expense	7,826	4,535	3,282
Total costs and expenses	240,815	227,755	191,601
Operating loss	(53,923)	(17,325)	(40,917)
Non-operating (expense) income:
Interest expense, net	(3,048)	(548)	(3,264)
Change in fair value of warrant liabilities, net	0	0	(6,760)
Other Nonoperating Income (Expense)	1,549	729	(2,101)
Total non-operating (expense) income	(1,499)	181	(12,125)
Loss before income taxes	(55,422)	(17,144)	(53,042)
Income tax benefit	0	0	0
Net loss	(55,422)	(17,144)	(53,042)
Adjustments to the carrying value of redeemable convertible preferred stock	0	0	(157)
Net loss attributable to common stockholders	$ (55,422)	$ (17,144)	$ (53,199)
Net loss per share attributable to common stockholders, basic and diluted (in USD per share)	$ (2.04)	$ (0.72)	$ (2.79)
Weighted-average common shares outstanding, basic and diluted (in shares)	27,213	23,746	19,060

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (55,422)	$ (17,144)	$ (53,042)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract]
Foreign currency translation adjustments	(1,504)	(680)	926
Total comprehensive loss	$ (56,926)	$ (17,824)	$ (52,116)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ (DEFICIT) EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2017		3,439,000
Beginning balance at Dec. 31, 2017	$ (208,686)	$ 0	$ 58,693	$ 1,066	$ (268,445)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)	357,000	356,000
Exercise of common stock options	$ 1,959
Exercise of common stock warrants (in shares)		1,142,000
Stock-based compensation	$ 26,813		26,813
Issuance of common stock (in shares)	5,821,000	888,000
Issuance of common stock	$ 17,774		17,774
APIC, Share-based Payment Arrangement, ESPP, Increase for Cost Recognition	1,958
Issuance of common stock warrants		$ 177
Stock and Warrants Issued During Period, Value, Preferred Stock and Warrants	1,735
Accretion of redeemable stock	(157)		(157)
Other comprehensive income (loss)	926			926
Net loss	(53,042)				(53,042)
Ending balance (in shares) at Dec. 31, 2018		22,466,000
Ending balance at Dec. 31, 2018	51,975	$ 7	371,463	1,992	(321,487)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, $0.0001 par value—100,000 shares authorized and 26,547 and 27,861 shares issued and outstanding as of December 31, 2019 and December 31, 2020, respectively	1
Additional paid-in capital	$ 66,100
Exercise of common stock options (in shares)	716,000	716,000
Exercise of common stock options	$ 12,052		$ 12,052
Exercise of common stock warrants (in shares)	17,659,000	821,000	17,659,000
Stock-based compensation	$ 15,888		$ 15,888
Issuance of common stock (in shares)	1,904,000	486,000
Issuance of restricted stock	$ 0	$ 0	0
Issuance of common stock	61,309		61,308
APIC, Share-based Payment Arrangement, ESPP, Increase for Cost Recognition	2,208
Other comprehensive income (loss)	(680)			(680)
Net loss	(17,144)				(17,144)
Ending balance (in shares) at Dec. 31, 2019		26,547,000
Ending balance at Dec. 31, 2019	143,267	$ 8	$ 480,578	1,312	(338,631)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, $0.0001 par value—100,000 shares authorized and 26,547 and 27,861 shares issued and outstanding as of December 31, 2019 and December 31, 2020, respectively	8
Additional paid-in capital	$ 480,578
Exercise of common stock options (in shares)	467,000	467,000
Exercise of common stock options	$ 10,176
Exercise of common stock warrants (in shares)	0	9,000	0
Stock-based compensation	$ 32,872		$ 32,872
Issuance of common stock (in shares)	779,000
Issuance of ESPP (in shares)	474,120
Issuance of common stock warrants	$ 2,837	$ 59	2,837
Other comprehensive income (loss)	(1,504)			(1,504)
Net loss	(55,422)				(55,422)
Stock Issued During Period, Shares, Restricted Stock Award, Gross		154,000
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt	51,416
Adjustments to Additional Paid in Capital, Convertible Debt with Conversion Feature	(26,450)
Ending balance (in shares) at Dec. 31, 2020		27,861,000
Ending balance at Dec. 31, 2020	157,192	$ 8	$ 551,429	$ (192)	$ (394,053)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock, $0.0001 par value—100,000 shares authorized and 26,547 and 27,861 shares issued and outstanding as of December 31, 2019 and December 31, 2020, respectively	8
Additional paid-in capital	$ 551,429

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net loss	$ (55,422)	$ (17,144)	$ (53,042)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Credit loss expense	1,196	1,201	130
Depreciation and amortization	7,826	4,535	3,282
Amortization of financing costs charged to interest expense	312	95	282
Amortization of right-of-use asset	3,766	0	0
Accretion of debt discount and non-cash interest expense	2,486	0	2,326
Stock-based compensation expense	32,396	15,851	26,790
Change in the fair value of warrant liabilities, net	0	0	6,760
Other non-cash expense (income), net	(1,003)	(570)	4,641
Amortization and impairment of deferred FI implementation costs	4,598	2,869	1,618
Settlement of paid-in-kind interest	0	0	(8,353)
Change in operating assets and liabilities:
Accounts receivable	(2,396)	(26,018)	(9,426)
Prepaid expenses and other assets	(65)	(2,224)	(2,275)
Deferred FI implementation costs	0	0	(9,250)
Recovery of deferred FI implementation costs	0	4,625	5,380
Accounts payable	16	(601)	911
Other accrued expenses	(1,238)	6,152	3,255
FI Share liability	(4,499)	14,301	3,742
Customer Incentive liability	4,429	8,385	4,234
Net cash (used in) provided by operating activities	(7,598)	11,457	(18,995)
Investing activities
Acquisition of property and equipment	(5,408)	(8,277)	(5,920)
Acquisition of patents	(76)	(31)	(23)
Capitalized software development costs	(4,633)	(2,712)	(1,399)
Net cash used in investing activities	(10,117)	(11,020)	(7,342)
Financing activities
Proceeds from issuance of debt	0	0	47,435
Principal payments of debt	(23)	(46,698)	(52,581)
Proceeds from issuance of convertible senior notes	223,100	0	0
Purchase of capped calls related to convertible senior notes	(26,450)	0	0
Proceeds from issuance of common stock	10,185	91,216	72,334
Equity issuance costs	0	(196)	(1,949)
Debt issuance costs	(382)	(143)	(48)
Net cash provided by financing activities	206,430	44,179	65,191
Effect of exchange rates on cash, cash equivalents and restricted cash	47	101	(246)
Net increase in cash, cash equivalents and restricted cash	188,762	44,717	38,608
Cash, cash equivalents, and restricted cash — Beginning of period	104,587	59,870	21,262
Cash, cash equivalents, and restricted cash — End of period	293,349	104,587	59,870
Cash and cash equivalents	293,239	104,458	39,623
Restricted cash	110	129	20,247
Supplemental schedule of non-cash investing and financing activities:
Cash paid for interest	63	1,266	9,733
Amounts accrued for property and equipment	242	456	640
Amounts accrued for capitalized software development costs	$ 68	$ 10	$ 0

NATURE OF OPERATIONS	12 Months Ended
NATURE OF OPERATIONS	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF OPERATIONS	NATURE OF OPERATIONS Cardlytics, Inc. (“we,” “our,” “us,” the “Company,” or “Cardlytics”) is a Delaware corporation and was formed on June 26, 2008. We operate an advertising platform within financial institutions’ (“FIs”) digital channels, which include online, mobile, email, and various real-time notifications. Our partnerships with FIs provide us with access to their anonymized purchase data and digital banking customers. By applying advanced analytics to this aggregation of purchase data, we make it actionable, helping marketers identify, reach and influence likely buyers at scale, and measure the true sales impact of their marketing spend. We have strong relationships with leading marketers across a variety of industries, including retail, restaurant, travel and entertainment, telecommunications, subscription services, direct to consumer, and grocery. Using our purchase intelligence presents customers with offers to save money at a time when they are thinking of their finances. We also operate in the U.K. through Cardlytics UK Limited ("Cardlytics UK"), a wholly-owned and operated subsidiary registered as a private limited company in England and Wales, and in India through Cardlytics Services India Private Limited, a wholly-owned and operated subsidiary registered as a private limited company in India. Reverse Stock Split On January 26, 2018, our board of directors approved an amended and restated certificate of incorporation to (1) effect a reverse split on outstanding shares of our common stock and redeemable convertible preferred stock on a one-for-four basis (the “Reverse Stock Split”), (2) modify the threshold for automatic conversion of our preferred stock into shares of our common stock in connection with an initial public offering to eliminate the requirement of gross proceeds to the Company of not less than $70.0 million and (3) authorize us to issue up to 100,000,000 shares of common stock, $0.0001 par value per share and 25,000,000 shares of redeemable convertible preferred stock, $0.0001 par value per share (collectively, the “Charter Amendment”). The authorized shares and par values of our common stock and redeemable convertible preferred stock were not adjusted as a result of the Reverse Stock Split. The Charter Amendment was approved by the Company’s stockholders on January 26, 2018 and became effective upon the filing of the Charter Amendment with the State of Delaware on January 26, 2018. All issued and outstanding common stock and preferred stock and related share and per share amounts contained in these financial statements have been retroactively adjusted to reflect the Reverse Stock Split for all periods presented. Proceeds from Issuance of Common Stock On February 13, 2018, we closed our initial public offering (“IPO”), in which we issued and sold 5,400,000 shares of common stock at a public offering price of $13.00 per share, resulting in gross proceeds of $70.2 million. On February 14, 2018, pursuant to the underwriters’ partial exercise of their over-allotment option to purchase up to an additional 810,000 shares from us, we issued and sold an additional 421,355 shares of our common stock, resulting in additional gross proceeds to us of $5.5 million. In total, we issued 5,821,355 shares of common stock and raised $75.7 million in gross proceeds, or $66.1 million in net proceeds after deducting underwriting discounts and commissions of $5.3 million and offering costs of $4.3 million. Upon the closing of the IPO, all of the outstanding shares of redeemable convertible preferred stock automatically converted into shares of common stock and all warrants to purchase shares of redeemable convertible preferred stock were automatically converted into warrants to purchase shares of common stock. Subsequent to the closing of the IPO, there were no shares of preferred stock or warrants to purchase shares of redeemable convertible preferred stock outstanding. Upon the completion of our IPO, our amended and restated certificate of incorporation authorized us to issue up to 100,000,000 shares of common stock, $0.0001 par value per share, and 10,000,000 shares of preferred stock, $0.0001 par value per share, all of which shares of preferred stock are undesignated. Our board of directors may establish the rights and preferences of the preferred stock from time to time. On September 13, 2019, we closed a public equity offering in which we sold 1,904,154 shares of common stock, which included 404,154 shares sold pursuant to the exercise by the underwriters of an option to purchase additional shares, at a public offering price of $34.00 per share. We received total net proceeds of $61.3 million after deducting underwriting discounts and commissions of $3.2 million and offering costs of $0.2 million. Selling stockholders, including certain of our executive officers and entities affiliated with certain of our directors, sold 1,194,365 shares of common stock in the offering at a public offering price of $34.00. We did not receive any proceeds from the sale of common stock by the selling stockholders. During 2018, 2019 and 2020, we received $2.0 million, $29.7 million and $10.2 million in proceeds from the exercise of options and warrants to purchase shares of common stock. 2020 Convertible Senior Notes In September 2020, we issued convertible senior notes with an aggregate principal amount of $230.0 million bearing an interest rate of 1.00% due in 2025 (the "Notes"). Refer to Note 7—Debt and Financing Arrangements for further details

SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

SIGNIFICANT ACCOUNTING POLICIES

Principles of Consolidation

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.

Use of Estimates

The preparation of financial statements in conformity with generally accepted accounting principles in the United States (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements. Actual results could differ from these estimates. Significant items subject to such estimates and assumptions include revenue recognition, internal-use software development costs, income taxes, stock-based compensation, income tax valuation allowance, contingencies and changes in fair value of our preferred stock warrants and common stock warrants. We base our estimates on historical experience and also on assumptions that we believe are reasonable. Changes in facts or circumstances may cause us to change our assumptions and estimates in future periods and it is possible that actual results could differ from our current or revised future estimates.

Restructuring

During the first quarter of 2020, we began a strategic shift within our organization to increase productivity and optimize performance. This plan has resulted in severance and medical benefits totaling $1.3 million during the year ended December 31, 2020. We recognize these costs when the extent of our actions is determined and the costs can be estimated. These charges are reflected on our consolidated statement of operations for the year ended December 31, 2020, as follows: $1.1 million in sales and marketing expense, $0.1 million in general and administrative expense and $0.1 million in research and development expense. Severance and medical benefits of $0.9 million have been paid to former employees through December 31, 2020.

Foreign Currency

The functional currency of our foreign wholly-owned subsidiaries is the local currency. We translate the financial statements of these subsidiaries into U.S. dollars each reporting period for purposes of consolidation. Assets and liabilities are translated at the period-end currency exchange rates, certain equity accounts are translated at historical exchange rates and income and expense amounts are translated at average currency exchange rates in effect for the period. The effect of these translation adjustments is reported in a separate component of stockholders’ deficit titled accumulated other comprehensive income.

We are also subject to gains and losses from foreign currency denominated transactions and the remeasurement of foreign currency denominated balance sheet accounts, both of which are included in other (expense) income, net in the accompanying consolidated statements of operations. We recorded a foreign currency loss (gain) totaling $1.2 million, $(0.8) million and $(1.6) million in 2018, 2019 and 2020, respectively.

FI Share and Other Third-Party Costs

We generally pay our FI partners a negotiated and fixed percentage of our billings to marketers less any Consumer Incentives that we pay to the FIs’ customers and certain third-party data costs ("FI Share"). FI Share and other third-party costs consist primarily of the FI Share that we pay our FI partners, media and data costs, and deferred FI implementation costs incurred pursuant to our agreements with certain FI partners, any incremental costs due to FIs as part of FI Share commitments, as well as a non-cash expense related to the vesting of warrants issued to an FI partner that accelerated upon the consummation of our IPO. To the extent that we use a specific FI customer’s anonymized purchase data in the delivery of our solutions, we pay the applicable FI partner an FI Share calculated based on the relative contribution of the data provided by the FI partner to the overall delivery of the services.

Delivery Costs

Delivery costs consist primarily of personnel-related costs of our campaign, data operations and production support teams, including salaries, benefits, bonuses and payroll taxes, as well as stock-based compensation expense. Delivery costs also include hosting facility costs, internally developed and purchased or licensed software costs, outsourcing costs and professional services costs.

Impacts of COVID-19 Pandemic

The COVID–19 pandemic resulted in a global slowdown of economic activity that decreased demand for a broad variety of goods and services and consumer discretionary spending, including spending by consumers with our marketers, and such decreased demand is likely to continue. Estimates and assumptions about future events and their effects cannot be determined with certainty and therefore require the exercise of judgment. Actual results could differ from those estimates and any such differences may be material to our financial statements.

Revenue during the second quarter of 2020 was significantly affected by the COVID-19 pandemic and its negative impact on both consumer spending and marketers' ability to spend advertising budgets on our solution. During the third and fourth quarters of 2020, we saw a recovery of both consumer spending as well as the advertising budgets of our clients. Due to continuing uncertainty regarding the severity and duration of the impacts of COVID-19 on the global economy, we will continue to monitor this situation and the potential impacts to our business.

Accounts Receivable

Accounts receivable are carried at the original invoiced amount less an allowance for credit losses (formerly allowance for doubtful accounts), determined based on the probability of future collection. When we become aware of circumstances that may decrease the likelihood of collection, we record a specific allowance against amounts due, which reduces the receivable to the amount that we believe will be collected. For all other accounts receivable, we determine the adequacy of the allowance for credit losses based on historical loss patterns, the number of days that billings are past due and an evaluation of the potential risk of loss associated with specific accounts.

The following table presents changes in the allowance for credit losses (in thousands):


	Year Ended December 31,
	2018		2019		2020
Beginning balance	$	105	$	169	$	255
Credit loss expense	130		1,201		1,196
Write-offs, net of recoveries	(66)		(1,115)		(864)
Ending balance	$	169	$	255	$	587

Unbilled receivables were $0.4 million, $0.6 million and $0.5 million as of December 31, 2018, 2019 and 2020, respectively. An unbilled receivable represents revenue earned and recognized from customer activity that was not billed prior to the end of the reporting period. Unbilled receivables are included in accounts receivable, net on our consolidated balance sheets.

Property and Equipment

Property and equipment are stated at cost. Expenditures for maintenance and repairs are expensed as incurred, while betterments that materially extend the life of an asset are capitalized. The cost of assets sold, retired or otherwise disposed of, and the related accumulated depreciation, are eliminated from the accounts and any resulting gain or loss is recognized.

Depreciation of property and equipment is determined using the straight-line method over the estimated useful lives of the applicable assets, which are as follows:


Computer equipment:						2–3 years
Furniture and fixtures:						5 years
Leasehold improvements:						Lesser of estimated useful life or life of the lease

Intangible Assets

Intangible assets are recorded at cost and consist of costs incurred for software patent applications. As of December 31, 2020, we had four issued patents and are pursuing ten additional patents relating to our software. We received approval for three patents in 2013 and one patent in 2018 and began amortizing the costs of obtaining these patents over the estimated remaining lives of the patents. If a patent application is rejected or if we abandon efforts to obtain a new patent, all deferred patent costs are expensed immediately. Deferred patent costs related to patents for which we have not yet obtained approval totaled $0.3 million and $0.3 million as of December 31, 2019 and 2020, respectively. Based on deferred patent costs as of December 31, 2020, the related amortization expense will be less than $0.1 million in each of the next five years. Intangible assets are as follows (in thousands):


	December 31,
	2019		2020
Deferred patent costs, gross	$	448	$	518
Less accumulated amortization	(59)		(71)
Deferred patent costs, net	$	389	$	447

Internal-Use Software Development Costs

Capitalized software development costs consist of costs incurred in the development of internal-use software, primarily associated with the development and enhancement of our offer management system and offer placement system. We capitalize the costs of software developed or obtained for internal use in accordance with ASC Topic 350-40, Internal Use Software. We begin to capitalize our costs upon completion of the preliminary project stage. We consider the preliminary project stage to be complete and the application development stage to have begun when preliminary development efforts are successfully completed, management has authorized and committed project funding and it is probable that the project will be completed and the software will be used as intended. These costs are amortized on a straight-line basis over the estimated useful life of the related asset, generally estimated to be three years. Costs incurred in the preliminary project stage and post-implementation operation stages are expensed as incurred and recorded in research and development expense on our consolidated statements of operations.

During 2018, 2019 and 2020, we capitalized the implementation of a new billing system as well as development costs for enhancements to our offer management system totaling $1.6 million, $2.6 million and $4.3 million, respectively. During the first quarter of 2020, we redesigned certain elements of this project and wrote off development costs totaling $1.0 million recognized in depreciation and amortization expense on our consolidated statement of operations.

Capitalized software development costs are as follows (in thousands):


	December 31,
	2019		2020
Capitalized software development costs, gross	$	5,537	$	9,230
Less accumulated amortization	(1,722)		(2,931)
Capitalized software development costs, net	$	3,815	$	6,299

Debt Issuance Costs

Costs incurred to obtain loans, other than lines of credit, are recorded as a reduction of the carrying amount of the related liability and amortized over the applicable loans’ life using the effective interest method. Costs incurred to obtain lines of credit are capitalized and included in other long-term assets on our consolidated balance sheets and amortized ratably over the term of the arrangement.

As described in Note 7—Debt and Financing Arrangements, we entered into a 2018 Loan Facility in 2018 and deferred $0.1 million of debt issuance costs associated with obtaining the 2018 Loan Facility and deferred $0.1 million of unamortized debt issuance costs attributed to our 2016 Line of Credit and 2016 Term Loan. We recognized a $0.9 million loss on extinguishment of debt related to the unamortized discount and unamortized debt issuance costs associated with our 2016 Term Loan and 2016 Line of Credit. This expense is included within other (expense) income, net on our consolidated statements of operations and is presented in other non-cash expenses on our consolidated statements of cash flows.

Further, as described in Note 7—Debt and Financing Arrangements, on September 22, 2020, we issued convertible senior notes with an aggregate principal amount of $230.0 million bearing an interest rate of 1.00% due in 2025 (the “Notes”), including the exercise in full of the initial purchasers’ option to purchase up to an additional $30.0 million principal amount of the Notes. The net proceeds from this offering were $222.7 million, after deducting the initial purchasers’ discounts and commissions and the offering expenses payable by us. In accounting for the $7.3 million issuance costs related to the Notes, the allocation of issuance costs incurred between the liability and equity components was based on their relative values.

Amortization of debt issuance costs included in interest expense, net totaled $0.3 million, $0.1 million and $0.3 million in 2018, 2019 and 2020, respectively.

Deferred debt issuance costs related to our lines of credit included in other long-term assets are as follows (in thousands):


	December 31,
	2019		2020
Debt issuance costs, gross	$	388	$	412
Less accumulated amortization	(271)		(377)
Debt issuance costs, net	$	117	$	35

Deferred debt issuance costs related to our Notes included in debt are as follows (in thousands):


	December 31,
	2019		2020
Debt issuance costs, gross	$	—	$	5,596
Less accumulated amortization	—		(217)
Debt issuance costs, net	$	—	$	5,379

Future amortization of debt issuance costs is as follows (in thousands):


Years Ending December 31,	Amortization
2021	$	909
2022	1,006
2023	1,151
2024	1,312
2025	1,036
Total	$	5,414

Deferred Offering Costs

Deferred offering costs consist of incremental costs directly attributable to equity offerings. Deferred offering costs are included in other long-term assets on our consolidated balance sheets. Upon completion of an offering, these amounts are offset against the proceeds of the offering.

Deferred offering costs is as follows (in thousands):


	Year Ended December 31,
	2018		2019		2020
Beginning balance	$	3,144	$	—	$	—
Deferred costs	1,135		196		—
Recognized against offering proceeds	(4,279)		(196)		—
Ending balance	$	—	$	—	$	—

Advertising

We expense advertising costs as incurred. These costs are included in sales and marketing expense on our consolidated statements of operations. Advertising costs include direct marketing costs such as print advertisements, market research, direct mail, public relations and trade show expenses and totaled $0.9 million, $1.4 million and $1.0 million in 2018, 2019 and 2020, respectively.

Stock-Based Compensation

We measure and recognize compensation expense based on the estimated fair value of the award on the grant date. The fair value is recognized as expense over the requisite service period, which is generally the vesting period of the respective award, on a straight-line basis when the only condition to vesting is continued service. We recognize the fair value of awards that contain performance conditions based upon the probability of the performance conditions being met. Expense for awards with performance conditions are estimated and adjusted on a quarterly basis based upon our assessment of the probability that the performance condition will be met. We recognize the fair value of awards that contain market conditions over the derived service period. Forfeitures are accounted for when they occur. Refer to Note 8—Stock-based Compensation for additional information regarding our specific award plans and estimates and assumptions used to determine fair value.

Redeemable Convertible Preferred Stock Warrant Liability

Warrants to purchase shares of our redeemable convertible preferred stock are accounted for as derivative liabilities in accordance with ASC Topic 815, Derivatives and Hedging due to the terms of the warrants and related agreements. We have determined that these warrants do not meet the scope exception of a contract indexed to our stock because of fair value protections contained in agreements governing our redeemable convertible preferred stock as described in Note 10—Redeemable Convertible Preferred Stock. We record preferred stock warrant liabilities on our consolidated balance sheets at their fair value. We record the changes in fair value of such instruments as non-cash gains or losses on our statements of operations. Upon the consummation of our IPO, all of the outstanding warrants to purchase shares of redeemable convertible preferred stock were automatically converted into warrants to purchase shares of common stock. Refer to Note 12—Fair Value Measurements for additional information.

Common Stock Warrant Liability

In connection with the Series G Stock financing, we issued warrants to purchase shares of our common stock that are accounted for as liabilities in accordance with ASC Topic 480, Distinguishing Liabilities From Equity due to the terms of the warrants and related agreements. We record these common stock warrant liabilities on our consolidated balance sheets at their fair value. We record the changes in fair value of such instruments as non-cash gains or losses in our statements of operations. Refer to Note 12—Fair Value Measurements for additional information.

Fair Value of Financial Instruments

When required by GAAP, assets and liabilities are reported at fair value on our consolidated financial statements. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Valuation inputs are arranged in a hierarchy that consists of the following levels:

•Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date.

•Level 2 inputs are inputs other than Level 1 inputs such as quoted prices for similar assets or liabilities; quoted prices in markets with insufficient volume or infrequent transactions (less active markets); or model-derived valuations in which all significant inputs are observable or can be derived principally from or corroborated by observable market data for substantially the full term of the assets or liabilities.

•Level 3 inputs are unobservable inputs for the asset or liability.

Our nonfinancial assets that we recognize or disclose at fair value on our consolidated financial statements on a nonrecurring basis include property and equipment, intangible assets, capitalized software development costs and deferred FI implementation costs. The fair values for these assets are evaluated when events or changes in circumstances indicate the carrying value may not be recoverable. Refer to Note 12—Fair Value Measurements for information regarding the fair value of our financial instruments.

Income Taxes

Income taxes are accounted for using the asset and liability method. Under this method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective income tax bases, and operating loss and tax credit carryforwards. Valuation allowances are provided when we determine that it is more likely than not that all of, or a portion of, deferred tax assets will not be utilized in the future.

Significant judgment is required in determining any valuation allowance recorded against deferred tax assets. In assessing the need for a valuation allowance, we consider all available evidence, including past operating results, estimates of future taxable income and the feasibility of tax planning strategies. In the event that we change our determination as to the amount of deferred tax assets that can be realized, we will adjust our valuation allowance with a corresponding impact to the provision for income taxes in the period in which such determination is made.

Estimates of future taxable income are based on assumptions that are consistent with our plans. Assumptions represent management’s best estimates and involve inherent uncertainties and the application of management’s judgment. If actual amounts differ from our estimates, the amount of our tax expense and liabilities could be materially impacted.

We have recorded a full valuation allowance related to our net deferred tax assets due to the uncertainty of the ultimate realization of the future benefits of those assets.

We recognize the tax effects of an uncertain tax position only if it is more likely than not to be sustained based solely on its technical merits as of the reporting date, and then, only in an amount more likely than not to be sustained upon review by the tax authorities. Where applicable, we classify associated interest and penalties as income tax expense. The total amounts of interest and penalties were not material. We consider many factors when evaluating and estimating our tax positions and tax benefits, which may require periodic adjustments and which may not accurately anticipate actual outcomes.

ACCOUNTING STANDARDS	12 Months Ended
ACCOUNTING STANDARDS	Dec. 31, 2020
Accounting Policies [Abstract]
ACCOUNTING STANDARDS	ACCOUNTING STANDARDS Recently Adopted Accounting Pronouncements In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-02, Leases (Topic 842) to increase the transparency and comparability among organizations as it relates to lease assets and lease liabilities, by requiring lessees to recognize a right-of-use asset and lease liability for all leases with terms of more than 12 months, with exceptions. Effective January 1, 2020, we early adopted this guidance using a modified retrospective approach, which was required for all leases that exist at or commence after the date of the initial application with an option to use certain practical expedients. We have elected to use these practical expedients, which allow us to treat all components of our leases as a single component, not to reassess lease classification or whether an arrangement is or contains a lease and not to reassess its initial accounting for direct lease costs. During the first quarter of 2020, we recorded right-of-use assets of $10.3 million, lease liabilities of $13.5 million and eliminated deferred rent liabilities of $3.2 million. These amounts represent right-of-use assets of $7.4 million, lease liabilities of $10.6 million and deferred rent liabilities of $3.2 million as of the adoption date of ASU 2016-02 and right-of-use assets and lease liabilities of $2.9 million, respectively, for office space entered into during the quarter. The adoption of this guidance did not have a significant impact on our consolidated statements of operations or cash flows. In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which is intended to provide more decision-useful information about expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. ASU 2016-13 revises the impairment model to utilize an expected loss methodology in place of the currently used incurred loss methodology, which will result in more timely recognition of losses on financial instruments, including, but not limited to, available for sale debt securities and accounts receivable. In November 2018, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments - Credit Losses, and in April 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments. These ASUs provide supplemental guidance and clarification to ASU 2016-13 and must be adopted concurrently with the adoption of ASU 2016-13, cumulatively referred to as “Topic 326.” Effective January 1, 2020, we adopted this guidance. The adoption of this guidance did not have a material effect on our consolidated financial statements. On January 1, 2020, we adopted ASU 2015-05, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement, to help entities evaluate the accounting for fees paid by a customer in a cloud computing arrangement (hosting arrangement) by providing guidance for determining when the arrangement includes a software license. The adoption of this guidance did not have a material effect on our consolidated financial statements. On January 1, 2020, we adopted ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement that is a Service Contract, which addresses the accounting for implementation, setup and other upfront costs incurred in a hosting arrangement. The adoption of this guidance did not have a material effect on our consolidated financial statements. On January 1, 2019, we early adopted ASU 2014-09, Revenue from Contracts with Customers (Topic 606), using the modified retrospective method, as permitted under ASU 2014-09. The adoption of ASU 2014-09 did not result in a material change in the timing or amount of revenue recognized, nor did it result in the capitalization of incremental contract costs. Accordingly, there was no cumulative effect adjustment recorded in the consolidated financial statements upon adoption. On January 1, 2019, we adopted ASU 2016-01, Financial Instruments-Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities, which is intended to enhance the reporting model for financial instruments to provide users of financial statements with more decision-useful information. The adoption of this guidance had no impact on our consolidated financial statements. Recently Issued Accounting Pronouncements In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion Options (“Subtopic 470-20”) and Derivatives and Hedging—Contracts in Entity’s Own Equity (“Subtopic 815-40”), which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity's own equity. ASU 2020-06 also improves and amends the related Earnings Per Share guidance for both Subtopics. The ASU is part of the FASB's simplification initiative, which aims to reduce unnecessary complexity in U.S. GAAP. ASU 2020-06 will be effective for annual reporting periods beginning after December 15, 2021. Early adoption is permitted, but not before annual reporting periods beginning after December 15, 2020. We are currently evaluating the impact of the new guidance on our consolidated financial statements.

REVENUE (Notes)

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

REVENUE

We have generated revenue through the sale of two categories of solutions that leverage our intelligence platform: (1) our proprietary native banking channel, the Cardlytics platform, and (2) our Other Platform Solutions. We have generated substantially all of our revenue from sales of the Cardlytics platform since inception.

Our Other Platform Solutions enabled marketers and marketing service providers to leverage the power of purchase intelligence outside the bank channel. We have shifted the majority of our efforts and resources to support the growth of the Cardlytics platform. As a result, we have not and do not expect to generate substantial, if any, revenue from Other Platform Solutions for the foreseeable future.

The Cardlytics Platform

The Cardlytics platform is our proprietary native bank advertising channel that enables marketers to reach consumers through the FIs' trusted and frequently visited digital banking channels. Working with the marketer, we design a campaign that targets customers based on their purchase history. The consumer is offered an incentive to make a purchase from the marketer within a specified period. We use a portion of the fees that we collect from marketers to provide these consumer incentives to our FIs’ customers after they make qualifying purchases ("Consumer Incentives").

The Cardlytics platform is priced predominantly in two ways: (1) Cost per Served Sale (“CPS”), and (2) Cost per Redemption (“CPR”).

•CPS. Our primary pricing model is CPS, which we created to meet the media buying preferences of marketers. We generate revenue by charging a percentage, which we refer to as the CPS Rate, of all purchases from the marketer by consumers (1) who are served marketing and (2) subsequently make a purchase from the marketer during the campaign period, regardless of whether consumers select the marketing and thereby becomes eligible to earn the applicable Consumer Incentive. We set CPS Rates for marketers based on our expectation of the marketer’s return on spend for the relevant campaign. Additionally, we set the amount of the Consumer Incentives payable for each campaign based on our estimation of our ability to drive incremental sales for the marketer. We seek to optimize the level of Consumer Incentives to retain a greater portion of billings. However, if the amount of Consumer Incentives exceeds the amount of billings that we are paid by the applicable marketer we are still responsible for paying the total Consumer Incentive. This has occurred infrequently and has been immaterial in amount for each of the periods presented. In some instances, we may also charge the marketer the Consumer Incentive, in which case the marketer determines the level of Consumer Incentive for the campaign.

•CPR. Under our CPR pricing model, marketers specify and fund the Consumer Incentive and pay us a separate negotiated, fixed marketing fee, which we refer to as the CPR Fee, for each purchase that we generate. We generate revenue if the consumer (1) is served marketing, (2) selects the marketing and thereby becomes eligible to earn the applicable Consumer Incentive and (3) makes a qualifying purchase from the marketer during the campaign period. We set the CPR Fee for marketers based on our estimation of the marketers’ return on spend for the relevant campaign. The CPR Fee is either a percentage of qualifying purchases or a flat amount. In some instances, we may solely charge the marketer the CPR Fee, in which case we determine the level of Consumer Incentive for the campaign.

The following table summarizes revenue by pricing model (in thousands):


	Year Ended December 31,
	2018		2019		2020
Cost per Served Sale	$	101,087	$	143,754	$	131,045
Cost per Redemption	43,389		63,295		53,838
Other	6,208		3,381		2,009
Revenue	$	150,684	$	210,430	$	186,892

Revenue Recognition

Our revenue generated from our platform consist of transaction-based fees made up of a significant volume of low-dollar transactions, sourced from multiple databases. The processing and recording of revenue is highly automated and is based on contractual terms with marketers, FIs, and other parties. Because of the nature of our transaction-based fees, we use automated systems to process and record our revenue transactions.

We determine revenue recognition through the following steps:

•identification of a contract with a customer,

•identification of the performance obligation(s) in the contract,

•determination of the transaction price,

•allocation of the transaction price to the performance obligation(s) in the contract, and

•recognition of revenue when or as the performance obligation(s) are satisfied.

We sell our solutions by entering into agreements directly with marketers or their marketing agencies, generally through the execution of insertion orders. The agreements state the terms of the arrangement, the negotiated fee, payment terms and the fixed period of time of the campaign. We consider a contract to exist when a campaign, which typically lasts 45 days, is published to an FI partner under the terms of an insertion order.

With respect to our Cardlytics platform service, our performance obligation is to offer incentives to FIs' customers to make purchases from the marketer within a specified period. This performance obligation is a series that represents a stand ready obligation to provide a targeted campaign for the marketer to FIs' customers. The Cardlytics platform fees represent variable consideration that is resolved when FIs' customers make qualifying purchases during the marketing campaign term.

Subsequent to a qualifying purchase, the associated fees are generally not subject to refund or adjustment unless the fees from the marketing campaign exceed a contractual maximum (marketer budget). We have not constrained our revenue because adjustments have historically been immaterial and given the short duration of our marketing campaigns, any adjustments are recognized during the period of the marketing campaign. We recognize revenue for the Cardlytics platform fees over time using the right to invoice practical expedient because the amount billed is equal to the value delivered to marketers through qualified purchases by FIs' customers during that period.

Consumer Incentives

We report our revenue on our consolidated statements of operations net of Consumer Incentives. We do not provide the goods or services that are purchased by our FIs’ customers from the marketers to which the Consumer Incentives relate. Accordingly, the marketer is deemed to be the principal in the relationship with the customer and, therefore, the Consumer Incentive is deemed to be a reduction in the purchase price paid by the customer for the marketer’s goods or services. While we are responsible for remitting Consumer Incentives to our FI partners for further payment to their customers, we function solely as an agent of marketers in these arrangements.

We invoice marketers monthly based on the qualifying purchases of FIs' customers as reported by our FI partners during the month. Invoice payment terms, negotiated on a marketer-by-marketer basis, are typically between 30 to 60 days. However, for certain marketing agencies with sequential liability terms, payments are not due to us until such marketing agency has received payment from its marketer client. Accounts receivable is recorded at the amount of gross billings to marketers, net of allowances, for the fees and Consumer Incentives that we are responsible to collect. Our accrued liabilities also include the amount of Consumer Incentives due to FI partners. As a result, accounts receivable and accrued liabilities may appear large in relation to revenue, which is reported on a net basis. During 2018, 2019 and 2020, Consumer Incentives totaled $68.3 million, $105.6 million and $76.5 million, respectively.

FI Share and Other Third-Party Costs

We report our revenue on our consolidated statements of operations gross of FI Share. FI Share costs are included in FI Share and other third-party costs in our consolidated statements of operations, rather than as a reduction of revenue, because we and not our FI partners act as the principal in our arrangements with marketers. We are responsible for the fulfillment and acceptability of the services purchased by marketers. We also have latitude in establishing the price of our services, have discretion in supplier selection and earn variable amounts. FI partners only supply consumer purchase data and digital marketing space and generally have no involvement in the marketing campaigns or contractual relationship with marketers.

Contract Costs

Given the short-term nature of our marketing campaigns, all contract costs are expensed as incurred since the expected period of benefit is less than one year. Costs to fulfill a contract include immaterial costs to set up a campaign that we expense as incurred due to the short-term nature of our marketing campaigns

LEASES

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

LEASES

Effective January 1, 2020, we early adopted ASU 2016-02, Leases (Topic 842). This standard requires us to recognize a right-of-use asset and a lease liability for all leases with an initial term in excess of twelve months. The asset reflects the present value of unpaid fixed lease payments coupled with initial direct costs, prepaid lease payments, and lease incentives. The amount of the lease liability is calculated as the present value of unpaid fixed lease payments. We evaluate each of our lease and service arrangements at inception to determine if the arrangement is, or contains, a lease and the appropriate classification of each identified lease. A lease exists if we obtain substantially all of the economic benefits of and have the right to control the use of an asset for a period of time. Right-of-use assets represent our right to use an underlying asset for the lease term, and lease liabilities represent our obligation to make lease payments arising from the lease agreement. Lease costs are recognized as expense on a straight-line basis over the lease term. We consider a termination or renewal option in the determination of the lease term when it is reasonably certain that we will exercise that option. We adopted ASU 2016-02 using a modified retrospective approach and did not restate comparative periods. We elected to take the package of practical expedients allowing us to not reassess (i) whether any expired or existing contracts are or contain leases, (ii) the lease classification for any expired or existing leases and (iii) initial direct costs for any existing leases. We have elected to account for all components in a contract as part of the single lease component to which they are related. Significant assumptions and judgments in calculating the right-of-use assets and lease liability include the determination of the applicable borrowing rate for each lease. Because our leases generally do not provide a readily determinable implicit interest rate, we use an incremental borrowing rate to measure the lease liability and associated right-of-use asset at the lease commencement date. The incremental borrowing rate used is a fully collateralized rate that considers our credit rating, market conditions and the term of the lease at the lease commencement date.

During the first quarter of 2020, we recorded right-of-use assets of $10.3 million, lease liabilities of $13.5 million and eliminated deferred rent liabilities of $3.2 million. These amounts represent right-of-use assets of $7.4 million, lease liabilities of $10.6 million and deferred rent liabilities of $3.2 million as of the adoption date of ASU 2016-02 and right-of-use assets and lease liabilities of $2.9 million, respectively, for office space entered into during the quarter. As of the adoption date, our office and data center leases have remaining lease terms ranging from one to six years.

During 2020, we recorded additional right-of-use assets and lease liabilities of $1.0 million for data center equipment leases entered into during the year. We also renewed certain data center lease agreements resulting in a lease modification and the recognition of additional right-of-use assets and lease liabilities of $2.2 million.

During 2020, we made cash payments of $4.0 million for operating leases which are included in cash flows (used in) provided by operating activities in our consolidated statement of cash flows.

The following table summarizes activity related to our leases (in thousands):


	Year Ended December 31, 2020
Operating lease expense	$	4,078
Variable lease expense	847
Short-term lease expense	232

The following table presents our weighted average borrowing rate and weighted average lease term:


	December 31, 2020
Weighted average borrowing rate	3.4	%
Weighted average remaining lease term (years)	3.25

The following table summarizes future maturities of lease liabilities as of December 31, 2020 (in thousands):


	Amount

2021	$	5,097
2022	4,681
2023	2,692
2024	1,807
2025	611
Total lease payments	14,888
Imputed interest	789
Total operating lease liabilities	$	14,099

The following table summarizes future payments for operating leases as of December 31, 2019, prior to our adoption of ASU 2016-02 (in thousands):


	Minimum Lease Payments
2020	$	3,040
2021	2,759
2022	2,808
2023	1,847
2024	1,807
Thereafter	611
Total	$	12,872

PROPERTY AND EQUIPMENT

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

PROPERTY AND EQUIPMENT

Significant components of property and equipment are as follows (in thousands):


	December 31,
	2019		2020
Computer equipment	$	21,269	$	27,105
Leasehold improvements	6,960		6,770
Furniture and fixtures	1,557		1,112
Construction in progress	1,125		125
Property and equipment, gross	30,911		35,112
Less accumulated depreciation	(16,621)		(21,247)
Property and equipment, net	$	14,290	$	13,865

Assets acquired under finance leases, included within computer equipment, are as follows (in thousands):


	December 31,
	2019		2020
Finance lease assets, gross	$	1,096	$	557
Less accumulated depreciation	(1,067)		(548)
Finance lease assets, net	$	29	$	9

Depreciation expense was $3.0 million, $4.0 million and $5.6 million in 2018, 2019 and 2020, respectively.

DEBT AND FINANCING ARRANGEMENTS

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

DEBT AND FINANCING ARRANGEMENTS

Our debt consists of the following (in thousands):


	December 31,
	2019		2020


Convertible senior notes, net	$	—	$	174,011
Finance leases	37		13
Total debt	37		174,024
Less current portion of long-term debt	(24)		(13)
Long-term debt, net of current portion	$	13	$	174,011

Accrued interest is included within accrued expenses in our consolidated balance sheet. We had no accrued interest on debt as of December 31, 2019 and $0.6 million of accrued interest as of December 31, 2020.

2020 Convertible Senior Notes

On September 22, 2020, we issued convertible senior notes with an aggregate principal amount of $230.0 million bearing an interest rate of 1.00% due in 2025 (the “Notes”), including the exercise in full of the initial purchasers’ option to purchase up to an additional $30.0 million principal amount of the Notes. The Notes were issued pursuant to an indenture, dated September 22, 2020 (the “Indenture”), between us and U.S. Bank National Association, as trustee.

The Notes are general senior, unsecured obligations and will mature on September 15, 2025, unless earlier converted, redeemed or repurchased. The Notes bear interest at a rate of 1.00% per year, payable semiannually in arrears on March 15 and September 15 of each year, beginning on March 15, 2021. The Notes are convertible at the option of the holders at any time prior to the close of business on the business day immediately preceding June 15, 2025, only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on December 31, 2020 (and only during such calendar quarter), if the last reported sale price of our common stock, for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price for the Notes on each applicable trading day; (2) during the five business day period after any ten consecutive trading day period (the “measurement period”) in which the trading price (as defined in the Indenture) per $1,000 principal amount of the Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of common stock and the conversion rate for the Notes on each such trading day; (3) if we call such Notes for redemption, at any time prior to the close of business on the scheduled trading day immediately preceding the redemption date; or (4) upon the occurrence of specified corporate events as set forth in the Indenture. On or after June 15, 2025 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders of the Notes may convert all or any portion of their Notes at any time, regardless of the foregoing circumstances. Upon conversion, we may satisfy our conversion obligation by paying and/or delivering, as the case may be, cash, shares of common stock or a combination of cash and shares of common stock, at our election, in the manner and subject to the terms and conditions provided in the Indenture. We currently intend to settle the principal amount of the Notes with cash.

The conversion rate for the Notes will initially be 11.7457 shares of common stock per $1,000 principal amount of Notes, which is equivalent to an initial conversion price of approximately $85.14 per share of common stock. The conversion rate for the Notes is subject to adjustment under certain circumstances in accordance with the terms of the Indenture. In addition, following certain corporate events that occur prior to the maturity date of the Notes or if we deliver a notice of redemption in respect of the Notes, we will, in certain circumstances, increase the conversion rate of the Notes for a holder who elects to convert its Notes in connection with such a corporate event or convert its notes called for redemption during the related redemption period (as defined in the Indenture), as the case may be.

We may not redeem the Notes prior to September 20, 2023. We may redeem for cash all or any portion of the Notes, at our option, on or after September 20, 2023 and prior to the 36th scheduled trading day immediately preceding the maturity date, if the last reported sale price of our common stock has been at least 130% of the conversion price for the Notes then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period (including the last trading day of such period) ending on, and including, the trading day immediately preceding the date on which we provide notice of redemption at a redemption price equal to 100% of the principal amount of the Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. No sinking fund is provided for the Notes. If we elect to redeem less than all of the Notes, at least $75.0 million aggregate principal amount of Notes must be outstanding and not subject to redemption as of the relevant redemption notice date.

If we undergo a Fundamental Change (as defined in the Indenture), then, except as set forth in the Indenture, holders may require, subject to certain exceptions, us to repurchase for cash all or any portion of their Notes at a fundamental change repurchase price equal to 100% of the principal amount of the Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date.

The Indenture includes customary covenants and sets forth certain events of default after which the Notes may be declared immediately due and payable and sets forth certain types of bankruptcy or insolvency events of default involving us after which the Notes become automatically due and payable. The following events are considered “events of default” under the Indenture:

•default in any payment of interest on any Note when due and payable and the default continues for a period of 30 days;

•default in the payment of principal of any Note when due and payable at its stated maturity, upon optional redemption, upon any required repurchase, upon declaration of acceleration or otherwise;

•failure by us to comply with our obligation to convert the Notes in accordance with the Indenture upon exercise of a holder’s conversion right, and such failure continues for three business days;

•failure by us to give a fundamental change notice, notice of a make-whole fundamental change or notice of a specified corporate event, in each case when due and such failure continues for one business day;

•failure by us to comply with its obligations in respect of any consolidation, merger or sale of assets;

•failure by us to comply with any of our other agreements in the Notes or the Indenture for 60 days after written notice of such failure from the trustee or the holders of at least 25% in principal amount of the Notes then outstanding;

•default by us or any of our significant subsidiaries (as defined in the Indenture) with respect to any mortgage, agreement or other instrument under which there may be outstanding, or by which there may be secured or evidenced, any indebtedness for money borrowed in excess of $35,000,000 (or its foreign currency equivalent), in the aggregate of us and/or any such significant subsidiary, whether such indebtedness now exists or shall hereafter be created, (i) resulting in such indebtedness becoming or being declared due and payable prior to its stated maturity date or (ii) constituting a failure to pay the principal of any such indebtedness when due and payable (after the expiration of all applicable grace periods) at its stated maturity, upon required repurchase, upon declaration of acceleration or otherwise, and in the cases of clauses (i) and (ii), such acceleration shall not have been rescinded or annulled or such failure to pay or default shall not have been cured or waived, or such indebtedness is not paid or discharged, as the case may be, within 30 days after written notice to us by the trustee or to us and the trustee by holders of at least 25% in aggregate principal amount of the Notes then outstanding in accordance with the Indenture; and

•certain events of bankruptcy, insolvency or reorganization of us or any of our significant subsidiaries.

If certain bankruptcy and insolvency-related events of default with respect to us occur, the principal of, and accrued and unpaid interest on, all of the then outstanding Notes shall automatically become due and payable. If an event of default with respect to the Notes, other than certain bankruptcy and insolvency-related events of default with respect to us, occurs and is continuing, the trustee by notice to us or the holders of at least 25% in principal amount of the outstanding Notes by notice to us and the trustee, may, and the trustee at the request of such holders shall, declare the principal of, and accrued and unpaid interest on, all of the then-outstanding Notes to be due and payable. Notwithstanding the foregoing, the Indenture provides that, to the extent we so elect, the sole remedy for an event of default relating to certain failures by us to comply with certain reporting covenants in the Indenture will, for the first 365 days after the occurrence of such event of default, consist exclusively of the right to receive additional interest on the Notes at a rate equal to 0.25% per annum of the principal amount of the Notes outstanding for each day during the first 180 days after the occurrence of such an event of default and 0.50% per annum of the principal amount of the Notes outstanding from the 181st day to, and including, the 365th day following the occurrence of such event of default, as long as such event of default is continuing (in addition to any additional interest that may accrue as a result of a registration default (as set forth in the Indenture).

The Indenture provides that we shall not consolidate with or merge with or into, or sell, convey, transfer or lease all or substantially all of the consolidated properties and assets of our subsidiaries, taken as a whole, to, another person (other than any such sale, conveyance, transfer or lease to one or more of our direct or indirect wholly owned subsidiaries), unless: (i) the resulting, surviving or transferee person (if not us) is a corporation organized and existing under the laws of the United States of America, any State thereof or the District of Columbia, and such corporation (if not us) expressly assumes by supplemental indenture all of our obligations under the Notes and the Indenture; and (ii) immediately after giving effect to such transaction, no default or event of default has occurred and is continuing under the Indenture.

The net proceeds from this offering were $222.7 million, after deducting the initial purchasers’ discounts and commissions and the offering expenses payable by us. We used $26.5 million of the net proceeds to pay the cost of the capped call transactions described below.

The Notes are accounted for in accordance with FASB ASC Subtopic 470-20, Debt with Conversion and Other Options. Pursuant to ASC Subtopic 470-20, issuers of certain convertible debt instruments, such as the Notes, that have a net settlement feature and may be settled wholly or partially in cash upon conversion are required to separately account for the liability (debt) and equity (conversion option) components of the instrument. The carrying amount of the liability component of the instrument was computed using a discount rate of 6.50%, which was determined by estimating the fair value of a similar liability without the conversion option using Level 3 inputs. The amount of the equity component is then calculated by deducting the fair value of the liability component from the principal amount of the instrument. The difference between the principal amount and the liability component represents a debt discount that is amortized to interest expense over the respective term of the Notes using the effective interest rate method. The equity component is recorded in Additional Paid-in Capital and is not remeasured as long as it continues to meet the conditions for equity classification. In accounting for the issuance costs related to the Notes, the allocation of issuance costs incurred between the liability and equity components was based on their relative values.

The net carrying amount of the liability component of the Notes is as follows (in thousands):


	December 31, 2020
Principal	$	230,000
Minus: Unamortized debt discount	(50,610)
Minus: Unamortized issuance costs	(5,379)
Net carrying amount of the liability component	$	174,011

The net carrying amount of the equity component of the Notes is as follows (in thousands):


	December 31, 2020
Proceeds allocated to the conversion options (debt discount)	$	53,096
Minus: Issuance costs	(1,680)
Net carrying amount of the equity component	$	51,416

Interest expense recognized related to the Notes is as follows (in thousands):


	Year Ended December 31, 2020
Contractual interest expense (due in cash)	$	626
Amortization of debt discount	2,486
Amortization of debt issuance costs	217
Total interest expense related to the Notes	$	3,329

Capped Call Transactions

In connection with the issuance of the Notes, we entered into privately negotiated capped call transactions (the "Capped Calls") with an affiliate of one of the initial Note purchasers and certain other financial institutions. The Capped Calls are intended to reduce potential dilution to our common stock upon any conversion of Notes and/or offset any cash payments we are required to make in excess of the principal amount of converted Notes, as the case may be. The Capped Calls are recorded in stockholders' equity and are not accounted for as derivatives. The cost of $26.5 million incurred to purchase the Capped Calls was recorded as a reduction to additional paid-in capital in the accompanying consolidated balance sheet.

The Capped Calls each have an initial strike price of $85.14 per share, subject to certain adjustments, which corresponds to the initial conversion price of the Notes. The Capped Calls have an initial cap price of $128.51 per share, subject to certain adjustments.

2018 Loan Facility

On May 21, 2018, we entered into a Loan and Security Agreement with Pacific Western Bank (the “Lender”) consisting of a $30.0 million asset–based revolving line of credit ("2018 Line of Credit") and a $20.0 million term loan ("2018 Term Loan") (collectively, the “2018 Loan Facility”). We used the entire $20.0 million in proceeds from the 2018 Term Loan and an advance of $27.4 million under the 2018 Line of Credit to repay all outstanding obligations under our prior line of credit and term loan.

On May 14, 2019, we amended our 2018 Loan Facility to increase the capacity of our Line of Credit, from $30.0 million to $40.0 million, and decrease the capacity of our 2018 Term Loan from $20.0 million to $10.0 million. This amendment also extended the maturity date of the 2018 Loan Facility from May 21, 2020 to May 14, 2021. We repaid $10.0 million of the principal balance of the 2018 Term Loan upon the execution of the amendment in May 2019 and repaid the remaining $10.0 million principal balance in September 2019.

On September 17, 2020, we amended our 2018 Loan Facility to allow for the issuance of the Notes. On December 30, 2020, we amended our 2018 Loan Facility to increase the capacity of our Line of Credit, from $40.0 million to $50.0 million. This amendment also extended the maturity date of the 2018 Loan Facility from May 14, 2021 to December 31, 2022. As of December 31, 2020, we had $50.0 million of unused borrowings available under our 2018 Line of Credit.

Prior to the December 2020 amendment, the 2018 Loan Facility contained moving trailing 12-month billing covenants, which ranged from $210.0 million to $255.0 million, during the term of the facility. The former terms of the 2018 Loan Facility also required us to maintain a total cash balance plus liquidity under the 2018 Line of Credit of not less than $5.0 million. Effective with the December 2020 amendment, the former billings and liquidity covenants were removed and were replaced with a requirement to maintain a cash to funded senior debt ratio under the 2018 Line of Credit of 1.25:1.00.

Under the 2018 Loan Facility relating to the 2018 Line of Credit, we are able to borrow up to the lesser of $50.0 million or 85% of the amount of our eligible accounts receivable. Interest on advances under the 2018 Line of Credit bears an interest rate equal to the prime rate minus 0.50%, or 2.75% as of December 31, 2020. In addition, we are required to pay an unused line fee of 0.15% per annum on the average daily unused amount of the $50.0 million revolving commitment. Interest accrued on the 2018 Term Loan at an annual rate of interest equal to the prime rate minus 2.75%, or 2.00% at the date of repayment in September 2019.

The 2018 Loan Facility includes customary representations, warranties and covenants (affirmative and negative), including restrictive covenants that prohibits mergers, acquisitions and dispositions of assets, incurrence of indebtedness and encumbrances on our assets and the payment or declaration of dividends; in each case subject to specified exceptions.

The 2018 Loan Facility also includes standard events of default, including in the event of a material adverse change. Upon the occurrence of an event of default, the lender may declare all outstanding obligations immediately due and payable and take such other actions as are set forth in the 2018 Loan Facility and increase the interest rate otherwise applicable to advances under the 2018 Line of Credit by an additional 3.00%. All of our obligations under the 2018 Loan Facility are secured by a first priority lien on substantially all of our assets. The 2018 Loan Facility does not include any prepayment penalties.

We believe we were in compliance with all financial covenants as of December 31, 2020.

2016 Line of Credit

In September 2016, we entered into a $50.0 million loan and security agreement ("2016 Line of Credit") maturing on March 14, 2019. The 2016 Line of Credit facility was repaid and terminated in May 2018 in connection with obtaining our 2018 Loan Facility. We recognized a $0.1 million loss on extinguishment of debt related to the unamortized debt issuance costs. This expense is included within other income (expense), net in our consolidated statements of operations and is presented in other non-cash expenses on our consolidated statement of statement of cash flows.

2016 Term Loan

In July 2016, we entered into a $24.0 million credit agreement ("2016 Term Loan") maturing on July 21, 2019. The 2016 Term Loan was repaid and terminated in May 2018 in connection with obtaining our 2018 Loan Facility. We recognized a $0.8 million loss on extinguishment of debt related to the unamortized discount and unamortized debt issuance costs. This expense is included within other income (expense), net in our consolidated statements of operations and is presented in other non-cash expenses on our consolidated statement of statement of cash flows.

Future Payments

Aggregate future payments of principal due upon maturity are as follows (in thousands):


Years Ending December 31,	Finance leases		Convertible Senior Notes
2021	$	13	$	—
2022	—		—
2023	—		—
2024	—		—
2025	—		230,000



Total debt	$	13	$	230,000

STOCK-BASED COMPENSATION

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

STOCK-BASED COMPENSATION

In January 2018, our board of directors and stockholders approved an increase in the total number of shares of common stock issuable under our 2008 Stock Plan ("2008 Plan") to 4,020,000 shares. Our board of directors has adopted and our stockholders have approved our 2018 Equity Incentive Plan ("2018 Plan"). Our 2018 Plan became effective on February 8, 2018, the date our registration statement in connection with our IPO was declared effective. We do not expect to grant any additional awards under the 2008 Plan. Any awards granted under the 2008 Plan will remain subject to the terms of our 2008 Plan and applicable award agreements.

Initially, the aggregate number of shares of our common stock that may be issued pursuant to stock awards under the 2018 Plan was the sum of (i) 1,875,000 shares plus (ii) 61,247 shares reserved, and remaining available for issuance, under our 2008 Plan at the time our 2018 Plan became effective and (iii) the number of shares subject to stock options or other stock awards granted under our 2008 Plan that would have otherwise returned to our 2008 Plan (such as upon the expiration or termination of a stock award prior to vesting). As of December 31, 2020, there were 1,222,316 shares of our common stock reserved for issuance under our 2018 Plan. The number of shares of our common stock reserved for issuance under our 2018 Plan will automatically increase on January 1 of each year, beginning on January 1, 2019 and continuing through and including January 1, 2028, by 5% of the total number of shares of our capital stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares determined by our board of directors. Accordingly, the number of shares of our common stock reserved for issuance under our 2018 Plan increased by 1,393,040 shares on January 1, 2021.

The 2018 Plan provides for the grant of stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance-based stock awards and other forms of equity compensation, which are collectively referred to as stock awards. Additionally, the 2018 Plan provides for the grant of performance cash awards.

The following table summarizes the allocation of stock-based compensation on the consolidated statements of operations (in thousands):


	Year Ended December 31,
	2018		2019		2020
Delivery costs	$	633	$	711	$	1,181
Sales and marketing expense	9,358		4,248		9,857
Research and development expense	4,087		1,619		4,713
General and administration expense	12,712		9,273		16,645
Total stock-based compensation expense	$	26,790	$	15,851	$	32,396

During 2018, 2019 and 2020, we capitalized less than $0.1 million, less than $0.1 million and $0.5 million, respectively, of stock-based compensation expense for software development.

Common Stock Options

The term of each option to purchase shares of our common stock pursuant to the Stock Plan is set by our board of directors or a committee thereof. Option awards are generally granted with an exercise price not less than the fair value per share of our common stock at the grant date. Option awards generally vest over four years and expire 10 years following the date of grant.

A summary of common stock option activity is as follows (in thousands, except per share amounts):


	Shares	Weighted-Average Exercise Price Per Share		Weighted Average Contractual Life (in years)	Aggregate Intrinsic Value(1) (in thousands)
Outstanding - December 31, 2017	2,514	$	18.42
Granted	29	24.24
Exercised	(357)	6.25
Forfeited	(197)	24.10
Cancelled	(215)	16.60
Outstanding - December 31, 2018	1,774	$	20.55
Granted	39	20.64
Exercised	(716)	16.84
Forfeited	(31)	23.95
Cancelled	(66)	22.37
Outstanding - December 31, 2019	1,000	$	22.99
Granted	—	—
Exercised	(467)	21.78			$	29,523
Forfeited	(19)	27.83
Cancelled	(1)	21.89
Outstanding - December 31, 2020	513	$	23.91	5.67	$	61,009
Exercisable - December 31, 2020	480	$	23.72	5.62	$	57,126

(1)For options exercised during the year, the aggregate intrinsic value represents the total pre-tax intrinsic value received by option holders based on the closing price of our common stock as reported on the Nasdaq Global Market on the exercise date. For options outstanding and exercisable at December 31, 2020, the aggregate intrinsic value represents the total pre-tax intrinsic value based on the $142.77 closing price of our common stock as reported on the Nasdaq Global Market on December 31, 2020 that would have been received by option holders had all in-the-money options been exercised on that date.

The total fair value of options vested during 2018, 2019 and 2020 was approximately $6.0 million, $4.8 million and $2.3 million respectively. As of December 31, 2020, $0.3 million of unrecognized compensation expense related to unvested options will be recognized over a weighted-average period of 0.3 years. All stock option awards outstanding as of December 31, 2020 are expected to vest.

Restricted Stock Units

We grant restricted stock units ("RSUs") to employees and our non-employee directors. The following table summarizes changes in RSUs, inclusive of performance-based RSUs:


	Shares (in thousands)	Weighted-Average Grant Date Fair Value Per Share		Weighted-Average Remaining Contractual Term (in years)	Unamortized Compensation Costs (in thousands)
Unvested - December 31, 2017	—	$	—
Granted	1,309	20.58
Vested	(850)	21.93
Forfeited/canceled	(78)	17.97
Unvested - December 31, 2018	381	$	18.11
Granted	1,978	17.78
Vested	(486)	14.97
Forfeited/canceled	(132)	18.92
Unvested - December 31, 2019	1,741	$	18.55
Granted	1,758	43.07
Vested	(779)	28.56
Forfeited	(286)	23.34
Unvested - December 31,2020	2,434	$	32.49	2.80	$	61,630

Service-based Restricted Stock Units

During 2018, we granted 434,377 RSUs to our employees and non-employee directors, which have annual vesting periods ranging from one to four years. As of December 31, 2018, there was approximately $4.5 million of unrecognized compensation expense related to RSUs, which is expected to be recognized over a weighted-average period of 2.4 years.

During 2019, we granted 725,832 RSUs to employees and our non-employee directors, which have annual vesting periods ranging from one to four years. As of December 31, 2019, there was approximately $20.4 million of unrecognized compensation expense related to RSUs, which is expected to be recognized over a weighted-average period of 3.1 years.

During 2020, we granted 1,233,617 RSUs to employees, executives, and our non-employee directors, which have annual vesting periods ranging from one to four years. During 2020, we granted 47,690 immediately vesting RSUs to employees in lieu of cash-based incentive compensation. As of December 31, 2020, there was approximately $61.6 million of unrecognized compensation expense related to RSUs, which is expected to be recognized over a weighted-average period of 2.8 years. The aggregate intrinsic value based on the $142.77 closing price of our common stock as reported on the Nasdaq Global Market on December 31, 2020 of unvested RSUs is $347.5 million as of December 31, 2020.

Subsequent to December 31, 2020, we granted 52,322 RSUs to employees, which have annual vesting periods ranging from one to four years. The unamortized stock-based compensation expense related to these RSUs is approximately $6.4 million.

Performance-based Restricted Stock Units

During 2018, we granted two separate tranches of performance-based RSUs ("2018 PSUs"), each to receive 437,500 shares of common stock, to executives. The vesting of the 875,000 2018 PSUs was contingent upon the completion of our IPO and includes other performance-based conditions. The performance condition in the first tranche was to be satisfied when we attained 70.0 million of FI monthly active users ("FI MAUs") within three years of the grant date. The performance condition in the second tranche was to be satisfied when we attained 85.0 million of average FI MAUs within five years of the grant date. FI MAUs is a performance metric defined within "Management's Discussion and Analysis of Financial Condition and Results of Operations." We recognize stock compensation for these 2018 PSUs based upon the expected timing of the achievement of these FI MAU targets. During 2018, 25,000 of the 2018 PSUs were forfeited prior to the FI MAU targets being reached. During 2018, both average FI MAU targets were reached, resulting in the vesting of both tranches of the 2018 PSUs and the issuance of 850,000 shares of our common stock to fully settle the 2018 PSUs. During 2018, we recognized $18.6 million of stock-based compensation expense related to these awards.

During 2019, we granted 1,252,500 performance-based RSUs (“2019 PSUs”). The 2019 PSUs are composed of four equal tranches, each of which have an independent performance-based vesting condition. The vesting criteria for the four tranches are as follows:

•a minimum growth rate in adjusted contribution over a trailing 12-month period,

•a minimum number of advertisers that are billed above a specified amount over a trailing 12-month period,

•a minimum cumulative adjusted EBITDA target over a trailing 12-month period, and

•a minimum trailing 30-day average closing price of our common stock.

The vesting conditions of each of the four tranches must be achieved within four years of the grant date. Upon a vesting event, 50% of the related tranche vests immediately, 25% of the related tranche vests six months after the achievement date and 25% of the related tranche vests 12 months after the achievement date. Adjusted EBITDA and adjusted contribution are performance metrics defined within Item 2. "Management's Discussion and Analysis of Financial Condition and Results of Operations." In August and November 2019, the compensation committee of our board of directors certified that the target minimum trailing 30-day average closing price of our common stock and target minimum cumulative adjusted EBITDA over a trailing 12-month period, respectively, were achieved resulting in the immediate vesting of 50% of the related PSU tranches. In February 2020, 25% of the 30-day average closing price of our common stock PSU tranche vested upon the six-month anniversary of the tranche's achievement date and the remaining 25% of the tranche vested in August 2020 upon the twelve-month anniversary of the tranche's achievement date. In May 2020, 25% of the adjusted EBITDA tranche vested upon the six-month anniversary of the tranche's achievement date, and the remaining 25% of the tranche vested in November 2020 upon the twelve-month anniversary of the tranche's achievement date.

In April 2020, we granted 476,608 performance-based restricted stock units ("2020 PSUs"), of which 443,276 units have a performance-based vesting condition based on a minimum average revenue per user ("ARPU") target over a trailing 12-month period and 33,332 units have the same performance-based vesting conditions as those that remain unmet under the 2019 PSUs described above. ARPU is a performance metric defined within Item 2. "Management's Discussion and Analysis of Financial Condition and Results of Operations." The ARPU vesting condition must be achieved within four years of the grant date. Upon the vesting event, 50% of the award vests immediately, 25% of the award vests six months after achievement date and 25% of the award vests 12 months after the achievement date.

Restricted Securities Units

During 2016, we granted $1.0 million of restricted securities units to certain executives in lieu of cash bonuses. Upon issuance, the restricted securities units were indexed to the 2016 convertible promissory notes. As a result of the Series G Stock financing in 2017, the restricted securities units became indexed to our Series G’ Stock upon conversion of the 2016 convertible promissory notes. Upon the consummation of our IPO in February 2018, the restricted securities units became indexed to our common stock.

Vesting requirements included both a service-based condition and a performance-based condition. The service-based condition required each recipient to remain employed until the earlier of i) the date 6 months from the restricted securities unit grant date, ii) the date of a qualified liquidity event, or iii) date of termination without cause. The performance-based condition required a sale of the Company or IPO event within a fixed period of time not more than 5 years from the restricted securities units grant date. The restricted securities units were considered liability classified awards, but due to the performance condition relating to sale of the Company or IPO, no compensation cost was recognized until one of these events occurred. These units vested upon the consummation of our IPO in February 2018, resulting in a non-cash expense of $0.5 million, and were settled upon the delivery of 37,406 shares of our common stock in August 2018.

Employee Stock Purchase Plan

Our board of directors adopted and our stockholders have approved our 2018 Employee Stock Purchase Plan ("2018 ESPP"). Our 2018 ESPP became effective on February 8, 2018, the date our registration statement in connection with our IPO was declared effective and enables eligible employees to purchase shares of our common stock at a discount. Purchases will be accomplished through participation in discrete offering periods. On each purchase date, eligible employees will purchase our common stock at a price per share equal to 85% of the lesser of the fair market value of our common stock on the first trading day of the offering period or the date of purchase. During 2018, 2019 and 2020, a total of 177,238, 154,601 and 59,173 shares of common stock were purchased by employees under the 2018 ESPP, respectively.

As of December 31, 2020, 474,120 shares of common stock were reserved for issuance pursuant to our 2018 ESPP. Additionally, the number of shares of our common stock reserved for issuance under our 2018 ESPP will automatically increase on January 1 of each year, beginning on January 1, 2019 and continuing through and including January 1, 2026, by the lesser of (i) 1% of the total number of shares of our common stock outstanding on December 31 of the preceding calendar year, (ii) 500,000 shares of our common stock or (iii) such lesser number of shares of common stock as determined by our board of directors. Accordingly, the number of shares of our common stock reserved for issuance under our 2018 ESPP increased by 278,608 shares on January 1, 2021. Shares subject to purchase rights granted under our 2018 ESPP that terminate without having been issued in full will not reduce the number of shares available for issuance under our 2018 ESPP.

INCOME TAXES

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

INCOME TAXES

Domestic and foreign components of loss before income taxes are as follows (in thousands):


	Year Ended December 31,
	2018		2019		2020
Domestic	$	(48,897)	$	(13,464)	$	(42,613)
Foreign	(4,145)		(3,680)		(12,809)
Loss before income taxes	$	(53,042)	$	(17,144)	$	(55,422)

The significant components of income tax (expense) benefit are as follows (in thousands):


	Year Ended December 31,
	2018		2019		2020
Current:
Federal	$	—	$	—	$	—
State	—		—		—
Foreign (1)	—		—		—
Total current	—		—		—
Deferred:
Federal	6,896		1,326		23,062
State	1,264		622		3,744
Foreign	916		222		1,713
Change in uncertain tax positions	(105)		598		(117)
Change in valuation allowance	(8,971)		(2,768)		(28,402)
Total deferred	—		—		—
Income tax benefit	$	—	$	—	$	—

(1)The current income tax (expense) during 2019 and 2020 excludes Indian income tax expense of less than $0.1 million and $0.3 million, respectively.

The following table summarizes the significant differences between the U.S. federal statutory tax rate and our effective tax rate:


	Year Ended December 31,
	2018		2019		2020
Tax benefit at federal statutory rate	21.00	%	21.00	%	21.00	%
State income taxes, net of federal benefit	1.91	%	—	%	—	%
Change in federal and state statutory rate	0.03	%	0.34	%	0.35	%
Foreign rate differential	(0.06)	%	(0.20)	%	(0.62)	%
Other adjustments	(5.97)	%	(5.18)	%	7.36	%
Valuation allowance	(16.91)	%	(16.18)	%	(28.57)	%
Income tax benefit	—	%	(0.22)	%	(0.48)	%

The significant components of deferred income taxes are as follows (in thousands):


	December 31,
	2019		2020
Net operating loss carry-forwards	$	64,348	$	92,387
Allowance for credit losses	28		94
Depreciation and amortization	(1,321)		(13,601)
Stock-based compensation	2,727		3,769

Deferred costs	2,275		1,462
IRC Section 163(j) interest expense limitation	436		89
Other tax credit carry-forward	1,419		1,771
Other temporary differences	319		20
Valuation allowance	(70,231)		(85,991)
Net long-term deferred tax asset	$	—	$	—

On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) was signed into law. Key provisions of the CARES Act include one-time payments to individuals, strengthened unemployment insurance, additional health-care funding, loans and grants to certain businesses, and temporary amendments to the Internal Revenue Code. The corporate income tax provisions of the CARES Act include allowing the carryback of NOLs generated in recent tax years, temporary removal of the 80% NOL usage limitation put in place under the Tax Cuts and Jobs Act ("TCJA"), temporary favorable adjustments to the business interest expense limitation calculated under Sec. 163(j), and the acceleration of refundable AMT credits.

We believe that the corporate income tax provisions of the CARES Act will not have a materially beneficial impact on the Company. Due to the Company’s history of losses, there is no potential for the carryback of NOLs. The temporary removal of the 80% income limitation on NOL usage has no impact as the Company generated a taxable loss for 2020 and has substantial NOLs generated in years prior to the enactment of the TCJA not subject to this 80% limitation. The changes to Sec. 163(j) are not expected to have a beneficial impact as the Company’s interest expense is limited under Sec. 163(j) due to taxable losses rather than the 30% ATI limit enacted under the TCJA. The Company did take advantage of payroll tax deferrals under the CARES Act and as a result has established a $0.8 million deferred tax asset for nondeductible payroll tax accruals that are being deferred to the December 31, 2021 and December 31, 2022 payment dates.

We have generated historical net losses and recorded a full valuation allowance against our net deferred tax assets. We expect to maintain a full valuation allowance in the near term. Realization of any of our net deferred tax assets depends upon future earnings, the timing and amount of which are uncertain.

The following table presents changes in our valuation allowance (in thousands):


	Year Ended December 31,
	2018		2019		2020
Beginning balance	$	(58,649)	$	(67,463)	$	(70,231)
Allowance for domestic and foreign net operating loss carry-forwards	(9,863)		(3,598)		(26,277)
Rate change on domestic net operating loss carry-forwards	(17)		(32)		(82)
Change in foreign currency	157		—		—
Convertible debt additional paid-in capital tax adjustment - valuation allowance impact	—		—		12,642
Other changes	909		862		(2,043)
Ending balance	$	(67,463)	$	(70,231)	$	(85,991)

As of December 31, 2019 and 2020 we have $266.8 million and $371.2 million, respectively, of gross U.S. federal net operating loss carry forwards that will begin to expire in the 2028 tax year. Additionally, we have $98.4 million and $155.8 million of gross state net operating loss carry-forwards as of December 31, 2019 and 2020, respectively that will expire between the 2021 and 2040 tax years for states that do not have indefinite carry-forward periods for net operating losses generated in recent years.

Ownership changes, as defined by IRC Section 382, may limit the amount of net operating losses that a company may utilize to offset future taxable income and taxes payable. Pursuant to IRC Section 382, an ownership change occurs when the stock ownership of 5% stockholders increases by more than 50% over a testing period of three years. We have experienced ownership changes in the past, and it is possible that we have undergone ownership changes subsequent to December 5, 2018, the date of our most recent evaluation, or that we may undergo such a change in the future. Any such ownership change may limit our ability to utilize net operating losses.

Our results during 2018, 2019 and 2020 reflect state tax credits related to hiring and research activities that are utilized through the reduction of state payroll tax withholdings totaling $0.7 million, $1.3 million and $1.4 million, respectively.

As of December 31, 2019 and 2020, Cardlytics UK had gross net operating losses of $12.1 million and $25.7 million, respectively. Foreign net operating loss carry-forwards expire according to the rules of each country. In the U.K., there is an indefinite carry-forward period. As of December 31, 2020, Cardlytics UK held cash and cash equivalents of $3.9 million. While our investment in Cardlytics UK is not considered to be permanently invested, we do not plan to repatriate these funds. Further, although the tax basis of our investment in Cardlytics UK exceeds its book basis, we have not recorded a deferred tax asset since we do not believe that a reversal of this temporary difference will occur in the foreseeable future.

The following table summarizes the activity related to our gross unrecognized tax benefits that would affect our effective tax rate, if recognized (in thousands):


	Year Ended December 31,
	2018		2019		2020
Beginning balance	$	678	$	783	$	185
Increase related to current year tax position	105		(598)		117
Ending balance	$	783	$	185	$	302

All such positions, if recognized, would impact our effective tax rate. We do not currently anticipate any of our positions to change significantly in the next 12 months. Our tax filings from inception remain subject to income tax examinations.

REDEEMABLE CONVERTIBLE PREFERRED STOCK

12 Months Ended

Dec. 31, 2020

Temporary Equity Disclosure [Abstract]

REDEEMABLE CONVERTIBLE PREFERRED STOCK

Upon the consummation of our IPO in 2018, all of the outstanding shares of redeemable convertible preferred stock were automatically converted into shares of common stock. Refer to Note 1—Nature of Operations for additional information regarding our IPO.

A summary of the change in carrying amount of the outstanding redeemable convertible preferred stock is as follows (in thousands):


	Series G’ Stock			Series G Stock
	Shares	Amount		Shares	Amount
Balance — December 31, 2017	1,296	$	44,672	346	$	5,110
Accretion of redeemable convertible preferred stock	—	—		—	108
Conversion of preferred stock to common stock	(1,296)	(44,672)		(346)	(5,218)
Balance — December 31, 2018	—	$	—	—	$	—


	Series F-R Stock			Series E-R Stock			Series D-R Stock
	Shares	Amount		Shares	Amount		Shares	Amount
Balance — December 31, 2017	1,199	58,449		795	$	29,972	1,396	$	32,728
Accretion of redeemable convertible preferred stock	—	38		—	1		—	7
Conversion of preferred stock to common stock	(1,199)	(58,487)		(795)	(29,973)		(1,396)	(32,735)
Balance — December 31, 2018	—	$	—	—	$	—	—	$	—


	Series C-R Stock			Series B-R Stock			Series A-R Stock
	Shares	Amount		Shares	Amount		Shares	Amount
Balance — December 31, 2017	1,508	$	18,366	2,247	$	5,288	1,857	$	1,852
Accretion of redeemable convertible preferred stock	—	3		—	—		—	—
Conversion of preferred stock to common stock	(1,508)	(18,369)		(2,247)	(5,288)		(1,857)	(1,852)
Balance — December 31, 2018	—	$	—	—	$	—	—	$	—

Common Stock Warrants Issued in Connection with the Series G Stock Financing

In connection with the Series G Stock financing in May 2017, we issued warrants to purchase an aggregate number of shares of common stock equal to the product obtained by multiplying 346,334 by a fraction, the numerator of which is the difference between $68.9516 and the volume weighted average closing price of our common stock over the 30 trading days (or such lesser number of days as our common stock has been traded on the Nasdaq Global Market) prior to the date on which such warrants vest and become exercisable and the denominator of which is such volume weighted average closing price, which warrants vested and became exercisable on August 8, 2018, which was 180 days following the date of our IPO, at an exercise price of $0.0004 per share. In August 2018, we issued warrants to purchase 792,434 shares of common stock at an exercise price of $0.0004 per share to the cash investors of our Series G financing, pursuant to our Series G stock purchase agreement. The warrants had a valuation of $15.3 million upon issuance and were immediately exercised. Refer to Note 12—Fair Value Measurements for additional information regarding the valuation of the warrants issued in connection with the Series G Stock financing.

Redemption

At any time on or after May 4, 2022, upon written request of the holders of not less than 66 2/3% of the shares of redeemable convertible preferred stock then-outstanding, voting together as a single class on an as-converted to common stock basis, we were required to redeem all outstanding shares of redeemable convertible preferred stock in eight quarterly installments. The Series A-R Stock, Series B-R Stock, Series C-R Stock, Series D-R Stock, Series E-R Stock, Series F-R Stock, Series G Stock and Series G’ Stock were redeemable at prices equal to $1.00, $2.3567, $12.2686, $23.64, $37.7344, $58.40, $34.4758 and $34.4758 per share, plus any declared or accumulated but unpaid dividends, respectively.

To the extent that we had insufficient funds to redeem all outstanding shares of redeemable convertible preferred stock, we were required to first redeem shares of Series G Stock and Series G’ Stock, then shares of Series F-R Stock, then shares of Series E-R Stock, then shares of Series D-R Stock, then shares of Series C-R Stock and then shares of Series B-R Stock and Series A-R Stock pari passu, in each case on a pro rata basis among the holders thereof.

The redeemable convertible preferred stock carrying amount was increased by periodic accretions, using the interest method, so that the carrying amount would equal the redemption amount at May 4, 2022. Accretion was recorded through a charge against additional paid-in capital.

Liquidation

Upon us (i) selling or otherwise disposing of all or substantially all of our property or business or merging with or into or consolidation with any other corporation, limited liability company or other entity, (ii) a majority of the voting power of our outstanding capital stock being transferred or disposed of as a result of a transaction or series of related transactions that are not issuances of capital stock by us primarily for the purposes of raising equity capital or (iii) any dissolution or winding-up of our business, the holders of Series A-R Stock, Series B-R Stock, Series C-R Stock, Series D-R Stock, Series E-R Stock, Series F-R Stock, Series G Stock and Series G’ Stock were entitled to receive payments in amounts per share equaling $1.00, $2.3567, $21.4701, $23.64, $37.7344, $58.40, $68.9516, and $34.4758, plus any declared but unpaid dividends, respectively. Holders of Series G Stock and Series G’ Stock are pari passu and were to be paid prior, and in preference to, any distribution of assets to the holders of all other classes of capital stock. Holders of Series F-R Stock were to be paid prior, and in preference to, any distribution of assets to the holders of Series E-R Stock, Series D-R Stock, Series C-R Stock, Series B-R Stock and Series A-R Stock. Holders of Series E-R Stock were to be paid prior, and in preference to, any distribution of assets to the holders of Series D-R Stock, Series C-R Stock, Series B-R Stock and Series A-R Stock. Holders of Series D-R Stock were to be paid prior, and in preference to, any distribution of assets to the holders of Series C-R Stock, Series B-R Stock and Series A-R Stock. Holders of Series C-R Stock were to be paid prior, and in preference to, any distribution of assets to the holders of Series B-R Stock and Series A-R Stock. Holders of Series A-R Stock and Series B-R Stock are pari passu and were to be paid prior, and in preference to, any distribution of assets to the holders of common stock.

Upon completion of the distributions detailed above, any remaining assets were to be distributed to the holders of common stock, Series A-R Stock, Series B-R Stock, Series C-R Stock, Series D-R Stock, Series E-R Stock, Series F-R Stock, Series G Stock and Series G’ Stock; such participation in the distribution of remaining assets would cease, however, when the amount that the holders of Series A-R Stock, Series B-R Stock, Series C-R Stock, Series D-R Stock, Series E-R Stock, Series F-R Stock, Series G Stock and Series G’ Stock were entitled to receive upon liquidation equals $2.00 per share, $4.7134 per share, $36.8058 per share, $70.92 per share, $113.2032 per share, $175.20 per share, $103.4274 per share and $103.4274 per share, respectively, plus any declared but unpaid dividends thereon.

If, however, as a result of a conversion from redeemable convertible preferred stock to common stock, a holder would receive, in the aggregate, an amount greater than the amount that would be distributed to such holder if such holder did not convert such series of redeemable convertible preferred stock into shares of common stock, such holder would have been deemed to have converted such holder’s shares of redeemable convertible preferred stock into shares of common stock for the purposes of determining the amount that such holder is entitled to receive upon liquidation and would not have been entitled to any distribution that would have otherwise been made to the holders of redeemable convertible preferred stock detailed above.

Dividends

No dividends have been declared or paid as of December 31, 2020.

Conversion

The holders of our redeemable convertible preferred stock also had the right, at any time, to convert any or all of their shares into such number of shares of common stock as is determined by dividing $1.00 in the case of Series A-R Stock, $2.3567 in the case of the Series B-R Stock, $12.2686 in the case of Series C-R Stock, $23.64 in the case of Series D-R Stock, $37.7344 in the case of Series E-R Stock, $50.0568 in the case of Series F-R Stock, and $34.4758 in the case of Series G Stock and Series G’ Stock by the applicable conversion price. The initial conversion price was $1.00 in the case of Series A-R Stock, $2.3567 in the case of the Series B-R Stock, $2.3567 in the case of Series C-R Stock, $23.64 in the case of Series D-R Stock, $37.7344 in the case of Series E-R Stock, $50.0568 in the case of Series F-R Stock and $34.4758 in the case of Series G Stock and Series G’ Stock. If, at any time following the initial issuance of shares of Series G Stock, we had issued any additional shares of capital stock without consideration or for a consideration per share less than the then-effective conversion price for our redeemable convertible preferred stock, the conversion price for all series of outstanding redeemable convertible preferred stock would have been subject to adjustment.

COMMON STOCK WARRANTS

12 Months Ended

Dec. 31, 2020

Other Liabilities Disclosure [Abstract]

COMMON STOCK WARRANTS

We have granted warrants to purchase shares of our common stock to certain FI partners that include both time-based and performance-based vesting conditions. These warrants are accounted for under ASC Topic 505-50, Equity-Based Payments to Non-Employees. Since the performance conditions contained in these warrants are directly related to revenue-producing activities, we incur non-cash expense in FI Share and other third-party costs on our consolidated statements of operations based on the vesting-date fair value of our common stock underlying these warrants.

A summary of common stock warrant activity, exclusive of the common stock warrants issued in connection with our Series G financing is as follows (in thousands, except per share amounts):


	Shares	Weighted-average exercise price per share
Warrants Outstanding - December 31, 2017	600	$	8.11
Granted	644	23.64
Exercised	(349)	4.69
Redeemable convertible preferred stock warrants converted to common stock warrants	110	12.16
Forfeited/canceled	(138)	5.85
Warrants Outstanding - December 31, 2018	867	21.89

Exercised	(821)	21.89

Forfeited/canceled	(34)	21.29
Warrants Outstanding - December 31, 2019	12	23.64

Exercised	(9)	23.64

Forfeited/canceled	(3)	23.64
Warrants Outstanding - December 31, 2020	—	$	—

The performance-based warrants to purchase 644,365 shares of our common stock vested upon the consummation of our IPO in February 2018 as discussed in Note 13—Related Parties. The conversion date fair value of the Series A Stock warrants and Series B Stock warrants, which were converted to common stock warrants upon our IPO, was reclassified from redeemable convertible preferred stock warrant liability to additional paid-in capital. See Note 12—Fair Value Measurements for more information.

FAIR VALUE MEASUREMENTS

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

FAIR VALUE MEASURMENTS

FAIR VALUE MEASUREMENTS

Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following table summarizes our liabilities measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):


	December 31, 2017
	Level 1		Level 2		Level 3		Total
Liabilities:
Preferred stock warrant liabilities(1)	$	—	$	—	$	2,285	$	2,285
Common stock warrant liabilities(1)	—		—		7,945		7,945
Total liabilities	$	—	$	—	$	10,230	$	10,230

(1)Warrant liabilities were zero as of December 31, 2018, 2019 and 2020.

Instruments Recorded at Fair Value Using Level 3 Inputs

Our redeemable convertible preferred stock warrants and common stock warrants issued in connection with the Series G Stock financing are measured and recorded at fair value on a recurring basis using Level 3 inputs. The carrying amount of the liability component of the Convertible Senior Notes was determined by estimating the fair value of a similar liability without the conversion option using Level 3 inputs. See Note 7—Debt and Financing Arrangements for additional information about the Convertible Senior Notes. The table below provides a roll forward of the changes in fair value of our preferred stock warrant and common stock warrant financial instruments (in thousands):


	Preferred Stock Warrant Liabilities		Common Stock Warrant Liabilities
Balance at December 31, 2017	$	2,285	$	7,945

Conversion of redeemable convertible preferred stock warrants to common stock warrants	(1,736)		—


Issuance of common stock warrants	(549)		7,309

Changes in fair value	—		(15,254)
Balance at December 31, 2018	$	—	$	—

Prior to our IPO, in valuing our instruments recorded at fair value using Level 3 inputs, our board of directors determined the equity value of our business generally using a combination of the income approach and the market approach valuation methods.

The income approach estimates value based on the expectation of future cash flows that a company will generate, such as cash earnings, cost savings, tax deductions and the proceeds from disposition. These future cash flows are discounted to their present values using a discount rate derived based on an analysis of the cost of capital of comparable publicly traded companies in similar lines of business, as of each valuation date, and is adjusted to reflect the risks inherent in our cash flows.

The market approach estimates the fair value of a company by applying market multiples of comparable publicly traded companies in a similar line of business. The market multiples are based on relevant metrics implied by the price that investors have paid for the equity of publicly traded companies. Given our significant focus on investing in and growing our business, we primarily utilized the forward-looking revenue multiple when performing valuation assessments under the market approach and considered both trading and transaction multiples. When considering which companies to include as our comparable industry peer companies, we focused on U.S.-based publicly traded companies that were broadly comparable to us based on consideration of industry, market and line of business. From the comparable companies, a representative market value multiple was determined and applied to our operating results to estimate the value of our company. The market value multiple was determined based on consideration of multiples of revenue to each of the comparable companies’ historical and forecasted revenue. In addition, the market approach considers IPO and merger and acquisition transactions involving companies similar to the company’s business being valued. Multiples of revenue are calculated for these transactions and then applied to the business being valued, after reduction by an appropriate discount.

Once an equity value was determined, we utilized probability-weighted expected return method (“PWERM”) to allocate the overall value of equity to the various share classes. The PWERM relies on a forward-looking analysis to predict the possible future value of a company. Under this method, discrete future outcomes, including an IPO and non-IPO scenarios, are weighted based on the estimated the probability of each scenario. The PWERM is used when discrete future outcomes can be predicted with reasonable certainty based on a probability distribution. We relied on the PWERM to allocate the value of equity under a liquidity scenario. The projected equity value relied upon in the PWERM scenario was based on (i) guideline IPO transactions involving companies that were considered broadly comparable to us and (ii) our expectation of the pre-money valuation that we needed to achieve to consider an IPO as a viable exit strategy.

Preferred Stock Warrants

Upon the consummation of our IPO, all of the outstanding warrants to purchase shares of redeemable convertible preferred stock were automatically converted into warrants to purchase shares of common stock. Refer to Note 10—Redeemable Convertible Preferred Stock for additional information regarding our IPO.

A summary of our preferred stock warrants is as follows (in thousands, except per share amounts):


Preferred Series	Grant date	Expiration date	Exercise price		December 31, 2017
Series B-R	2/26/2010	2/25/2020	$	2.36	59
Series D-R	9/21/2012	9/20/2022	$	23.64	38
Series D-R	9/21/2012	9/20/2022	$	23.64	13
Total preferred stock warrants					110

The fair value of the warrants to purchase Series B-R Stock and Series D-R Stock decreased from $26.80 per share and $13.63 per share on December 31, 2017 to $20.18 per share and $10.57 per share on February 8, 2018, respectively, the date at which they converted to warrants to purchase shares of our common stock and were reclassified to additional paid-in capital on our consolidated balance sheet. The decrease in the fair value of the warrants to purchase Series B-R Stock and Series D-R Stock primarily resulted from the timing of future potential liquidity events, changes to our forecasted financial results and changes in the valuation of comparable companies. Warrant liabilities related to redeemable convertible preferred stock were zero as of December 31, 2018, 2019 and 2020.

Common Stock Warrants

Common Stock Warrants Issued in Connection with the Series G Stock Financing

To determine the fair value of our common stock warrant liability issued in connection with our Series G Stock financing, we utilized a Monte Carlo simulation, which allows for the modeling of complex securities and evaluates many possible outcomes to forecast the stock price of the company post-IPO. As part of the valuation, we considered various scenarios related to the pricing, timing and probability of an IPO. We applied an annual equity volatility of 59% and a discount for lack of marketability of 11% to arrive at a valuation of $7.5 million on the issuance date.

Subsequent to our IPO, the fair value of the common stock warrant liability was estimated based on the fair market value of our common stock at each reporting period, discounted from the date of settlement. In August 2018, we issued warrants to purchase 792,434 shares of common stock at an exercise price of $0.0004 per share to the cash investors of our Series G financing, pursuant to our Series G stock purchase agreement. The warrants had a valuation of $15.3 million upon issuance and were subsequently exercised, resulting in the issuance of 792,434 shares of our common stock. As a result of change in fair value of the common stock warrant liability, we recognized a non-cash loss of $7.3 million in 2018.

Performance-based Warrants Issued to FIS

In May 2013, we granted 10-year performance-based warrants to purchase up to 644,365 shares of Series E Stock at an exercise price of $23.64 per share. Since FIS did not participate in the convertible promissory note financing in 2016, their warrants to purchase preferred stock were converted to warrants to purchase common stock. The warrants vested upon the completion of our IPO in February 2018 resulting in a non-cash expense of $2.5 million. We determined the fair value of these common warrants on the date of IPO using the Black-Scholes option pricing model, which is affected by the fair value of our common stock as well as the following significant inputs:


			February 8, 2018
Weighted-average grant date fair value			$3.91
Significant inputs:
Value of common stock			$13.00
Expected term			5.3 years
Volatility			50%
Risk-free interest rate			2.0%
Dividend yield			—%

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

RELATED PARTIES

12 Months Ended

Dec. 31, 2020

RELATED PARTIES

Common Stock Warrants Issued in Connection with the Series G Stock Financing

In connection with the Series G Stock financing in 2017, we issued warrants to purchase an aggregate number of shares of common stock equal to the product obtained by multiplying 346,334 by a fraction, the numerator of which is the difference between $68.9516 and the volume weighted average closing price of our common stock over the 30 trading days (or such lesser number of days as our common stock has been traded on the Nasdaq Global Market) prior to the date on which such warrants vest and become exercisable and the denominator of which is such volume weighted average closing price, which warrants vested and became exercisable on August 8, 2018, which was 180 days following the date of our IPO, at an exercise price of $0.0004 per share. In August 2018, we issued warrants to purchase 792,434 shares of common stock at an exercise price of $0.0004 per share to the cash investors of our Series G financing, pursuant to our Series G stock purchase agreement. The warrants had a valuation of $15.3 million upon issuance and were subsequently exercised, resulting in the issuance of 792,434 shares of our common stock. The following table summarizes the participation in the common stock warrants issued in connection with the Series G Stock financing by our directors, executive officers and holders of more than 5% of any class of our capital stock as of the date of such transactions (in thousands):


Related Party						Warrants to Purchase Common Stock
Entities affiliated with Polaris Venture Partners(1)						66
Canaan VIII L.P.(2)						123
Entities affiliated with Mark A. Johnson(3)						80
John Klinck						13
David Adams						7

(1)Consists of 64,038 warrants to purchase common stock issued to Polaris Venture Partners V, L.P. ("PVP V"), 1,247 warrants to purchase common stock issued to Polaris Venture Partners Entrepreneurs’ Fund V, L.P. (“PVP EF V”), 438 warrants to purchase common stock issued to Polaris Venture Partners Founders’ Fund V, L.P. (“PVP FF V”), and 641 warrants to purchase common stock issued to Polaris Venture Partners Special Founders’ Fund V, L.P. (“PVP SFF V”). Polaris Venture Management Co. V, L.L.C. is a general partner of each of PVP V, PVP EF V, PVP FF V and PVP SFF V and may be deemed to have the sole voting and dispositive power over the shares held by PVP V, PVP EF V, PVP FF V and PVP SFF V. Bryce Youngren, an active member of our board of directors at the time of transaction, is a Managing Partner of Polaris Partners and may be deemed to share voting and dispositive power over the shares held by PVP V, PVP EF V, PVP FF V and PVP SFF V.

(2)John V. Balen, a member of our board of directors, is a managing member of Canaan Partners VIII LLC, the general partner of Canaan VIII L.P. Mr. Balen does not have voting or investment power over any shares held directly by Canaan VIII L.P.

(3)Consists of 66,365 warrants to purchase common stock issued to TTV Ivy Holdings, LLC, and 13,273 warrants to purchase common stock issued to Mr. Johnson. TTV Capital is a provider of management services to TTP GP II, LLC, which is a general partner of TTP Fund II, L.P. TTV Capital is the manager of TTV Ivy Holdings Manager, LLC, which is the general partner of TTV Ivy Holdings, LLC. Mark A. Johnson, a member of our board of directors, is a member of each of TTP GP II, LLC and TTV Ivy Holdings Managers, LLC and holds the title of partner of TTV Capital, and may be deemed to share voting and dispositive power over the shares held by TTP Fund II L.P. and TTV Ivy Holdings, LLC.

Agreements with Fidelity Information Services, LLC

We are party to a reseller agreement with Fidelity Information Services LLC (“FIS”). Pursuant to the reseller agreement, FIS markets and sells our services to financial institutions that are current or potential customers of FIS in exchange for a revenue share percentage. We are also obligated to make milestone payments to FIS related to the integration and deployment of our solutions. Prior to our IPO, FIS was entitled to elect a member of our board of directors, who was Robert Legters until his resignation immediately prior to our IPO in February 2018.

In May 2013, FIS purchased 397,515 shares of our Series E Stock. We also granted 10-year performance-based warrants to purchase up to 644,365 shares of Series E Stock at an exercise price of $23.64 per share. The warrants were exercisable subject to the attainment of certain milestones related to the number of active accounts for which our solutions have been enabled with accelerated vesting upon an IPO. Since FIS did not participate in the convertible promissory note financing in 2016, their warrants to purchase preferred stock were converted to warrants to purchase common stock. The warrants vested upon the completion of our IPO in February 2018, resulting in a non-cash expense of $2.5 million based on the vesting-date fair value of our common stock underlying these warrants. Since the performance conditions were directly related to revenue-producing activities, we recognized this expense in FI Share and other third-party costs on our consolidated statement of operations. This expense is presented in other non-cash expenses on our consolidated statement of cash flows. Refer to Note 12—Fair Value Measurements for additional information regarding the valuation of the performance-based warrants issued to FIS.

In September 2019, FIS exercised all of their warrants to purchase common stock, resulting in cash proceeds of $15.2 million and the issuance of 644,365 shares of our common stock.

COMMITMENTS AND CONTINGENCIES

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

FI Implementation Costs

Agreements with certain FI partners require us to fund the development of specific enhancements, pay for certain implementation fees, or make milestone payments upon the deployment of our solution. Amounts paid to FI partners are included in deferred FI implementation costs on our consolidated balance sheets the earlier of when paid or earned and are amortized over the remaining term of the related contractual arrangements. Amortization and impairment is included in FI Share and other third-party costs on our consolidated statements of operations and is presented in amortization and impairment of deferred FI implementation costs on our consolidated statement of cash flows. Certain of these agreements provide for future reductions in FI Share due to the FI partner. These reductions in FI Share are recorded as a reduction to deferred implementation costs and also result in a cumulative adjustment to accumulated amortization. During 2018, development payments to a certain FI partner totaled $9.3 million which was partially offset by recoveries through FI Share payment reductions of $4.6 million in 2019.

During 2020, one of our FI partners notified us of plans to end the use of certain platform features prior to the end of our contractual arrangement with the FI partner. As a result, we recognized a write off of deferred FI implementation costs totaling $0.7 million in FI Share and other third-party costs on our consolidated statements of operations.

The following table presents changes in deferred FI implementation costs (in thousands):


	December 31,
	2018		2019		2020
Beginning balance	$	13,625	$	15,877	$	8,383
Deferred costs	9,250		—		—
Recoveries through FI Share	(5,380)		(4,625)		—
Amortization	(1,618)		(2,869)		(3,915)
Impairment	—		—		(683)
Ending balance	$	15,877	$	8,383	$	3,785

Payments to FI partners for enhancements not yet placed in service totaled $1.0 million as of December 31, 2020. Future amortization, based on the amounts earned as of December 31, 2020, is $2.8 million in 2021.

We have a minimum FI Share commitment with a certain FI partner totaling $10.0 million over a 12-month period following the completion of certain milestones, which were not met as of December 31, 2020. Any expected shortfall penalty will be accrued during the 12-month period following the completion of the milestones.

Other Commitments

We lease property and equipment under non-cancelable operating lease agreements. Refer to Note 5—Leases for further details. In September 2020, we issued convertible senior notes with an aggregate principal amount of $230.0 million bearing an interest rate of 1.00% due in 2025. Refer to Note 7—Debt and Financing Arrangements for further details.

Litigation

From time to time, we may become involved in legal actions arising in the ordinary course of business including, but not limited to, intellectual property infringement and collection matters. We make assumptions and estimates concerning the likelihood and amount of any potential loss relating to these matters using the latest information available. We record a liability for litigation if an unfavorable outcome is probable and the amount of loss or range of loss can be reasonably estimated. If an unfavorable outcome is probable and a reasonable estimate of the loss is a range, we accrue the best estimate within the range. If no amount within the range is a better estimate than any other amount, we accrue the minimum amount within the range. If an unfavorable outcome is probable but the amount of the loss cannot be reasonably estimated, we disclose the nature of the litigation and indicates that an estimate of the loss or range of loss cannot be made. If an unfavorable outcome is reasonably possible and the estimated loss is material, we disclose the nature and estimate of the possible loss of the litigation. We do not disclose information with respect to litigation where an unfavorable outcome is considered to be remote or where the estimated loss would not be material. Based on current expectations, such matters, both individually and in the aggregate, are not expected to have a material adverse effect on our liquidity, results of operations, business or financial condition.

EARNINGS PER SHARE

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

EARNINGS PER SHARE

Diluted net loss per share is the same as basic net loss per share for 2018, 2019 and 2020 because the effects of potentially dilutive items were anti-dilutive, given our net loss during these periods. The following securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive (in thousands):


	December 31,
	2018	2019	2020









Common stock options	1,774	1,000	513
Common stock warrants	867	12	—
Convertible Senior Notes	—	—	2,701


Restricted stock units	381	1,741	2,434


Common stock issuable pursuant to the ESPP	36	7	4

SEGMENTS

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

SEGMENTS

As of December 31, 2020, we have three operating segments: the Cardlytics platform in the U.S. and U.K. and Other Platform Solutions, as determined by the information that our Chief Executive Officer, who we consider our chief operating decision-maker, uses to make strategic goals and operating decisions. Our Cardlytics platform operating segments in the U.S. and U.K. represent our proprietary native bank advertising channels and are aggregated into one reportable segment given their similar economic characteristics, nature of service, types of customers and method of distribution. Prior to the year ended December 31, 2020, we referred to the Cardlytics platform as Cardlytics Direct.

Our Other Platform Solutions enabled marketers and marketing service providers to leverage the power of purchase intelligence outside the bank channel. We have shifted the substantial majority of our efforts and resources to support the growth of Cardlytics platform. As a result, we no longer generate revenue from Other Platform Solutions and do not expect to generate revenue from Other Platform Solutions for the foreseeable future.

Revenue can be directly attributable to each segment. With the exception of a non-cash equity expense and deferred FI implementation costs, FI Share is also directly attributable to each segment. Our chief operating decision maker allocates resources to, and evaluate the performance of, our operating segments based on revenue and adjusted contribution. The accounting policies of each of our reportable segments are the same as those described in the summary of significant accounting policies.

The following table provides information regarding our reportable segments (in thousands):


	Year Ended December 31,
	2018		2019		2020
Cardlytics platform:
Adjusted contribution(2)	$	69,364	$	95,219	$	82,182
Plus: FI Share and other third-party costs (1)(2)	79,959		115,211		104,710
Revenue	$	149,323	$	210,430	$	186,892
Other Platform Solutions:
Adjusted contribution(2)	$	86	$	—	$	—
Plus: FI Share and other third-party costs (1)(2)	1,275		—		—
Revenue	$	1,361	$	—	$	—
Total:
Adjusted contribution(2)	$	69,450	$	95,219	$	82,182
Plus: FI Share and other third-party costs (1)(2)	81,234		115,211		104,710
Revenue	$	150,684	$	210,430	$	186,892

(1)Adjusted FI Share and other third-party costs presented above represents GAAP FI Share and other third-party data costs less a non-cash equity expense included in FI Share and deferred FI implementation costs, which are detailed below in our reconciliation of GAAP loss before income taxes to adjusted contribution.

(2)Adjusted contribution and FI Share and other third-party costs include the impact of a $0.8 million gain during 2018 related to the renewal of our agreement with an FI partner, which contains certain amendments that are retroactively applied as of January 1, 2018.

Adjusted Contribution

Adjusted contribution measures the degree by which revenue generated from our marketers exceeds the cost to obtain the purchase data and the digital advertising space from our FI partners. Adjusted contribution demonstrates how incremental marketing spend on our platform generates incremental amounts to support our sales and marketing, research and development, general and administration and other investments. Adjusted contribution is calculated by taking our total revenue less our FI Share and other third-party costs exclusive of a non-cash equity expense and deferred FI implementation costs, which are non-cash costs. Adjusted contribution does not take into account all costs associated with generating revenue from advertising campaigns, including sales and marketing expenses, research and development expenses, general and administrative expenses and other expenses, which we do not take into consideration when making decisions on how to manage our advertising campaigns.

The following table presents a reconciliation of loss before income taxes presented in accordance with GAAP to adjusted contribution (in thousands):


	Year Ended December 31,
	2018		2019		2020
Adjusted contribution(1)(2)(3)	$	69,450	$	95,219	$	82,182
Minus:
Non-cash equity expense included in FI Share(1)	2,519		—		—
Deferred FI implementation costs(3)	1,618		2,869		4,598
Delivery costs	10,632		12,893		14,310
Sales and marketing expense	41,878		43,828		45,307
Research and development expense	16,210		11,699		17,532
General and administration expense	34,228		36,720		46,532
Depreciation and amortization expense	3,282		4,535		7,826

Total non-operating expense (income)	12,125		(181)		1,499
Loss before income taxes	$	(53,042)	$	(17,144)	$	(55,422)

(1)Non-cash equity expense included in FI Share and deferred FI implementation costs are excluded from FI Share and other third-party costs, which is shown above in our reconciliation of GAAP revenue to non-GAAP adjusted contribution.

(2)Adjusted contribution includes the impact of a $0.8 million gain during 2018 related to the renewal of our agreement with an FI partner, which contains certain amendments that are retroactively applied as of January 1, 2018.

(3)Deferred FI implementation costs for 2020 includes the impact of a $0.7 million write off related to certain platform features.

The following tables provide geographical information (in thousands):


	Year Ended December 31,
	2018		2019		2020
Revenue:
United States	$	131,563	$	186,864	$	172,808
United Kingdom	19,121		23,566		14,084
Total	$	150,684	$	210,430	$	186,892


	December 31,
	2019		2020
Property and equipment:
United States	$	12,052	$	9,549
United Kingdom	2,010		4,162
India	228		154
Total	$	14,290	$	13,865

Capital expenditures within the United Kingdom were $0.1 million, $2.0 million and $2.8 million during 2018, 2019 and 2020, respectively.

Concentrations of Risk

Cash and Cash Equivalents

Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash and cash equivalents and accounts receivable. A majority of our cash and cash equivalents are held in fully FDIC–insured demand deposit accounts that distribute funds, and credit risk, over a vast number of financial institutions. Our remaining cash and cash equivalents are held in treasury obligation funds and money market accounts with three financial institutions, which we believe are of high credit quality.

Marketers

Our accounts receivable are diversified among a large number of marketers segregated by both geography and industry. During 2018, 2019 and 2020, our top five marketers accounted for 23%, 27% and 35% of our revenue. No marketer represented a significant concentration of our accounts receivable as of December 31, 2018. As of December 31, 2019 and December 31, 2020 our top five marketers accounted for 26% and 31% of our accounts receivable, respectively, with one marketer representing over 10% as of December 31, 2019 and December 31, 2020, respectively.

FI Partners

Our business is substantially dependent on a limited number of FI partners. We require participation from our FI partners in the Cardlytics platform and access to their purchase data in order to offer our solutions to marketers and their agencies. We must have FI partners with a sufficient number of customers and levels of customer engagement to ensure that we have robust purchase data and marketing space to support a broad array of incentive programs for marketers. Our agreements with a substantial majority of our FI partners have terms of three to seven years but are generally terminable by the FI partner on 90 days or less prior notice. If an FI partner terminates its agreement with us, we would lose that FI as a source of purchase data and online banking customers.

During 2018, Bank of America, National Association (“Bank of America”) accounted for over 60% of the total FI Share we paid to all FIs. No other FI partner accounted for over 10% of FI Share during this period. For each year during 2019 and 2020, Bank of America and JPMorgan Chase Bank, National Association (“Chase”) combined to account for over 75% of the total FI Share we paid to all FIs, with each representing over 25%. No other FI partner accounted for over 10% of FI Share during these periods.

SIGNIFICANT ACCOUNTING POLICIES (Policies)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Principles of Consolidation

The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation.

Use of Estimates

Restructuring

Foreign Currency

FI Share and Other Third-Party Costs

Delivery Costs

Impacts of COVID-19 Pandemic

Accounts Receivable

The following table presents changes in the allowance for credit losses (in thousands):


	Year Ended December 31,
	2018		2019		2020
Beginning balance	$	105	$	169	$	255
Credit loss expense	130		1,201		1,196
Write-offs, net of recoveries	(66)		(1,115)		(864)
Ending balance	$	169	$	255	$	587

Property and Equipment

Depreciation of property and equipment is determined using the straight-line method over the estimated useful lives of the applicable assets, which are as follows:


Computer equipment:						2–3 years
Furniture and fixtures:						5 years
Leasehold improvements:						Lesser of estimated useful life or life of the lease

Intangible assets

Intangible Assets

Internal Use Software

Internal-Use Software Development Costs

Debt Issuance Costs

Amortization of debt issuance costs included in interest expense, net totaled $0.3 million, $0.1 million and $0.3 million in 2018, 2019 and 2020, respectively.

Deferred Offering Costs

Advertising

Stock-Based Compensation

Redeemable Convertible Preferred Stock Warrant Liability

Redeemable Convertible Preferred Stock Warrant LiabilityWarrants to purchase shares of our redeemable convertible preferred stock are accounted for as derivative liabilities in accordance with ASC Topic 815, Derivatives and Hedging due to the terms of the warrants and related agreements. We have determined that these warrants do not meet the scope exception of a contract indexed to our stock because of fair value protections contained in agreements governing our redeemable convertible preferred stock as described in Note 10—Redeemable Convertible Preferred Stock. We record preferred stock warrant liabilities on our consolidated balance sheets at their fair value. We record the changes in fair value of such instruments as non-cash gains or losses on our statements of operations.

Common Stock Warrant Liability

Common Stock Warrant LiabilityIn connection with the Series G Stock financing, we issued warrants to purchase shares of our common stock that are accounted for as liabilities in accordance with ASC Topic 480, Distinguishing Liabilities From Equity due to the terms of the warrants and related agreements. We record these common stock warrant liabilities on our consolidated balance sheets at their fair value. We record the changes in fair value of such instruments as non-cash gains or losses in our statements of operations

Fair Value of Financial Instruments

•Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date.

•Level 3 inputs are unobservable inputs for the asset or liability.

Income Taxes

We have recorded a full valuation allowance related to our net deferred tax assets due to the uncertainty of the ultimate realization of the future benefits of those assets.

Revenue

Revenue Recognition

We determine revenue recognition through the following steps:

•identification of a contract with a customer,

•identification of the performance obligation(s) in the contract,

•determination of the transaction price,

•allocation of the transaction price to the performance obligation(s) in the contract, and

•recognition of revenue when or as the performance obligation(s) are satisfied.

FI Share and Other Third-Party Costs

Contract Costs

Consumer Incentives

SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Schedule of allowance for doubtful accounts

The following table presents changes in the allowance for credit losses (in thousands):


	Year Ended December 31,
	2018		2019		2020
Beginning balance	$	105	$	169	$	255
Credit loss expense	130		1,201		1,196
Write-offs, net of recoveries	(66)		(1,115)		(864)
Ending balance	$	169	$	255	$	587

Schedule of property and equipment, useful life

Depreciation of property and equipment is determined using the straight-line method over the estimated useful lives of the applicable assets, which are as follows:


Computer equipment:						2–3 years
Furniture and fixtures:						5 years
Leasehold improvements:						Lesser of estimated useful life or life of the lease

Significant components of property and equipment are as follows (in thousands):


	December 31,
	2019		2020
Computer equipment	$	21,269	$	27,105
Leasehold improvements	6,960		6,770
Furniture and fixtures	1,557		1,112
Construction in progress	1,125		125
Property and equipment, gross	30,911		35,112
Less accumulated depreciation	(16,621)		(21,247)
Property and equipment, net	$	14,290	$	13,865

Schedule of indefinite-lived intangible assets

Intangible assets are as follows (in thousands):


	December 31,
	2019		2020
Deferred patent costs, gross	$	448	$	518
Less accumulated amortization	(59)		(71)
Deferred patent costs, net	$	389	$	447

Capitalized software development costs are as follows (in thousands):


	December 31,
	2019		2020
Capitalized software development costs, gross	$	5,537	$	9,230
Less accumulated amortization	(1,722)		(2,931)
Capitalized software development costs, net	$	3,815	$	6,299

Schedule of debt issuance costs

Deferred debt issuance costs related to our lines of credit included in other long-term assets are as follows (in thousands):


	December 31,
	2019		2020
Debt issuance costs, gross	$	388	$	412
Less accumulated amortization	(271)		(377)
Debt issuance costs, net	$	117	$	35

Deferred debt issuance costs related to our Notes included in debt are as follows (in thousands):


	December 31,
	2019		2020
Debt issuance costs, gross	$	—	$	5,596
Less accumulated amortization	—		(217)
Debt issuance costs, net	$	—	$	5,379

Schedule of future amortization of debt issuance costs

Future amortization of debt issuance costs is as follows (in thousands):


Years Ending December 31,	Amortization
2021	$	909
2022	1,006
2023	1,151
2024	1,312
2025	1,036
Total	$	5,414

Schedule of restructuring costs

Deferred offering costs is as follows (in thousands):


	Year Ended December 31,
	2018		2019		2020
Beginning balance	$	3,144	$	—	$	—
Deferred costs	1,135		196		—
Recognized against offering proceeds	(4,279)		(196)		—
Ending balance	$	—	$	—	$	—

Schedule of deferred costs

Deferred offering costs is as follows (in thousands):


	Year Ended December 31,
	2018		2019		2020
Beginning balance	$	3,144	$	—	$	—
Deferred costs	1,135		196		—
Recognized against offering proceeds	(4,279)		(196)		—
Ending balance	$	—	$	—	$	—

REVENUE (Tables)

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue [Table Text Block]

The following table summarizes revenue by pricing model (in thousands):


	Year Ended December 31,
	2018		2019		2020
Cost per Served Sale	$	101,087	$	143,754	$	131,045
Cost per Redemption	43,389		63,295		53,838
Other	6,208		3,381		2,009
Revenue	$	150,684	$	210,430	$	186,892

LEASES (Tables)

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Lease, Cost

The following table summarizes activity related to our leases (in thousands):


	Year Ended December 31, 2020
Operating lease expense	$	4,078
Variable lease expense	847
Short-term lease expense	232

The following table presents our weighted average borrowing rate and weighted average lease term:


	December 31, 2020
Weighted average borrowing rate	3.4	%
Weighted average remaining lease term (years)	3.25

Lessee, Operating Lease, Liability, Maturity

The following table summarizes future maturities of lease liabilities as of December 31, 2020 (in thousands):


	Amount

2021	$	5,097
2022	4,681
2023	2,692
2024	1,807
2025	611
Total lease payments	14,888
Imputed interest	789
Total operating lease liabilities	$	14,099

The following table summarizes future payments for operating leases as of December 31, 2019, prior to our adoption of ASU 2016-02 (in thousands):


	Minimum Lease Payments
2020	$	3,040
2021	2,759
2022	2,808
2023	1,847
2024	1,807
Thereafter	611
Total	$	12,872

PROPERTY AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Schedule of property and equipment

Depreciation of property and equipment is determined using the straight-line method over the estimated useful lives of the applicable assets, which are as follows:


Computer equipment:						2–3 years
Furniture and fixtures:						5 years
Leasehold improvements:						Lesser of estimated useful life or life of the lease

Significant components of property and equipment are as follows (in thousands):


	December 31,
	2019		2020
Computer equipment	$	21,269	$	27,105
Leasehold improvements	6,960		6,770
Furniture and fixtures	1,557		1,112
Construction in progress	1,125		125
Property and equipment, gross	30,911		35,112
Less accumulated depreciation	(16,621)		(21,247)
Property and equipment, net	$	14,290	$	13,865

Schedule of capital leased assets

Assets acquired under finance leases, included within computer equipment, are as follows (in thousands):


	December 31,
	2019		2020
Finance lease assets, gross	$	1,096	$	557
Less accumulated depreciation	(1,067)		(548)
Finance lease assets, net	$	29	$	9

DEBT AND FINANCING ARRANGEMENTS (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Schedule of long-term debt instruments

Our debt consists of the following (in thousands):


	December 31,
	2019		2020


Convertible senior notes, net	$	—	$	174,011
Finance leases	37		13
Total debt	37		174,024
Less current portion of long-term debt	(24)		(13)
Long-term debt, net of current portion	$	13	$	174,011

Convertible Debt

The net carrying amount of the liability component of the Notes is as follows (in thousands):


	December 31, 2020
Principal	$	230,000
Minus: Unamortized debt discount	(50,610)
Minus: Unamortized issuance costs	(5,379)
Net carrying amount of the liability component	$	174,011

The net carrying amount of the equity component of the Notes is as follows (in thousands):


	December 31, 2020
Proceeds allocated to the conversion options (debt discount)	$	53,096
Minus: Issuance costs	(1,680)
Net carrying amount of the equity component	$	51,416

Interest expense recognized related to the Notes is as follows (in thousands):


	Year Ended December 31, 2020
Contractual interest expense (due in cash)	$	626
Amortization of debt discount	2,486
Amortization of debt issuance costs	217
Total interest expense related to the Notes	$	3,329

Schedule of maturities of debt and capital lease

Aggregate future payments of principal due upon maturity are as follows (in thousands):


Years Ending December 31,	Finance leases		Convertible Senior Notes
2021	$	13	$	—
2022	—		—
2023	—		—
2024	—		—
2025	—		230,000



Total debt	$	13	$	230,000

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-Name Accounting Standards Codification
-Topic 835
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-Section 45
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-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

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-Topic 505
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 942
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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
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-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

STOCK-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Allocation of recognized period costs

The following table summarizes the allocation of stock-based compensation on the consolidated statements of operations (in thousands):


	Year Ended December 31,
	2018		2019		2020
Delivery costs	$	633	$	711	$	1,181
Sales and marketing expense	9,358		4,248		9,857
Research and development expense	4,087		1,619		4,713
General and administration expense	12,712		9,273		16,645
Total stock-based compensation expense	$	26,790	$	15,851	$	32,396

Summary of common stock option activity

Common Stock Options

A summary of common stock option activity is as follows (in thousands, except per share amounts):


	Shares	Weighted-Average Exercise Price Per Share		Weighted Average Contractual Life (in years)	Aggregate Intrinsic Value(1) (in thousands)
Outstanding - December 31, 2017	2,514	$	18.42
Granted	29	24.24
Exercised	(357)	6.25
Forfeited	(197)	24.10
Cancelled	(215)	16.60
Outstanding - December 31, 2018	1,774	$	20.55
Granted	39	20.64
Exercised	(716)	16.84
Forfeited	(31)	23.95
Cancelled	(66)	22.37
Outstanding - December 31, 2019	1,000	$	22.99
Granted	—	—
Exercised	(467)	21.78			$	29,523
Forfeited	(19)	27.83
Cancelled	(1)	21.89
Outstanding - December 31, 2020	513	$	23.91	5.67	$	61,009
Exercisable - December 31, 2020	480	$	23.72	5.62	$	57,126

Summary of RSU activity

We grant restricted stock units ("RSUs") to employees and our non-employee directors. The following table summarizes changes in RSUs, inclusive of performance-based RSUs:


	Shares (in thousands)	Weighted-Average Grant Date Fair Value Per Share		Weighted-Average Remaining Contractual Term (in years)	Unamortized Compensation Costs (in thousands)
Unvested - December 31, 2017	—	$	—
Granted	1,309	20.58
Vested	(850)	21.93
Forfeited/canceled	(78)	17.97
Unvested - December 31, 2018	381	$	18.11
Granted	1,978	17.78
Vested	(486)	14.97
Forfeited/canceled	(132)	18.92
Unvested - December 31, 2019	1,741	$	18.55
Granted	1,758	43.07
Vested	(779)	28.56
Forfeited	(286)	23.34
Unvested - December 31,2020	2,434	$	32.49	2.80	$	61,630

INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of domestic and foreign components of income (loss) before income taxes

Domestic and foreign components of loss before income taxes are as follows (in thousands):


	Year Ended December 31,
	2018		2019		2020
Domestic	$	(48,897)	$	(13,464)	$	(42,613)
Foreign	(4,145)		(3,680)		(12,809)
Loss before income taxes	$	(53,042)	$	(17,144)	$	(55,422)

Schedule of components of income tax (expense) benefit

The significant components of income tax (expense) benefit are as follows (in thousands):


	Year Ended December 31,
	2018		2019		2020
Current:
Federal	$	—	$	—	$	—
State	—		—		—
Foreign (1)	—		—		—
Total current	—		—		—
Deferred:
Federal	6,896		1,326		23,062
State	1,264		622		3,744
Foreign	916		222		1,713
Change in uncertain tax positions	(105)		598		(117)
Change in valuation allowance	(8,971)		(2,768)		(28,402)
Total deferred	—		—		—
Income tax benefit	$	—	$	—	$	—

(1)The current income tax (expense) during 2019 and 2020 excludes Indian income tax expense of less than $0.1 million and $0.3 million, respectively.

Schedule of effective tax rate

The following table summarizes the significant differences between the U.S. federal statutory tax rate and our effective tax rate:


	Year Ended December 31,
	2018		2019		2020
Tax benefit at federal statutory rate	21.00	%	21.00	%	21.00	%
State income taxes, net of federal benefit	1.91	%	—	%	—	%
Change in federal and state statutory rate	0.03	%	0.34	%	0.35	%
Foreign rate differential	(0.06)	%	(0.20)	%	(0.62)	%
Other adjustments	(5.97)	%	(5.18)	%	7.36	%
Valuation allowance	(16.91)	%	(16.18)	%	(28.57)	%
Income tax benefit	—	%	(0.22)	%	(0.48)	%

Schedule of deferred income taxes

The significant components of deferred income taxes are as follows (in thousands):


	December 31,
	2019		2020
Net operating loss carry-forwards	$	64,348	$	92,387
Allowance for credit losses	28		94
Depreciation and amortization	(1,321)		(13,601)
Stock-based compensation	2,727		3,769

Deferred costs	2,275		1,462
IRC Section 163(j) interest expense limitation	436		89
Other tax credit carry-forward	1,419		1,771
Other temporary differences	319		20
Valuation allowance	(70,231)		(85,991)
Net long-term deferred tax asset	$	—	$	—

Summary of changes in valuation allowance

The following table presents changes in our valuation allowance (in thousands):


	Year Ended December 31,
	2018		2019		2020
Beginning balance	$	(58,649)	$	(67,463)	$	(70,231)
Allowance for domestic and foreign net operating loss carry-forwards	(9,863)		(3,598)		(26,277)
Rate change on domestic net operating loss carry-forwards	(17)		(32)		(82)
Change in foreign currency	157		—		—
Convertible debt additional paid-in capital tax adjustment - valuation allowance impact	—		—		12,642
Other changes	909		862		(2,043)
Ending balance	$	(67,463)	$	(70,231)	$	(85,991)

Schedule of unrecognized tax benefits activity

The following table summarizes the activity related to our gross unrecognized tax benefits that would affect our effective tax rate, if recognized (in thousands):


	Year Ended December 31,
	2018		2019		2020
Beginning balance	$	678	$	783	$	185
Increase related to current year tax position	105		(598)		117
Ending balance	$	783	$	185	$	302

REDEEMABLE CONVERTIBLE PREFERRED STOCK (Tables)

12 Months Ended

Dec. 31, 2020

Temporary Equity Disclosure [Abstract]

Summary of the change in carrying amount of the outstanding redeemable convertible preferred stock

A summary of the change in carrying amount of the outstanding redeemable convertible preferred stock is as follows (in thousands):


	Series G’ Stock			Series G Stock
	Shares	Amount		Shares	Amount
Balance — December 31, 2017	1,296	$	44,672	346	$	5,110
Accretion of redeemable convertible preferred stock	—	—		—	108
Conversion of preferred stock to common stock	(1,296)	(44,672)		(346)	(5,218)
Balance — December 31, 2018	—	$	—	—	$	—


	Series F-R Stock			Series E-R Stock			Series D-R Stock
	Shares	Amount		Shares	Amount		Shares	Amount
Balance — December 31, 2017	1,199	58,449		795	$	29,972	1,396	$	32,728
Accretion of redeemable convertible preferred stock	—	38		—	1		—	7
Conversion of preferred stock to common stock	(1,199)	(58,487)		(795)	(29,973)		(1,396)	(32,735)
Balance — December 31, 2018	—	$	—	—	$	—	—	$	—


	Series C-R Stock			Series B-R Stock			Series A-R Stock
	Shares	Amount		Shares	Amount		Shares	Amount
Balance — December 31, 2017	1,508	$	18,366	2,247	$	5,288	1,857	$	1,852
Accretion of redeemable convertible preferred stock	—	3		—	—		—	—
Conversion of preferred stock to common stock	(1,508)	(18,369)		(2,247)	(5,288)		(1,857)	(1,852)
Balance — December 31, 2018	—	$	—	—	$	—	—	$	—

COMMON STOCK WARRANTS (Tables)

12 Months Ended

Dec. 31, 2020

Other Liabilities Disclosure [Abstract]

Summary of common stock warrant activity

A summary of common stock warrant activity, exclusive of the common stock warrants issued in connection with our Series G financing is as follows (in thousands, except per share amounts):


	Shares	Weighted-average exercise price per share
Warrants Outstanding - December 31, 2017	600	$	8.11
Granted	644	23.64
Exercised	(349)	4.69
Redeemable convertible preferred stock warrants converted to common stock warrants	110	12.16
Forfeited/canceled	(138)	5.85
Warrants Outstanding - December 31, 2018	867	21.89

Exercised	(821)	21.89

Forfeited/canceled	(34)	21.29
Warrants Outstanding - December 31, 2019	12	23.64

Exercised	(9)	23.64

Forfeited/canceled	(3)	23.64
Warrants Outstanding - December 31, 2020	—	$	—

A summary of our preferred stock warrants is as follows (in thousands, except per share amounts):


Preferred Series	Grant date	Expiration date	Exercise price		December 31, 2017
Series B-R	2/26/2010	2/25/2020	$	2.36	59
Series D-R	9/21/2012	9/20/2022	$	23.64	38
Series D-R	9/21/2012	9/20/2022	$	23.64	13
Total preferred stock warrants					110

FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Schedule of financial assets and liabilities measured at fair value on a recurring basis


	December 31, 2017
	Level 1		Level 2		Level 3		Total
Liabilities:
Preferred stock warrant liabilities(1)	$	—	$	—	$	2,285	$	2,285
Common stock warrant liabilities(1)	—		—		7,945		7,945
Total liabilities	$	—	$	—	$	10,230	$	10,230

(1)Warrant liabilities were zero as of December 31, 2018, 2019 and 2020.

Schedule of reconciliation of the redeemable convertible preferred stock warrant liability


	Preferred Stock Warrant Liabilities		Common Stock Warrant Liabilities
Balance at December 31, 2017	$	2,285	$	7,945

Conversion of redeemable convertible preferred stock warrants to common stock warrants	(1,736)		—


Issuance of common stock warrants	(549)		7,309

Changes in fair value	—		(15,254)
Balance at December 31, 2018	$	—	$	—

Fair value inputs

We determined the fair value of these common warrants on the date of IPO using the Black-Scholes option pricing model, which is affected by the fair value of our common stock as well as the following significant inputs:


			February 8, 2018
Weighted-average grant date fair value			$3.91
Significant inputs:
Value of common stock			$13.00
Expected term			5.3 years
Volatility			50%
Risk-free interest rate			2.0%
Dividend yield			—%

Summary of our preferred stock warrants

A summary of common stock warrant activity, exclusive of the common stock warrants issued in connection with our Series G financing is as follows (in thousands, except per share amounts):


	Shares	Weighted-average exercise price per share
Warrants Outstanding - December 31, 2017	600	$	8.11
Granted	644	23.64
Exercised	(349)	4.69
Redeemable convertible preferred stock warrants converted to common stock warrants	110	12.16
Forfeited/canceled	(138)	5.85
Warrants Outstanding - December 31, 2018	867	21.89

Exercised	(821)	21.89

Forfeited/canceled	(34)	21.29
Warrants Outstanding - December 31, 2019	12	23.64

Exercised	(9)	23.64

Forfeited/canceled	(3)	23.64
Warrants Outstanding - December 31, 2020	—	$	—

A summary of our preferred stock warrants is as follows (in thousands, except per share amounts):


Preferred Series	Grant date	Expiration date	Exercise price		December 31, 2017
Series B-R	2/26/2010	2/25/2020	$	2.36	59
Series D-R	9/21/2012	9/20/2022	$	23.64	38
Series D-R	9/21/2012	9/20/2022	$	23.64	13
Total preferred stock warrants					110

RELATED PARTIES (Tables)

12 Months Ended

Dec. 31, 2020

Schedule of related party transactions

The following table summarizes the participation in the common stock warrants issued in connection with the Series G Stock financing by our directors, executive officers and holders of more than 5% of any class of our capital stock as of the date of such transactions (in thousands):


Related Party						Warrants to Purchase Common Stock
Entities affiliated with Polaris Venture Partners(1)						66
Canaan VIII L.P.(2)						123
Entities affiliated with Mark A. Johnson(3)						80
John Klinck						13
David Adams						7

COMMITMENTS AND CONTINGENCIES (Tables)

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Deferred FI implementation costs

The following table presents changes in deferred FI implementation costs (in thousands):


	December 31,
	2018		2019		2020
Beginning balance	$	13,625	$	15,877	$	8,383
Deferred costs	9,250		—		—
Recoveries through FI Share	(5,380)		(4,625)		—
Amortization	(1,618)		(2,869)		(3,915)
Impairment	—		—		(683)
Ending balance	$	15,877	$	8,383	$	3,785

EARNINGS PER SHARE (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Schedule of antidilutive securities

The following securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive (in thousands):


	December 31,
	2018	2019	2020









Common stock options	1,774	1,000	513
Common stock warrants	867	12	—
Convertible Senior Notes	—	—	2,701


Restricted stock units	381	1,741	2,434


Common stock issuable pursuant to the ESPP	36	7	4

SEGMENTS (Tables)

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Schedule of segment reporting information

The following table provides information regarding our reportable segments (in thousands):


	Year Ended December 31,
	2018		2019		2020
Cardlytics platform:
Adjusted contribution(2)	$	69,364	$	95,219	$	82,182
Plus: FI Share and other third-party costs (1)(2)	79,959		115,211		104,710
Revenue	$	149,323	$	210,430	$	186,892
Other Platform Solutions:
Adjusted contribution(2)	$	86	$	—	$	—
Plus: FI Share and other third-party costs (1)(2)	1,275		—		—
Revenue	$	1,361	$	—	$	—
Total:
Adjusted contribution(2)	$	69,450	$	95,219	$	82,182
Plus: FI Share and other third-party costs (1)(2)	81,234		115,211		104,710
Revenue	$	150,684	$	210,430	$	186,892

The following table presents a reconciliation of loss before income taxes presented in accordance with GAAP to adjusted contribution (in thousands):


	Year Ended December 31,
	2018		2019		2020
Adjusted contribution(1)(2)(3)	$	69,450	$	95,219	$	82,182
Minus:
Non-cash equity expense included in FI Share(1)	2,519		—		—
Deferred FI implementation costs(3)	1,618		2,869		4,598
Delivery costs	10,632		12,893		14,310
Sales and marketing expense	41,878		43,828		45,307
Research and development expense	16,210		11,699		17,532
General and administration expense	34,228		36,720		46,532
Depreciation and amortization expense	3,282		4,535		7,826

Total non-operating expense (income)	12,125		(181)		1,499
Loss before income taxes	$	(53,042)	$	(17,144)	$	(55,422)

(3)Deferred FI implementation costs for 2020 includes the impact of a $0.7 million write off related to certain platform features.

Schedule of revenue by geographic areas

The following tables provide geographical information (in thousands):


	Year Ended December 31,
	2018		2019		2020
Revenue:
United States	$	131,563	$	186,864	$	172,808
United Kingdom	19,121		23,566		14,084
Total	$	150,684	$	210,430	$	186,892


	December 31,
	2019		2020
Property and equipment:
United States	$	12,052	$	9,549
United Kingdom	2,010		4,162
India	228		154
Total	$	14,290	$	13,865

NATURE OF OPERATIONS (Details) - USD ($)						12 Months Ended
NATURE OF OPERATIONS (Details) - USD ($)	Sep. 11, 2019	Feb. 14, 2018	Feb. 14, 2018	Feb. 13, 2018	Jan. 26, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Proceeds from issuance of common stock, threshold					$ 70,000,000.0
Common stock, shares authorized (in shares)					100,000,000	100,000,000
Par value (in usd per share)					$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, par or stated value per share (in usd per share)						$ 0.0001
Shares authorized (in shares)					25,000,000
Sale of stock, number of shares issued in transaction (in shares)	1,904,154	421,355	5,821,355
Proceeds from IPO		$ 5,500,000	$ 75,700,000
Proceeds from IPO, net			66,100,000
Sale of stock, discounts and commissions			5,300,000
Issuance costs	$ 200,000		$ 4,300,000			$ 0	$ 196,000	$ 4,279,000
Preferred stock, shares authorized (in shares)							10,000,000
Proceeds from Issuance Seconday Public Offering, Net	$ 61,300,000
Debt instrument, face amount						$ 230,000,000.0
Debt Instrument, Interest Rate, Stated Percentage						1.00%
IPO
Debt Instrument [Line Items]
Sale of stock, number of shares issued in transaction (in shares)				5,400,000
Sale of stock, price per share (in usd per share)				$ 13.00
Proceeds from IPO				$ 70,200,000
Over-Allotment Option
Debt Instrument [Line Items]
Sale of stock, number of shares issued in transaction (in shares)	404,154	810,000
SPO
Debt Instrument [Line Items]
Sale of stock, discounts and commissions	$ 3,200,000
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised	1,194,365
Share-based Compensation Arrangement by Share-based Payment Award, Option, Nonvested, Weighted Average Exercise Price	$ 34.00

SIGNIFICANT ACCOUNTING POLICIES - Revenue (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Concentration Risk [Line Items]
Capitalized software development costs, net	$ 6,299	$ 3,815

SIGNIFICANT ACCOUNTING POLICIES - Accounts Receivable (Details) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning balance	$ 255	$ 169	$ 105
Credit loss expense	1,196	1,201	130
Write-offs, net of recoveries	(864)	(1,115)	(66)
Ending balance	587	255	169
Unbilled receivables	$ 500	$ 600	$ 400

SIGNIFICANT ACCOUNTING POLICIES - Intangible Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) patent	Dec. 31, 2019 USD ($) patent	Dec. 31, 2014 patent	Dec. 31, 2018 USD ($)
Accounting Policies [Abstract]
Number of patents \| patent	4	1	3
Finite-lived intangible assets, not yet capitalized		$ 300		$ 300
Deferred patent costs, gross	$ 518	448
Less accumulated amortization	(71)	(59)
Deferred patent costs, net	$ 447	$ 389

SIGNIFICANT ACCOUNTING POLICIES - Capitalized Software (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Capitalized Computer Software, Gross	$ 9,230	$ 5,537
Less accumulated amortization	(2,931)	(1,722)
Capitalized software development costs, net	$ 6,299	$ 3,815

SIGNIFICANT ACCOUNTING POLICIES - Debt Issuance Costs (Details) - USD ($) $ in Thousands		12 Months Ended
	Sep. 22, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 21, 2018
Debt Instrument [Line Items]
Debt issuance costs, gross	$ 1,680
Loss on extinguishment of debt			$ 900
Amortization of financing costs charged to interest expense		$ 312	95	$ 282
Debt issuance costs, net	5,379
2019		909
2020		1,006
Debt Issuance Costs Amortization, Year Three		1,151
Debt Issuance Costs Amortization, Year Four		1,312
Debt Issuance Costs Amortization, Year Five		1,036
Total		5,414
Accretion of debt discount and non-cash interest expense	$ 217	2,486	0	$ 2,326
Lines of credit
Debt Instrument [Line Items]
Debt issuance costs, gross		412	388
Less accumulated amortization		(377)	(271)
Debt issuance costs, net		35	117
Term loans
Debt Instrument [Line Items]
Debt issuance costs, gross		5,596	0
Less accumulated amortization		(217)	0
Debt issuance costs, net		$ 5,379	$ 0
2016 Line of Credit and 2016 Term Loan
Debt Instrument [Line Items]
Debt issuance costs, net					$ 100

SIGNIFICANT ACCOUNTING POLICIES - Deferred Offering Costs (Details) - USD ($) $ in Thousands			12 Months Ended
	Sep. 11, 2019	Feb. 14, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred Financial Institution Costs [Roll Forward]
Beginning balance			$ 0	$ 0	$ 3,144
Deferred costs			0	196	1,135
Recognized against offering proceeds	$ (200)	$ (4,300)	0	(196)	(4,279)
Ending balance			$ 0	$ 0	$ 0

SIGNIFICANT ACCOUNTING POLICIES - Advertising costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Advertising expense	$ 1.0	$ 1.4	$ 0.9

ACCOUNTING STANDARDS (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets under operating leases, net	$ 10,764	$ 10,300		$ 0
Operating Lease, Liability	$ 14,099	$ 13,500
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets under operating leases, net			$ 10,300
Operating Lease, Liability			$ 13,500

REVENUE (Details) - USD ($) $ in Thousands	12 Months Ended
REVENUE (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consumer incentives, expense	$ 76,500	$ 105,600	$ 68,300
Revenue from Contract with Customer, Excluding Assessed Tax	186,892	210,430	150,684
Cost per Served Sales [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	131,045	143,754	101,087
Cost per Redemption [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	53,838	63,295	43,389
Cost Other [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 2,009	$ 3,381	$ 6,208

LEASES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
LEASES - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Liability	$ 14,099	$ 13,500
Right-of-use assets under operating leases, net	10,764	10,300	$ 0
Deferred Rent Credit		$ 3,200
Operating Lease, Modification	$ 2,200

LEASES - Lease Information (Details) $ in Thousands	12 Months Ended
LEASES - Lease Information (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Leases [Abstract]
Operating Lease, Expense	$ 4,078
Variable Lease, Cost	847
Short-term Lease, Cost	$ 232
Lease, Weighted Average Discount Rate, Percent	3.40%
Lease, Weighted Average Remaining Lease Term	3 years 3 months

LEASES - Maturity of Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Mar. 31, 2020
Leases [Abstract]
2021	$ 5,097
2022	4,681
2023	2,692
2024	1,807
2025	611
Total lease payments	14,888
Imputed interest	789
Operating Lease, Liability	$ 14,099	$ 13,500

LEASES - Future Payments for Operating Leases (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Leases [Abstract]
2020	$ 3,040
2021	2,759
2022	2,808
2023	1,847
2024	1,807
Thereafter	611
Total	$ 12,872

PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 35,112	$ 30,911
Less accumulated depreciation	(21,247)	(16,621)
Property, Plant and Equipment, Net	13,865	14,290
Finance lease assets, gross	557	1,096
Less accumulated depreciation	(548)	(1,067)
Finance lease assets, net	9	29
Depreciation expense	5,600	4,000	$ 3,000
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	27,105	21,269
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	6,770	6,960
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,112	1,557
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 125	$ 1,125

DEBT AND FINANCING ARRANGEMENTS - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 22, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Convertible senior notes, net	$ 174,011		$ 0
Long-term finance lease liabilities	0		13
Debt and Lease Obligation	174,024		37
Less current portion of long-term debt	(13)		(24)
Long-term debt, net of current portion	174,011		13
Debt issuance costs, net		$ 5,379
Finance leases
Debt Instrument [Line Items]
Long-term finance lease liabilities	$ 13		$ 37

DEBT AND FINANCING ARRANGEMENTS - Narrative (Details)		12 Months Ended
DEBT AND FINANCING ARRANGEMENTS - Narrative (Details)	Sep. 22, 2020 USD ($) numberOfDays $ / shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	May 31, 2019 USD ($)	May 14, 2019 USD ($)	May 21, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jul. 31, 2016 USD ($)
Debt Instrument [Line Items]
Cash paid for interest		$ 63,000	$ 1,266,000	$ 9,733,000
Debt instrument, face amount		$ 230,000,000.0
Debt issuance costs, gross	$ 1,680,000
Debt issuance costs, net	$ 5,379,000
Maximum borrowing capacity, percentage of accounts receivable		85.00%
Repayments of lines of credit		$ 23,000	46,698,000	52,581,000
Loss on extinguishment of debt			900,000
Debt Instrument, Interest Rate, Stated Percentage		1.00%
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger	130.00%
Debt Instrument, Convertible, Conversion Ratio	11.7457
Conversion Price (in usd per share) \| $ / shares	$ 85,140
Debt Instrument, Redemption Price, Percentage	100.00%
Proceeds from issuance of convertible senior notes	$ 222,700,000	$ 223,100,000	0	$ 0
Debt Instrument, Call Feature	26.5 million
Debt Instrument, Convertible, Threshold Consecutive Trading Days \| numberOfDays	30,000
Long-term finance lease liabilities		0	13,000
Lines of credit
Debt Instrument [Line Items]
Line Of Credit Facility, Covenant, Minimum 12 Month Revenue		210,000,000.0
Line of Credit Facility, Maximum Month-end Outstanding Amount		255,000,000.0
2016 Line of Credit and 2016 Term Loan
Debt Instrument [Line Items]
Debt issuance costs, net							$ 100,000
Lines of credit
Debt Instrument [Line Items]
Debt issuance costs, gross		412,000	388,000
Debt issuance costs, net		$ 35,000	117,000
Debt instrument, interest rate		2.75%
Commitment fee percentage		0.15%
Debt instrument, interest rate increase event of default		3.00%
Debt Instrument, Annual Principal Payment					$ 10,000,000.0
Long-term finance lease liabilities							27,400,000
Lines of credit \| Loan Facility, Threshold Two \| Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.50%
Lines of credit \| 2016 Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity								$ 50,000,000.0
Loss on extinguishment of debt			100,000
Term loans
Debt Instrument [Line Items]
Debt instrument, face amount							20,000,000.0
Debt issuance costs, gross		$ 5,596,000	0
Debt issuance costs, net		$ 5,379,000	0
Debt instrument, interest rate		2.00%
Debt Instrument, Unamortized Premium, Current						$ 10,000,000.0
Term loans \| Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate		2.75%
Term loans \| 2016 Term Loan
Debt Instrument [Line Items]
Debt instrument, face amount									$ 24,000,000.0
Loss on extinguishment of debt			800,000
Finance leases
Debt Instrument [Line Items]
Long-term finance lease liabilities		$ 13,000	$ 37,000
Revolving Credit Facility \| Lines of credit
Debt Instrument [Line Items]
Maximum borrowing capacity							$ 30,000,000.0
Line of Credit, Current						$ 40,000,000.0

DEBT AND FINANCING ARRANGEMENTS - Net Carrying Amount of Liability Component (Details) $ in Thousands	Sep. 22, 2020 USD ($)
Debt Disclosure [Abstract]
Long-term Debt, Gross	$ 230,000
Minus: Unamortized debt discount	(50,610)
Minus: Unamortized issuance costs	(5,379)
Long-term Debt	$ 174,011

DEBT AND FINANCING ARRANGEMENTS - Net Carrying Amount of Equity Component (Details) - USD ($) $ in Thousands		12 Months Ended
	Sep. 22, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Debt Instrument, Convertible, Carrying Amount of Equity Component	$ 53,096
Debt Issuance Costs, Gross	(1,680)
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments	$ 51,416	$ 12,642	$ 0	$ 0

DEBT AND FINANCING ARRANGEMENTS - Interest Expense Recognition (Details) - USD ($) $ in Thousands		12 Months Ended
	Sep. 22, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Interest Expense, Debt, Excluding Amortization	$ 626
Amortization of Debt Discount (Premium)	2,486
Accretion of debt discount and non-cash interest expense	217	$ 2,486	$ 0	$ 2,326
Interest Expense, Debt	$ 3,329

DEBT AND FINANCING ARRANGEMENTS - Future Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 22, 2020
Long-term Debt, Fiscal Year Maturity [Abstract]
Less unamortized debt issuance costs		$ (5,379)
Finance leases
2019	$ 13
Total principal payments	$ 13
Total debt
Less unamortized debt issuance costs		$ (5,379)

STOCK-BASED COMPENSATION - Narrative (Details) $ / shares in Units, $ in Thousands				1 Months Ended		2 Months Ended	3 Months Ended		12 Months Ended
	Jan. 01, 2020 shares	Jan. 01, 2019 shares	Feb. 08, 2018 $ / shares shares	Aug. 31, 2018 shares	Feb. 28, 2018 USD ($)	Mar. 01, 2021 USD ($) shares	Dec. 31, 2019 USD ($) user shares	Mar. 31, 2019 tranche shares	Dec. 31, 2020 USD ($) user shares	Dec. 31, 2019 USD ($) user shares	Dec. 31, 2018 shares	Dec. 31, 2017 USD ($) shares	Jan. 31, 2018 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Document Period End Date									Dec. 31, 2020
Number of shares authorized (in shares)			1,875,000
Number of shares remaining available for issuance (in shares)			61,247
Number of shares authorized, annual increase									5.00%
Number of additional shares authorized (in shares)	1,393,040	1,222,316
Amounts accrued for capitalized software development costs \| $									$ 100
Expiration period									10 years
Weighted-average grant date fair value (in usd per share) \| $ / shares			$ 3.91
Options vested in period, fair value \| $									$ 4,800	$ 6,000
Issuance of ESPP (in shares)	278,608,000								474,120
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized									2 years 9 months 18 days
Granted (in shares)									1,758,000	1,978,000	1,309,000
Unvested PSU (in shares)							1,741,000		2,434,000	1,741,000	381,000	0
Forfeited, prior to FI MAU (in shares)									286,000	132,000	78,000
Vested (in shares)									779,000	486,000	850,000
Compensation not yet recognized, awards other than options \| $							$ 20,400		$ 61,630	$ 20,400
Awards granted \| $												$ 1,000
Restricted stock units \| Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)									1,233,617	725,832
Performance-based restricted share unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of tranches \| tranche								2
Granted (in shares)								437,500
Unvested PSU (in shares)							875,000		1,252,500	875,000
Vested (in shares)							850,000
Performance-based restricted share unit \| Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award, performance conditions \| user							70,000,000.0		0.50	70,000,000.0
Forfeited, prior to FI MAU (in shares)										25,000
Performance-based restricted share unit \| Share-based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award, performance conditions \| user							85,000,000.0		0.25	85,000,000.0
Stock option expense \| $									$ 18,600
Restricted securities units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU, service condition period										6 months
Award period for sale of company or IPO										5 years
Stock option expense \| $					$ 500
Stock issued during period, RSU (in shares)				37,406
Common stock issuable pursuant to the ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized, annual increase							1.00%			1.00%
Purchase price of common stock, percent			85.00%
ESPP, number of shares authorized, annual increase (in shares)							500,000			500,000
2008 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)													4,020,000
Subsequent Event \| Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)						52,322
Compensation not yet recognized, awards other than options \| $						$ 6,400

STOCK-BASED COMPENSATION - Allocation of Stock-based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jun. 28, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Monthly Average Closing Price, Common Stock, Threshold	$ 142.77
Total stock-based compensation expense		$ 32,396	$ 15,851	$ 26,790
Delivery costs
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense		1,181	711	633
Sales and marketing expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense		9,857	4,248	9,358
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense		4,713	1,619	4,087
General and administration expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense		$ 16,645	$ 9,273	$ 12,712

STOCK-BASED COMPENSATION - Summary of Common Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Shares
Beginning balance (in shares)	1,000	1,774	2,514
Granted (in shares)	0	39	29
Exercised (in shares)	(467)	(716)	(357)
Forfeited (in shares)	(19)	(31)	(197)
Canceled (in shares)	(1)	(66)	(215)
Ending balance (in shares)	513	1,000	1,774
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Number of Exercisable Options	480
Weighted-Average Exercise Price
Beginning balance (in usd per share)	$ 22.99	$ 20.55	$ 18.42
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	0	20.64	24.24
Exercised (in usd per share)	21.78	16.84	6.25
Forfeited (in usd per share)	27.83	23.95	24.10
Canceled (in usd per share)	21.89	22.37	16.60
Ending balance (in usd per share)	23.91	$ 22.99	$ 20.55
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price	$ 23.72
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	$ 29,523
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	61,009
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value	$ 57,126
Employee Stock Option [Member]
Weighted-Average Exercise Price
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	5 years 7 months 13 days

STOCK-BASED COMPENSATION - Summary of RSU Activity (Details) $ / shares in Units, $ in Thousands	1 Months Ended	2 Months Ended	3 Months Ended		12 Months Ended
	Feb. 28, 2018 USD ($)	Mar. 01, 2021 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) user $ / shares shares	Mar. 31, 2019 $ / shares shares	Dec. 31, 2020 USD ($) user $ / shares shares	Dec. 31, 2019 USD ($) user $ / shares shares	Dec. 31, 2018 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value \| $					$ 57,126
Document Period End Date					Dec. 31, 2020
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value \| $					$ 347,500
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition					2 years 9 months 18 days
Shares
Unvested — Beginning balance (in shares)		2,434,000		381,000	1,741,000	381,000	0
Granted (in shares)					1,758,000	1,978,000	1,309,000
Vested (in shares)					(779,000)	(486,000)	(850,000)
Forfeited (in shares)					(286,000)	(132,000)	(78,000)
Unvested — Ending balance (in shares)			1,741,000		2,434,000	1,741,000	381,000
Weighted-Average Grant Date Fair Value
Unvested — Beginning balance (in usd per share) \| $ / shares		$ 32.49		$ 18.11	$ 18.55	$ 18.11	$ 0
Granted (in usd per share) \| $ / shares					43.07	17.78	20.58
Vested (in usd per share) \| $ / shares					28.56	14.97	21.93
Forfeited (in usd per share) \| $ / shares					23.34	18.92	17.97
Unvested — Ending balance (in usd per share) \| $ / shares			$ 18.55		$ 32.49	$ 18.55	$ 18.11
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options \| $			$ 20,400		$ 61,630	$ 20,400
Performance Shares [Member]
Shares
Unvested — Beginning balance (in shares)		1,252,500			875,000
Granted (in shares)				437,500
Vested (in shares)			(850,000)
Unvested — Ending balance (in shares)			875,000		1,252,500	875,000
Restricted securities units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock or Unit Option Plan Expense \| $	$ 500
Subsequent Event \| Restricted stock units
Shares
Granted (in shares)		52,322
Weighted-Average Grant Date Fair Value
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options \| $		$ 6,400
Share-based Compensation Award, Tranche Three [Member] \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Performance Conditions \| user					0.25
Share-based Compensation Award, Tranche Two \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Performance Conditions \| user			85,000,000.0		0.25	85,000,000.0
Stock or Unit Option Plan Expense \| $					$ 18,600
Share-based Compensation Award, Tranche One \| Restricted stock units
Shares
Granted (in shares)					1,233,617	725,832
Share-based Compensation Award, Tranche One \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Performance Conditions \| user			70,000,000.0		0.50	70,000,000.0
Shares
Forfeited (in shares)						(25,000)

INCOME TAXES - Domestic and Foreign Components (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Domestic	$ (42,613)	$ (13,464)	$ (48,897)
Foreign	(12,809)	(3,680)	(4,145)
Loss before income taxes	$ (55,422)	$ (17,144)	$ (53,042)

INCOME TAXES - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ 0	$ 0	$ 0
State	0	0	0
Foreign (1)	0	0	0
Total current	0	0	0
Deferred:
Federal	23,062	1,326	6,896
State	3,744	622	1,264
Foreign	1,713	222	916
Change in uncertain tax positions	(117)	598	(105)
Change in valuation allowance	(28,402)	(2,768)	(8,971)
Total deferred	0	0	0
Income tax benefit	$ 0	$ 0	$ 0

INCOME TAXES - Effective Income Tax Rate (Details)	12 Months Ended
INCOME TAXES - Effective Income Tax Rate (Details)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Tax benefit at federal statutory rate	21.00%	21.00%	21.00%
State income taxes, net of federal benefit	0.00%	0.00%	1.91%
Change in federal and state statutory rate	0.35%	0.34%	0.03%
Foreign rate differential	(0.62%)	(0.20%)	(0.06%)
Other adjustments	7.36%	(5.18%)	(5.97%)
Valuation allowance	(28.57%)	(16.18%)	(16.91%)
Income tax benefit	(0.48%)	(0.22%)	0.00%

INCOME TAXES - Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Net operating loss carry-forwards	$ 92,387	$ 64,348
Allowance for credit losses	94	28
Depreciation and amortization	(13,601)	(1,321)
Stock-based compensation	3,769	2,727
Change in fair value of convertible promissory notes	1,462	2,275
IRC Section 163(j) interest expense limitation	89	436
Other tax credit carry-forward	1,771	1,419
Other temporary differences	20	319
Valuation allowance	(85,991)	(70,231)	$ (67,463)	$ (58,649)
Net long-term deferred tax asset	$ 0	$ 0

INCOME TAXES - Change in Valuation Allowance (Details) - USD ($) $ in Thousands		12 Months Ended
	Sep. 22, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation Allowance [Roll Forward]
Beginning balance		$ (70,231)	$ (67,463)	$ (58,649)
Allowance for domestic and foreign net operating loss carry-forwards		(26,277)	(3,598)	(9,863)
Rate change on domestic net operating loss carry-forwards		(82)	(32)	(17)
Change in foreign currency		0	0	157
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments	$ 51,416	12,642	0	0
Other changes		(2,043)	862	909
Ending balance		$ (85,991)	$ (70,231)	$ (67,463)

INCOME TAXES - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Tax credits	$ 1,400	$ 1,300	$ 700
Cash and cash equivalents	293,239	104,458	$ 39,623
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	371,200	266,800
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	155,800	98,400
Foreign
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 25,700	$ 12,100

INCOME TAXES - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 185	$ 783	$ 678
Increase related to current year tax position	(117)	(598)	(105)
Ending balance	$ 302	$ 185	$ 783

REDEEMABLE CONVERTIBLE PREFERRED STOCK - Outstanding Stock (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Aug. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Series G and Series G’ Stock (in shares)		(779,000)	(1,904,000)	(5,821,000)
Document Period End Date		Dec. 31, 2020
Series G’ Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)			0
Beginning balance			$ 0
Ending balance (in shares)				0
Ending balance				$ 0
Series G Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)			0
Beginning balance			$ 0
Conversion of preferred stock to common stock (in shares)	(792,434)
Ending balance (in shares)				0
Ending balance				$ 0
Series F-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)			0	1,199,000
Beginning balance			$ 0	$ 58,449
Conversion of preferred stock to common stock				$ (38)
Ending balance (in shares)				0
Ending balance				$ 0
Series E-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)			0	795,000
Beginning balance			$ 0	$ 29,972
Ending balance (in shares)				0
Ending balance				$ 0
Temporary Equity, Accretion to Redemption Value				$ 1
Series D-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)			0	1,396,000
Beginning balance			$ 0	$ 32,728
Ending balance (in shares)				0
Ending balance				$ 0
Temporary Equity, Accretion to Redemption Value				$ 7
Series C-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)			0	1,508,000
Beginning balance			$ 0	$ 18,366
Ending balance (in shares)				0
Ending balance				$ 0
Temporary Equity, Accretion to Redemption Value				$ 3
Series B-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)			0	2,247,000
Beginning balance			$ 0	$ 5,288
Ending balance (in shares)				0
Ending balance				$ 0
Temporary Equity, Accretion to Redemption Value				$ 0
Series A-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)			0	1,857,000
Beginning balance			$ 0	$ 1,852
Ending balance (in shares)				0
Ending balance				$ 0
Temporary Equity, Accretion to Redemption Value				$ 0

REDEEMABLE CONVERTIBLE PREFERRED STOCK - Financing and Issuances (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Aug. 31, 2018	May 31, 2017	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 22, 2020	Aug. 08, 2018	Jan. 26, 2018	May 31, 2013
Temporary Equity [Line Items]
Shares authorized (in shares)								25,000,000
Shares authorized (in shares)			100,000,000					100,000,000
Issuance costs			$ 0	$ 196	$ 1,949
Conversion Price (in usd per share)						$ 85,140
Exercise price of warrants (in usd per share)									$ 23.64
Exercise of common stock warrants (in shares)			0	17,659,000
Issuance of Series G and Series G’ Stock (in shares)			779,000	1,904,000	5,821,000
Series G Stock
Temporary Equity [Line Items]
Shares issued (in shares)		346,334
Class of warrant, numerator input value (in usd per share)		$ 68.9516
Exercise price of warrants (in usd per share)	$ 0.0004						$ 0.0004
Exercise of common stock warrants (in shares)	792,434
Issuance of stock	$ 15,300
Additional Paid-In Capital
Temporary Equity [Line Items]
Exercise of common stock warrants (in shares)			0	17,659,000
Common stock
Temporary Equity [Line Items]
Exercise of common stock warrants (in shares)			9,000	821,000	1,142,000
Issuance of Series G and Series G’ Stock (in shares)				486,000	888,000

REDEEMABLE CONVERTIBLE PREFERRED STOCK - Protective Provisions, Redemptions, Liquidation and Conversion (Details)	Dec. 31, 2020 $ / shares
Series G’ Stock
Temporary Equity [Line Items]
Redemption price per share (in usd per share)	$ 34.4758
Liquidation of business payment per share (in usd per share)	34.4758
Liquidation preference (in usd per share)	103.4274
Series G Stock
Temporary Equity [Line Items]
Redemption price per share (in usd per share)	34.4758
Liquidation of business payment per share (in usd per share)	68.9516
Liquidation preference (in usd per share)	103.4274
Series F-R Stock
Temporary Equity [Line Items]
Redemption price per share (in usd per share)	58.40
Liquidation of business payment per share (in usd per share)	58.40
Liquidation preference (in usd per share)	175.20
Conversion price (in usd per share)	50.0568
Series E-R Stock
Temporary Equity [Line Items]
Redemption price per share (in usd per share)	37.7344
Liquidation of business payment per share (in usd per share)	37.7344
Liquidation preference (in usd per share)	113.2032
Conversion price (in usd per share)	37.7344
Series D-R Stock
Temporary Equity [Line Items]
Redemption price per share (in usd per share)	23.64
Liquidation of business payment per share (in usd per share)	23.64
Liquidation preference (in usd per share)	70.92
Conversion price (in usd per share)	23.64
Series C-R Stock
Temporary Equity [Line Items]
Redemption price per share (in usd per share)	12.2686
Liquidation of business payment per share (in usd per share)	21.4701
Liquidation preference (in usd per share)	36.8058
Conversion price (in usd per share)	12.2686
Series B-R Stock
Temporary Equity [Line Items]
Redemption price per share (in usd per share)	2.3567
Liquidation of business payment per share (in usd per share)	2.3567
Liquidation preference (in usd per share)	4.7134
Conversion price (in usd per share)	2.3567
Series A-R Stock
Temporary Equity [Line Items]
Liquidation of business payment per share (in usd per share)	1.00
Liquidation preference (in usd per share)	2.00
Conversion price (in usd per share)	1.00
Series G Stock and G’ Stock
Temporary Equity [Line Items]
Conversion price (in usd per share)	$ 34.4758

COMMON STOCK WARRANTS - Warrant Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Shares
Warrants outstanding, beginning balance (in shares)		110,000
Exercised (in shares)	(644,365)
Warrants outstanding, ending balance (in shares)			110,000
Weighted-average exercise price per share
Redeemable convertible preferred stock warrants converted to common stock warrants (in dollars per share)		$ 12.16	$ 110,000
Common Stock Warrants
Shares
Warrants outstanding, beginning balance (in shares)	12,000	867,000	600,000
Granted (in shares)			644,000
Exercised (in shares)	(9,000)	(821,000)	(349,000)
Forfeited/cancelled (in shares)	(3,000)	(34,000)	(138,000)
Warrants outstanding, ending balance (in shares)	0	12,000	867,000	600,000
Weighted-average exercise price per share
Warrants outstanding, beginning balance (in dollars per share)	$ 23.64	$ 21.89	$ 8.11
Granted (in dollars per share)			23.64
Exercised (in dollars per share)	23.64	21.89	4.69
Forfeited/cancelled (in dollars per share)	23.64	21.29	5.85
Warrants outstanding, ending balance (in dollars per share)	$ 0	$ 23.64	$ 21.89	$ 8.11
Performance-based Warrants
Shares
Redeemable convertible preferred stock warrants converted to common stock warrants (in shares)				644,365

COMMON STOCK WARRANTS - Narrative (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2020	May 31, 2013
Class of Warrant or Right [Line Items]
Class of warrant (in shares)		110,000			644,365
Exercise price of warrants converted (in dollars per share)	$ 12.16	$ 110,000
Common Stock Warrants
Class of Warrant or Right [Line Items]
Class of warrant (in shares)	12,000	867,000	600,000	0
Warrants issued/granted (in shares)		644,000
Exercise price of warrants issued/granted (in dollars per share)		$ 23.64
Performance-based Warrants
Class of Warrant or Right [Line Items]
Warrants converted (in shares)			644,365

FAIR VALUE MEASUREMENTS - Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability	$ 0
Convertible Debt, Fair Value Disclosures		$ 10,230
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible Debt, Fair Value Disclosures		0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible Debt, Fair Value Disclosures		0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible Debt, Fair Value Disclosures		10,230
Preferred Stock Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		2,285
Preferred Stock Warrants \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		0
Preferred Stock Warrants \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		0
Preferred Stock Warrants \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		2,285
Common Stock Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		7,945
Common Stock Warrants \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		0
Common Stock Warrants \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		0
Common Stock Warrants \| Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability		$ 7,945

FAIR VALUE MEASUREMENTS - Instruments Recorded at Fair Value Using Level 3 Inputs (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Preferred Stock Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 2,285
Exercise/Conversion to common stock	(1,736)
Changes in fair value	(549)
Fair value, ending balance	0
Common Stock Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	7,945
Issuance of stock	7,309
Changes in fair value	(15,254)
Fair value, ending balance	$ 0

FAIR VALUE MEASUREMENTS - Preferred Stock Warrants (Details) - $ / shares	Dec. 31, 2020	Dec. 31, 2018	May 31, 2013
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)			$ 23.64
Class of warrant (in shares)		110,000	644,365
Series B-R Stock \| Grant One
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)	$ 2.36
Class of warrant (in shares)		59,000
Series D-R Stock \| Grant One
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)	23.64
Class of warrant (in shares)		38,000
Series D-R Stock \| Grant Two
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)	$ 23.64
Class of warrant (in shares)		13,000

FAIR VALUE MEASUREMENTS - Narrative (Details) $ / shares in Units, $ in Thousands	1 Months Ended			12 Months Ended
	Aug. 31, 2018 USD ($) $ / shares shares	Feb. 28, 2018 USD ($)	May 31, 2013 $ / shares shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) $ / shares shares	Aug. 08, 2018 $ / shares	Feb. 08, 2018 $ / shares	May 31, 2017 USD ($) shares
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value per share (in usd per share) \| $ / shares								$ 13.00
Fair value of warrants issued				$ 0
Exercise price of warrants (in usd per share) \| $ / shares			$ 23.64
Exercise of common stock warrants (in shares) \| shares				0	17,659,000
Change in fair value of warrant liabilities, net				$ 0	$ 0	$ (6,760)
Class of warrant (in shares) \| shares			644,365			110,000
Warrant, term			10 years
Common Stock Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrants issued						$ 7,945
Liability value					0	7,945
Stock option expense		$ 2,500
Preferred Stock Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of warrants issued						2,285
Liability value					$ 0	$ 2,285
Series B-R Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value per share (in usd per share) \| $ / shares						$ 26.80		20.18
Series D-R Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value per share (in usd per share) \| $ / shares						$ 13.63		$ 10.57
Series G Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Shares issued (in shares) \| shares									346,334
Exercise price of warrants (in usd per share) \| $ / shares	$ 0.0004						$ 0.0004
Liability value									$ 7,500
Exercise of common stock warrants (in shares) \| shares	792,434
Conversion of securities to common stock (in shares) \| shares	792,434
Issuance of stock	$ 15,300
Change in fair value of warrant liabilities, net				$ 7,300
Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant inputs								0.50
Volatility \| Series G Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant inputs									0.59
Measurement Input, Discount for Lack of Marketability [Member] \| Series G Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant inputs			0.11

FAIR VALUE MEASUREMENTS - Warrants Pricing Model (Details)	Feb. 08, 2018 $ / shares
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Weighted-average grant date fair value (in usd per share)	$ 3.91
Value of common stock (in usd per share)	$ 13.00
Expected term	5 years 3 months 18 days
Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant inputs	0.50
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant inputs	0.020
Dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant inputs	0

RELATED PARTIES - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			12 Months Ended
	Aug. 31, 2018	Feb. 28, 2018	May 31, 2013	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Aug. 08, 2018
Related Party Transaction [Line Items]
Debt instrument, face amount				$ 230,000
Issuance of Series G and Series G’ Stock (in shares)				779,000	1,904,000	5,821,000
Warrant, term			10 years
Class of warrant (in shares)			644,365			110,000
Exercise price of warrants (in usd per share)			$ 23.64
Series G Stock
Related Party Transaction [Line Items]
Exercise price of warrants (in usd per share)	$ 0.0004						$ 0.0004
Conversion to common stock (in shares)	792,434
Series E
Related Party Transaction [Line Items]
Issuance of Series G and Series G’ Stock (in shares)			397,515
Common Stock Warrants
Related Party Transaction [Line Items]
Stock option expense		$ 2,500
Stockholders' Equity \| Shareholder Concentration Risk
Related Party Transaction [Line Items]
Concentration risk					5.00%

RELATED PARTIES - Series G / Series G’ (Details) - shares	Dec. 31, 2020	Dec. 31, 2018	May 31, 2013
Related Party Transaction [Line Items]
Class of warrant (in shares)		110,000	644,365
Series G Stock
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Series G’ Stock
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Polaris Venture Partners \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	66,000
Canaan VIII L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	123,000
Entities affiliated with Mark A. Johnson \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	80,000
Mark A. Johnson \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	13,273
John Klinck \| Director
Related Party Transaction [Line Items]
Class of warrant (in shares)	13,000
David Adams \| Director
Related Party Transaction [Line Items]
Class of warrant (in shares)	7,000
Polaris Venture Partners V, L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	64,038
Polaris Venture Partners Entrepreneurs’ Fund V, L.L. \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	1,247
Polaris Venture Partners Founders’ Fund V, L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	438
Polaris Venture Partners Special Founders’ Fund V, L.P. \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	641
TTV Ivy Holdings, LLC \| Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)	66,365

RELATED PARTIES - Agreements with Aimia Inc. and Affiliated Entities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) shares
Related Party Transaction [Line Items]
Proceeds from Warrant Exercises \| $	$ 15.2
Class of Warrant or Right, Exercised \| shares	644,365

COMMITMENTS AND CONTINGENCIES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Financial institution partners, payments to partners, not yet earned	$ 1,000
Decrease to FI share liability	4,499	$ (14,301)	$ (3,742)
Financial Institution Share Commitment
Loss Contingencies [Line Items]
FI share commitment	$ 10,000

COMMITMENTS AND CONTINGENCIES - Deferred FI Implementation Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred Financial Institution Costs [Roll Forward]
Beginning balance	$ 8,383	$ 15,877	$ 13,625
Deferred costs	0	0	9,250
Recoveries through FI Share	0	(4,625)	(5,380)
Amortization	(3,915)	(2,869)	(1,618)
Impairment of Ongoing Project	(683)	0	0
Ending balance	$ 3,785	$ 8,383	$ 15,877

COMMITMENTS AND CONTINGENCIES - Payments to FI Partners (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2021	$ 2,800

EARNINGS PER SHARE (Details) - shares shares in Thousands	12 Months Ended
EARNINGS PER SHARE (Details) - shares shares in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	513	1,000	1,774
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	12	867
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	2,434	1,741	381
Common stock issuable pursuant to the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	4	7	36
Senior Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	2,701	0	0

SEGMENTS - Narrative (Details) $ in Thousands	12 Months Ended
SEGMENTS - Narrative (Details) $ in Thousands	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments \| segment	3
Capital expenditures	$ 5,408	$ 8,277	$ 5,920
United Kingdom
Segment Reporting Information [Line Items]
Capital expenditures	$ 2,800	$ 2,000

SEGMENTS - Revenue by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Adjusted Contribution	$ 82,182	$ 95,219	$ 69,450
Plus: FI Share and other third-party costs	104,710	115,211	81,234
Revenues	186,892	210,430	150,684
Cardlytics Direct
Segment Reporting Information [Line Items]
Adjusted Contribution	82,182	95,219	69,364
Plus: FI Share and other third-party costs	104,710	115,211	79,959
Revenues	186,892	210,430	149,323
Other Platform Solutions
Segment Reporting Information [Line Items]
Adjusted Contribution	0	0	86
Plus: FI Share and other third-party costs	0	0	1,275
Revenues	$ 0	$ 0	$ 1,361

SEGMENTS - Adjusted Contribution Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting [Abstract]
Adjusted contribution(1)(2)(3)	$ 82,182	$ 95,219	$ 69,450
Non-cash equity expense included in FI Share	0	0	2,519
Amortization and impairment of deferred FI implementation costs	4,598	2,869	1,618
Delivery costs	14,310	12,893	10,632
Sales and marketing expense	45,307	43,828	41,878
Research and development expense	17,532	11,699	16,210
General and administration expense	46,532	36,720	34,228
Depreciation and amortization expense	7,826	4,535	3,282
Total non-operating expense (income)	1,499	(181)	12,125
Loss before income taxes	$ (55,422)	$ (17,144)	$ (53,042)

SEGMENTS - Geographical Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 186,892	$ 210,430	$ 150,684
Property and equipment	13,865	14,290
United States
Segment Reporting Information [Line Items]
Revenues	172,808	186,864	131,563
Property and equipment	9,549	12,052
United Kingdom
Segment Reporting Information [Line Items]
Revenues	14,084	23,566	$ 19,121
Property and equipment	4,162	2,010
INDIA
Segment Reporting Information [Line Items]
Property and equipment	$ 154	$ 228

SUBSEQUENT EVENTS (Details) $ in Thousands	Feb. 26, 2021 USD ($)
Subsequent Event [Line Items]
Business Acquisition, Total Cost	$ 275,000
Business Acquisition, Cash Paid	150,000
Business Acquisition, Equity Cost	125,000
Business Acquisition, performance based restricted stock expense	$ 8,000