Cardlytics (CDLX) 10-Q 8 Aug 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - $ / shares	6 Months Ended
	Jun. 30, 2019	Jul. 31, 2019	Dec. 31, 2018
Document Information [Line Items]
Document Transition Report	false
Document Quarterly Report	true
Title of 12(b) Security	Common Stock
Trading Symbol	CDLX
Security Exchange Name	NASDAQ
Common stock, par or stated value per share (in usd per share)	$ 0.0001		$ 0.0001
Entity Incorporation, State or Country Code	DE
Entity Registrant Name	CARDLYTICS, INC.
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Entity File Number	001-38386
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	true
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001666071
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	true
Entity Small Business	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding (in shares)		22,842,058
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

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 32,495	$ 39,623
Restricted cash	10,254	20,247
Accounts receivable, net	63,772	58,125
Other receivables	3,171	2,417
Prepaid expenses and other assets	5,609	3,956
Total current assets	115,301	124,368
Long-term assets:
Property and equipment, net	11,895	10,230
Intangible assets, net	369	370
Capitalized software development costs, net	2,529	1,625
Deferred FI implementation costs, net	12,181	15,877
Other long-term assets, net	1,281	1,293
Total assets	143,556	153,763
Current liabilities:
Accounts payable	1,212	2,099
Accrued liabilities:
Accrued compensation	5,709	5,936
Accrued expenses	4,012	4,388
FI Share liability	30,587	27,656
Consumer Incentive liability	15,485	11,476
Deferred billings	397	346
Current portion of long-term debt	22	21
Total current liabilities	57,424	51,922
Long-term liabilities:
Deferred liabilities	2,913	3,173
Long-term debt, net of current portion	36,681	46,693
Total liabilities	97,018	101,788
Stockholders’ equity:
Common stock, $0.0001 par value—100,000 shares authorized and 22,466 and 22,828 shares issued and outstanding as of December 31, 2018 and June 30, 2019, respectively	7	7
Additional paid-in capital	378,773	371,463
Accumulated other comprehensive income	2,069	1,992
Accumulated deficit	(334,311)	(321,487)
Total stockholders’ equity	46,538	51,975
Total liabilities and stockholders’ equity	$ 143,556	$ 153,763

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Common stock, par or stated value per share (in usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	22,828,000	22,466,000
Common stock, shares outstanding (in shares)	22,828,000	22,466,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Revenue	$ 48,730	$ 35,570	$ 84,718	$ 68,283
Costs and expenses:
FI Share and other third-party costs	27,620	19,747	46,624	41,167
Delivery costs	3,370	2,559	6,616	4,502
Sales and marketing expense	11,047	10,247	20,384	18,463
Research and development expense	2,782	4,888	5,723	8,347
General and administration expense	8,340	8,979	15,340	15,561
Depreciation and amortization expense	1,053	784	2,014	1,694
Total costs and expenses	54,212	47,204	96,701	89,734
Operating loss	(5,482)	(11,634)	(11,983)	(21,451)
Other (expense) income:
Interest expense, net	(338)	(992)	(642)	(2,741)
Change in fair value of warrant liabilities, net	0	1,611	0	(7,561)
Other expense, net	(690)	(2,038)	(199)	(1,355)
Total other expense	(1,028)	(1,419)	(841)	(11,657)
Loss before income taxes	(6,510)	(13,053)	(12,824)	(33,108)
Income tax benefit	0	0	0	0
Net loss	(6,510)	(13,053)	(12,824)	(33,108)
Adjustments to the carrying value of preferred stock	0	0	0	(157)
Net loss attributable to common stockholders	$ (6,510)	$ (13,053)	$ (12,824)	$ (33,265)
Net loss per share attributable to common stockholders, basic and diluted (in USD per share)	$ (0.29)	$ (0.64)	$ (0.57)	$ (1.99)
Weighted-average common shares outstanding, basic and diluted (in shares)	22,731	20,300	22,618	16,716

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (6,510)	$ (13,053)	$ (12,824)	$ (33,108)
Other comprehensive income:
Foreign currency translation adjustments	449	880	77	372
Total comprehensive loss	$ (6,061)	$ (12,173)	$ (12,747)	$ (32,736)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ (DEFICIT) EQUITY (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Stock Issued During Period, Shares, Conversion of Convertible Securities		10,643
Stock Issued During Period, Value, Conversion of Convertible Securities	$ 196,594	$ 6	$ 196,588
Adjustments to Additional Paid in Capital, Preferred Stock Warrant Conversion, Common Stock Warrant	1,736		1,736
Beginning balance (in shares) at Dec. 31, 2017		3,439
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)		64
Exercise of common stock options	$ 144		$ 144
Stock Issued During Period, Shares, Warrants Exercised In Period	0	349	0
Stock-based compensation			$ 11,251
Vesting of common stock warrants	$ 11,251
Stock Issued During Period, Shares, New Issues		5,821
Stock Issued During Period, Value, New Issues	66,101	$ 1	66,100
Vesting of performance-based common stock warrants	2,519
Accretion of redeemable convertible preferred stock to redemption value	(157)		(157)
Other comprehensive loss	372			372
Net loss	(33,108)				(33,108)
Ending balance (in shares) at Jun. 30, 2018		20,316
Ending balance at Jun. 30, 2018	36,766	$ 7	336,874	1,438	(301,553)
Beginning balance (in shares) at Mar. 31, 2018		20,226
Beginning balance at Mar. 31, 2018	40,558	$ 7	328,493	558	(288,500)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		38
Exercise of common stock options	36		36
Stock-based compensation			0
Vesting of common stock warrants	0	$ 52
Stock Issued During Period, Shares, New Issues		0
Stock Issued During Period, Value, New Issues	8,345	$ 0	8,345
Other comprehensive loss	880			880
Net loss	(13,053)				(13,053)
Ending balance (in shares) at Jun. 30, 2018		20,316
Ending balance at Jun. 30, 2018	36,766	$ 7	336,874	1,438	(301,553)
Beginning balance (in shares) at Dec. 31, 2018		22,466
Beginning balance at Dec. 31, 2018	$ 51,975	$ 7	371,463	1,992	(321,487)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)	110	111
Exercise of common stock options	$ 1,348		1,348
Stock-based compensation	4,797		4,797
Settlement of restricted stock (in shares)		157
Other comprehensive loss	77			77
Net loss	(12,824)				(12,824)
Ending balance (in shares) at Jun. 30, 2019		22,828
Ending balance at Jun. 30, 2019	46,538	$ 7	378,773	2,069	(334,311)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, Employee Stock Purchase Plan	1,165	$ 94	1,165
Beginning balance (in shares) at Mar. 31, 2019		22,570
Beginning balance at Mar. 31, 2019	47,177	$ 7	373,351	1,620	(327,801)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		80
Exercise of common stock options	1,175		1,175
Stock-based compensation	3,082		3,082
Settlement of restricted stock (in shares)		84
Other comprehensive loss	449			449
Net loss	(6,510)				(6,510)
Ending balance (in shares) at Jun. 30, 2019		22,828
Ending balance at Jun. 30, 2019	46,538	$ 7	378,773	$ 2,069	$ (334,311)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, Employee Stock Purchase Plan	$ 1,165	$ 94	$ 1,165

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating activities
Net loss	$ (12,824)	$ (33,108)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,014	1,694
Amortization of financing costs charged to interest expense	50	229
Accretion of debt discount and non-cash interest expense	0	2,326
Termination of U.K. agreement expense	4,780	11,245
Change in fair value of warrant liabilities, net	0	7,561
Other non-cash expense, net	1,003	3,857
Amortization of deferred FI implementation costs	1,384	758
Settlement Of Paid-in-Kind Interest	0	8,311
Change in operating assets and liabilities:
Accounts receivable	(7,024)	7,701
Prepaid expenses and other assets	(1,622)	(1,509)
Deferred FI implementation costs	0	(2,250)
Recovery of deferred FI implementation costs	2,312	2,692
Accounts payable	(306)	(839)
Other accrued expenses	323	(237)
FI Share liability	2,932	(3,185)
Customer Incentive liability	4,009	(1,409)
Net cash used in operating activities	(2,969)	(12,785)
Investing activities
Acquisition of property and equipment	(4,019)	(1,492)
Acquisition of patents	(5)	(12)
Capitalized software development costs	(1,139)	(657)
Net cash used in investing activities	(5,163)	(2,161)
Proceeds from Issuance of Long-term Debt	0	47,435
Financing activities
Principal payments of debt	(10,010)	(51,811)
Proceeds from issuance of common stock	1,213	70,527
Equity issuance costs	0	(1,897)
Debt issuance costs	(93)	(48)
Net cash from (used in) financing activities	(8,890)	64,206
Effect of exchange rates on cash, cash equivalents and restricted cash	(99)	(54)
Net increase (decrease) in cash, cash equivalents and restricted cash	(17,121)	49,206
Cash, cash equivalents, and restricted cash — Beginning of period	59,870	21,262
Cash, cash equivalents, and restricted cash — End of period	42,749	70,468
Supplemental schedule of non-cash investing and financing activities:
Amounts accrued for property and equipment	53	1,225
Amounts accrued for capitalized software development costs	$ 0	$ 86

OVERVIEW OF BUSINESS AND BASIS

OVERVIEW OF BUSINESS AND BASIS OF PRESENTATION	6 Months Ended
	Jun. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
OVERVIEW OF BUSINESS AND BASIS OF PRESENTATION	OVERVIEW OF BUSINESS AND BASIS OF PRESENTATION Cardlytics, Inc. (“we,” “our,” “us,” the “Company,” or “Cardlytics”) is a Delaware corporation and was formed on June 26, 2008. We make marketing more relevant and measurable through our purchase intelligence platform. Using one of the largest aggregations of purchase data through our partnerships with banks and credit unions, we have a secure view into where and when consumers are spending their money. By applying advanced analytics to this massive aggregation of anonymized 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 also operate in the United Kingdom through Cardlytics UK Limited, a wholly-owned and operated subsidiary registered as a private limited company in England and Wales. Unaudited Interim Results The accompanying unaudited interim condensed consolidated financial statements and information have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and in accordance with the rules and regulations of the Securities and Exchange Commission. Accordingly, they do not include all of the information and disclosures required by GAAP for complete financial statements. In the opinion of management, these financial statements contain all normal and recurring adjustments considered necessary to present fairly the financial position, results of operations, and cash flows for the periods presented. The results for interim periods presented are not necessarily indicative of the results to be expected for the full year due to the seasonality of our business, which has been historically impacted by higher consumer spending during the fourth quarter. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes thereto included on our Annual Report on Form 10-K ("Annual Report") for the fiscal year ended December 31, 2018 . Use of Estimates The preparation of financial statements in conformity with 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. Significant items subject to such estimates and assumptions include revenue recognition, internal-use software development costs, income taxes, stock-based compensation, derivative instruments, income tax valuation allowance and contingencies. 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.

SIGNIFICANT ACCOUNTING POLICIES

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS	SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS Recently Adopted Accounting Pronouncements On January 1, 2019, we early adopted Accounting Standards Update (“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 condensed 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 condensed consolidated financial statements. Except for the adoption of ASU 2014-09 and ASU 2016-01, there have been no changes to the Company’s accounting policies, and these unaudited interim condensed consolidated financial statements have been prepared on a basis consistent with that used to prepare our audited annual consolidated financial statements for the year ended December 31, 2018, and include, in the opinion of management, all adjustments, consisting of normal recurring items, necessary for the fair statement of the condensed consolidated financial statements. Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) , which supersedes ASC Topic 840, Leases . The ASU does not significantly change the lessees’ recognition, measurement and presentation of expenses and cash flows from the previous accounting standard. The ASU’s primary change is the requirement for lessee entities to recognize a lease liability for payments and a right of use asset representing the right to use the leased asset during the term on operating lease arrangements. Lessees are permitted to make an accounting policy election to not recognize the asset and liability for leases with a term of twelve months or less. Lessors’ accounting under the ASU is largely unchanged from the previous accounting standard. In addition, the ASU expands the disclosure requirements of lease arrangements. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842) - Targeted Improvements , which provides the option of applying the requirements of the new lease standard in the period of adoption with no restatement to comparative periods. For public entities, this ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. For non-public entities, this ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. We have made the election to use the extended transition period for complying with new or revised accounting standards under Section 102(b)(1) of the JOBS Act, therefore we will be required to adopt this ASU for annual reporting periods beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted. Although we are currently evaluating the impact of this guidance on our consolidated financial statements, we expect that most of our operating lease commitments will be recognized as operating lease liabilities and right-of-use assets upon adoption of the new guidance. Revenue We have generated revenue through the sale of two categories of solutions that leverage our intelligence platform: (1) our proprietary native banking channel Cardlytics Direct and (2) our Other Platform Solutions. We have generated substantially all of our revenue from sales of Cardlytics Direct 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 Cardlytics Direct. As a result, we do not expect to generate substantial, if any, revenue from Other Platform Solutions for the foreseeable future. Cardlytics Direct Cardlytics Direct is our proprietary native bank advertising channel that enables marketers to reach consumers through the FIs' trusted and frequently visited online and mobile 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"). Leveraging our powerful predictive analytics, we are able to create compelling Consumer Incentives that have the potential to increase return on advertising spend for marketers. We generally pay our FI partners an FI Share, which is a negotiated and fixed percentage of our billings to marketers less any Consumer Incentives that we pay to FIs’ customers and certain third-party data costs. Cardlytics Direct 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): Three Months Ended Six Months Ended June 30, 2018 2019 2018 2019 Cost per Served Sale $ 24,010 $ 33,549 $ 42,455 $ 54,558 Cost per Redemption 9,456 14,276 21,211 28,240 Other 2,104 905 4,617 1,920 Revenue $ 35,570 $ 48,730 $ 68,283 $ 84,718 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. 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 Direct 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. Cardlytics Direct 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 Cardlytics Direct 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 condensed 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. Consumer Incentives totaled $15.8 million and $25.0 million during the three months ended June 30, 2018 and 2019 , respectively, and totaled $31.9 million and $47.6 million during the six months ended June 30, 2018 and 2019 , respectively. FI Share and Other Third-Party Costs We report our revenue on our condensed consolidated statements of operations gross of FI Share. FI Share costs are included in FI Share and other third-party costs in our condensed 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. Concentrations of Risk Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash and cash equivalents and accounts receivable. Our cash and cash equivalents are held with three financial institutions, which we believe are of high credit quality. We believe that our accounts receivable credit risk exposure is limited as a result of being diversified among a large number of marketers segregated by both geography and industry. Historically, we have not experienced significant write-downs of our accounts receivable. One marketer represented 12% of our accounts receivable as of June 30, 2019. During each of the six months ended June 30, 2018 a marketer accounted for 10% of our revenue. During each of the six months ended June 30, 2019 a different marketer accounted for 10% of our revenue. No other marketer accounted for over 10% of revenue or accounts receivable during the periods presented. Our business is substantially dependent on a limited number of FI partners. We require participation from our FI partners in Cardlytics Direct 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 six months ended June 30, 2018 and 2019 , Bank of America, National Association ("Bank of America") accounted for 67% and 41% of the total FI Share we paid to all FIs, respectively. JPMorgan Chase Bank, National Association (“Chase”) accounted for 0% and 35% of the total FI Share we paid to all FIs during the six months ended June 30, 2018 and 2019 , respectively. During the six months ended June 30, 2018 and 2019 , an FI partner in the U.K. accounted for 10% and 8% of FI Share, respectively. No other FI partners accounted for over 10% of FI Share during the six months ended June 30, 2018 and 2019. Cash, Cash Equivalents and Restricted Cash Cash and cash equivalents consist of cash held in checking accounts, upon which we earn up to a 1.06% annual rate of interest as of June 30, 2019 . Restricted cash primarily represents deposits held in an account controlled by our lender as additional security for our payment obligations under our 2018 Term Loan, upon which we earn a 0.51% annual rate of interest as of June 30, 2019 . During the second quarter of 2019, we used $10.0 million of restricted cash and to partially repay the 2018 Term Loan. Refer to Note 3—Debt , for additional information regarding our 2018 Term Loan. Cash, cash equivalents and restricted cash as presented on our condensed consolidated statements of cash flows consists of the following (in thousands): December 31, June 30, 2017 2018 2018 2019 Cash and cash equivalents $ 21,262 $ 39,623 $ 50,468 $ 32,495 Restricted cash — 20,247 20,000 10,254 Cash, cash equivalents and restricted cash $ 21,262 $ 59,870 $ 70,468 $ 42,749

DEBT

DEBT	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
DEBT	DEBT Our debt consists of the following (in thousands): December 31, 2018 June 30, 2019 Lines of credit $ 26,677 $ 26,677 Term loans (1) 19,980 9,979 Capital leases 57 47 Total debt 46,714 36,703 Less current portion of long-term debt (21 ) (22 ) Long-term debt, net of current portion $ 46,693 $ 36,681 (1) Net of unamortized debt issuance costs of $20 and $21 as of December 31, 2018 and June 30, 2019 , respectively. Interest payments during the six months ended June 30, 2018 and 2019 totaled $8.7 million and $0.8 million , respectively. 2018 Loan Facility On May 14, 2019, we amended our loan facility with Pacific Western Bank ("2018 Loan Facility") to increase the capacity of our asset-based revolving line of credit (“2018 Line of Credit”), from $30.0 million to $40.0 million , and decrease the capacity of our term loan (“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. Upon the execution of the amendment, we repaid $10.0 million of the principal balance of the 2018 Term Loan, resulting in a remaining balance of $10.0 million outstanding. The 2018 Loan Facility does not include any prepayment penalties. On March 27, 2019, we amended the 2018 Loan Facility to replace moving trailing 12-month revenue covenants with moving trailing 12-month billing covenants, which range from $210.0 million to $255.0 million , during the term of the facility. The moving 12-month billings covenant was $219.0 million for June 2019. Under the amended terms of the 2018 Loan Facility relating to the 2018 Line of Credit, we are able to borrow up to the lesser of $40.0 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 5.00% as of June 30, 2019 . In addition, we are required to pay an unused line fee of 0.15% per annum on the average daily unused amount of the $40.0 million revolving commitment. Interest accrues on the 2018 Term Loan at an annual rate of interest equal to the prime rate minus 2.75% , or 2.75% as of June 30, 2019 . All of our obligations under the 2018 Loan Facility are also secured by a first priority lien on substantially all of our assets. Under the terms of the 2018 Loan Facility, as amended, we are required to maintain a deposit of $10.0 million in an account controlled by our lender as additional security for our payment obligations. The 2018 Loan Facility also requires us to maintain a total cash balance plus liquidity under the 2018 Line of Credit of not less than $5.0 million . 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 the 2018 Term Loan or advances under the 2018 Line of Credit by an additional 3.00% . As of June 30, 2019 , we had $13.3 million of unused available borrowings under our 2018 Line of Credit. We were in compliance with all financial covenants as of June 30, 2019 . Future Payments Aggregate future payments of principal and interest due upon maturity are as follows (in thousands): Years Ending December 31, Debt Capital leases Total debt 2019 (remainder of year) $ — $ 10 $ 10 2020 — 24 24 2021 36,677 13 36,690 Total principal payments 36,677 47 36,724 Less unamortized debt issuance costs (21 ) — (21 ) Total debt $ 36,656 $ 47 $ 36,703

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	6 Months Ended
	Jun. 30, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION 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 initial public offering ("IPO") was declared effective. We do not expect to grant any additional awards under our 2008 Stock Plan ("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 is 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). 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, in January 2019, the number of shares of our common stock reserved for issuance under our 2018 Plan automatically increased by 1,123,312 shares, representing 5% of the total number of shares of our capital stock outstanding on December 31, 2018. The following table summarizes the allocation of stock-based compensation in the consolidated statements of operations (in thousands): Three Months Ended Six Months Ended 2018 2019 2018 2019 Delivery costs $ 183 $ 199 $ 268 $ 363 Sales and marketing expense 2,668 952 3,611 1,659 Research and development expense 1,756 363 2,226 566 General and administration expense 3,738 1,558 5,140 2,192 Total stock-based compensation expense $ 8,345 $ 3,072 $ 11,245 $ 4,780 During each of the six months ended June 30, 2018 and 2019 , we capitalized less than $0.1 million of stock-based compensation expense for software development. Common Stock Options Options to purchase shares of common stock generally vest over four years and expire 10 years following the date of grant. A summary of common stock option activity is as follows: Shares (in thousands) Weighted-Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (1) (in thousands) Options outstanding — December 31, 2018 1,774 $ 20.55 2.01 $ 1,214 Granted 39 20.64 Exercised (110 ) 12.13 Forfeited (21 ) 23.91 Canceled (62 ) 21.61 Options outstanding — June 30, 2019 1,620 21.03 1.57 $ 10,205 Exercisable — June 30, 2019 1,238 $ 20.05 6.40 $ 9,047 (1) The aggregate intrinsic value represents the total pre-tax intrinsic value based on the $10.83 and $25.98 closing price of our common stock as reported on the Nasdaq Global Market on December 31, 2018 and June 28, 2019 , respectively, that would have been received by option holders had all in-the-money options been exercised on that date. The weighted-average grant-date fair value of options granted during the six months ended June 30, 2018 and 2019 was $10.00 and $0.47 , respectively. The total fair value of options vested during the six months ended June 30, 2018 and 2019 was approximately $4.0 million and $2.2 million , respectively. As of June 30, 2019 , unamortized stock-based compensation expense related to unvested common stock options was $4.4 million , and the weighted-average period over which such stock-based compensation expense will be recognized was 1.6 years. Restricted Stock Units We grant restricted stock units ("RSUs") to employees and our non-employee directors. A summary of RSU activity, inclusive of performance-based RSUs, is as follows: Shares (in thousands) Weighted-Average Grant Date Fair Value Weighted-Average Remaining Contractual Term (in years) Unamortized Compensation Costs (in thousands) Unvested — December 31, 2018 381 $ 18.11 2.42 $ 4,536 Granted 1,714 15.34 Vested (157 ) 17.55 Forfeited (92 ) 19.41 Unvested — June 30, 2019 1,846 $ 20.68 3.42 $ 26,295 During the six months ended June 30, 2019 , we granted 461,332 RSUs, exclusive of performance-based RSUs, to employees and non-employee directors, which have annual vesting periods ranging from one to four years. Subsequent to June 30, 2019 , we granted 78,191 RSUs to employees. The unamortized stock-based compensation expense related to these RSUs is $2.1 million . Performance-based RSUs In February 2018, we granted 875,000 performance-based restricted stock units ("2018 PSUs"). We recognized $6.9 million in stock-based compensation expense during the six months ended June 30, 2018 . The performance targets were achieved during the fourth quarter of 2018, resulting in the issuance of 850,000 shares of our common stock to fully settle the 2018 PSUs. During 2018, 25,000 of the 2018 PSUs were forfeited prior to the performance targets being reached. In April 2019, we granted 1,252,500 performance-based restricted stock units (“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 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." Employee Stock Purchase Plan Our 2018 Employee Stock Purchase Plan ("2018 ESPP") enables eligible employees to purchase shares of our common stock at a discount. Purchases are accomplished through participation in discrete offering periods. On each purchase date, participating employees 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 the six months ended June 30, 2019 , 93,584 shares of common stock were purchased by employees under the 2018 ESPP. Initially, the aggregate number of shares of our common stock that may be issued pursuant to our 2018 ESPP was 375,000 shares. 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, on January 1, 2019, the number of shares of our common stock reserved for issuance under our 2018 ESPP increased by 224,662 shares, representing 1% of the total number of shares of our common stock outstanding on December 31, 2018.

RELATED PARTIES

RELATED PARTIES	6 Months Ended
	Jun. 30, 2019
Related Party Transactions [Abstract]
RELATED PARTIES	RELATED PARTIES 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. In 2013, FIS purchased shares of our redeemable convertible preferred stock and we also granted performance-based warrants to purchase preferred stock with accelerated vesting upon an IPO. Since FIS did not participate in a subsequent financing, 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-based vesting conditions of the warrants were directly related to revenue-producing activities, we recognized this expense in FI Share and other third-party costs on our condensed consolidated statement of operations. This expense is presented in other non-cash expenses on our condensed consolidated statement of statement of cash flows.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES FI Implementation Costs Agreements with certain FI partners require us to fund the development of user interface 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 condensed consolidated balance sheets the earlier of when paid or earned and are amortized over the remaining term of the related contractual arrangements. Amortization is included in FI Share and other third-party costs on our condensed consolidated statements of operations and is presented in amortization of deferred FI implementation costs on our condensed 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 FI 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 is expected to be partially offset by recoveries through FI Share payment reductions of $4.6 million in 2019, $2.3 million of which has been recovered through June 30, 2019 . The following table presents changes in deferred FI implementation costs (in thousands): Three Months Ended Six Months Ended 2018 2019 2018 2019 Beginning balance $ 12,119 $ 14,067 $ 13,625 $ 15,877 Deferred costs 2,000 — 2,250 — Recoveries through FI Share (1,348 ) (1,155 ) (2,692 ) (2,312 ) Amortization (346 ) (731 ) (758 ) (1,384 ) Ending balance $ 12,425 $ 12,181 $ 12,425 $ 12,181 We have an FI Share commitment to a certain FI partner totaling $10.0 million over a 12-month period following the completion of certain milestones by the FI partner, which were not met as of June 30, 2019 . Any expected shortfall will be accrued during the 12-month period following the completion of the milestones. 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

EARNINGS PER SHARE	6 Months Ended
	Jun. 30, 2019
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE Diluted net loss per share is the same as basic net loss per share for the three and six months ended June 30, 2018 and 2019 because the effects of potentially dilutive items were anti-dilutive, given our net loss during these periods. The following securities outstanding as of June 30, 2018 and June 30, 2019 have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive (in thousands): June 30, 2018 2019 Common stock options 2,232 1,620 Common stock warrants 868 868 Common stock warrants issuable pursuant to Series G Stock financing 751 — Restricted stock units 1,232 1,846 Common stock issuable pursuant to the ESPP 95 22

SEGMENTS

SEGMENTS	6 Months Ended
	Jun. 30, 2019
Segment Reporting [Abstract]
SEGMENTS	SEGMENTS As of June 30, 2019 , we have two operating segments: Cardlytics Direct in the U.S. and U.K., as determined by the information that both our Chief Executive Officer and our President and Chief Operating Officer, who we consider our chief operating decision makers, use to make strategic goals and operating decisions. Our Cardlytics Direct 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 2019, we offered Other Platform Solutions, which was deemed to be a separate operating segment. Our Other Platform Solutions enabled marketers and marketing service providers to leverage the power of purchase intelligence outside the bank channel. We have shifted our efforts and resources to support the growth of Cardlytics Direct. As a result, we do not expect to generate substantial, if any, revenue from Other Platform Solutions for the foreseeable future. Revenue and FI Share and other third-party costs can be directly attributable to each segment. Our chief operating decision makers allocate 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): Three Months Ended Six Months Ended 2018 2019 2018 2019 Cardlytics Direct: Adjusted contribution $ 16,240 $ 21,841 $ 30,462 $ 39,478 Plus: Adjusted FI Share and other third-party costs (1) 18,858 26,889 36,757 45,240 Revenue $ 35,098 $ 48,730 $ 67,219 $ 84,718 Other Platform Solutions: Adjusted contribution $ (71 ) $ — $ (69 ) $ — Plus: Adjusted FI Share and other third-party costs (1) 543 — 1,133 — Revenue $ 472 $ — $ 1,064 $ — Total: Adjusted contribution $ 16,169 $ 21,841 $ 30,393 $ 39,478 Plus: Adjusted FI Share and other third-party costs (1) 19,401 26,889 37,890 45,240 Revenue $ 35,570 $ 48,730 $ 68,283 $ 84,718 (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 amortization of deferred FI implementation costs, which are detailed below in our reconciliation of GAAP loss before income taxes to adjusted contribution. Adjusted Contribution Adjusted contribution represents our revenue less FI Share and other third-party costs excluding a non-cash equity expense included in FI Share and amortization of deferred FI implementation costs. The following table presents a reconciliation of loss before income taxes presented in accordance with GAAP to adjusted contribution (in thousands): Three Months Ended Six Months Ended 2018 2019 2018 2019 Adjusted contribution $ 16,169 $ 21,841 $ 30,393 $ 39,478 Minus: Non-cash equity expense included in FI Share (1) — — 2,519 — Amortization of deferred FI implementation costs (1) 346 731 758 1,384 Delivery costs 2,559 3,370 4,502 6,616 Sales and marketing expense 10,247 11,047 18,463 20,384 Research and development expense 4,888 2,782 8,347 5,723 General and administration expense 8,979 8,340 15,561 15,340 Depreciation and amortization expense 784 1,053 1,694 2,014 Total other expense 1,419 1,028 11,657 841 Loss before income taxes $ (13,053 ) $ (6,510 ) $ (33,108 ) $ (12,824 ) (1) Non-cash equity expense included in FI Share and amortization of deferred FI implementation costs are excluded from adjusted FI Share and other third party costs, which is shown above in our reconciliation of GAAP revenue to adjusted contribution. The following table provides geographical information (in thousands): Three Months Ended Six Months Ended 2018 2019 2018 2019 Revenue: United States $ 30,735 $ 43,123 $ 59,722 $ 74,471 United Kingdom 4,835 5,607 8,561 10,247 Total $ 35,570 $ 48,730 $ 68,283 $ 84,718 December 31, 2018 June 30, 2019 Property and equipment: United States $ 9,794 $ 11,279 United Kingdom 436 616 Total $ 10,230 $ 11,895 Capital expenditures within the United Kingdom were less than $0.1 million and $0.3 million during the six months ended June 30, 2018 and 2019 , respectively.

SIGNIFICANT ACCOUNTING POLICI_2

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS (Policies)	6 Months Ended
	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue [Table Text Block]	Three Months Ended Six Months Ended June 30, 2018 2019 2018 2019 Cost per Served Sale $ 24,010 $ 33,549 $ 42,455 $ 54,558 Cost per Redemption 9,456 14,276 21,211 28,240 Other 2,104 905 4,617 1,920 Revenue $ 35,570 $ 48,730 $ 68,283 $ 84,718
Revenue Recognition, Policy [Policy Text Block]	FI Share and Other Third-Party Costs We report our revenue on our condensed consolidated statements of operations gross of FI Share. FI Share costs are included in FI Share and other third-party costs in our condensed 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. Revenue We have generated revenue through the sale of two categories of solutions that leverage our intelligence platform: (1) our proprietary native banking channel Cardlytics Direct and (2) our Other Platform Solutions. We have generated substantially all of our revenue from sales of Cardlytics Direct 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 Cardlytics Direct. As a result, we do not expect to generate substantial, if any, revenue from Other Platform Solutions for the foreseeable future. Cardlytics Direct Cardlytics Direct is our proprietary native bank advertising channel that enables marketers to reach consumers through the FIs' trusted and frequently visited online and mobile 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"). Leveraging our powerful predictive analytics, we are able to create compelling Consumer Incentives that have the potential to increase return on advertising spend for marketers. We generally pay our FI partners an FI Share, which is a negotiated and fixed percentage of our billings to marketers less any Consumer Incentives that we pay to FIs’ customers and certain third-party data costs. Cardlytics Direct 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): Three Months Ended Six Months Ended June 30, 2018 2019 2018 2019 Cost per Served Sale $ 24,010 $ 33,549 $ 42,455 $ 54,558 Cost per Redemption 9,456 14,276 21,211 28,240 Other 2,104 905 4,617 1,920 Revenue $ 35,570 $ 48,730 $ 68,283 $ 84,718 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. 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 Direct 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. Cardlytics Direct fees represent variable consideration that is resolved when FIs' customers make qualifying purchases during the marketing campaign term.
Basis of Accounting	Unaudited Interim Results The accompanying unaudited interim condensed consolidated financial statements and information have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and in accordance with the rules and regulations of the Securities and Exchange Commission. Accordingly, they do not include all of the information and disclosures required by GAAP for complete financial statements. In the opinion of management, these financial statements contain all normal and recurring adjustments considered necessary to present fairly the financial position, results of operations, and cash flows for the periods presented. The results for interim periods presented are not necessarily indicative of the results to be expected for the full year due to the seasonality of our business, which has been historically impacted by higher consumer spending during the fourth quarter. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and related notes thereto included on our Annual Report on Form 10-K ("Annual Report") for the fiscal year ended December 31, 2018 .
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with 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. Significant items subject to such estimates and assumptions include revenue recognition, internal-use software development costs, income taxes, stock-based compensation, derivative instruments, income tax valuation allowance and contingencies. 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.
Consumer Incentives	Consumer Incentives We report our revenue on our condensed 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. Consumer Incentives totaled $15.8 million and $25.0 million during the three months ended June 30, 2018 and 2019 , respectively, and totaled $31.9 million and $47.6 million during the six months ended June 30, 2018 and 2019 , respectively.
Concentration of Risk	Concentrations of Risk Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash and cash equivalents and accounts receivable. Our cash and cash equivalents are held with three financial institutions, which we believe are of high credit quality. We believe that our accounts receivable credit risk exposure is limited as a result of being diversified among a large number of marketers segregated by both geography and industry. Historically, we have not experienced significant write-downs of our accounts receivable. One marketer represented 12% of our accounts receivable as of June 30, 2019. During each of the six months ended June 30, 2018 a marketer accounted for 10% of our revenue. During each of the six months ended June 30, 2019 a different marketer accounted for 10% of our revenue. No other marketer accounted for over 10% of revenue or accounts receivable during the periods presented. Our business is substantially dependent on a limited number of FI partners. We require participation from our FI partners in Cardlytics Direct 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 six months ended June 30, 2018 and 2019 , Bank of America, National Association ("Bank of America") accounted for 67% and 41% of the total FI Share we paid to all FIs, respectively. JPMorgan Chase Bank, National Association (“Chase”) accounted for 0% and 35% of the total FI Share we paid to all FIs during the six months ended June 30, 2018 and 2019 , respectively. During the six months ended June 30, 2018 and 2019 , an FI partner in the U.K. accounted for 10% and 8% of FI Share, respectively. No other FI partners accounted for over 10% of FI Share during the six months ended June 30, 2018
Recently Issued and Adopted Accounting Pronouncements	December 31, June 30, 2017 2018 2018 2019 Cash and cash equivalents $ 21,262 $ 39,623 $ 50,468 $ 32,495 Restricted cash — 20,247 20,000 10,254 Cash, cash equivalents and restricted cash $ 21,262 $ 59,870 $ 70,468 $ 42,749

SIGNIFICANT ACCOUNTING POLICI_3

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS (Tables)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Disaggregation of Revenue [Table Text Block]	Three Months Ended Six Months Ended June 30, 2018 2019 2018 2019 Cost per Served Sale $ 24,010 $ 33,549 $ 42,455 $ 54,558 Cost per Redemption 9,456 14,276 21,211 28,240 Other 2,104 905 4,617 1,920 Revenue $ 35,570 $ 48,730 $ 68,283 $ 84,718
Schedule of cash and cash equivalents	Cash, cash equivalents and restricted cash as presented on our condensed consolidated statements of cash flows consists of the following (in thousands): December 31, June 30, 2017 2018 2018 2019 Cash and cash equivalents $ 21,262 $ 39,623 $ 50,468 $ 32,495 Restricted cash — 20,247 20,000 10,254 Cash, cash equivalents and restricted cash $ 21,262 $ 59,870 $ 70,468 $ 42,749
Schedule of restricted cash	Cash and cash equivalents consist of cash held in checking accounts, upon which we earn up to a 1.06% annual rate of interest as of June 30, 2019 . Restricted cash primarily represents deposits held in an account controlled by our lender as additional security for our payment obligations under our 2018 Term Loan, upon which we earn a 0.51% annual rate of interest as of June 30, 2019 . During the second quarter of 2019, we used $10.0 million of restricted cash and to partially repay the 2018 Term Loan. Refer to Note 3—Debt , for additional information regarding our 2018 Term Loan. Cash, cash equivalents and restricted cash as presented on our condensed consolidated statements of cash flows consists of the following (in thousands): December 31, June 30, 2017 2018 2018 2019 Cash and cash equivalents $ 21,262 $ 39,623 $ 50,468 $ 32,495 Restricted cash — 20,247 20,000 10,254 Cash, cash equivalents and restricted cash $ 21,262 $ 59,870 $ 70,468 $ 42,749

DEBT (Tables)

DEBT (Tables)	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
Schedule of long-term debt instruments	Our debt consists of the following (in thousands): December 31, 2018 June 30, 2019 Lines of credit $ 26,677 $ 26,677 Term loans (1) 19,980 9,979 Capital leases 57 47 Total debt 46,714 36,703 Less current portion of long-term debt (21 ) (22 ) Long-term debt, net of current portion $ 46,693 $ 36,681
Schedule of maturities of debt and capital lease	Aggregate future payments of principal and interest due upon maturity are as follows (in thousands): Years Ending December 31, Debt Capital leases Total debt 2019 (remainder of year) $ — $ 10 $ 10 2020 — 24 24 2021 36,677 13 36,690 Total principal payments 36,677 47 36,724 Less unamortized debt issuance costs (21 ) — (21 ) Total debt $ 36,656 $ 47 $ 36,703

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	6 Months Ended
	Jun. 30, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Allocation of recognized period costs	The following table summarizes the allocation of stock-based compensation in the consolidated statements of operations (in thousands): Three Months Ended Six Months Ended 2018 2019 2018 2019 Delivery costs $ 183 $ 199 $ 268 $ 363 Sales and marketing expense 2,668 952 3,611 1,659 Research and development expense 1,756 363 2,226 566 General and administration expense 3,738 1,558 5,140 2,192 Total stock-based compensation expense $ 8,345 $ 3,072 $ 11,245 $ 4,780
Summary of common stock option activity	Options to purchase shares of common stock generally vest over four years and expire 10 years following the date of grant. A summary of common stock option activity is as follows: Shares (in thousands) Weighted-Average Exercise Price Weighted Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (1) (in thousands) Options outstanding — December 31, 2018 1,774 $ 20.55 2.01 $ 1,214 Granted 39 20.64 Exercised (110 ) 12.13 Forfeited (21 ) 23.91 Canceled (62 ) 21.61 Options outstanding — June 30, 2019 1,620 21.03 1.57 $ 10,205 Exercisable — June 30, 2019 1,238 $ 20.05 6.40 $ 9,047
Summary of RSU activity	We grant restricted stock units ("RSUs") to employees and our non-employee directors. A summary of RSU activity, inclusive of performance-based RSUs, is as follows: Shares (in thousands) Weighted-Average Grant Date Fair Value Weighted-Average Remaining Contractual Term (in years) Unamortized Compensation Costs (in thousands) Unvested — December 31, 2018 381 $ 18.11 2.42 $ 4,536 Granted 1,714 15.34 Vested (157 ) 17.55 Forfeited (92 ) 19.41 Unvested — June 30, 2019 1,846 $ 20.68 3.42 $ 26,295

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Deferred FI implementation costs	The following table presents changes in deferred FI implementation costs (in thousands): Three Months Ended Six Months Ended 2018 2019 2018 2019 Beginning balance $ 12,119 $ 14,067 $ 13,625 $ 15,877 Deferred costs 2,000 — 2,250 — Recoveries through FI Share (1,348 ) (1,155 ) (2,692 ) (2,312 ) Amortization (346 ) (731 ) (758 ) (1,384 ) Ending balance $ 12,425 $ 12,181 $ 12,425 $ 12,181

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	6 Months Ended
	Jun. 30, 2019
Earnings Per Share [Abstract]
Schedule of antidilutive securities	The following securities outstanding as of June 30, 2018 and June 30, 2019 have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive (in thousands): June 30, 2018 2019 Common stock options 2,232 1,620 Common stock warrants 868 868 Common stock warrants issuable pursuant to Series G Stock financing 751 — Restricted stock units 1,232 1,846 Common stock issuable pursuant to the ESPP 95 22

SEGMENTS (Tables)

SEGMENTS (Tables)	6 Months Ended
	Jun. 30, 2019
Segment Reporting [Abstract]
Schedule of segment reporting information	The following table provides information regarding our reportable segments (in thousands): Three Months Ended Six Months Ended 2018 2019 2018 2019 Cardlytics Direct: Adjusted contribution $ 16,240 $ 21,841 $ 30,462 $ 39,478 Plus: Adjusted FI Share and other third-party costs (1) 18,858 26,889 36,757 45,240 Revenue $ 35,098 $ 48,730 $ 67,219 $ 84,718 Other Platform Solutions: Adjusted contribution $ (71 ) $ — $ (69 ) $ — Plus: Adjusted FI Share and other third-party costs (1) 543 — 1,133 — Revenue $ 472 $ — $ 1,064 $ — Total: Adjusted contribution $ 16,169 $ 21,841 $ 30,393 $ 39,478 Plus: Adjusted FI Share and other third-party costs (1) 19,401 26,889 37,890 45,240 Revenue $ 35,570 $ 48,730 $ 68,283 $ 84,718 (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 amortization of deferred FI implementation costs, which are detailed below in our reconciliation of GAAP loss before income taxes to adjusted contribution. The following table presents a reconciliation of loss before income taxes presented in accordance with GAAP to adjusted contribution (in thousands): Three Months Ended Six Months Ended 2018 2019 2018 2019 Adjusted contribution $ 16,169 $ 21,841 $ 30,393 $ 39,478 Minus: Non-cash equity expense included in FI Share (1) — — 2,519 — Amortization of deferred FI implementation costs (1) 346 731 758 1,384 Delivery costs 2,559 3,370 4,502 6,616 Sales and marketing expense 10,247 11,047 18,463 20,384 Research and development expense 4,888 2,782 8,347 5,723 General and administration expense 8,979 8,340 15,561 15,340 Depreciation and amortization expense 784 1,053 1,694 2,014 Total other expense 1,419 1,028 11,657 841 Loss before income taxes $ (13,053 ) $ (6,510 ) $ (33,108 ) $ (12,824 ) (1) Non-cash equity expense included in FI Share and amortization of deferred FI implementation costs are excluded from adjusted FI Share and other third party costs, which is shown above in our reconciliation of GAAP revenue to adjusted contribution.
Schedule of revenue by geographic areas	The following table provides geographical information (in thousands): Three Months Ended Six Months Ended 2018 2019 2018 2019 Revenue: United States $ 30,735 $ 43,123 $ 59,722 $ 74,471 United Kingdom 4,835 5,607 8,561 10,247 Total $ 35,570 $ 48,730 $ 68,283 $ 84,718 December 31, 2018 June 30, 2019 Property and equipment: United States $ 9,794 $ 11,279 United Kingdom 436 616 Total $ 10,230 $ 11,895

OVERVIEW OF BUSINESS AND BASI_2

OVERVIEW OF BUSINESS AND BASIS OF PRESENTATION (Details) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Par value (in usd per share)	$ 0.0001	$ 0.0001

SIGNIFICANT ACCOUNTING POLICI_4

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS - Consumer Incentives (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Accounting Policies [Abstract]
Consumer incentives, expense	$ 25	$ 15.8	$ 47.6	$ 31.9

SIGNIFICANT ACCOUNTING POLICI_5

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS - Concentrations of Risk (Details)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Concentration Risk [Line Items]
Document Period End Date	Jun. 30, 2019
Financial institutions agreement, notice period	90 days
Minimum
Concentration Risk [Line Items]
Financial institutions agreement, term	3 years
Maximum
Concentration Risk [Line Items]
Financial institutions agreement, term	7 years
One Customer | Customer Concentration Risk | Accounts Receivable
Concentration Risk [Line Items]
Concentration risk	12.00%	10.00%
Two Customer [Member] [Member] | Customer Concentration Risk | Accounts Receivable
Concentration Risk [Line Items]
Concentration risk		10.00%
Bank of America | Supplier Concentration Risk | Financial Institution Partner
Concentration Risk [Line Items]
Concentration risk	41.00%	67.00%
Chase | Supplier Concentration Risk | Financial Institution Partner
Concentration Risk [Line Items]
Concentration risk	35.00%	0.00%
Largest FI Partner Three [Member] [Domain] | Supplier Concentration Risk | Financial Institution Partner
Concentration Risk [Line Items]
Concentration risk	8.00%	10.00%

SIGNIFICANT ACCOUNTING POLICI_6

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Document Period End Date	Jun. 30, 2019
Interest-bearing deposits, interest rate	1.06%
Restricted cash deposits, interest rate	0.51%
Cash and cash equivalents	$ 32,495	$ 39,623	$ 50,468	$ 21,262
Restricted cash	10,254	20,247	20,000	0
Cash, cash equivalents and restricted cash	$ 42,749	$ 59,870	$ 70,468	$ 21,262

SIGNIFICANT ACCOUNTING POLICI_7

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS - Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 48,730	$ 35,570	$ 84,718	$ 68,283
Cost per Served Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	33,549	24,010	54,558	42,455
Cost per Redemption [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	14,276	9,456	28,240	21,211
Cost Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 905	$ 2,104	$ 1,920	$ 4,617

DEBT - Schedule of Debt (Detail

DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total debt	$ 36,703	$ 46,714
Less current portion of long-term debt	(22)	(21)
Long-term debt, net of current portion	36,681	46,693
Lines of credit
Debt Instrument [Line Items]
Total debt	26,677	26,677
Term loans
Debt Instrument [Line Items]
Total debt	9,979	19,980
Capital leases
Debt Instrument [Line Items]
Total debt	$ 47	$ 57

DEBT - Narrative (Details)

DEBT - Narrative (Details) - USD ($)	6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	May 14, 2019	Dec. 31, 2018	May 21, 2018
Debt Instrument [Line Items]
Cash paid for interest	$ 800,000	$ 8,700,000
Less unamortized debt issuance costs	$ (21,000)		$ (21,000)		$ (20,000)
Maximum borrowing capacity, percentage of accounts receivable	85.00%		85.00%
Debt instrument, required cash balance	$ 5,000,000		$ 5,000,000
Debt Instrument, Required Billings Threshold			219,000,000
Principal payments of debt	10,010,000	$ 51,811,000
Lines of credit
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	210,000,000
Line of Credit Facility, Maximum Month-end Outstanding Amount	255,000,000
Lines of credit
Debt Instrument [Line Items]
Maximum borrowing capacity	40,000,000		40,000,000
Debt Instrument, Annual Principal Payment	10,000,000		10,000,000
Restricted Cash, Current	$ 10,000,000		$ 10,000,000
Debt instrument, interest rate	5.00%		5.00%
Commitment fee percentage	0.15%
Debt instrument, interest rate increase event of default	3.00%		3.00%
Line of credit facility, remaining borrowing capacity	$ 13,300,000		$ 13,300,000
Lines of credit | Loan Facility, Threshold Two [Member] | Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Term loans
Debt Instrument [Line Items]
Debt instrument, face amount						$ 20,000,000
Debt Instrument, Unamortized Premium, Current				$ 10,000,000
Debt instrument, interest rate	2.75%		2.75%
Term loans | Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate	2.75%
Revolving Credit Facility | Lines of credit
Debt Instrument [Line Items]
Maximum borrowing capacity						$ 30,000,000
Line of Credit, Current				$ 40,000,000

DEBT - Future Payments (Details

DEBT - Future Payments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt
2019 (remainder of year)	$ 0
2020	0
2021	36,677
Total principal payments	36,677
Less unamortized debt issuance costs	(21)	$ (20)
Total debt	36,656
Capital leases
2019 (remainder of the year)	10
2020	24
2021	13
Total principal payments	47
Total debt
2019 (remainder of the year)	10
2020	24
2021	36,690
Total principal payments	36,724
Less unamortized debt issuance costs	(21)	$ (20)
Total debt	$ 36,703

STOCK-BASED COMPENSATION - Narr

STOCK-BASED COMPENSATION - Narrative (Details) $ / shares in Units, $ in Millions	Aug. 08, 2019USD ($)shares	Feb. 08, 2018shares	Jun. 30, 2019USD ($)usershares	Mar. 31, 2018	Jun. 30, 2019USD ($)user$ / sharesshares	Jun. 30, 2018USD ($)$ / shares	Aug. 13, 2019	Dec. 31, 2018shares	Feb. 28, 2018shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capital Lease Obligations Incurred | $					$ 0.1
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%
Award vesting period					4 years
Expiration period					10 years
Weighted-average grant date fair value (in usd per share) | $ / shares					$ 0.47	$ 10
Options vested in period, fair value | $					$ 2.2	$ 4
Compensation not yet recognized | $			$ 4.4		$ 4.4
Common stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized					1 year 7 months 6 days
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)					1,714,000
Unvested PSU (in shares)			1,846,000		1,846,000			381,000
Compensation cost not yet recognized					3 years 5 months 1 day			2 years 5 months 1 day
Restricted stock units | Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)					461,332
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested PSU (in shares)			1,252,500		1,252,500				875,000
Compensation cost, modification | $						$ 6.9
Performance Shares [Member] | Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU, performance condition, period					3 years
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Performance Conditions | user			0.50		0.50
Performance Shares [Member] | Share-based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU, performance condition, period					5 years
Share-Based Compensation Arrangement By Share-Based Payment Award, Non-Option Equity Instruments, Performance Conditions | user			0.25		0.25
Performance Shares [Member] | Share-based Compensation Award, Tranche Three [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		0.25
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized, annual increase								1.00%
ESPP, purchase price percentage		85.00%
ESPP, number of shares authorized, annual increase (in shares)			500,000		500,000
Employees and non-employee directors | Minimum | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			1 year
Employees and non-employee directors | Maximum | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period				4 years
Subsequent Event | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period							4 years
Granted (in shares)	78,191
Compensation not yet recognized, awards other than options | $	$ 2.1

STOCK-BASED COMPENSATION - Allo

STOCK-BASED COMPENSATION - Allocation of Stock-based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	Jun. 28, 2019	Dec. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Feb. 28, 2018	Feb. 08, 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	$ 25.98	$ 10.83
Stock Issued During Period, Shares, Employee Stock Purchase Plans					93,584
Number of shares authorized (in shares)								1,875,000
Number of shares authorized, annual increase		5.00%
Total stock-based compensation expense			$ 3,072	$ 8,345	$ 4,780	$ 11,245
Delivery costs
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense			199	183	363	268
Sales and marketing expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense			952	2,668	1,659	3,611
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense			363	1,756	566	2,226
General and administration expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense			$ 1,558	$ 3,738	$ 2,192	$ 5,140
ESPP
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
ESPP, number of shares authorized, annual increase (in shares)			500,000		500,000
Number of shares authorized, annual increase		1.00%
2018 Employee Stock Purchase Plan [Member] | ESPP
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Number of shares authorized (in shares)							375,000

STOCK-BASED COMPENSATION - Summ

STOCK-BASED COMPENSATION - Summary of Common Stock Option Activity (Details) - USD ($)	Jan. 01, 2019	Jun. 30, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value		$ 10,205,000	$ 1,214,000
Document Period End Date		Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number		1,238,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price		$ 20.05
Award vesting period		4 years
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	1,123,312
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value		$ 9,047,000
Shares
Beginning balance (in shares)	1,774,000	1,774,000
Granted (in shares)		39,000
Exercised (in shares)		(110,000)
Forfeited (in shares)		(21,000)
Canceled (in shares)		(62,000)
Ending balance (in shares)		1,620,000	1,774,000
Weighted-Average Exercise Price
Beginning balance (in usd per share)	$ 20.55	$ 20.55
Granted (in usd per share)		20.64
Exercised (in usd per share)		12.13
Forfeited (in usd per share)		23.91
Canceled (in usd per share)		21.61
Ending balance (in usd per share)		$ 21.03	$ 20.55
Common stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term		1 year 6 months 25 days	2 years 3 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term		6 years 4 months 24 days
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	224,662

STOCK-BASED COMPENSATION - Su_2

STOCK-BASED COMPENSATION - Summary of RSU Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 08, 2019	Feb. 28, 2018	Dec. 31, 2018	Mar. 31, 2018	Jun. 30, 2019	Aug. 13, 2019	Dec. 31, 2018
Weighted-Average Grant Date Fair Value
Award vesting period					4 years
Restricted securities units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option expense					$ 26,295		$ 4,536
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized					3 years 5 months 1 day		2 years 5 months 1 day
Shares
Unvested — Beginning balance (in shares)					381,000
Granted (in shares)					1,714,000
Vested (in shares)					(157,000)
Forfeited (in shares)					(92,000)
Unvested — Ending balance (in shares)			381,000		1,846,000		381,000
Weighted-Average Grant Date Fair Value
Unvested — Beginning balance (in usd per share)					$ 18.11
Granted (in usd per share)					15.34
Vested (in usd per share)					17.55
Forfeited (in usd per share)					19.41
Unvested — Ending balance (in usd per share)			$ 18.11		$ 20.68		$ 18.11
Performance Shares [Member]
Shares
Vested (in shares)			(850,000,000)
Forfeited (in shares)							(25,000,000)
Unvested — Ending balance (in shares)		875,000			1,252,500
Subsequent Event | Restricted stock units
Shares
Granted (in shares)	78,191
Weighted-Average Grant Date Fair Value
Award vesting period						4 years
Compensation not yet recognized, awards other than options	$ 2,100
Maximum | Employees and non-employee directors | Restricted stock units
Weighted-Average Grant Date Fair Value
Award vesting period				4 years

RELATED PARTIES - Narrative (De

RELATED PARTIES - Narrative (Details) $ in Millions	1 Months Ended
	Feb. 28, 2018USD ($)
Common Stock Warrants
Related Party Transaction [Line Items]
Stock option expense	$ 2.5

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Amounts not yet paid to FI		$ 9.3
FI share, expense	$ 2.3
Non-cash gain on financial institution share	4.6
Financial Institution Share Commitment
Loss Contingencies [Line Items]
FI share commitment	$ 10

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Deferred FI Implementation Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Deferred Financial Institution Costs [Roll Forward]
Beginning balance	$ 12,119	$ 14,067	$ 15,877	$ 13,625
Deferred costs	0	2,000	0	2,250
Recoveries through FI Share	(1,155)	(1,348)	(2,312)	(2,692)
Amortization	(731)	(346)	(1,384)	(758)
Ending balance	$ 12,181	$ 12,425	$ 12,181	$ 12,425

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,620	2,232
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	868	868
Common stock warrants | Redeemable Convertible Preferred Stock Series G, Two [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	751
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,846	1,232
Common stock issuable pursuant to the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	22	95

SEGMENTS - Narrative (Details)

SEGMENTS - Narrative (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019USD ($)segment	Jun. 30, 2018USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	2
Capital expenditures	$ 4,019	$ 1,492
United Kingdom
Segment Reporting Information [Line Items]
Capital expenditures	$ 300	$ 100

SEGMENTS - Revenue by Segment (

SEGMENTS - Revenue by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Adjusted contribution	$ 21,841	$ 16,169	$ 39,478	$ 30,393
Plus: FI Share and other third-party costs	26,889	19,401	45,240	37,890
Revenues	48,730	35,570	84,718	68,283
Non-cash gain on financial institution share			4,600
Cardlytics Direct
Segment Reporting Information [Line Items]
Adjusted contribution	21,841	16,240	39,478	30,462
Plus: FI Share and other third-party costs	26,889	18,858	45,240	36,757
Revenues	48,730	35,098	84,718	67,219
Other Platform Solutions
Segment Reporting Information [Line Items]
Adjusted contribution	0	(71)	0	(69)
Plus: FI Share and other third-party costs	0	543	0	1,133
Revenues	$ 0	$ 472	$ 0	$ 1,064

SEGMENTS - Adjusted Contributio

SEGMENTS - Adjusted Contribution Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting [Abstract]
Adjusted contribution	$ 21,841	$ 16,169	$ 39,478	$ 30,393
Non-cash equity expense included in FI Share	0	0	0	2,519
Amortization of deferred FI implementation costs	731	346	1,384	758
Delivery costs	3,370	2,559	6,616	4,502
Sales and marketing expense	11,047	10,247	20,384	18,463
Research and development expense	2,782	4,888	5,723	8,347
General and administration expense	8,340	8,979	15,340	15,561
Depreciation and amortization expense	1,053	784	2,014	1,694
Total other expense (income)	1,028	1,419	841	11,657
Loss before income taxes	$ (6,510)	$ (13,053)	$ (12,824)	$ (33,108)

SEGMENTS - Geographical Informa

SEGMENTS - Geographical Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 48,730	$ 35,570	$ 84,718	$ 68,283
Property and equipment	11,895		11,895		$ 10,230
United States
Segment Reporting Information [Line Items]
Revenues	43,123	30,735	74,471	59,722
Property and equipment	11,279		11,279		9,794
United Kingdom
Segment Reporting Information [Line Items]
Revenues	5,607	$ 4,835	10,247	$ 8,561
Property and equipment	$ 616		$ 616		$ 436