Cardlytics (CDLX) 10-Q 12 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - $ / shares	9 Months Ended
	Sep. 30, 2019	Oct. 31, 2019	Dec. 31, 2018
Document Information [Line Items]
Entity Shell Company	false
Document Transition Report	false
Document Quarterly Report	true
Title of 12(b) Security	Common Stock
Trading Symbol	CDLX
Entity Incorporation, State or Country Code	DE
Entity Registrant Name	CARDLYTICS, INC.
Security Exchange Name	NASDAQ
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity File Number	001-38386
Entity Current Reporting Status	Yes
Document Fiscal Year Focus	2019
Entity Interactive Data Current	Yes
Entity Ex Transition Period	false
Document Fiscal Period Focus	Q3
Entity Emerging Growth Company	true
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001666071
Entity Common Stock, Shares Outstanding (in shares)		25,711,713
Entity Address, City or Town	Atlanta
Entity Address, Address Line One	675 Ponce de Leon Ave. NE, Ste 6000
Entity Tax Identification Number	26-3039436
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30308
Common stock, par or stated value per share (in usd per share)	$ 0.0001		$ 0.0001
Local Phone Number	792-5802
City Area Code	(888)

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Document Period End Date	Sep. 30, 2019
Current assets:
Cash and cash equivalents	$ 95,184	$ 39,623
Restricted cash	246	20,247
Accounts receivable, net	61,691	58,125
Other receivables	3,634	2,417
Prepaid expenses and other assets	5,320	3,956
Total current assets	166,075	124,368
Long-term assets:
Property and equipment, net	12,125	10,230
Intangible assets, net	375	370
Capitalized software development costs, net	3,099	1,625
Deferred FI implementation costs, net	10,235	15,877
Other long-term assets, net	1,338	1,293
Total assets	193,247	153,763
Current liabilities:
Accounts payable	1,946	2,099
Accrued liabilities:
Accrued compensation	6,944	5,936
Accrued expenses	3,906	4,388
FI Share liability	33,697	27,656
Consumer Incentive liability	15,873	11,476
Deferred billings	745	346
Current portion of long-term debt	23	21
Total current liabilities	63,134	51,922
Long-term liabilities:
Deferred liabilities	2,773	3,173
Long-term debt, net of current portion	19	46,693
Total liabilities	65,926	101,788
Stockholders’ equity:
Common stock, $0.0001 par value—100,000 shares authorized and 22,466 and 25,664 shares issued and outstanding as of December 31, 2018 and September 30, 2019, respectively	8	7
Additional paid-in capital	466,737	371,463
Accumulated other comprehensive income	2,634	1,992
Accumulated deficit	(342,058)	(321,487)
Total stockholders’ equity	127,321	51,975
Total liabilities and stockholders’ equity	$ 193,247	$ 153,763

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - $ / shares	Sep. 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)	25,664,000	22,466,000
Common stock, shares outstanding (in shares)	25,664,000	22,466,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenue	$ 56,419	$ 34,582	$ 141,137	$ 102,865
Costs and expenses:
FI Share and other third-party costs	32,470	17,982	79,094	59,149
Delivery costs	3,070	3,007	9,686	7,509
Sales and marketing expense	11,074	9,452	31,458	27,915
Research and development expense	3,018	4,097	8,741	12,444
General and administration expense	12,218	7,925	27,558	23,486
Depreciation and amortization expense	1,167	777	3,181	2,471
Total costs and expenses	63,017	43,240	159,718	132,974
Operating loss	(6,598)	(8,658)	(18,581)	(30,109)
Other income (expense):
Interest expense, net	(218)	(254)	(860)	(2,995)
Change in fair value of warrant liabilities, net	0	801	0	(6,760)
Other expense	(931)	(257)	(1,130)	(1,612)
Total other income (expense)	(1,149)	290	(1,990)	(11,367)
Loss before income taxes	(7,747)	(8,368)	(20,571)	(41,476)
Net loss	(7,747)	(8,368)	(20,571)	(41,476)
Adjustments to the carrying value of preferred stock	0	0	0	(157)
Net loss attributable to common stockholders	$ (7,747)	$ (8,368)	$ (20,571)	$ (41,633)
Net loss per share attributable to common stockholders, basic and diluted (in USD per share)	$ (0.33)	$ (0.40)	$ (0.90)	$ (2.29)
Weighted-average common shares outstanding, basic and diluted (in shares)	23,561	20,970	22,936	18,150

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (7,747)	$ (8,368)	$ (20,571)	$ (41,476)
Other comprehensive income:
Foreign currency translation adjustments	565	202	642	574
Total comprehensive loss	$ (7,182)	$ (8,166)	$ (19,929)	$ (40,902)

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		$ 6	$ 1,736
Adjustments to Additional Paid in Capital, Preferred Stock Warrant Conversion, Common Stock Warrant	$ 196,594		196,588
Stock and Warrants Issued During Period, Value, Preferred Stock and Warrants		$ 0
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)		329
Exercise of common stock options	$ 1,799		$ 1,799
Stock Issued During Period, Shares, Warrants Exercised In Period	0	1,142	0
Stock-based compensation			$ 16,968
Settlement of restricted stock (in shares)		0
Vesting of common stock warrants	$ 16,968
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures		37
Stock Issued During Period, Value, New Issues	66,101	$ 1	66,100
Stock Issued During Period, Shares, New Issues		5,821
Stock Issued During Period, Value, Restricted Stock Award, Gross		$ 0	0
Accretion of redeemable convertible preferred stock to redemption value			(157)
Preferred Stock, Accretion of Redemption Discount	(157)			0
Other comprehensive income	574			574
Net loss	(41,476)				(41,476)
Ending balance (in shares) at Sep. 30, 2018		21,411
Ending balance at Sep. 30, 2018	51,227	$ 7	359,501	1,640	(309,921)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adjustments to Additional Paid in Capital, Convertible Debt with Conversion Feature	17,774
Beginning balance (in shares) at Jun. 30, 2018		20,316
Beginning balance at Jun. 30, 2018	36,766	$ 7	336,874	1,438	(301,553)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		265
Exercise of common stock options	1,655		1,655
Stock-based compensation			0
Settlement of restricted stock (in shares)		37
Vesting of common stock warrants	15,255	$ 793	15,255
Stock Issued During Period, Value, New Issues	5,717	$ 0	5,717
Other comprehensive income	202			202
Net loss	(8,368)				(8,368)
Ending balance (in shares) at Sep. 30, 2018		21,411
Ending balance at Sep. 30, 2018	51,227	$ 7	359,501	1,640	(309,921)
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)	215	215
Exercise of common stock options	$ 2,850		$ 2,850
Stock Issued During Period, Shares, Warrants Exercised In Period	17,659	821	17,659
Stock-based compensation	$ 12,292		$ 12,292
Settlement of restricted stock (in shares)		164
Stock Issued During Period, Value, New Issues	61,309	$ 1	61,308
Stock Issued During Period, Shares, New Issues		1,904
Other comprehensive income	642			642
Net loss	(20,571)				(20,571)
Ending balance (in shares) at Sep. 30, 2019		25,664
Ending balance at Sep. 30, 2019	127,321	$ 8	466,737	2,634	(342,058)
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 Jun. 30, 2019		22,828
Beginning balance at Jun. 30, 2019	46,538	$ 7	378,773	2,069	(334,311)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		104
Exercise of common stock options	$ 1,502		$ 1,502
Stock Issued During Period, Shares, Warrants Exercised In Period	17,659	821	17,659
Stock-based compensation	$ 7,495		$ 7,495
Settlement of restricted stock (in shares)		7
Stock Issued During Period, Value, New Issues	61,309	$ 1	61,308
Stock Issued During Period, Shares, New Issues		1,904
Other comprehensive income	565			565
Net loss	(7,747)				(7,747)
Ending balance (in shares) at Sep. 30, 2019		25,664
Ending balance at Sep. 30, 2019	$ 127,321	$ 8	$ 466,737	$ 2,634	$ (342,058)

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Cash paid for interest			$ 1,259	$ 9,158
Cash and cash equivalents	$ 95,184	$ 47,812	95,184	47,812
Capitalized Software Development Costs Incurred but Not yet Paid	0	9	0	9
Restricted cash	246	20,000	246	20,000
Operating activities
Net loss	(7,747)	(8,368)	(20,571)	(41,476)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization			3,181	2,471
Amortization of financing costs charged to interest expense			72	255
Accretion of debt discount and non-cash interest expense			0	2,326
Termination of U.K. agreement expense			12,266	16,968
Change in fair value of warrant liabilities, net	0	(801)	0	6,760
Other non-cash expense, net			2,434	4,136
Amortization of deferred FI implementation costs	789	378	2,173	1,136
Settlement Of Paid-in-Kind Interest			0	(8,353)
Change in operating assets and liabilities:
Accounts receivable			(5,789)	10,883
Prepaid expenses and other assets			(1,368)	(1,797)
Deferred FI implementation costs			0	(5,750)
Recovery of deferred FI implementation costs	(1,157)	(1,344)	3,469	4,036
Accounts payable			(401)	221
Other accrued expenses			1,453	24
FI Share liability			6,041	(3,728)
Customer Incentive liability			4,397	(2,412)
Net cash (used in) from operating activities			7,357	(14,300)
Investing activities
Acquisition of property and equipment			(4,561)	(3,190)
Acquisition of patents			(14)	(14)
Capitalized software development costs			(1,836)	(981)
Net cash used in investing activities			(6,411)	(4,185)
Proceeds from Issuance of Long-term Debt			0	47,435
Financing activities
Principal payments of debt			(46,692)	(52,475)
Proceeds from issuance of common stock			81,922	72,179
Equity issuance costs			(38)	(1,949)
Debt issuance costs			(143)	(48)
Net cash from financing activities			35,049	65,142
Effect of exchange rates on cash, cash equivalents and restricted cash			(435)	(107)
Net increase in cash, cash equivalents and restricted cash			35,560	46,550
Cash, cash equivalents, and restricted cash — Beginning of period			59,870	21,262
Cash, cash equivalents, and restricted cash — End of period	95,430	67,812	95,430	67,812
Supplemental schedule of non-cash investing and financing activities:
Amounts accrued for property and equipment	$ 991	$ 1,697	$ 991	$ 1,697

OVERVIEW OF BUSINESS AND BASIS

OVERVIEW OF BUSINESS AND BASIS OF PRESENTATION	9 Months Ended
	Sep. 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, and in India through Cardlytics Services India Private Limited, a wholly-owned and operated subsidiary registered as a private limited company in India. Proceeds from Issuance of Common Stock On September 13, 2019 , we closed a public equity offering in which we sold 1,904,154 shares of common stock, which included 404,154 shares sold pursuant to the exercise by the underwriters of an option to purchase additional shares, at a public offering price of $34.00 per share. We received total net proceeds of $61.0 million after deducting underwriting discounts and commissions of $3.2 million and offering costs of $0.5 million . Selling stockholders, including certain of our executive officers and entities affiliated with certain of our directors, sold 1,194,365 shares of common stock in the offering at a public offering price of $34.00 . We did not receive any proceeds from the sale of common stock by the selling stockholders. During the three and nine months ended September 30, 2019 , we also received $19.2 million and $20.5 million in proceeds from the exercise of options and warrants to purchase shares of common stock, respectively. 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	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS	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 April 2015, the FASB issued ASU 2015-05, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement , to help entities evaluate the accounting for fees paid by a customer in a cloud computing arrangement (hosting arrangement) by providing guidance for determining when the arrangement includes a software license. If a cloud computing arrangement includes a license to internal-use software, then the software license is accounted for by the customer in accordance with Subtopic 350-40. This generally means that an intangible asset is recognized for the software license and, to the extent that the payments attributable to the software license are made over time, a liability also is recognized. If a cloud computing arrangement does not include a software license, the entity should account for the arrangement as a service contract. This generally means that the fees associated with the hosting element (service) of the arrangement are expensed as incurred. For public entities, this ASU is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. For non-public entities, this ASU is effective for fiscal years beginning after December 15, 2020, and interim periods within fiscal years beginning after December 15, 2021. Early adoption is permitted, including adoption in any interim period, for all entities. 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, and therefore we will be required to adopt this ASU for annual reporting periods beginning after December 15, 2020. We plan to early adopt this ASU on January 1, 2020 on a prospective basis. We do not expect the adoption to have a material effect on our consolidated financial statements. 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 requires lessees 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 annual periods beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. On October 16, 2019, the FASB "tentatively affirmed" its decision issued on August 15, 2019, to change the effective date of ASC Topic 842 for private entities for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. The final ASU regarding the change in effective date is pending. 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, and therefore we will be required to adopt this ASU for annual reporting periods beginning after December 15, 2019. 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 (Notes)

REVENUE (Notes)	9 Months Ended
	Sep. 30, 2019
Revenue from Contract with Customer [Abstract]
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 $14.0 million and $26.3 million during the three months ended September 30, 2018 and 2019 , respectively, and totaled $45.9 million and $73.9 million during the nine months ended September 30, 2018 and 2019 , respectively.
Revenue Recognition, Policy [Policy Text Block]	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 purchase intelligence platform, we are able to create compelling Consumer Incentives that have the potential to increase return on advertising spend for marketers and measure the effectiveness of the advertising. 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 September 30, Nine Months Ended September 30, 2018 2019 2018 2019 Cost per Served Sale $ 25,320 $ 40,000 $ 67,775 $ 94,558 Cost per Redemption 8,236 15,611 29,447 43,851 Other 1,026 808 5,643 2,728 Revenue $ 34,582 $ 56,419 $ 102,865 $ 141,137 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. 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
Disaggregation of Revenue [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2018 2019 2018 2019 Cost per Served Sale $ 25,320 $ 40,000 $ 67,775 $ 94,558 Cost per Redemption 8,236 15,611 29,447 43,851 Other 1,026 808 5,643 2,728 Revenue $ 34,582 $ 56,419 $ 102,865 $ 141,137

DEBT

DEBT	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
DEBT	DEBT Our debt consists of the following (in thousands): December 31, 2018 September 30, 2019 Lines of credit $ 26,677 $ — Term loans (1) 19,980 — Capital leases 57 42 Total debt 46,714 42 Less current portion of long-term debt (21 ) (23 ) Long-term debt, net of current portion $ 46,693 $ 19 (1) Net of unamortized debt issuance costs of $20 and $0 as of December 31, 2018 and September 30, 2019 , 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. We repaid $10.0 million of the principal balance of the 2018 Term Loan upon the execution of the amendment in May 2019 and repaid the remaining $10.0 million principal balance in September 2019. In September 2019, we reduced our outstanding borrowings under our 2018 Line of Credit by $26.7 million . 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 $225.0 million for September 2019. 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 . 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 4.50% as of September 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 accrued on the 2018 Term Loan at an annual rate of interest equal to the prime rate minus 2.75% , or 2.50% at the date of repayment in September 2019. The 2018 Loan Facility includes customary representations, warranties and covenants (affirmative and negative), including restrictive covenants that prohibits mergers, acquisitions and dispositions of assets, incurrence of indebtedness and encumbrances on our assets and the payment or declaration of dividends; in each case subject to specified exceptions. The 2018 Loan Facility also includes standard events of default, including in the event of a material adverse change. Upon the occurrence of an event of default, the lender may declare all outstanding obligations immediately due and payable and take such other actions as are set forth in the 2018 Loan Facility and increase the interest rate otherwise applicable to advances under the 2018 Line of Credit by an additional 3.00% . All of our obligations under the 2018 Loan Facility are secured by a first priority lien on substantially all of our assets. As of September 30, 2019 , we had $40.0 million of unused available borrowings under our 2018 Line of Credit. We were in compliance with all financial covenants as of September 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) $ — $ 5 $ 5 2020 — 24 24 2021 — 13 13 Total debt $ — $ 42 $ 42

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	9 Months Ended
	Sep. 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 Nine Months Ended 2018 2019 2018 2019 Delivery costs $ 203 $ 176 $ 471 $ 539 Sales and marketing expense 1,939 1,432 5,550 3,091 Research and development expense 915 638 3,141 1,204 General and administration expense 2,666 5,240 7,806 7,432 Total stock-based compensation expense $ 5,723 $ 7,486 $ 16,968 $ 12,266 During each of the nine months ended September 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 Vesting Period (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 (215 ) 13.25 Forfeited (28 ) 23.82 Canceled (65 ) 22.36 Options outstanding — September 30, 2019 1,505 21.46 1.33 $ 18,871 Exercisable — September 30, 2019 1,195 $ 20.70 (1) The aggregate intrinsic value represents the total pre-tax intrinsic value based on the $10.83 and $33.52 per share closing price of our common stock as reported on the Nasdaq Global Market on December 31, 2018 and September 30, 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 nine months ended September 30, 2018 and 2019 was $10.00 and $0.47 per share, respectively. The total fair value of options vested during the nine months ended September 30, 2018 and 2019 was approximately $5.0 million and $3.2 million , respectively. As of September 30, 2019 , unamortized stock-based compensation expense related to unvested common stock options was $3.6 million , and the weighted-average period over which such stock-based compensation expense will be recognized was 1.3 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 Vesting Period (in years) Unamortized Compensation Costs (in thousands) Unvested — December 31, 2018 381 $ 18.11 2.42 $ 4,536 Granted 1,792 15.86 Vested (1) (324 ) 14.65 Forfeited (112 ) 19.02 Unvested — September 30, 2019 1,737 $ 16.38 3.06 $ 21,519 (1) Includes 160 RSUs that have vested but have not been settled. During the nine months ended September 30, 2019 , we granted 539,523 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 September 30, 2019 , we granted 186,309 RSUs to employees. The unamortized stock-based compensation expense related to these RSUs is $6.8 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 nine months ended September 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." In August 2019, the Compensation Committee of our Board of Directors certified that the target minimum trailing 30-day average closing price of our common stock was achieved resulting in the immediate vesting of 50% of the related PSU tranche. 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 nine months ended September 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	9 Months Ended
	Sep. 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. In September 2019, FIS exercised all of their warrants to purchase common stock, resulting in cash proceeds of $15.2 million and the issuance of 644,365 shares of our common stock.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 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, $3.5 million of which has been recovered through September 30, 2019 . The following table presents changes in deferred FI implementation costs (in thousands): Three Months Ended Nine Months Ended 2018 2019 2018 2019 Beginning balance $ 12,425 $ 12,181 $ 13,625 $ 15,877 Deferred costs 3,500 — 5,750 — Recoveries through FI Share (1,344 ) (1,157 ) (4,036 ) (3,469 ) Amortization (378 ) (789 ) (1,136 ) (2,173 ) Ending balance $ 14,203 $ 10,235 $ 14,203 $ 10,235 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 September 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	9 Months Ended
	Sep. 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 nine months ended September 30, 2018 and 2019 because the effects of potentially dilutive items were anti-dilutive, given our net loss during these periods. The following securities as of September 30, 2018 and September 30, 2019 have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive (in thousands): September 30, 2018 2019 Common stock options 1,862 1,505 Common stock warrants 868 13 Unvested restricted stock units 1,200 1,737 Common stock issuable pursuant to the ESPP 151 49

SEGMENTS

SEGMENTS	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
SEGMENTS	SEGMENTS As of September 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 have not and 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 September 30, Nine Months Ended September 30, 2018 2019 2018 2019 Cardlytics Direct: Adjusted contribution $ 16,906 $ 24,738 $ 47,368 $ 64,216 Plus: Adjusted FI Share and other third-party costs (1) 17,514 31,681 54,271 76,921 Revenue $ 34,420 $ 56,419 $ 101,639 $ 141,137 Other Platform Solutions: Adjusted contribution $ 72 $ — $ 3 $ — Plus: Adjusted FI Share and other third-party costs (1) 90 — 1,223 — Revenue $ 162 $ — $ 1,226 $ — Total: Adjusted contribution $ 16,978 $ 24,738 $ 47,371 $ 64,216 Plus: Adjusted FI Share and other third-party costs (1) 17,604 31,681 55,494 76,921 Revenue $ 34,582 $ 56,419 $ 102,865 $ 141,137 (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 measures the degree by which revenue generated from our marketers exceeds the cost to obtain the purchase data and the digital advertising space from our FI partners. Adjusted contribution demonstrates how incremental marketing spend on our platform generates incremental amounts to support our sales and marketing, research and development, general and administration and other investments. Adjusted contribution is calculated by taking our total revenue less our FI Share and other third party costs exclusive of a non-cash equity expense and amortization of deferred FI implementation costs, which are non-cash costs. Adjusted contribution does not take into account all costs associated with generating revenue from advertising campaigns, including sales and marketing expenses, research and development expenses, general and administrative expenses and other expenses, which we do not take into consideration when making decisions on how to manage our advertising campaigns. The following table presents a reconciliation of loss before income taxes presented in accordance with GAAP to adjusted contribution (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2019 2018 2019 Adjusted contribution $ 16,978 $ 24,738 $ 47,371 $ 64,216 Minus: Non-cash equity expense included in FI Share (1) — — 2,519 — Amortization of deferred FI implementation costs (1) 378 789 1,136 2,173 Delivery costs 3,007 3,070 7,509 9,686 Sales and marketing expense 9,452 11,074 27,915 31,458 Research and development expense 4,097 3,018 12,444 8,741 General and administration expense 7,925 12,218 23,486 27,558 Depreciation and amortization expense 777 1,167 2,471 3,181 Total other expense (income) (290 ) 1,149 11,367 1,990 Loss before income taxes $ (8,368 ) $ (7,747 ) $ (41,476 ) $ (20,571 ) (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 September 30, Nine Months Ended September 30, 2018 2019 2018 2019 Revenue: United States $ 30,884 $ 50,997 $ 90,606 $ 125,468 United Kingdom 3,698 5,422 12,259 15,669 Total $ 34,582 $ 56,419 $ 102,865 $ 141,137 December 31, 2018 September 30, 2019 Property and equipment: United States $ 9,794 $ 11,583 United Kingdom 436 384 India $ — $ 158 Total $ 10,230 $ 12,125 Capital expenditures within the United Kingdom were less than $0.1 million and $0.3 million during the nine months ended September 30, 2018 and 2019 , respectively. Concentrations of Risk Customers 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 10% of our accounts receivable as of September 30, 2019 . During the nine months ended September 30, 2018 , a marketer accounted for 10% of our revenue. During the nine months ended September 30, 2019 , a marketer accounted for 11% of our revenue. No other marketer accounted for over 10% of revenue or accounts receivable during the periods presented. FI Partners 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 nine months ended September 30, 2018 and 2019 , Bank of America, National Association accounted for 68% and 38% of the total FI Share we paid to all FIs, respectively. JPMorgan Chase Bank, National Association accounted for 0% and 40% of the total FI Share we paid to all FIs during the nine months ended September 30, 2018 and 2019 , respectively. No other FI partners accounted for over 10% of FI Share during the nine months ended September 30, 2018 and 2019 .

SIGNIFICANT ACCOUNTING POLICI_2

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS (Policies)	9 Months Ended
	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2018 2019 2018 2019 Cost per Served Sale $ 25,320 $ 40,000 $ 67,775 $ 94,558 Cost per Redemption 8,236 15,611 29,447 43,851 Other 1,026 808 5,643 2,728 Revenue $ 34,582 $ 56,419 $ 102,865 $ 141,137
Revenue Recognition, Policy [Policy Text Block]	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 purchase intelligence platform, we are able to create compelling Consumer Incentives that have the potential to increase return on advertising spend for marketers and measure the effectiveness of the advertising. 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 September 30, Nine Months Ended September 30, 2018 2019 2018 2019 Cost per Served Sale $ 25,320 $ 40,000 $ 67,775 $ 94,558 Cost per Redemption 8,236 15,611 29,447 43,851 Other 1,026 808 5,643 2,728 Revenue $ 34,582 $ 56,419 $ 102,865 $ 141,137 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. 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
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 $14.0 million and $26.3 million during the three months ended September 30, 2018 and 2019 , respectively, and totaled $45.9 million and $73.9 million during the nine months ended September 30, 2018 and 2019 , respectively.

SIGNIFICANT ACCOUNTING POLICI_3

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS (Tables)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Disaggregation of Revenue [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2018 2019 2018 2019 Cost per Served Sale $ 25,320 $ 40,000 $ 67,775 $ 94,558 Cost per Redemption 8,236 15,611 29,447 43,851 Other 1,026 808 5,643 2,728 Revenue $ 34,582 $ 56,419 $ 102,865 $ 141,137

DEBT (Tables)

DEBT (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Schedule of long-term debt instruments	Our debt consists of the following (in thousands): December 31, 2018 September 30, 2019 Lines of credit $ 26,677 $ — Term loans (1) 19,980 — Capital leases 57 42 Total debt 46,714 42 Less current portion of long-term debt (21 ) (23 ) Long-term debt, net of current portion $ 46,693 $ 19
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) $ — $ 5 $ 5 2020 — 24 24 2021 — 13 13 Total debt $ — $ 42 $ 42

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	9 Months Ended
	Sep. 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 Nine Months Ended 2018 2019 2018 2019 Delivery costs $ 203 $ 176 $ 471 $ 539 Sales and marketing expense 1,939 1,432 5,550 3,091 Research and development expense 915 638 3,141 1,204 General and administration expense 2,666 5,240 7,806 7,432 Total stock-based compensation expense $ 5,723 $ 7,486 $ 16,968 $ 12,266
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 Vesting Period (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 (215 ) 13.25 Forfeited (28 ) 23.82 Canceled (65 ) 22.36 Options outstanding — September 30, 2019 1,505 21.46 1.33 $ 18,871 Exercisable — September 30, 2019 1,195 $ 20.70
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 Vesting Period (in years) Unamortized Compensation Costs (in thousands) Unvested — December 31, 2018 381 $ 18.11 2.42 $ 4,536 Granted 1,792 15.86 Vested (1) (324 ) 14.65 Forfeited (112 ) 19.02 Unvested — September 30, 2019 1,737 $ 16.38 3.06 $ 21,519

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	9 Months Ended
	Sep. 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 Nine Months Ended 2018 2019 2018 2019 Beginning balance $ 12,425 $ 12,181 $ 13,625 $ 15,877 Deferred costs 3,500 — 5,750 — Recoveries through FI Share (1,344 ) (1,157 ) (4,036 ) (3,469 ) Amortization (378 ) (789 ) (1,136 ) (2,173 ) Ending balance $ 14,203 $ 10,235 $ 14,203 $ 10,235

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Schedule of antidilutive securities	September 30, 2018 2019 Common stock options 1,862 1,505 Common stock warrants 868 13 Unvested restricted stock units 1,200 1,737 Common stock issuable pursuant to the ESPP 151 49

SEGMENTS (Tables)

SEGMENTS (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Schedule of segment reporting information	The following table provides information regarding our reportable segments (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2019 2018 2019 Cardlytics Direct: Adjusted contribution $ 16,906 $ 24,738 $ 47,368 $ 64,216 Plus: Adjusted FI Share and other third-party costs (1) 17,514 31,681 54,271 76,921 Revenue $ 34,420 $ 56,419 $ 101,639 $ 141,137 Other Platform Solutions: Adjusted contribution $ 72 $ — $ 3 $ — Plus: Adjusted FI Share and other third-party costs (1) 90 — 1,223 — Revenue $ 162 $ — $ 1,226 $ — Total: Adjusted contribution $ 16,978 $ 24,738 $ 47,371 $ 64,216 Plus: Adjusted FI Share and other third-party costs (1) 17,604 31,681 55,494 76,921 Revenue $ 34,582 $ 56,419 $ 102,865 $ 141,137 (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 September 30, Nine Months Ended September 30, 2018 2019 2018 2019 Adjusted contribution $ 16,978 $ 24,738 $ 47,371 $ 64,216 Minus: Non-cash equity expense included in FI Share (1) — — 2,519 — Amortization of deferred FI implementation costs (1) 378 789 1,136 2,173 Delivery costs 3,007 3,070 7,509 9,686 Sales and marketing expense 9,452 11,074 27,915 31,458 Research and development expense 4,097 3,018 12,444 8,741 General and administration expense 7,925 12,218 23,486 27,558 Depreciation and amortization expense 777 1,167 2,471 3,181 Total other expense (income) (290 ) 1,149 11,367 1,990 Loss before income taxes $ (8,368 ) $ (7,747 ) $ (41,476 ) $ (20,571 ) (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 September 30, Nine Months Ended September 30, 2018 2019 2018 2019 Revenue: United States $ 30,884 $ 50,997 $ 90,606 $ 125,468 United Kingdom 3,698 5,422 12,259 15,669 Total $ 34,582 $ 56,419 $ 102,865 $ 141,137 December 31, 2018 September 30, 2019 Property and equipment: United States $ 9,794 $ 11,583 United Kingdom 436 384 India $ — $ 158 Total $ 10,230 $ 12,125

OVERVIEW OF BUSINESS AND BASI_2

OVERVIEW OF BUSINESS AND BASIS OF PRESENTATION (Details) - USD ($) $ / shares in Units, $ in Millions	Sep. 11, 2019	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Sale of Stock, Number of Shares Issued in Transaction	1,904,154
Proceeds from Issuance Seconday Public Offering, Net	$ 61
Common stock, shares authorized (in shares)		100,000,000	100,000,000
Sale of Stock, Issuance Costs	$ 0.5
SPO [Member]
Debt Instrument [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Option, Nonvested, Weighted Average Exercise Price	$ 34
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Exercised	1,194,365
sale of stock, discounts and commissions	$ 3.2
Over-Allotment Option [Member]
Debt Instrument [Line Items]
Sale of Stock, Number of Shares Issued in Transaction	404,154

SIGNIFICANT ACCOUNTING POLICI_4

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS - Consumer Incentives (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accounting Policies [Abstract]
Consumer incentives, expense	$ 26.3	$ 14	$ 73.9	$ 45.9

SIGNIFICANT ACCOUNTING POLICI_5

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS - Concentrations of Risk (Details)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Concentration Risk [Line Items]
Document Period End Date	Sep. 30, 2019
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	10.00%
Two Customer [Member] [Member] | Customer Concentration Risk | Accounts Receivable
Concentration Risk [Line Items]
Concentration risk	11.00%
Bank of America | Supplier Concentration Risk | Financial Institution Partner
Concentration Risk [Line Items]
Concentration risk	38.00%	68.00%
Chase | Supplier Concentration Risk | Financial Institution Partner
Concentration Risk [Line Items]
Concentration risk	40.00%	0.00%

SIGNIFICANT ACCOUNTING POLICI_6

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Document Period End Date	Sep. 30, 2019
Cash and cash equivalents	$ 95,184	$ 39,623	$ 47,812
Restricted cash	246		20,000
Cash, cash equivalents and restricted cash	$ 95,430	$ 59,870	$ 67,812	$ 21,262

SIGNIFICANT ACCOUNTING POLICI_7

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS - Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 56,419	$ 34,582	$ 141,137	$ 102,865
Cost per Served Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	40,000	25,320	94,558	67,775
Cost per Redemption [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	15,611	8,236	43,851	29,447
Cost Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 808	$ 1,026	$ 2,728	$ 5,643

REVENUE (Details)

REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue from Contract with Customer, Excluding Assessed Tax	$ 56,419	$ 34,582	$ 141,137	$ 102,865
Cost per Redemption [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 15,611	$ 8,236	$ 43,851	$ 29,447

DEBT - Schedule of Debt (Detail

DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Total debt	$ 42	$ 46,714
Less current portion of long-term debt	(23)	(21)
Long-term debt, net of current portion	19	46,693
Lines of credit
Debt Instrument [Line Items]
Total debt	0	26,677
Term loans
Debt Instrument [Line Items]
Total debt	0	19,980
Capital leases
Debt Instrument [Line Items]
Total debt	$ 42	$ 57

DEBT - Narrative (Details)

DEBT - Narrative (Details) - USD ($)	9 Months Ended		14 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	May 31, 2019	May 14, 2019	Dec. 31, 2018	May 21, 2018
Debt Instrument [Line Items]
Cash paid for interest	$ 1,259,000	$ 9,158,000
Less unamortized debt issuance costs	$ 0		$ 0			$ (20,000)
Document Period End Date	Sep. 30, 2019
Maximum borrowing capacity, percentage of accounts receivable	85.00%		85.00%
Debt Instrument, Required Billings Threshold			$ 225,000,000
Principal payments of debt	$ 46,692,000	$ 52,475,000
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	$ 26,700,000		$ 26,700,000	$ 10,000,000
Debt instrument, interest rate	4.50%		4.50%
Commitment fee percentage	0.15%
Debt instrument, interest rate increase event of default	3.00%		3.00%
Line of credit facility, remaining borrowing capacity	$ 40,000,000		$ 40,000,000
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	2.50%		2.50%
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	Sep. 30, 2019	Dec. 31, 2018
Debt
2019 (remainder of year)	$ 0
2020	0
2021	0
Total principal payments	0
Less unamortized debt issuance costs	0	$ (20)
Total debt	0
Capital leases
2019 (remainder of the year)	5
2020	24
2021	13
Total principal payments	42
Total debt
2019 (remainder of the year)	5
2020	24
2021	13
Total principal payments	42
Less unamortized debt issuance costs	0	$ (20)
Total debt	$ 42

STOCK-BASED COMPENSATION - Narr

STOCK-BASED COMPENSATION - Narrative (Details) $ / shares in Units, $ in Millions	Nov. 12, 2019USD ($)shares	Feb. 08, 2018shares	Sep. 30, 2019USD ($)usershares	Jun. 30, 2018USD ($)$ / shares	Sep. 30, 2019USD ($)user$ / sharesshares	Sep. 30, 2018USD ($)	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				$ 10	$ 0.47
Options vested in period, fair value | $				$ 5	$ 3.2
Compensation not yet recognized | $			$ 3.6		$ 3.6
Common stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized					1 year 3 months 18 days
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)					1,792,000
Unvested PSU (in shares)			1,737,000		1,737,000		381,000
Compensation cost not yet recognized					3 years 21 days		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)					539,523
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)	186,309
Compensation not yet recognized, awards other than options | $	$ 6.8

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	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 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	$ 33.52	$ 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			$ 7,486	$ 5,723	$ 12,266	$ 16,968
Delivery costs
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense			176	203	539	471
Sales and marketing expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense			1,432	1,939	3,091	5,550
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense			638	915	1,204	3,141
General and administration expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense			$ 5,240	$ 2,666	$ 7,432	$ 7,806
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 ($) $ / shares in Units, $ in Thousands	Jan. 01, 2019	Sep. 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		$ 18,871	$ 1,214
Document Period End Date		Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number		1,195,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price		$ 20.70
Award vesting period		4 years
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	1,123,312
Shares (in thousands)
Beginning balance (in shares)	1,774,000	1,774,000
Granted (in shares)		39,000
Exercised (in shares)		(215,000)
Forfeited (in shares)		(28,000)
Canceled (in shares)		(65,000)
Ending balance (in shares)		1,505,000	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)		13.25
Forfeited (in usd per share)		23.82
Canceled (in usd per share)		22.36
Ending balance (in usd per share)		$ 21.46	$ 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 3 months 29 days	2 years 3 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	Nov. 12, 2019	Feb. 28, 2018	Dec. 31, 2018	Sep. 30, 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				$ 21,519	$ 4,536
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized				3 years 21 days	2 years 5 months 1 day
Shares (in thousands)
Unvested — Beginning balance (in shares)				381,000
Granted (in shares)				1,792,000
Vested (in shares)				(324,000)
Forfeited (in shares)				(112,000)
Unvested — Ending balance (in shares)			381,000	1,737,000	381,000
Weighted-Average Grant Date Fair Value
Unvested — Beginning balance (in usd per share)				$ 18.11
Granted (in usd per share)				15.86
Vested (in usd per share)				14.65
Forfeited (in usd per share)				19.02
Unvested — Ending balance (in usd per share)			$ 18.11	$ 16.38	$ 18.11
Performance Shares [Member]
Shares (in thousands)
Vested (in shares)			(850,000)
Forfeited (in shares)					(25,000)
Unvested — Ending balance (in shares)		875,000		1,252,500
Subsequent Event | Restricted stock units
Shares (in thousands)
Granted (in shares)	186,309
Weighted-Average Grant Date Fair Value
Award vesting period	4 years
Compensation not yet recognized, awards other than options	$ 6,800
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) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Feb. 28, 2018	Sep. 30, 2019
Related Party Transaction [Line Items]
Proceeds from Warrant Exercises		$ 15.2
Class of Warrant or Right, Exercised		644,365
Common Stock Warrants
Related Party Transaction [Line Items]
Stock option expense	$ 2.5

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Amounts not yet paid to FI		$ 9.3
FI share, expense	$ 4.6
Non-cash gain on financial institution share	3.5
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		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Deferred Financial Institution Costs [Roll Forward]
Beginning balance	$ 12,181	$ 12,425	$ 15,877	$ 13,625
Deferred costs	0	3,500	0	5,750
Recoveries through FI Share	1,157	1,344	(3,469)	(4,036)
Amortization	789	378	2,173	1,136
Ending balance	$ 10,235	$ 14,203	$ 10,235	$ 14,203

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - shares shares in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,505	1,862
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	13	868
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,737	1,200
Common stock issuable pursuant to the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	49	151

SEGMENTS - Narrative (Details)

SEGMENTS - Narrative (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)segment	Sep. 30, 2018USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	2
Capital expenditures	$ 4,561	$ 3,190
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		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Adjusted contribution	$ 24,738	$ 16,978	$ 64,216	$ 47,371
Plus: FI Share and other third-party costs	31,681	17,604	76,921	55,494
Revenues	56,419	34,582	141,137	102,865
Non-cash gain on financial institution share			3,500
Cardlytics Direct
Segment Reporting Information [Line Items]
Adjusted contribution	24,738	16,906	64,216	47,368
Plus: FI Share and other third-party costs	31,681	17,514	76,921	54,271
Revenues	56,419	34,420	141,137	101,639
Other Platform Solutions
Segment Reporting Information [Line Items]
Adjusted contribution	0	72	0	3
Plus: FI Share and other third-party costs	0	90	0	1,223
Revenues	$ 0	$ 162	$ 0	$ 1,226

SEGMENTS - Adjusted Contributio

SEGMENTS - Adjusted Contribution Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting [Abstract]
Adjusted contribution	$ 24,738	$ 16,978	$ 64,216	$ 47,371
Non-cash equity expense included in FI Share	0	0	0	2,519
Amortization of deferred FI implementation costs	789	378	2,173	1,136
Delivery costs	3,070	3,007	9,686	7,509
Sales and marketing expense	11,074	9,452	31,458	27,915
Research and development expense	3,018	4,097	8,741	12,444
General and administration expense	12,218	7,925	27,558	23,486
Depreciation and amortization expense	1,167	777	3,181	2,471
Total other expense	1,149	(290)	1,990	11,367
Loss before income taxes	$ (7,747)	$ (8,368)	$ (20,571)	$ (41,476)

SEGMENTS - Geographical Informa

SEGMENTS - Geographical Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Document Period End Date			Sep. 30, 2019
Revenues	$ 56,419	$ 34,582	$ 141,137	$ 102,865
Property and equipment	12,125		12,125		$ 10,230
United States
Segment Reporting Information [Line Items]
Revenues	50,997	30,884	125,468	90,606
Property and equipment	11,583		11,583		9,794
United Kingdom
Segment Reporting Information [Line Items]
Revenues	5,422	$ 3,698	15,669	$ 12,259
Property and equipment	$ 384		$ 384		$ 436

SEGMENTS Concentration of Risk

SEGMENTS Concentration of Risk (Details)	9 Months Ended
	Sep. 30, 2019
Revenue, Major Customer [Line Items]
Document Period End Date	Sep. 30, 2019
Accounts Receivable | Customer Concentration Risk | One Customer
Revenue, Major Customer [Line Items]
Concentration risk	10.00%
Accounts Receivable | Customer Concentration Risk | Two Customer [Member] [Member]
Revenue, Major Customer [Line Items]
Concentration risk	11.00%

COMMON STOCK WARRANTS (Details)

COMMON STOCK WARRANTS (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Exercised	(644,365)
Common stock warrants
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Outstanding	13,000	868,000
Warrants and Rights Outstanding	$ 23.64	$ 21.89
Class of Warrant or Right, Exercised	(821,000)
Class or Warrant or Right, Exercise Price of Warrant or Right, Exercised	$ 21.89
Class or Warrant or Right, Forfeited And Canceled	(34,000)
Class or Warrant or Right, Exercise Price of Warrant or Right, Forfeited and Canceled	$ 21.29

Uncategorized Items - cdlxform1

Label	Element	Value
Stock Issued During Period, Value, Conversion of Convertible Securities	us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities	$ 1,736,000
Adjustments to Additional Paid in Capital, Convertible Debt with Conversion Feature	us-gaap_AdjustmentsToAdditionalPaidInCapitalConvertibleDebtWithConversionFeature	$ 17,774,000