Cardlytics (CDLX) 10-Q 13 Nov 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 31, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	Cardlytics, Inc.
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Entity Central Index Key	1,666,071
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Small Business	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding (in shares)		21,411,500

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 47,812	$ 21,262
Restricted cash	20,000	0
Accounts receivable, net	36,822	48,348
Other receivables	3,530	2,898
Prepaid expenses and other assets	3,686	2,121
Total current assets	111,850	74,629
Long-term assets:
Property and equipment, net	9,273	7,319
Intangible assets, net	365	528
Capitalized software development costs, net	1,278	433
Deferred FI implementation costs, net	14,203	13,625
Other long-term assets, net	1,104	4,224
Total assets	138,073	100,758
Current liabilities:
Accounts payable	2,437	1,554
Accrued liabilities:
Accrued compensation	5,487	4,638
Accrued expenses	3,537	4,615
FI Share liability	20,185	23,914
Consumer Incentive liability	4,830	7,242
Deferred billings	250	132
Current portion of long-term debt	21	44
Total current liabilities	36,747	42,139
Long-term liabilities:
Deferred liabilities	3,305	3,670
Long-term warrant liability	0	10,230
Long-term debt, net of current portion	46,794	56,968
Total liabilities	86,846	113,007
Commitments and contingencies (Note 8)
Redeemable convertible preferred stock:
Redeemable convertible preferred stock	0	196,437
Stockholders’ (deficit) equity:
Common stock, $0.0001 par value—83,000 and 100,000 shares authorized and 3,439 and 21,411 shares issued and outstanding as of December 31, 2017 and September 30, 2018, respectively	7	0
Additional paid-in capital	359,501	58,693
Accumulated other comprehensive income	1,640	1,066
Accumulated deficit	(309,921)	(268,445)
Total stockholders’ (deficit) equity	51,227	(208,686)
Total liabilities and stockholders’ (deficit) equity	138,073	100,758
Series G’ Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock	0	44,672
Series G Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock	0	5,110
Series F-R Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock	0	58,449
Series E-R Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock	0	29,972
Series D-R Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock	0	32,728
Series C-R Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock	0	18,366
Series B-R Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock	0	5,288
Series A-R Stock
Redeemable convertible preferred stock:
Redeemable convertible preferred stock	$ 0	$ 1,852

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
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	83,000,000
Common stock, shares issued (in shares)	21,411,000	3,439,000
Common stock, shares outstanding (in shares)	21,411,000	3,439,000
Series G’ Stock
Redeemable convertible preferred stock, par value (in usd per share)	$ 0	$ 0.0001
Redeemable convertible preferred stock, shares authorized (in shares)	0	5,339,000
Redeemable convertible preferred stock, shares issued (in shares)	0	1,296,000
Redeemable convertible preferred stock, shares outstanding (in shares)	0	1,296,000
Series G Stock
Redeemable convertible preferred stock, par value (in usd per share)	$ 0	$ 0.0001
Redeemable convertible preferred stock, shares authorized (in shares)	0	1,385,000
Redeemable convertible preferred stock, shares issued (in shares)	0	346,000
Redeemable convertible preferred stock, shares outstanding (in shares)	0	346,000
Series F-R Stock
Redeemable convertible preferred stock, par value (in usd per share)	$ 0	$ 0.0001
Redeemable convertible preferred stock, shares authorized (in shares)	0	5,000,000
Redeemable convertible preferred stock, shares issued (in shares)	0	1,199,000
Redeemable convertible preferred stock, shares outstanding (in shares)	0	1,199,000
Series E-R Stock
Redeemable convertible preferred stock, par value (in usd per share)	$ 0	$ 0.0001
Redeemable convertible preferred stock, shares authorized (in shares)	0	7,400,000
Redeemable convertible preferred stock, shares issued (in shares)	0	795,000
Redeemable convertible preferred stock, shares outstanding (in shares)	0	795,000
Series D-R Stock
Redeemable convertible preferred stock, par value (in usd per share)	$ 0	$ 0.0001
Redeemable convertible preferred stock, shares authorized (in shares)	0	5,787,000
Redeemable convertible preferred stock, shares issued (in shares)	0	1,396,000
Redeemable convertible preferred stock, shares outstanding (in shares)	0	1,396,000
Series C-R Stock
Redeemable convertible preferred stock, par value (in usd per share)	$ 0	$ 0.0001
Redeemable convertible preferred stock, shares authorized (in shares)	0	6,032,000
Redeemable convertible preferred stock, shares issued (in shares)	0	1,508,000
Redeemable convertible preferred stock, shares outstanding (in shares)	0	1,508,000
Series B-R Stock
Redeemable convertible preferred stock, par value (in usd per share)	$ 0	$ 0.0001
Redeemable convertible preferred stock, shares authorized (in shares)	0	9,596,000
Redeemable convertible preferred stock, shares issued (in shares)	0	2,247,000
Redeemable convertible preferred stock, shares outstanding (in shares)	0	2,247,000
Series A-R Stock
Redeemable convertible preferred stock, par value (in usd per share)	$ 0	$ 0.0001
Redeemable convertible preferred stock, shares authorized (in shares)	0	7,528,000
Redeemable convertible preferred stock, shares issued (in shares)	0	1,857,000
Redeemable convertible preferred stock, shares outstanding (in shares)	0	1,857,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenue	$ 34,582	$ 31,406	$ 102,865	$ 91,099
Costs and expenses:
FI Share and other third-party costs	17,982	14,529	59,149	50,886
Delivery costs	3,007	1,646	7,509	5,095
Sales and marketing expense	9,452	8,302	27,915	23,454
Research and development expense	4,097	3,421	12,444	9,527
General and administration expense	7,925	5,276	23,486	14,738
Depreciation and amortization expense	777	771	2,471	2,303
Total costs and expenses	43,240	33,945	132,974	106,003
Operating loss	(8,658)	(2,539)	(30,109)	(14,904)
Other income (expense):
Interest expense, net	(254)	(1,763)	(2,995)	(6,427)
Change in fair value of warrant liabilities, net	801	1,381	(6,760)	(412)
Change in fair value of convertible promissory notes	0	0	0	(1,244)
Change in fair value of convertible promissory notes—related parties	0	0	0	6,213
Other income (expense), net	(257)	447	(1,612)	1,189
Total other income (expense)	290	65	(11,367)	(681)
Loss before income taxes	(8,368)	(2,474)	(41,476)	(15,585)
Income tax benefit	0	0	0	0
Net loss	(8,368)	(2,474)	(41,476)	(15,585)
Adjustments to the carrying value of redeemable convertible preferred stock	0	(350)	(157)	(5,383)
Net loss attributable to common stockholders	$ (8,368)	$ (2,824)	$ (41,633)	$ (20,968)
Net loss per share attributable to common stockholders, basic and diluted (in USD per share)	$ (0.40)	$ (0.80)	$ (2.29)	$ (6.68)
Weighted-average common shares outstanding, basic and diluted (in shares)	20,970	3,542	18,150	3,140

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (8,368)	$ (2,474)	$ (41,476)	$ (15,585)
Other comprehensive (loss) income:
Foreign currency translation adjustments	202	(374)	574	(942)
Total comprehensive loss	$ (8,166)	$ (2,848)	$ (40,902)	$ (16,527)

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
Beginning balance (in shares) at Dec. 31, 2016		2,590
Beginning balance at Dec. 31, 2016	$ (216,835)	$ 0	$ 29,867	$ 2,102	$ (248,804)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)	154	156
Exercise of common stock options	$ 597		597
Stock-based compensation	3,707		3,707
Vesting of common stock warrants	312
Deemed dividend related to beneficial conversion feature	(4,488)
Beneficial conversion feature of Series G stock	4,488
Conversion of securities to common stock (in shares)		801
Conversion of preferred stock to common stock	24,392		24,392
Accretion of redeemable convertible preferred stock to redemption value	(895)		(895)
Other comprehensive income	(942)			(942)
Net loss	(15,585)				(15,585)
Ending balance (in shares) at Sep. 30, 2017		3,547
Ending balance at Sep. 30, 2017	(205,249)	$ 0	57,980	1,160	(264,389)
Beginning balance (in shares) at Jun. 30, 2017		3,540
Beginning balance at Jun. 30, 2017	(203,566)	$ 0	56,815	1,534	(261,915)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		7
Exercise of common stock options	33		33
Stock-based compensation	1,482		1,482
Accretion of redeemable convertible preferred stock to redemption value	(350)		(350)
Other comprehensive income	(374)			(374)
Net loss	(2,474)				(2,474)
Ending balance (in shares) at Sep. 30, 2017		3,547
Ending balance at Sep. 30, 2017	(205,249)	$ 0	57,980	1,160	(264,389)
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	329
Exercise of common stock options	$ 1,799		1,799
Exercise of common stock warrants (in shares)		1,142
Stock-based compensation	16,968		16,968
Settlement of restricted stock (in shares)		37
Issuance of common stock in connection with our IPO (in shares)		5,821
Issuance of common stock in connection with our IPO	66,101	$ 1	66,100
Vesting of common stock warrants	17,774		17,774
Conversion of securities to common stock (in shares)		10,643
Conversion of preferred stock to common stock	196,594	$ 6	196,588
Conversion of preferred stock warrants to common stock warrants	1,736		1,736
Accretion of redeemable convertible preferred stock to redemption value	(157)		(157)
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)
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
Exercise of common stock warrants (in shares)		793
Stock-based compensation	5,717		5,717
Settlement of restricted stock (in shares)		37
Vesting of common stock warrants	15,255		15,255
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)

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Operating activities
Net loss	$ (8,368)	$ (2,474)	$ (41,476)	$ (15,585)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization			2,471	2,303
Amortization of financing costs charged to interest expense			255	421
Accretion of debt discount and non-cash interest expense			2,326	5,434
Termination of U.K. agreement expense			16,968	3,707
Change in the fair value of warrant liabilities, net	(801)	(1,381)	6,760	412
Change in the fair value of convertible promissory notes	0	0	0	1,244
Change in the fair value of convertible promissory notes - related parties	0	0	0	(6,213)
Other non-cash (income) expense, net			4,136	(1,069)
Amortization of deferred FI implementation costs	378	365	1,136	1,110
Settlement of paid-in-kind interest			(8,353)	0
Change in operating assets and liabilities:
Accounts receivable			10,883	3,256
Prepaid expenses and other assets			(1,797)	(1,092)
Deferred FI implementation costs			(5,750)	(6,650)
Recovery of deferred FI implementation costs	1,344	1,185	4,036	3,137
Accounts payable			221	(991)
Other accrued expenses			24	(333)
FI Share liability			(3,728)	(5,153)
Customer Incentive liability			(2,412)	(509)
Net cash used in operating activities			(14,300)	(16,571)
Investing activities
Acquisition of property and equipment			(3,190)	(971)
Acquisition of patents			(14)	(52)
Capitalized software development costs			(981)	(76)
Net cash used in investing activities			(4,185)	(1,099)
Financing activities
Proceeds from issuance of debt			47,435	12,500
Principal payments of debt			(52,475)	(74)
Proceeds from issuance of common stock			72,179	597
Proceeds from issuance of Series G preferred stock			0	11,940
Equity issuance costs			(1,949)	(2,190)
Debt issuance costs			(48)	(142)
Net cash from financing activities			65,142	22,631
Effect of exchange rates on cash, cash equivalents and restricted cash			(107)	257
Net increase in cash, cash equivalents and restricted cash			46,550	5,218
Cash, cash equivalents, and restricted cash — Beginning of period			21,262	22,968
Cash, cash equivalents, and restricted cash — End of period	67,812	28,186	67,812	28,186
Supplemental schedule of non-cash investing and financing activities:
Amounts accrued for property and equipment	1,697	0	1,697	0
Amounts accrued for capitalized software development costs	$ 9	$ 0	$ 9	$ 0

OVERVIEW OF BUSINESS AND BASIS

OVERVIEW OF BUSINESS AND BASIS OF PRESENTATION	9 Months Ended
	Sep. 30, 2018
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 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. Initial Public Offering On February 13, 2018, we closed our initial public offering (“IPO”), in which we issued and sold 5,400,000 shares of common stock at a public offering price of $13.00 per share, resulting in gross proceeds of $70.2 million . On February 14, 2018, pursuant to the underwriters’ partial exercise of their over-allotment option to purchase up to an additional 810,000 shares from us, we issued and sold an additional 421,355 shares of our common stock, resulting in additional gross proceeds to us of $5.5 million . In total, we issued 5,821,355 shares of common stock and raised $75.7 million in gross proceeds, or $66.1 million in net proceeds after deducting underwriting discounts and commissions of $5.3 million and offering costs of $4.3 million . Upon the closing of the IPO, all of the outstanding shares of redeemable convertible preferred stock automatically converted into shares of common stock and all warrants to purchase shares of redeemable convertible preferred stock were automatically converted into warrants to purchase shares of common stock. Subsequent to the closing of the IPO, there were no shares of preferred stock or warrants to purchase shares of redeemable convertible preferred stock outstanding. The consolidated financial statements as of December 31, 2017, including share and per share amounts, do not give effect to the IPO or conversion of the redeemable convertible preferred stock, as the IPO and such conversions were completed subsequent to December 31, 2017. Upon the completion of our IPO, our amended and restated certificate of incorporation authorized us to issue up to 100,000,000 shares of common stock, $0.0001 par value per share, and 10,000,000 shares of preferred stock, $0.0001 par value per share, all of which shares of preferred stock are undesignated. Our board of directors may establish the rights and preferences of the preferred stock from time to time. Reverse Stock Split On January 26, 2018, our board of directors approved an amended and restated certificate of incorporation to (1) effect a reverse split on outstanding shares of our common stock and redeemable convertible preferred stock on a one-for-four basis (the “Reverse Stock Split”), (2) modify the threshold for automatic conversion of our preferred stock into shares of our common stock in connection with an initial public offering to eliminate the requirement of gross proceeds to the Company of not less than $70.0 million and (3) authorize us to issue up to 100,000,000 shares of common stock, $0.0001 par value per share and 25,000,000 shares of redeemable convertible preferred stock, $0.0001 par value per share (collectively, the “Charter Amendment”). The authorized shares and par values of our common stock and redeemable convertible preferred stock were not adjusted as a result of the Reverse Stock Split. The Charter Amendment was approved by the Company’s stockholders on January 26, 2018 and became effective upon the filing of the Charter Amendment with the State of Delaware on January 26, 2018. All issued and outstanding common stock and preferred stock and related share and per share amounts contained in these financial statements have been retroactively adjusted to reflect the Reverse Stock Split for all periods presented. 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 (“U.S. 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 U.S. 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, 2017 . There have been no material changes to our accounting policies from those disclosed in the audited consolidated financial statements and related notes thereto included in our Annual Report for year ended December 31, 2017 . Use of Estimates

SIGNIFICANT ACCOUNTING POLICIES

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS	SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS Consumer Incentives Our Cardlytics Direct solution is our proprietary native bank advertising channel that enables marketers to reach consumers via their trusted and frequently visited online and mobile banking channels as well as email. 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, which we refer to as Consumer Incentives. We report our revenue on our condensed consolidated statements of operations net of Consumer Incentives. We generally pay Consumer Incentives only with respect to our Cardlytics Direct service. 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. 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 $14.1 million and $14.0 million during the three months ended September 30, 2017 and 2018 and totaled $42.1 million and $45.9 million during the nine months ended September 30, 2017 and 2018 , respectively. Concentrations of Risk Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash and cash equivalents and accounts receivable. Our cash and cash equivalents are held with three financial institutions, which we believe are of high credit quality. We believe that our accounts receivable credit risk exposure is limited as a result of being diversified among a large number of marketers segregated by both geography and industry. Historically, we have not experienced significant write-downs of our accounts receivable. No marketer represented a significant concentration of our accounts receivable as of December 31, 2017 or September 30, 2018 . During the nine months ended September 30, 2017 and 2018 , a marketer in the U.S. accounted for 7% and 10% of our revenue, respectively. No other marketer accounted for over 10% of revenue during the nine months ended September 30, 2017 and 2018 . 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 five 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 the nine months ended September 30, 2017 and 2018 , our largest FI partner in the U.S. accounted for approximately 63% and 68% of FI Share, respectively. During the nine months ended September 30, 2017 and 2018 , an FI partner in the U.K. accounted for 11% and 9% of FI Share, respectively. No other FI partners accounted for over 10% of FI Share during the nine months ended September 30, 2017 and 2018 . Cash, Cash Equivalents and Restricted Cash Cash and cash equivalents consist of cash held in checking accounts, upon which we earn up to a 1.0% annual rate of interest as of September 30, 2018 . Restricted cash represents deposits held in a blocked account in favor of the lender as additional security for our payment obligations under our 2018 Term Loan, upon which we earn a 0.9% annual rate of interest as of September 30, 2018 . See Note 3—Debt, for additional information regarding our 2018 Term Loan. Cash, cash equivalents and restricted cash as presented on our condensed consolidated statements of cash flows consists of the following (in thousands): December 31, September 30, 2016 2017 2017 2018 Cash and cash equivalents $ 22,838 $ 21,262 $ 28,186 $ 47,812 Restricted cash 130 — — 20,000 Cash, cash equivalents and restricted cash $ 22,968 $ 21,262 $ 28,186 $ 67,812 Deferred Offering Costs Deferred offering costs consist of incremental costs directly attributable to equity offerings. Deferred offering costs are included in other long-term assets on our condensed consolidated balance sheets. Upon completion of an offering, these amounts are offset against the proceeds of the offering. Nine Months Ended 2017 2018 Beginning balance $ — $ 3,144 Deferred costs $ 2,449 $ 1,135 Recognized against offering proceeds — (4,279 ) Ending balance $ 2,449 $ — Fair Value of Financial Instruments When required by U.S. GAAP, assets and liabilities are reported at fair value on our condensed consolidated financial statements. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Valuation inputs are arranged in a hierarchy that consists of the following levels: • Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. • Level 2 inputs are inputs other than Level 1 inputs such as quoted prices for similar assets or liabilities; quoted prices in markets with insufficient volume or infrequent transactions (less active markets); or model-derived valuations in which all significant inputs are observable or can be derived principally from or corroborated by observable market data for substantially the full term of the assets or liabilities. • Level 3 inputs are unobservable inputs for the asset or liability. Our nonfinancial assets that we recognize or disclose at fair value on our condensed consolidated financial statements on a nonrecurring basis include property and equipment, intangible assets, capitalized software development costs and deferred FI implementation costs. The fair values for these assets are evaluated when events or changes in circumstances indicate the carrying value may not be recoverable. Preferred Stock Warrants Outstanding warrants to purchase shares of our redeemable convertible preferred stock are accounted for as derivative liabilities in accordance with ASC Topic 815, Derivatives and Hedging (“ASC 815”) due to the terms of the warrants and related agreements. We have determined that these warrants do not meet the scope exception of a contract indexed to our stock because of fair value protections contained in agreements governing our redeemable convertible preferred stock. We record preferred stock warrant liabilities on our condensed consolidated balance sheets at their fair value. We record the changes in fair value of such instruments as non-cash gains or losses on our condensed consolidated statements of operations. Upon our IPO, all warrants to purchase shares of our redeemable convertible preferred stock were converted to warrants to purchase shares of our common stock. See Note 6—Fair Value Measurements, for additional information regarding the valuation of warrants to purchase shares of our redeemable convertible preferred stock. Common Stock Warrants Issued in Connection with the Series G Stock Financing In connection with the Series G Stock financing, we issued warrants to purchase shares of our common stock that are accounted for as liabilities in accordance with ASC Topic 480, Distinguishing Liabilities From Equity due to the terms of the warrants and related agreements. We record these common stock warrant liabilities in our consolidated balance sheets at their fair value. We record the changes in fair value of such instruments as non-cash gains or losses in our statements of operations. In August 2018 we issued warrants to purchase 792,434 shares of common stock at an exercise price of $0.0004 per share to the cash investors of our Series G financing, pursuant to our Series G stock purchase agreement. The warrants had a valuation of $15.3 million upon issuance and were subsequently exercised, resulting in the issuance of 792,434 shares of our common stock. See Note 6—Fair Value Measurements, for additional information regarding the valuation of the warrants issued in connection with the Series G Stock financing. Convertible Promissory Notes The redemption features included in the terms of the convertible promissory notes were determined to be derivative liabilities as a result of a significant discount within the redemption features for the note holders. Embedded derivatives that are not clearly and closely related to the host contract are required to be bifurcated and recorded at fair value unless the fair value option is elected on the host contract. Under the fair value option, bifurcation of the embedded derivative is not necessary as all related gains (losses) on the host contract and derivative will be reflected in the consolidated statements of operations. We elected the fair value option for the convertible promissory notes upon their issuance. The convertible promissory notes are measured using unobservable inputs that required a high level of judgment to determine fair value, and are therefore classified as Level 3. See Note 6—Fair Value Measurements for additional information regarding the valuation of the convertible promissory notes. Income Taxes On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (“Tax Act”) was signed into law making significant changes to the Internal Revenue Code. Changes include, but are not limited to, a corporate tax rate decrease to 21% effective for tax years beginning after December 31, 2017. This change in tax rate resulted in a reduction in our net U.S. deferred tax assets, which was fully offset by a reduction in our valuation allowance. The other provisions of the Tax Act, including the one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings, did not have a material impact on our financial statements as of December 31, 2017. As of December 31, 2017, pursuant to guidance provided in Staff Account Bulletin No. 118, we had not completed our accounting for the effects of the Tax Act; however, we made a reasonable estimate of the effects on our existing deferred tax balances and the one-time transition tax, including a provisional reduction in U.S. deferred tax assets, which was fully offset by a reduction in our valuation allowance. We have completed our accounting for the Tax Act and no changes were made to the provisional adjustments recorded as of December 31, 2017. Recently Adopted Accounting Pronouncements In May 2017, the FASB issued ASU 2017-09, Scope of Modification Accounting , which amends the scope of modification accounting for share-based payment arrangements, provides guidance on the types of changes to the terms or conditions of share-based payment awards to which an entity would be required to apply modification accounting under ASC Topic 718, Compensation—Stock Compensation . For all entities, the ASU is effective prospectively for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We adopted this ASU on January 1, 2018 and it did not have an impact on our condensed consolidated financial statements. Recently Issued Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606). ASU 2014-09 supersedes the recognition guidance in ASC Topic 605 and most industry specific revenue guidance and requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. In addition, this ASU requires disclosures of the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. This ASU supersedes most existing GAAP revenue recognition principles, and it permits the use of either the retrospective or modified retrospective transition method. For public entities, this ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within those annual periods. For non-public entities, this ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. We have made the election to use the extended transition period for complying with new or revised accounting standards under Section 102(b)(1) of the Jumpstart Our Business Startups Act of 2012 ("JOBS Act"), therefore we will be required to apply this ASU for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Retrospective application will be required for each period presented through either the recasting of the prior periods for the effects of the adoption of this ASU or retrospectively through a cumulative catch up recognized at the date of adoption. During the first quarter of 2018, we began assessing the impacts, if any, that this ASU may have on our results of operations, current accounting policies, processes, controls, systems and financial statement disclosures. Based on our initial assessment, we expect to adopt this new standard using the modified retrospective transition method, which would result in a cumulative adjustment as of the date of the adoption. We also expect to continue to report our revenue on our condensed consolidated statements of operations net of Consumer Incentives and gross of FI Share. We are continuing to assess the impact of this standard on our financial position, results of operations and related disclosures and have not yet determined whether the effect will be material. In January 2016, the FASB issued 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. This ASU requires equity investments to be measured at fair value with changes in fair values recognized in net earnings, (public entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes), simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment and eliminates the requirement to disclose fair values, the methods and significant assumptions used to estimate the fair value of financial instruments measured at amortized cost. This ASU also clarifies that management should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale debt securities in combination with other deferred tax assets. For public business entities, this ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within those annual periods. For non-public business entities, this ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within fiscal years beginning after December 15, 2019. Early adoption is permitted. We have made the election to use the extended transition period for complying with new or revised accounting standards under Section 102(b)(1) of the JOBS Act, therefore we will be required to apply this ASU for annual reporting periods beginning after December 15, 2018, and interim periods within fiscal years beginning after December 15, 2019. We are currently evaluating the potential impact of this recently issued guidance on our condensed 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’s primary change is the requirement for lessee entities to recognize a lease liability for payments and a right of use asset representing the right to use the leased asset during the term on operating lease arrangements. Lessees are permitted to make an accounting policy election to not recognize the asset and liability for leases with a term of twelve months or less. Lessors’ accounting under the ASU is largely unchanged from the previous accounting standard. In addition, the ASU expands the disclosure requirements of lease arrangements. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842) - Targeted Improvements , which provides the option of applying the requirements of the new lease standard in the period of adoption with no restatement to comparative periods. For public entities, this ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. For non-public entities, this ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. We have made the election to use the extended transition period for complying with new or revised accounting standards under Section 102(b)(1) of the JOBS Act, therefore we will be required to adopt this ASU for annual reporting periods beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted. Although we are currently evaluating the impact of this guidance on our condensed 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. In August 2018, the SEC issued Release No. 33-10532, Disclosure Update and Simplification, that extends to interim periods the annual disclosure requirement in SEC Regulation S-X, Rule 3-04 of presenting changes in stockholders’ equity. An analysis of changes in stockholders’ equity (deficit) will now be required for the current and comparative quarter-to-date and year-to-date interim periods. In response to this ruling, we have presented consolidated statements of stockholders' equity (deficit) for the three and nine months ended September 30, 2017 and 2018

DEBT

DEBT	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
DEBT	DEBT Our debt consists of the following (in thousands): December 31, 2017 September 30, 2018 Lines of credit $ 25,081 $ 26,777 Term loans, net of unamortized discount and debt issuance costs of $1,058 and $25 at December 31, 2017 and September 30, 2018, respectively 31,830 19,975 Capital leases 101 63 Convertible promissory notes (converted into Series G' Stock in May 2017) — — Total debt $ 57,012 $ 46,815 Less current portion of long-term debt (44 ) (21 ) Long-term debt, net of current portion $ 56,968 $ 46,794 Accrued interest included in debt totaled $6.2 million and zero as of December 31, 2017 and September 30, 2018 , respectively. Interest payments during the during the nine months ended September 30, 2017 and 2018 totaled $0.6 million and $9.2 million , respectively. New Loan Facility On May 21, 2018, we entered into a New Loan Facility consisting of a $30.0 million asset-based revolving line of credit ("2018 Line of Credit") and a $20.0 million term loan ("2018 Term Loan") maturing on May 21, 2020. We used the entire $20.0 million in proceeds from the 2018 Term Loan and an advance of $ 27.4 million under the 2018 Line of Credit to repay all outstanding obligations under our 2016 Line of Credit and 2016 Term Loan. Upon repayment, both the 2016 Line of Credit and the 2016 Term Loan were terminated. We deferred $0.1 million of debt issuance costs associated with obtaining the New Loan Facility and deferred $0.1 million of unamortized debt issuance costs attributed to our 2016 Line of Credit and 2016 Term Loan. Under the terms of the New Loan Facility relating to the 2018 Line of Credit, we are able to borrow up to the lesser of $30.0 million or 85% of the amount of our eligible accounts receivable. Interest on advances under the 2018 Line of Credit varies depending on the amount of unrestricted cash deposits we maintain with the lender on the last day of the month. The interest rate is equal to the prime rate minus 0.75% if our unrestricted deposits exceed $40.0 million , the prime rate minus 0.50% if our unrestricted deposits are between $40.0 million and $20.0 million , and the prime rate if our unrestricted deposits are below $20.0 million . As of September 30, 2018 , the indicative rate for advances on the 2018 Line of Credit was the prime rate minus 0.75% , or 4.50% . In addition, we are required to pay an unused line fee of 0.15% per annum on the average daily unused amount of the $30.0 million revolving commitment. We are also required to pay the lender a one-time success fee of $75,000 in the event that we achieve trailing twelve month revenue of $200.0 million or more at the end of any month after the closing date of the New Loan Facility. Interest accrues on the 2018 Term Loan at an annual rate of interest equal to the prime rate minus 2.75% , or 2.50% as of September 30, 2018 . All of our obligations under the New Loan Facility are also secured by a first priority lien on substantially all of our assets. Under the terms of the New Loan Facility, we are required to maintain a deposit of $20.0 million in a blocked account in favor of the lender as additional security for our payment obligations. The New Loan Facility contains a moving minimum trailing twelve month revenue covenant, which was $130.8 million for the period ended September 30, 2018 . The New Loan Facility also requires us to maintain a total cash balance plus liquidity under the 2018 Line of Credit of not less than $5.0 million . The New Loan Facility includes customary representations, warranties and covenants (affirmative and negative), including restrictive covenants that include restrictions on mergers, acquisitions and dispositions of assets, incurrence of indebtedness and encumbrances on our assets and a prohibition from the payment or declaration of dividends; in each case subject to specified exceptions. The New 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 New Loan Facility and increase the interest rate otherwise applicable to the 2018 Term Loan or advances under the 2018 Line of Credit by an additional 3.00% . In August 2018, we repaid $0.7 million of the outstanding balance under our 2018 Line of Credit. As of September 30, 2018 , we had $3.1 million of unused available borrowings under our 2018 Line of Credit. We were in compliance with all financial covenants as of September 30, 2018 . 2016 Line of Credit In September 2016, we entered into a $50.0 million loan and security agreement ("2016 Line of Credit") maturing on March 14, 2019. The 2016 Line of Credit facility was repaid and terminated in May 2018 in connection with obtaining our New Loan Facility. We recognized a $0.1 million loss on extinguishment of debt related to the unamortized debt issuance costs. This expense is included within other income, net in our condensed consolidated statements of operations and is presented in other non-cash expenses on our condensed consolidated statement of statement of cash flows. 2016 Term Loan In July 2016, we entered into a $24.0 million credit agreement ("2016 Term Loan") maturing on July 21, 2019. The 2016 Term Loan was repaid and terminated in May 2018 in connection with obtaining our New Loan Facility. We recognized a $0.8 million loss on extinguishment of debt related to the unamortized discount and unamortized debt issuance costs. This expense is included within other income, net in our condensed consolidated statements of operations and is presented in other non-cash expenses on our condensed consolidated statement of statement of cash flows. Convertible Promissory Notes During 2016, we issued unsecured convertible promissory notes with an aggregate principal amount of $50.7 million . In May 2017, we issued and sold shares of Series G redeemable convertible preferred stock, which resulted in the conversion of the convertible promissory notes into either shares of our common stock or shares of our Series G’ Stock. See Note 5—Redeemable Convertible Preferred Stock for a description of the Series G Stock financing that resulted in the conversion of the convertible promissory notes. The redemption features included in the terms of the convertible promissory notes were determined to be derivative liabilities as a result of a significant discount within the redemption features for the note holders. Embedded derivatives that are not clearly and closely related to the host contract are required to be bifurcated and recorded at fair value unless the fair value option is elected on the host contract. Under the fair value option, bifurcation of the embedded derivative is not necessary as all related gains (losses) on the host contract and derivative will be reflected in the consolidated statements of operations. We elected the fair value option for the convertible promissory notes and recognized losses from their initial measurement during the second and third quarters of 2016. Subsequent changes in fair value of the convertible promissory notes are included in change in fair value of convertible promissory notes on our condensed consolidated statements of operations. See Note 6—Fair Value Measurements for additional information regarding the valuation of the convertible promissory notes. Paid-in-kind interest related to the convertible promissory notes is recognized in interest expense, net on our condensed consolidated statements of operations and totaled $1.7 million during the nine months ended September 30, 2017 . 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 2018 (remainder of year) $ — $ 6 $ 6 2019 — 20 20 2020 46,777 24 46,801 2021 — 13 13 Total principal payments $ 46,777 $ 63 $ 46,840 Less unamortized debt issuance costs (25 ) — (25 ) Less unamortized debt discount — — — Total debt $ 46,752 $ 63 $ 46,815

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	9 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION In May 2017, our board of directors and stockholders approved an increase in the total number of shares of common stock issuable under our 2008 Stock Plan ("2008 Plan") from 3,120,000 to 3,495,000 shares. In January 2018, our board of directors and stockholders approved an increase in the total number of shares of common stock issuable under our 2008 Plan to 4,020,000 shares. Our board of directors has adopted and our stockholders have approved our 2018 Equity Incentive Plan ("2018 Plan"). Our 2018 Plan became effective on February 8, 2018, the date our registration statement in connection with our IPO was declared effective. We do not expect to grant any additional awards under the 2008 Stock 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. The 2018 Plan provides for the grant of stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance-based stock awards and other forms of equity compensation, which are collectively referred to as stock awards. Additionally, the 2018 Plan provides for the grant of performance cash awards. The following table summarizes the allocation of stock-based compensation in the consolidated statements of operations (in thousands): Three Months Ended Nine Months Ended 2017 2018 2017 2018 Delivery costs $ 62 $ 203 $ 146 $ 471 Sales and marketing expense 524 1,939 1,390 5,550 Research and development expense 281 915 691 3,141 General and administration expense 615 2,666 1,480 7,806 Total stock-based compensation expense $ 1,482 $ 5,723 $ 3,707 $ 16,968 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 (in thousands, except per share amounts): Shares Weighted-Average Exercise Price Options outstanding — December 31, 2016 2,137 $ 15.00 Granted 799 23.80 Exercised (154 ) 3.84 Forfeited (145 ) 17.68 Cancelled (104 ) 11.29 Options outstanding — September 30, 2017 2,533 $ 18.44 Shares Weighted-Average Exercise Price Options outstanding — December 31, 2017 2,514 $ 18.42 Granted 29 24.24 Exercised (329 ) 6.27 Forfeited (154 ) 24.99 Canceled (198 ) 15.87 Options outstanding — September 30, 2018 1,862 $ 20.38 The weighted-average grant-date fair value of options granted during the nine months ended September 30, 2017 and 2018 was $12.11 and $10.00 , respectively. The total fair value of options vested during the nine months ended September 30, 2017 and 2018 was approximately $3.2 million and $5.0 million , respectively. As of September 30, 2018 , $7.6 million of unrecognized compensation expense related to unvested options will be recognized over a weighted-average period of 2.2 years. Restricted Stock Units A summary of restricted stock unit activity is as follows (in thousands, except per share amounts): Shares Weighted-Average Grant Date Fair Value Unvested — December 31, 2017 — $ — Granted 1,269 20.61 Vested — — Forfeited (69 ) 18.07 Canceled — — Unvested — September 30, 2018 1,200 $ 20.75 During the first quarter of 2018, we granted two separate tranches of performance-based restricted stock units ("PSUs"), each to receive 437,500 shares of common stock, to employees. The vesting of the 875,000 PSUs was contingent upon the completion of our IPO and includes other performance-based conditions. The performance condition in the first tranche will be satisfied if we attain 70.0 million of FI monthly active users ("FI MAUs") within three years of the grant date. The performance condition in the second tranche will be satisfied if we attain 85.0 million of FI MAUs within five years of the grant date. FI MAUs is a performance metric defined within "Management's Discussion and Analysis of Financial Condition and Results of Operations." We recognize stock compensation for these PSUs based upon the expected timing of the achievement of these FI MAU targets. During the nine months ended September 30, 2018 , we recognized $10.7 million in stock-based compensation expense related to these PSUs. During the first quarter of 2018, we granted 335,562 restricted stock units ("RSUs") to employees and our non-employee directors, which have annual vesting periods ranging from one to four years. During the second quarter of 2018, we granted 32,070 RSUs to employees, which have annual vesting periods of four years. During the third quarter of 2018, we granted 26,590 RSUs to employees, which have annual vesting periods of four years. As of September 30, 2018 , there was approximately $12.6 million of unrecognized compensation expense related to RSUs and PSUs, which is expected to be recognized over a weighted-average period of 1.15 years. Subsequent to September 30, 2018 , we granted 40,155 RSUs to employees, which have annual vesting periods of four years. The unamortized stock-based compensation expense related to these RSUs is $0.8 million . Restricted Securities Units During 2016, we granted $1.0 million of restricted securities units to certain executives in lieu of cash bonuses. Upon issuance, the restricted securities units were indexed to the convertible promissory notes. As a result of the Series G Stock financing, the restricted securities units became indexed to our Series G’ Stock upon conversion of the convertible promissory notes. Upon the completion of our IPO in February 2018, the restricted securities units became indexed to our common stock. Vesting requirements include both a service-based condition and a performance-based condition. The service-based condition requires each recipient to remain employed until the earlier of i) the date 6 months from the restricted securities unit grant date, ii) the date of a qualified liquidity event, or iii) date of termination without cause. The performance-based condition requires a sale of the Company or IPO event within a fixed period of time not more than 5 years from the restricted securities units grant date. The restricted securities units are considered liability classified awards, but due to the performance condition relating to sale of the Company or IPO, no compensation cost was recognized until one of these events occurred. These units vested upon the completion of our IPO in February 2018 resulting in a non-cash expense of $0.5 million and were settled upon the delivery of 37,406 shares of our common stock in August 2018. Employee Stock Purchase Plan Our board of directors has adopted and our stockholders have approved our 2018 Employee Stock Purchase Plan ("2018 ESPP"). Our 2018 ESPP became effective on February 8, 2018, the date our registration statement in connection with our IPO was declared effective and enables eligible employees to purchase shares of our common stock at a discount. Purchases will be accomplished through participation in discrete offering periods. On each purchase date, eligible employees will purchase our common stock at a price per share equal to 85% of the lesser of the fair market value of our common stock on the first trading day of the offering period or the date of purchase. No shares of common stock have been purchased under the 2018 ESPP as the initial offering period has not yet ended. The maximum number of shares of our common stock that may be issued under our 2018 ESPP is 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

REDEEMABLE CONVERTIBLE PREFERRE

REDEEMABLE CONVERTIBLE PREFERRED STOCK	9 Months Ended
	Sep. 30, 2018
Temporary Equity Disclosure [Abstract]
REDEEMABLE CONVERTIBLE PREFERRED STOCK	REDEEMABLE CONVERTIBLE PREFERRED STOCK Upon the consummation of our IPO, all of the outstanding shares of redeemable convertible preferred stock were automatically converted into shares of common stock. See Note 1—Overview of Business and Basis of Presentation for additional information regarding our IPO. A summary of the change in carrying amount of the outstanding redeemable convertible preferred stock is as follows (in thousands): Series G’ Stock Series G Stock Shares Amount Shares Amount Balance — December 31, 2017 1,296 $ 44,672 346 $ 5,110 Accretion of redeemable convertible preferred stock — — — 108 Conversion of preferred stock to common stock (1,296 ) (44,672 ) (346 ) (5,218 ) Balance — September 30, 2018 — $ — — $ — Series F-R Stock Series E-R Stock Series D-R Stock Shares Amount Shares Amount Shares Amount Balance — December 31, 2017 1,199 $ 58,449 795 $ 29,972 1,396 $ 32,728 Accretion of redeemable convertible preferred stock — 38 — 1 — 7 Conversion of preferred stock to common stock (1,199 ) (58,487 ) (795 ) (29,973 ) (1,396 ) (32,735 ) Balance — September 30, 2018 — $ — — $ — — $ — Series C-R Stock Series B-R Stock Series A-R Stock Shares Amount Shares Amount Shares Amount Balance — December 31, 2017 1,508 $ 18,366 2,247 $ 5,288 1,857 $ 1,852 Accretion of redeemable convertible preferred stock — 3 — — — — Conversion of preferred stock to common stock (1,508 ) (18,369 ) (2,247 ) (5,288 ) (1,857 ) (1,852 ) Balance — September 30, 2018 — $ — — $ — — $ — During the second quarter of 2016, we issued convertible promissory notes to our founders and the existing holders of our redeemable convertible preferred stock. Shares of redeemable convertible preferred stock held by investors that participated in the financing were exchanged for shares of replacement preferred stock. These replacement shares have rights and preferences equal to their corresponding original series and are designated as Series A-R Stock, Series B-R Stock, Series C-R Stock, Series D-R Stock, Series E-R Stock and Series F-R Stock. Shares of redeemable convertible preferred stock held by investors that did not participate in the financing were converted to common stock. In February 2017, we amended and restated our certificate of incorporation reducing the authorized number of shares of our redeemable convertible preferred stock to 82,683,212 and canceled Series A Stock, Series B Stock, Series C Stock, Series D Stock, Series E Stock and Series F Stock. Pursuant to our convertible promissory note financing, these series of preferred stock were either exchanged for shares of replacement preferred stock with rights and preferences equal to their corresponding original series or converted to common stock. Series G Stock Financing In May 2017, we amended and restated our certificate of incorporation and increased the authorized number of shares of our common stock to 83,000,000 and increased the authorized number of shares of our redeemable convertible preferred stock to 96,131,002 . In May 2017, we issued and sold, for aggregate consideration of $11.9 million , an aggregate of 346,334 shares of Series G redeemable convertible preferred stock, par value $0.0001 per share with a stated price of $34.4758 per share (“Series G Stock”), and warrants to purchase shares of our common stock. Issuance costs incurred in connection with the sale of Series G Stock totaled $0.1 million . Conversion of Convertible Promissory Notes into Series G’ Stock In connection with the Series G Stock financing in May 2017, certain convertible promissory notes converted into 1,295,746 shares of Series G’ redeemable convertible preferred stock, par value $0.0001 per share (“Series G’ Stock”), at a price per share of $27.58 . Common Stock Warrants Issued in Connection with the Series G Stock Financing In connection with the Series G Stock financing, we issued warrants to purchase an aggregate of number of shares of common stock equal to the product obtained by multiplying 346,334 by a fraction, the numerator of which is the difference between $68.9516 and the volume weighted average closing price of our common stock over the 30 trading days (or such lesser number of days as our common stock has been traded on the Nasdaq Global Market) prior to the date on which such warrants vest and become exercisable and the denominator of which is such volume weighted average closing price, which warrants will become vested and exercisable upon the earlier to occur of the date (i) August 8, 2018, which is 180 days following the date of our IPO and (ii) 10 days prior to a sale of our company, at an exercise price of $0.0004 per share. In August 2018 we issued warrants to purchase 792,434 shares of common stock at an exercise price of $0.0004 per share to the cash investors of our Series G financing, pursuant to our Series G stock purchase agreement. The warrants had a valuation of $15.3 million upon issuance and were immediately exercised. See Note 6—Fair Value Measurements, for additional information regarding the valuation of the warrants issued in connection with the Series G Stock financing. Beneficial conversion feature The aggregate proceeds of $11.9 million from the Series G Stock financing were first allocated to the warrants to purchase shares of our common stock, which qualify as liabilities under ASC 480 and are recorded at fair value, with the residual value of $4.5 million allocated to our Series G Stock. As a result of this allocation, Series G Stock was determined to contain a beneficial conversion feature with an intrinsic value of $6.1 million . The amount assigned to the beneficial conversion feature was limited to the $4.5 million residual value allocated to Series G Stock and is classified as a component of additional paid-in capital. During the second quarter of 2017, we recorded a deemed dividend of $4.5 million

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
FAIR VALUE MEASURMENTS	FAIR VALUE MEASUREMENTS Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following table summarizes our liabilities measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): December 31, 2017 Level 1 Level 2 Level 3 Total Liabilities: Preferred stock warrants $ — $ — $ 2,285 $ 2,285 Common stock warrants — — 7,945 7,945 Convertible promissory notes — — — — Total liabilities $ — $ — $ 10,230 $ 10,230 September 30, 2018 Level 1 Level 2 Level 3 Total Liabilities: Preferred stock warrants $ — $ — $ — $ — Common stock warrants — — — — Convertible promissory notes — — — — Total liabilities $ — $ — $ — $ — Instruments Recorded at Fair Value Using Level 3 Inputs Our redeemable convertible preferred stock warrants, common stock warrants issued in connection with the Series G Stock financing and our convertible promissory notes are measured and recorded at fair value on a recurring basis using Level 3 inputs. The table below provides a roll forward of the changes in fair value of Level 3 financial instruments (in thousands): Preferred Stock Warrants Common Stock Warrants Convertible Promissory Notes Balance at December 31, 2016 $ 2,197 $ — $ 72,332 Conversion of convertible promissory notes to Series G’ preferred stock — — (44,672 ) Conversion of convertible promissory notes to common stock — — (24,392 ) Accrued interest on convertible promissory notes — — 1,701 Issuance of common stock warrants — 7,452 — Changes in fair value (119 ) 531 (4,969 ) Balance at September 30, 2017 $ 2,078 $ 7,983 $ — Preferred Stock Warrants Common Stock Warrants Convertible Promissory Notes Balance at December 31, 2017 $ 2,285 $ 7,945 $ — Changes in fair value (549 ) 7,309 — Conversion of preferred stock warrants to common stock warrants (1,736 ) — — Exercise of common stock warrants — (15,254 ) — Balance at September 30, 2018 $ — $ — $ — In valuing our instruments recorded at fair value using Level 3 inputs, our board of directors determined the equity value of our business generally using a combination of the income approach and the market approach valuation methods. The income approach estimates value based on the expectation of future cash flows that a company will generate, such as cash earnings, cost savings, tax deductions and the proceeds from disposition. These future cash flows are discounted to their present values using a discount rate derived based on an analysis of the cost of capital of comparable publicly traded companies in similar lines of business, as of each valuation date, and is adjusted to reflect the risks inherent in our cash flows. The market approach estimates the fair value of a company by applying market multiples of comparable publicly traded companies in a similar line of business. The market multiples are based on relevant metrics implied by the price that investors have paid for the equity of publicly traded companies. Given our significant focus on investing in and growing our business, we primarily utilized the forward-looking revenue multiple when performing valuation assessments under the market approach and considered both trading and transaction multiples. When considering which companies to include as our comparable industry peer companies, we focused on U.S.-based publicly traded companies that were broadly comparable to us based on consideration of industry, market and line of business. From the comparable companies, a representative market value multiple was determined and applied to our operating results to estimate the value of our company. The market value multiple was determined based on consideration of multiples of revenue to each of the comparable companies’ historical and forecasted revenue. In addition, the market approach considers IPO and merger and acquisition transactions involving companies similar to the company’s business being valued. Multiples of revenue are calculated for these transactions and then applied to the business being valued, after reduction by an appropriate discount. Once an equity value was determined, we utilized the option pricing method ("OPM"), or probability-weighted expected return method (“PWERM”) to allocate the overall value of equity to the various share classes. The OPM was used in valuations as of and for dates prior to December 31, 2016 and the PWERM was used in all subsequent valuations. The OPM treats common stock and convertible preferred stock as call options on a company’s enterprise value with exercise prices based on the liquidation preferences of the convertible preferred stock. Under this method, the common stock only has value if the funds available for distribution to stockholders exceed the value of the liquidation preference at the time of an assumed liquidity event. The value assigned to the common stock is the remaining value after the convertible preferred stock is liquidated. The OPM prices the call option using the Black-Scholes model. The PWERM relies on a forward-looking analysis to predict the possible future value of a company. Under this method, discrete future outcomes, including an IPO and non-IPO scenarios, are weighted based on the estimated the probability of each scenario. The PWERM is used when discrete future outcomes can be predicted with reasonable certainty based on a probability distribution. We relied on the PWERM to allocate the value of equity under a liquidity scenario. The projected equity value relied upon in the PWERM scenario was based on (i) guideline IPO transactions involving companies that were considered broadly comparable to us and (ii) our expectation of the pre-money valuation that we needed to achieve to consider an IPO as a viable exit strategy. The following table summarizes key assumptions used in the PWERM for estimating the fair value of our redeemable convertible preferred stock warrant liability: September 30, 2017 Weighted-average cost of capital applicable to preferred stock warrants 21% Discount for lack of marketability 7% to 13% Volatility 55% Risk-free interest rate 1.2% to 1.4% Preferred Stock Warrants A summary of our preferred stock warrants is as follows (in thousands, except per share amounts): Warrants outstanding Preferred Series Grant date Expiration date Exercise price December 31, 2017 September 30, 2018 Series B-R 2/26/2010 2/25/2020 $ 2.36 59 — Series D-R 9/21/2012 9/20/2022 $ 23.64 38 — Series D-R 9/21/2012 9/20/2022 $ 23.64 13 — Total 110 — The fair value of the warrants to purchase Series B-R Stock and Series D-R Stock decreased from $26.80 per share and $13.63 per share on December 31, 2017 to $20.18 per share and $10.57 per share on February 8, 2018, respectively, the date at which they converted to warrants to purchase shares of our common stock and were reclassified to additional paid-in capital on our condensed consolidated balance sheet. The decrease in the fair value of the warrants to purchase Series B-R Stock and Series D-R Stock primarily resulted from the timing of future potential liquidity events, changes to our forecasted financial results and changes in the valuation of comparable companies. Common Stock Warrants Issued in Connection with the Series G Stock Financing In connection with the Series G Stock financing, we issued warrants to purchase an aggregate number of shares of common stock equal to the product obtained by multiplying 346,334 by a fraction, the numerator of which is the difference between $68.9516 and the volume weighted average closing price of our common stock over the 30 trading days (or such lesser number of days as our common stock has been traded on the Nasdaq Global Market) prior to the date on which such warrants vest and become exercisable and the denominator of which is such volume weighted average closing price, which warrants will become vested and exercisable upon the earlier to occur of the date (i) August, 8, 2018, which is 180 days following the date of our IPO and (ii) 10 days prior to a sale of our company, at an exercise price of $0.0004 per share. To determine the fair value of our common stock warrant liability issued in connection with our Series G Stock financing, we utilized a Monte Carlo simulation, which allows for the modeling of complex securities and evaluates many possible outcomes to forecast the stock price of the company post-IPO. As part of the valuation, we considered various scenarios related to the pricing, timing and probability of an IPO. We applied an annual equity volatility of 59% and a discount for lack of marketability of 11% to arrive at a valuation of $7.5 million on the issuance date. Subsequent to our IPO, the fair value of the common stock warrant liability was estimated based on the fair market value of our common stock at each reporting period, discounted from the date of settlement. In August 2018 we issued warrants to purchase 792,434 shares of common stock at an exercise price of $0.0004 per share to the cash investors of our Series G financing, pursuant to our Series G stock purchase agreement. The warrants had a valuation of $15.3 million upon issuance and were subsequently exercised, resulting in the issuance of 792,434 shares of our common stock. As a result of change in fair value of the common stock warrant liability, we recognized a non-cash gain of $1.2 million during the three months ended September 30, 2017 and a non-cash gain of $0.8 million during the three months ended September 30, 2018 . Convertible Promissory Notes The redemption features included in the terms of the convertible promissory notes were determined to be derivative liabilities due to a significant discount within the redemption features for the note holders. Embedded derivatives that are not clearly and closely related to the host contract are required to be bifurcated and recorded at fair value unless the fair value option is elected on the host contract. Under the fair value option, bifurcation of the embedded derivative is not necessary as all related gains (losses) on the host contract and derivative will be reflected in the consolidated statements of operations. We elected the fair value option for the convertible promissory notes, therefore direct costs and fees associated with the issuance were recognized in earnings as incurred and were not deferred. To determine the fair value of our convertible promissory notes through their conversion in May 2017, we utilized key assumptions from the PWERM, as shown above. Under this method, we considered the redemption features of the convertible promissory notes to determine the fair value under discrete future outcomes, including IPO and non-IPO scenarios. Under certain non-IPO scenarios, holders of the convertible promissory notes will receive two times preference on the outstanding principal amount. We weighted the fair values based on the estimated probability of each scenario to determine the overall fair value of the convertible promissory notes as of the balance sheet date. See Note 5—Redeemable Convertible Preferred Stock for a description of the Series G Stock financing in May 2017 that resulted in the conversion of the convertible promissory notes into shares of our Series G’ Stock. Performance-based Warrants Issued to FIS In May 2013, we granted 10 -year performance-based warrants to purchase up to 644,365 shares of Series E Stock at an exercise price of $23.64 per share. Since FIS did not participate in the convertible promissory note financing, their warrants to purchase preferred stock were converted to warrants to purchase common stock. The warrants vested upon the completion of our IPO in February 2018 resulting in a non-cash expense of $2.5 million . We determined the fair value of these common warrants on the date of IPO using the Black-Scholes option pricing model, which is affected by the fair value of our common stock as well as the following significant inputs: February 8, 2018 Weighted-average grant date fair value $3.91 Significant inputs: Value of common stock $13.00 Expected term 5.3 years Volatility 50% Risk-free interest rate 2.0% Dividend yield —%

RELATED PARTIES

RELATED PARTIES	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
RELATED PARTIES	RELATED PARTIES Series G / Series G’ In May 2017, we issued and sold, for aggregate consideration of $11.9 million , an aggregate of 346,334 shares of our Series G Stock and warrants to purchase shares of our common stock. In connection with the issuance of our Series G Stock, the principal and accrued interest under the convertible promissory notes converted into an aggregate of 1,295,746 shares of our Series G’ redeemable convertible preferred stock and 801,329 shares of our common stock. The following table summarizes the participation in the foregoing transactions by our directors, executive officers and holders of more than 5% of any class of our capital stock as of the date of such transactions (in thousands): Related Party Shares of Series G Preferred Stock Shares of Series G’ Preferred Stock Shares of Common Stock Warrants to Purchase Common Stock Entities affiliated with Aimia, Inc. (1) — 382 801 — Entities affiliated with Polaris Venture Partners (2) 29 212 — 66 Canaan VIII L.P. (3) 54 260 — 123 Entities affiliated with Discovery Capital (4) — 106 — — Scott D. Grimes — 26 — — Lynne M. Laube — 14 — — Entities affiliated with Mark A. Johnson (5) 35 15 — 80 John Klinck 6 — — 13 David Adams 3 — — 7 (1) Consists of 159,207 shares of Series G’ redeemable convertible preferred stock issued to Aeroplan Holdings Europe Sàrl, 223,020 shares of Series G’ redeemable convertible preferred stock issued to Aimia EMEA Limited and 801,329 shares of common stock issued to Aimia EMEA Limited. (2) Consists of 27,988 shares of Series G redeemable convertible preferred stock purchased by Polaris Venture Partners V, L.P. (“PVP V”), 205,020 shares of Series G’ redeemable convertible preferred stock issued to PVP V, 64,038 warrants to purchase common stock issued to PVP V, 545 shares of Series G redeemable convertible preferred stock purchased by Polaris Venture Partners Entrepreneurs’ Fund V, L.L. (“PVP EF V”), 3,995 shares of Series G’ redeemable convertible preferred stock issued to PVP EF V, 1,247 warrants to purchase common stock issued to PVP EF V, 191 shares of Series G redeemable convertible preferred stock purchased by Polaris Venture Partners Founders’ Fund V, L.P. (“PVP FF V”), 1,404 shares of Series G’ redeemable convertible preferred stock issued to PVP FF V, 438 warrants to purchase common stock issued to PVP FF V, 280 shares of Series G redeemable convertible preferred stock purchased by Polaris Venture Partners Special Founders’ Fund V, L.P. (“PVP SFF V”), 2,050 shares of Series G’ redeemable convertible preferred stock issued to PVP SFF V and 641 warrants to purchase common stock issued to PVP SFF V. Polaris Venture Management Co. V, L.L.C. is a general partner of each of PVP V, PVP EF V, PVP FF V and PVP SFF V and may be deemed to have the sole voting and dispositive power over the shares held by PVP V, PVP EF V, PVP FF V and PVP SFF V. Bryce Youngren, a member of our board of directors, is a Managing Partner of Polaris Partners and may be deemed to share voting and dispositive power over the shares held by PVP V, PVP EF V, PVP FF V and PVP SFF V. (3) John V. Balen, a member of our board of directors, is a managing member of Canaan Partners VIII LLC, the general partner of Canaan VIII L.P. Mr. Balen does not have voting or investment power over any shares held directly by Canaan VIII L.P. (4) Consists of 95,272 shares of Series G’ redeemable convertible preferred stock issued to Discovery Opportunity Master Fund, Ltd. and 11,072 shares of Series G’ redeemable convertible preferred stock issued to Discovery Global Focus Master Fund, Ltd. (5) Consists of 15,045 shares of Series G’ redeemable convertible preferred stock issued to TTP Fund II, L.P., 29,005 shares of Series G redeemable convertible preferred stock purchased by TTV Ivy Holdings, LLC, 66,365 warrants to purchase common stock issued to TTV Ivy Holdings, LLC, 5,801 shares of Series G redeemable convertible preferred stock purchased by Mr. Johnson, and 13,273 warrants to purchase common stock issued to Mr. Johnson. TTV Capital is a provider of management services to TTP GP II, LLC, which is a general partner of TTP Fund II, L.P. TTV Capital is the manager of TTV Ivy Holdings Manager, LLC, which is the general partner of TTV Ivy Holdings, LLC. Mark A. Johnson, a member of our board of directors, is a member of each of TTP GP II, LLC and TTV Ivy Holdings Managers, LLC and holds the title of partner of TTV Capital, and may be deemed to share voting and dispositive power over the shares held by TTP Fund II L.P. and TTV Ivy Holdings, LLC. Agreements with Fidelity Information Services, LLC We are party to a reseller agreement with Fidelity Information Services LLC (“FIS”). Pursuant to the reseller agreement, FIS markets and sells our services to financial institutions that are current or potential customers of FIS in exchange for a revenue share percentage. We are also obligated to make milestone payments to FIS related to the integration and deployment of our solutions. Prior to our IPO, FIS was entitled to elect a member of our board of directors, who was Robert Legters until his resignation immediately prior to our IPO in February 2018. In May 2013, FIS purchased 397,515 shares of our Series E Stock. We also granted 10 -year performance-based warrants to purchase up to 644,365 shares of Series E Stock at an exercise price of $23.64 per share. The warrants were exercisable subject to the attainment of certain milestones related to the number of active accounts for which our solutions have been enabled with accelerated vesting upon an IPO. Since FIS did not participate in the convertible promissory note financing, 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

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2018
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 and impairment 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 implementation costs and also result in a cumulative adjustment to accumulated amortization. Scheduled amounts not yet paid to FI partners totaled $3.5 million as of September 30, 2018 . The following table presents changes in deferred FI implementation costs (in thousands): Three Months Ended Nine Months Ended 2017 2018 2017 2018 Beginning balance $ 8,754 $ 12,425 $ 8,451 $ 13,625 Deferred costs 3,650 3,500 6,650 5,750 Recoveries through FI Share (1,185 ) (1,344 ) (3,137 ) (4,036 ) Amortization (365 ) (378 ) (1,110 ) (1,136 ) Ending balance $ 10,854 $ 14,203 $ 10,854 $ 14,203 During the first half of 2017, we accrued expenses totaling $3.0 million related to an expected shortfall in meeting a 2017 minimum FI Share commitment recorded in FI Share and other third-party costs on our consolidated statement of operations. In the third quarter of 2017, we amended the agreement with the FI partner and removed the 2017 minimum FI Share commitment, resulting in a non-cash gain of $3.0 million that was recognized upon the reversal of the accrued shortfall. 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, which were not met as of September 30, 2018 . Any expected shortfall will be accrued during the 12-month period following the completion of the milestones. Litigation

EARNINGS PER SHARE

EARNINGS PER SHARE	9 Months Ended
	Sep. 30, 2018
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 nine months ended September 30, 2017 and 2018 because the effects of potentially dilutive items were anti-dilutive, given our net loss during these periods. The following securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive (in thousands: September 30, 2017 2018 Redeemable convertible preferred stock: Series A-R 1,857 — Series B-R 2,247 — Series C-R 1,508 — Series D-R 1,396 — Series E-R 795 — Series F-R 1,199 — Series G 346 — Series G’ 1,296 — Common stock options 2,533 1,862 Common stock warrants 1,245 868 Common stock warrants issuable pursuant to Series G Stock financing 639 — Redeemable convertible preferred stock warrants 110 — Restricted stock units — 1,200 Common stock issuable pursuant to the ESPP — 151

SEGMENTS

SEGMENTS	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
SEGMENTS	SEGMENTS We have three operating segments: our Cardlytics Direct solutions in the United States and United Kingdom and Other Platform Solutions, as determined by the information that both our Chief Executive Officer and 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 United States and United Kingdom 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. Our Other Platform Solutions segment represents solutions that enable marketers and marketing service providers to leverage the power of purchase intelligence across all of their marketing investments. Revenues can be directly attributable to each segment. With the exception of a non-cash equity expense and the amortization and impairment of deferred FI implementation costs, FI Share is also 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. In early 2018, we began a strategic shift to focus the majority of our efforts and resources to support the growth of Cardlytics Direct. At this time, we have not yet determined what impact this strategic change will have on our reportable segment structure. The following table provides information regarding our reportable segments (in thousands): Three Months Ended Nine Months Ended 2017 2018 2017 2018 Cardlytics Direct: Adjusted contribution (2)(3) $ 16,805 $ 16,906 $ 37,673 $ 47,368 Plus: FI Share and other third-party costs (1) 13,409 17,514 45,942 54,271 Revenue $ 30,214 $ 34,420 $ 83,615 $ 101,639 Other Platform Solutions: Adjusted contribution $ 437 $ 72 $ 3,650 $ 3 Plus: FI Share and other third-party costs (1) 755 90 3,834 1,223 Revenue $ 1,192 $ 162 $ 7,484 $ 1,226 Total: Adjusted contribution (2)(3) $ 17,242 $ 16,978 $ 41,323 $ 47,371 Plus: FI Share and other third-party costs (1) 14,164 17,604 49,776 55,494 Revenue $ 31,406 $ 34,582 $ 91,099 $ 102,865 (1) FI Share and other third party costs presented above excludes a non-cash equity expense and amortization and impairment of deferred FI implementation costs, which are detailed below in our reconciliation of U.S. GAAP loss before income taxes to non-GAAP adjusted contribution. (2) Adjusted contribution includes the impact of a non-cash gain totaling $3.0 million during the three months ended September 30, 2017 related to the reversal of an accrued expense for an expected shortfall in meeting a minimum FI Share commitment. There was no impact to the nine months ended September 30, 2017 and there was no corresponding accrued expense during the three and nine months ended September 30, 2018. (3) Adjusted contribution includes the impact of a $0.8 million gain during the three and nine months ended September 30, 2018 related to the renewal of our agreement with Lloyds, which contains certain amendments that are retroactively applied as of January 1, 2018. Adjusted Contribution Adjusted contribution represents our revenue less FI Share and other third-party costs excluding a non-cash equity expense included in FI Share and amortization and impairment of deferred FI implementation costs. During the first quarter of 2018, we refined our definition of adjusted contribution used by our chief operating decision makers to exclude the impact of a non-cash charge related to the issuance of equity to an FI partner and the impact of amortization and impairment of deferred FI implementation costs. We believe these changes are warranted and appropriate since these investments are expected to yield meaningful long-term relationships with our FI partners and provide incentive for our FI partners to invest in the user interfaces that complement our platform. We have recast all historical disclosures of adjusted contribution for the periods presented. The following table presents a reconciliation of loss before income taxes presented in accordance with U.S. GAAP to adjusted contribution (in thousands): Three Months Ended Nine Months Ended 2017 2018 2017 2018 Adjusted contribution $ 17,242 $ 16,978 $ 41,323 $ 47,371 Minus: Non-cash equity expense included in FI Share (1) — — — 2,519 Amortization of deferred FI implementation costs (1) 365 378 1,110 1,136 Delivery costs 1,646 3,007 5,095 7,509 Sales and marketing expense 8,302 9,452 23,454 27,915 Research and development expense 3,421 4,097 9,527 12,444 General and administration expense 5,276 7,925 14,738 23,486 Depreciation and amortization expense 771 777 2,303 2,471 Total other income (expense) (65 ) (290 ) 681 11,367 Loss before income taxes $ (2,474 ) $ (8,368 ) $ (15,585 ) $ (41,476 ) (1) Non-cash equity expense included in FI Share and amortization and impairment of deferred FI implementation costs are excluded from FI Share and other third party costs, which is shown above in our reconciliation of U.S. GAAP revenue to non-GAAP adjusted contribution.. The following table provides geographical information (in thousands): Three Months Ended Nine Months Ended 2017 2018 2017 2018 Revenue: United States $ 26,841 $ 30,884 $ 80,606 $ 90,606 United Kingdom 4,565 3,698 10,493 12,259 Total $ 31,406 $ 34,582 $ 91,099 $ 102,865 December 31, 2017 September 30, 2018 Property and equipment: United States $ 6,813 $ 8,955 United Kingdom 506 318 Total $ 7,319 $ 9,273 Capital expenditures within the United Kingdom were $0.3 million and less than $0.1 million during the nine months ended September 30, 2017 and 2018

SIGNIFICANT ACCOUNTING POLICI_2

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
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 (“U.S. 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 U.S. 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, 2017
Use of Estimates	Use of EstimatesThe preparation of financial statements in conformity with U.S. 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, contingencies and changes in fair value of our convertible promissory notes. 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 Our Cardlytics Direct solution is our proprietary native bank advertising channel that enables marketers to reach consumers via their trusted and frequently visited online and mobile banking channels as well as email. 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, which we refer to as Consumer Incentives. We report our revenue on our condensed consolidated statements of operations net of Consumer Incentives. We generally pay Consumer Incentives only with respect to our Cardlytics Direct service. 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.
Concentration of Risk	Concentrations of Risk Financial instruments that potentially subject us to concentrations of credit risk consist primarily of cash and cash equivalents and accounts receivable. Our cash and cash equivalents are held with three financial institutions, which we believe are of high credit quality. We believe that our accounts receivable credit risk exposure is limited as a result of being diversified among a large number of marketers segregated by both geography and industry. Historically, we have not experienced significant write-downs of our accounts receivable. No marketer represented a significant concentration of our accounts receivable as of December 31, 2017 or September 30, 2018 . During the nine months ended September 30, 2017 and 2018 , a marketer in the U.S. accounted for 7% and 10% of our revenue, respectively. No other marketer accounted for over 10% of revenue during the nine months ended September 30, 2017 and 2018 . 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 five years but are generally terminable by the FI partner on 90
Deferred Offering Costs	Deferred Offering CostsDeferred offering costs consist of incremental costs directly attributable to equity offerings. Deferred offering costs are included in other long-term assets on our condensed consolidated balance sheets. Upon completion of an offering, these amounts are offset against the proceeds of the offering.
Fair Value of Financial Instruments	Fair Value of Financial Instruments When required by U.S. GAAP, assets and liabilities are reported at fair value on our condensed consolidated financial statements. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Valuation inputs are arranged in a hierarchy that consists of the following levels: • Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date. • Level 2 inputs are inputs other than Level 1 inputs such as quoted prices for similar assets or liabilities; quoted prices in markets with insufficient volume or infrequent transactions (less active markets); or model-derived valuations in which all significant inputs are observable or can be derived principally from or corroborated by observable market data for substantially the full term of the assets or liabilities. • Level 3 inputs are unobservable inputs for the asset or liability. Our nonfinancial assets that we recognize or disclose at fair value on our condensed consolidated financial statements on a nonrecurring basis include property and equipment, intangible assets, capitalized software development costs and deferred FI implementation costs. The fair values for these assets are evaluated when events or changes in circumstances indicate the carrying value may not be recoverable. Preferred Stock Warrants Outstanding warrants to purchase shares of our redeemable convertible preferred stock are accounted for as derivative liabilities in accordance with ASC Topic 815, Derivatives and Hedging (“ASC 815”) due to the terms of the warrants and related agreements. We have determined that these warrants do not meet the scope exception of a contract indexed to our stock because of fair value protections contained in agreements governing our redeemable convertible preferred stock. We record preferred stock warrant liabilities on our condensed consolidated balance sheets at their fair value. We record the changes in fair value of such instruments as non-cash gains or losses on our condensed consolidated statements of operations. Upon our IPO, all warrants to purchase shares of our redeemable convertible preferred stock were converted to warrants to purchase shares of our common stock. See Note 6—Fair Value Measurements, for additional information regarding the valuation of warrants to purchase shares of our redeemable convertible preferred stock. Common Stock Warrants Issued in Connection with the Series G Stock Financing In connection with the Series G Stock financing, we issued warrants to purchase shares of our common stock that are accounted for as liabilities in accordance with ASC Topic 480, Distinguishing Liabilities From Equity due to the terms of the warrants and related agreements. We record these common stock warrant liabilities in our consolidated balance sheets at their fair value. We record the changes in fair value of such instruments as non-cash gains or losses in our statements of operations. In August 2018 we issued warrants to purchase 792,434 shares of common stock at an exercise price of $0.0004 per share to the cash investors of our Series G financing, pursuant to our Series G stock purchase agreement. The warrants had a valuation of $15.3 million upon issuance and were subsequently exercised, resulting in the issuance of 792,434 shares of our common stock. See Note 6—Fair Value Measurements, for additional information regarding the valuation of the warrants issued in connection with the Series G Stock financing. Convertible Promissory Notes
Income Taxes	Income Taxes On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (“Tax Act”) was signed into law making significant changes to the Internal Revenue Code. Changes include, but are not limited to, a corporate tax rate decrease to 21% effective for tax years beginning after December 31, 2017. This change in tax rate resulted in a reduction in our net U.S. deferred tax assets, which was fully offset by a reduction in our valuation allowance. The other provisions of the Tax Act, including the one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings, did not have a material impact on our financial statements as of December 31, 2017.
Recently Issued and Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In May 2017, the FASB issued ASU 2017-09, Scope of Modification Accounting , which amends the scope of modification accounting for share-based payment arrangements, provides guidance on the types of changes to the terms or conditions of share-based payment awards to which an entity would be required to apply modification accounting under ASC Topic 718, Compensation—Stock Compensation . For all entities, the ASU is effective prospectively for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. We adopted this ASU on January 1, 2018 and it did not have an impact on our condensed consolidated financial statements. Recently Issued Accounting Pronouncements In May 2014, the FASB issued Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606). ASU 2014-09 supersedes the recognition guidance in ASC Topic 605 and most industry specific revenue guidance and requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. In addition, this ASU requires disclosures of the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. This ASU supersedes most existing GAAP revenue recognition principles, and it permits the use of either the retrospective or modified retrospective transition method. For public entities, this ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within those annual periods. For non-public entities, this ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. We have made the election to use the extended transition period for complying with new or revised accounting standards under Section 102(b)(1) of the Jumpstart Our Business Startups Act of 2012 ("JOBS Act"), therefore we will be required to apply this ASU for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Retrospective application will be required for each period presented through either the recasting of the prior periods for the effects of the adoption of this ASU or retrospectively through a cumulative catch up recognized at the date of adoption. During the first quarter of 2018, we began assessing the impacts, if any, that this ASU may have on our results of operations, current accounting policies, processes, controls, systems and financial statement disclosures. Based on our initial assessment, we expect to adopt this new standard using the modified retrospective transition method, which would result in a cumulative adjustment as of the date of the adoption. We also expect to continue to report our revenue on our condensed consolidated statements of operations net of Consumer Incentives and gross of FI Share. We are continuing to assess the impact of this standard on our financial position, results of operations and related disclosures and have not yet determined whether the effect will be material. In January 2016, the FASB issued 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. This ASU requires equity investments to be measured at fair value with changes in fair values recognized in net earnings, (public entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes), simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment and eliminates the requirement to disclose fair values, the methods and significant assumptions used to estimate the fair value of financial instruments measured at amortized cost. This ASU also clarifies that management should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale debt securities in combination with other deferred tax assets. For public business entities, this ASU is effective for fiscal years beginning after December 15, 2017, including interim periods within those annual periods. For non-public business entities, this ASU is effective for fiscal years beginning after December 15, 2018, and interim periods within fiscal years beginning after December 15, 2019. Early adoption is permitted. We have made the election to use the extended transition period for complying with new or revised accounting standards under Section 102(b)(1) of the JOBS Act, therefore we will be required to apply this ASU for annual reporting periods beginning after December 15, 2018, and interim periods within fiscal years beginning after December 15, 2019. We are currently evaluating the potential impact of this recently issued guidance on our condensed 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’s primary change is the requirement for lessee entities to recognize a lease liability for payments and a right of use asset representing the right to use the leased asset during the term on operating lease arrangements. Lessees are permitted to make an accounting policy election to not recognize the asset and liability for leases with a term of twelve months or less. Lessors’ accounting under the ASU is largely unchanged from the previous accounting standard. In addition, the ASU expands the disclosure requirements of lease arrangements. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842) - Targeted Improvements , which provides the option of applying the requirements of the new lease standard in the period of adoption with no restatement to comparative periods. For public entities, this ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. For non-public entities, this ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. We have made the election to use the extended transition period for complying with new or revised accounting standards under Section 102(b)(1) of the JOBS Act, therefore we will be required to adopt this ASU for annual reporting periods beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted. Although we are currently evaluating the impact of this guidance on our condensed 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. In August 2018, the SEC issued Release No. 33-10532, Disclosure Update and Simplification, that extends to interim periods the annual disclosure requirement in SEC Regulation S-X, Rule 3-04 of presenting changes in stockholders’ equity. An analysis of changes in stockholders’ equity (deficit) will now be required for the current and comparative quarter-to-date and year-to-date interim periods. In response to this ruling, we have presented consolidated statements of stockholders' equity (deficit) for the three and nine months ended September 30, 2017 and 2018

SIGNIFICANT ACCOUNTING POLICI_3

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS (Tables)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Schedule of cash and cash equivalents	Cash, cash equivalents and restricted cash as presented on our condensed consolidated statements of cash flows consists of the following (in thousands): December 31, September 30, 2016 2017 2017 2018 Cash and cash equivalents $ 22,838 $ 21,262 $ 28,186 $ 47,812 Restricted cash 130 — — 20,000 Cash, cash equivalents and restricted cash $ 22,968 $ 21,262 $ 28,186 $ 67,812
Schedule of restricted cash	Cash, cash equivalents and restricted cash as presented on our condensed consolidated statements of cash flows consists of the following (in thousands): December 31, September 30, 2016 2017 2017 2018 Cash and cash equivalents $ 22,838 $ 21,262 $ 28,186 $ 47,812 Restricted cash 130 — — 20,000 Cash, cash equivalents and restricted cash $ 22,968 $ 21,262 $ 28,186 $ 67,812
Schedule of deferred costs	Nine Months Ended 2017 2018 Beginning balance $ — $ 3,144 Deferred costs $ 2,449 $ 1,135 Recognized against offering proceeds — (4,279 ) Ending balance $ 2,449 $ —

DEBT (Tables)

DEBT (Tables)	9 Months Ended
	Sep. 30, 2018
Debt Disclosure [Abstract]
Schedule of long-term debt instruments	Our debt consists of the following (in thousands): December 31, 2017 September 30, 2018 Lines of credit $ 25,081 $ 26,777 Term loans, net of unamortized discount and debt issuance costs of $1,058 and $25 at December 31, 2017 and September 30, 2018, respectively 31,830 19,975 Capital leases 101 63 Convertible promissory notes (converted into Series G' Stock in May 2017) — — Total debt $ 57,012 $ 46,815 Less current portion of long-term debt (44 ) (21 ) Long-term debt, net of current portion $ 56,968 $ 46,794
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 2018 (remainder of year) $ — $ 6 $ 6 2019 — 20 20 2020 46,777 24 46,801 2021 — 13 13 Total principal payments $ 46,777 $ 63 $ 46,840 Less unamortized debt issuance costs (25 ) — (25 ) Less unamortized debt discount — — — Total debt $ 46,752 $ 63 $ 46,815

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	9 Months Ended
	Sep. 30, 2018
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 2017 2018 2017 2018 Delivery costs $ 62 $ 203 $ 146 $ 471 Sales and marketing expense 524 1,939 1,390 5,550 Research and development expense 281 915 691 3,141 General and administration expense 615 2,666 1,480 7,806 Total stock-based compensation expense $ 1,482 $ 5,723 $ 3,707 $ 16,968
Summary of common stock option activity	A summary of common stock option activity is as follows (in thousands, except per share amounts): Shares Weighted-Average Exercise Price Options outstanding — December 31, 2016 2,137 $ 15.00 Granted 799 23.80 Exercised (154 ) 3.84 Forfeited (145 ) 17.68 Cancelled (104 ) 11.29 Options outstanding — September 30, 2017 2,533 $ 18.44 Shares Weighted-Average Exercise Price Options outstanding — December 31, 2017 2,514 $ 18.42 Granted 29 24.24 Exercised (329 ) 6.27 Forfeited (154 ) 24.99 Canceled (198 ) 15.87 Options outstanding — September 30, 2018 1,862 $ 20.38
Summary of RSU activity	A summary of restricted stock unit activity is as follows (in thousands, except per share amounts): Shares Weighted-Average Grant Date Fair Value Unvested — December 31, 2017 — $ — Granted 1,269 20.61 Vested — — Forfeited (69 ) 18.07 Canceled — — Unvested — September 30, 2018 1,200 $ 20.75

REDEEMABLE CONVERTIBLE PREFER_2

REDEEMABLE CONVERTIBLE PREFERRED STOCK (Tables)	9 Months Ended
	Sep. 30, 2018
Temporary Equity Disclosure [Abstract]
Summary of the change in carrying amount of the outstanding redeemable convertible preferred stock	A summary of the change in carrying amount of the outstanding redeemable convertible preferred stock is as follows (in thousands): Series G’ Stock Series G Stock Shares Amount Shares Amount Balance — December 31, 2017 1,296 $ 44,672 346 $ 5,110 Accretion of redeemable convertible preferred stock — — — 108 Conversion of preferred stock to common stock (1,296 ) (44,672 ) (346 ) (5,218 ) Balance — September 30, 2018 — $ — — $ — Series F-R Stock Series E-R Stock Series D-R Stock Shares Amount Shares Amount Shares Amount Balance — December 31, 2017 1,199 $ 58,449 795 $ 29,972 1,396 $ 32,728 Accretion of redeemable convertible preferred stock — 38 — 1 — 7 Conversion of preferred stock to common stock (1,199 ) (58,487 ) (795 ) (29,973 ) (1,396 ) (32,735 ) Balance — September 30, 2018 — $ — — $ — — $ — Series C-R Stock Series B-R Stock Series A-R Stock Shares Amount Shares Amount Shares Amount Balance — December 31, 2017 1,508 $ 18,366 2,247 $ 5,288 1,857 $ 1,852 Accretion of redeemable convertible preferred stock — 3 — — — — Conversion of preferred stock to common stock (1,508 ) (18,369 ) (2,247 ) (5,288 ) (1,857 ) (1,852 ) Balance — September 30, 2018 — $ — — $ — — $ —

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Schedule of financial assets and liabilities measured at fair value on a recurring basis	Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The following table summarizes our liabilities measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): December 31, 2017 Level 1 Level 2 Level 3 Total Liabilities: Preferred stock warrants $ — $ — $ 2,285 $ 2,285 Common stock warrants — — 7,945 7,945 Convertible promissory notes — — — — Total liabilities $ — $ — $ 10,230 $ 10,230 September 30, 2018 Level 1 Level 2 Level 3 Total Liabilities: Preferred stock warrants $ — $ — $ — $ — Common stock warrants — — — — Convertible promissory notes — — — — Total liabilities $ — $ — $ — $ —
Schedule of reconciliation of the redeemable convertible preferred stock warrant liability	Our redeemable convertible preferred stock warrants, common stock warrants issued in connection with the Series G Stock financing and our convertible promissory notes are measured and recorded at fair value on a recurring basis using Level 3 inputs. The table below provides a roll forward of the changes in fair value of Level 3 financial instruments (in thousands): Preferred Stock Warrants Common Stock Warrants Convertible Promissory Notes Balance at December 31, 2016 $ 2,197 $ — $ 72,332 Conversion of convertible promissory notes to Series G’ preferred stock — — (44,672 ) Conversion of convertible promissory notes to common stock — — (24,392 ) Accrued interest on convertible promissory notes — — 1,701 Issuance of common stock warrants — 7,452 — Changes in fair value (119 ) 531 (4,969 ) Balance at September 30, 2017 $ 2,078 $ 7,983 $ — Preferred Stock Warrants Common Stock Warrants Convertible Promissory Notes Balance at December 31, 2017 $ 2,285 $ 7,945 $ — Changes in fair value (549 ) 7,309 — Conversion of preferred stock warrants to common stock warrants (1,736 ) — — Exercise of common stock warrants — (15,254 ) — Balance at September 30, 2018 $ — $ — $ —
Fair value inputs	We determined the fair value of these common warrants on the date of IPO using the Black-Scholes option pricing model, which is affected by the fair value of our common stock as well as the following significant inputs: February 8, 2018 Weighted-average grant date fair value $3.91 Significant inputs: Value of common stock $13.00 Expected term 5.3 years Volatility 50% Risk-free interest rate 2.0% Dividend yield —% September 30, 2017 Weighted-average cost of capital applicable to preferred stock warrants 21% Discount for lack of marketability 7% to 13% Volatility 55% Risk-free interest rate 1.2% to 1.4%
Summary of our preferred stock warrants	A summary of our preferred stock warrants is as follows (in thousands, except per share amounts): Warrants outstanding Preferred Series Grant date Expiration date Exercise price December 31, 2017 September 30, 2018 Series B-R 2/26/2010 2/25/2020 $ 2.36 59 — Series D-R 9/21/2012 9/20/2022 $ 23.64 38 — Series D-R 9/21/2012 9/20/2022 $ 23.64 13 — Total 110 —

RELATED PARTIES (Tables)

RELATED PARTIES (Tables)	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
Schedule of related party transactions	The following table summarizes the participation in the foregoing transactions by our directors, executive officers and holders of more than 5% of any class of our capital stock as of the date of such transactions (in thousands): Related Party Shares of Series G Preferred Stock Shares of Series G’ Preferred Stock Shares of Common Stock Warrants to Purchase Common Stock Entities affiliated with Aimia, Inc. (1) — 382 801 — Entities affiliated with Polaris Venture Partners (2) 29 212 — 66 Canaan VIII L.P. (3) 54 260 — 123 Entities affiliated with Discovery Capital (4) — 106 — — Scott D. Grimes — 26 — — Lynne M. Laube — 14 — — Entities affiliated with Mark A. Johnson (5) 35 15 — 80 John Klinck 6 — — 13 David Adams 3 — — 7 (1) Consists of 159,207 shares of Series G’ redeemable convertible preferred stock issued to Aeroplan Holdings Europe Sàrl, 223,020 shares of Series G’ redeemable convertible preferred stock issued to Aimia EMEA Limited and 801,329 shares of common stock issued to Aimia EMEA Limited. (2) Consists of 27,988 shares of Series G redeemable convertible preferred stock purchased by Polaris Venture Partners V, L.P. (“PVP V”), 205,020 shares of Series G’ redeemable convertible preferred stock issued to PVP V, 64,038 warrants to purchase common stock issued to PVP V, 545 shares of Series G redeemable convertible preferred stock purchased by Polaris Venture Partners Entrepreneurs’ Fund V, L.L. (“PVP EF V”), 3,995 shares of Series G’ redeemable convertible preferred stock issued to PVP EF V, 1,247 warrants to purchase common stock issued to PVP EF V, 191 shares of Series G redeemable convertible preferred stock purchased by Polaris Venture Partners Founders’ Fund V, L.P. (“PVP FF V”), 1,404 shares of Series G’ redeemable convertible preferred stock issued to PVP FF V, 438 warrants to purchase common stock issued to PVP FF V, 280 shares of Series G redeemable convertible preferred stock purchased by Polaris Venture Partners Special Founders’ Fund V, L.P. (“PVP SFF V”), 2,050 shares of Series G’ redeemable convertible preferred stock issued to PVP SFF V and 641 warrants to purchase common stock issued to PVP SFF V. Polaris Venture Management Co. V, L.L.C. is a general partner of each of PVP V, PVP EF V, PVP FF V and PVP SFF V and may be deemed to have the sole voting and dispositive power over the shares held by PVP V, PVP EF V, PVP FF V and PVP SFF V. Bryce Youngren, a member of our board of directors, is a Managing Partner of Polaris Partners and may be deemed to share voting and dispositive power over the shares held by PVP V, PVP EF V, PVP FF V and PVP SFF V. (3) John V. Balen, a member of our board of directors, is a managing member of Canaan Partners VIII LLC, the general partner of Canaan VIII L.P. Mr. Balen does not have voting or investment power over any shares held directly by Canaan VIII L.P. (4) Consists of 95,272 shares of Series G’ redeemable convertible preferred stock issued to Discovery Opportunity Master Fund, Ltd. and 11,072 shares of Series G’ redeemable convertible preferred stock issued to Discovery Global Focus Master Fund, Ltd. (5) Consists of 15,045 shares of Series G’ redeemable convertible preferred stock issued to TTP Fund II, L.P., 29,005 shares of Series G redeemable convertible preferred stock purchased by TTV Ivy Holdings, LLC, 66,365 warrants to purchase common stock issued to TTV Ivy Holdings, LLC, 5,801 shares of Series G redeemable convertible preferred stock purchased by Mr. Johnson, and 13,273 warrants to purchase common stock issued to Mr. Johnson. TTV Capital is a provider of management services to TTP GP II, LLC, which is a general partner of TTP Fund II, L.P. TTV Capital is the manager of TTV Ivy Holdings Manager, LLC, which is the general partner of TTV Ivy Holdings, LLC. Mark A. Johnson, a member of our board of directors, is a member of each of TTP GP II, LLC and TTV Ivy Holdings Managers, LLC and holds the title of partner of TTV Capital, and may be deemed to share voting and dispositive power over the shares held by TTP Fund II L.P. and TTV Ivy Holdings, LLC.

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	9 Months Ended
	Sep. 30, 2018
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 2017 2018 2017 2018 Beginning balance $ 8,754 $ 12,425 $ 8,451 $ 13,625 Deferred costs 3,650 3,500 6,650 5,750 Recoveries through FI Share (1,185 ) (1,344 ) (3,137 ) (4,036 ) Amortization (365 ) (378 ) (1,110 ) (1,136 ) Ending balance $ 10,854 $ 14,203 $ 10,854 $ 14,203

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Schedule of antidilutive securities	The following securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive (in thousands: September 30, 2017 2018 Redeemable convertible preferred stock: Series A-R 1,857 — Series B-R 2,247 — Series C-R 1,508 — Series D-R 1,396 — Series E-R 795 — Series F-R 1,199 — Series G 346 — Series G’ 1,296 — Common stock options 2,533 1,862 Common stock warrants 1,245 868 Common stock warrants issuable pursuant to Series G Stock financing 639 — Redeemable convertible preferred stock warrants 110 — Restricted stock units — 1,200 Common stock issuable pursuant to the ESPP — 151

SEGMENTS (Tables)

SEGMENTS (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Reporting [Abstract]
Schedule of segment reporting information	The following table provides information regarding our reportable segments (in thousands): Three Months Ended Nine Months Ended 2017 2018 2017 2018 Cardlytics Direct: Adjusted contribution (2)(3) $ 16,805 $ 16,906 $ 37,673 $ 47,368 Plus: FI Share and other third-party costs (1) 13,409 17,514 45,942 54,271 Revenue $ 30,214 $ 34,420 $ 83,615 $ 101,639 Other Platform Solutions: Adjusted contribution $ 437 $ 72 $ 3,650 $ 3 Plus: FI Share and other third-party costs (1) 755 90 3,834 1,223 Revenue $ 1,192 $ 162 $ 7,484 $ 1,226 Total: Adjusted contribution (2)(3) $ 17,242 $ 16,978 $ 41,323 $ 47,371 Plus: FI Share and other third-party costs (1) 14,164 17,604 49,776 55,494 Revenue $ 31,406 $ 34,582 $ 91,099 $ 102,865 (1) FI Share and other third party costs presented above excludes a non-cash equity expense and amortization and impairment of deferred FI implementation costs, which are detailed below in our reconciliation of U.S. GAAP loss before income taxes to non-GAAP adjusted contribution. (2) Adjusted contribution includes the impact of a non-cash gain totaling $3.0 million during the three months ended September 30, 2017 related to the reversal of an accrued expense for an expected shortfall in meeting a minimum FI Share commitment. There was no impact to the nine months ended September 30, 2017 and there was no corresponding accrued expense during the three and nine months ended September 30, 2018. (3) Adjusted contribution includes the impact of a $0.8 million Three Months Ended Nine Months Ended 2017 2018 2017 2018 Adjusted contribution $ 17,242 $ 16,978 $ 41,323 $ 47,371 Minus: Non-cash equity expense included in FI Share (1) — — — 2,519 Amortization of deferred FI implementation costs (1) 365 378 1,110 1,136 Delivery costs 1,646 3,007 5,095 7,509 Sales and marketing expense 8,302 9,452 23,454 27,915 Research and development expense 3,421 4,097 9,527 12,444 General and administration expense 5,276 7,925 14,738 23,486 Depreciation and amortization expense 771 777 2,303 2,471 Total other income (expense) (65 ) (290 ) 681 11,367 Loss before income taxes $ (2,474 ) $ (8,368 ) $ (15,585 ) $ (41,476 ) (1)
Schedule of revenue by geographic areas	The following table provides geographical information (in thousands): Three Months Ended Nine Months Ended 2017 2018 2017 2018 Revenue: United States $ 26,841 $ 30,884 $ 80,606 $ 90,606 United Kingdom 4,565 3,698 10,493 12,259 Total $ 31,406 $ 34,582 $ 91,099 $ 102,865 December 31, 2017 September 30, 2018 Property and equipment: United States $ 6,813 $ 8,955 United Kingdom 506 318 Total $ 7,319 $ 9,273

OVERVIEW OF BUSINESS AND BASI_2

OVERVIEW OF BUSINESS AND BASIS OF PRESENTATION (Details)	Feb. 14, 2018USD ($)shares	Feb. 14, 2018USD ($)shares	Feb. 13, 2018USD ($)$ / sharesshares	Jan. 26, 2018USD ($)$ / sharesshares	Sep. 30, 2018USD ($)$ / sharesshares	Sep. 30, 2017USD ($)	Dec. 31, 2017$ / sharesshares	May 31, 2017shares	Feb. 28, 2017shares
Debt Instrument [Line Items]
Sale of stock, number of shares issued in transaction (in shares) | shares	421,355	5,821,355
Proceeds from IPO | $	$ 5,500,000	$ 75,700,000
Proceeds from IPO, net | $		66,100,000
Sale of stock, discounts and commissions | $		5,300,000
Issuance costs | $		$ 4,300,000			$ 4,279,000	$ 0
Stock split, conversion ratio					0.25
Common stock, shares authorized (in shares) | shares				100,000,000	100,000,000		83,000,000	83,000,000
Par value (in usd per share) | $ / shares				$ 0.0001	$ 0.0001		$ 0.0001
Proceeds from issuance of common stock, threshold | $				$ 70,000,000
Preferred stock, shares authorized (in shares) | shares					10,000,000
Preferred stock, par or stated value per share (in usd per share) | $ / shares					$ 0.0001
Shares authorized (in shares) | shares				25,000,000				96,131,002	82,683,212
Redeemable convertible preferred stock, par value (in usd per share) | $ / shares				$ 0.0001
IPO
Debt Instrument [Line Items]
Sale of stock, number of shares issued in transaction (in shares) | shares			5,400,000
Sale of stock, price per share (in usd per share) | $ / shares			$ 13
Proceeds from IPO | $			$ 70,200,000
Over-Allotment Option
Debt Instrument [Line Items]
Sale of stock, number of shares issued in transaction (in shares) | shares	810,000

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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accounting Policies [Abstract]
Consumer incentives, expense	$ 14	$ 14.1	$ 45.9	$ 42.1

SIGNIFICANT ACCOUNTING POLICI_5

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS - Concentrations of Risk (Details)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Concentration Risk [Line Items]
Financial institutions agreement, notice period	90 days
Minimum
Concentration Risk [Line Items]
Financial institutions agreement, term	3 years
Maximum
Concentration Risk [Line Items]
Financial institutions agreement, term	5 years
One Customer | Customer Concentration Risk | Accounts Receivable
Concentration Risk [Line Items]
Concentration risk	10.00%	7.00%
United States | Largest FI Partner | Supplier Concentration Risk | Financial Institution Partner
Concentration Risk [Line Items]
Concentration risk	68.00%	63.00%
United Kingdom | Largest FI Partner | Supplier Concentration Risk | Financial Institution Partner
Concentration Risk [Line Items]
Concentration risk	9.00%	11.00%

SIGNIFICANT ACCOUNTING POLICI_6

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS - Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Interest-bearing deposits, interest rate	1.00%
Restricted cash deposits, interest rate	0.90%
Cash and cash equivalents	$ 47,812	$ 21,262	$ 28,186	$ 22,838
Restricted cash	20,000	0	0	130
Cash, cash equivalents and restricted cash	$ 67,812	$ 21,262	$ 28,186	$ 22,968

SIGNIFICANT ACCOUNTING POLICI_7

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS - Deferred Offering Costs (Details) - USD ($) $ in Thousands	Feb. 14, 2018	Sep. 30, 2018	Sep. 30, 2017
Deferred Financial Institution Costs [Roll Forward]
Beginning balance		$ 3,144	$ 0
Deferred costs		1,135	2,449
Recognized against offering proceeds	$ (4,300)	(4,279)	0
Ending balance		$ 0	$ 2,449

SIGNIFICANT ACCOUNTING POLICI_8

SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING STANDARDS - Fair Value of Financial Instruments (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		9 Months Ended
	Aug. 31, 2018	May 31, 2017	Sep. 30, 2018	Aug. 08, 2018	May 31, 2013
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)					$ 23.64
Series G Stock
Class of Stock [Line Items]
Exercise of common stock warrants (in shares)	792,434
Conversion of securities to common stock (in shares)	792,434		346,000
Exercise price of warrants (in usd per share)	$ 0.0004			$ 0.0004
Issuance of Series G and Series G’ Stock	$ 15.3	$ 11.9

DEBT - Schedule of Debt (Detail

DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Total debt	$ 46,815	$ 57,012
Less current portion of long-term debt	(21)	(44)
Long-term debt, net of current portion	46,794	56,968
Lines of credit
Debt Instrument [Line Items]
Total debt	26,777	25,081
Term loans
Debt Instrument [Line Items]
Total debt	19,975	31,830
Unamortized discount (premium) and debt issuance costs	25	1,058
Capital leases
Debt Instrument [Line Items]
Total debt	63	101
Convertible Promissory Notes
Debt Instrument [Line Items]
Total debt	$ 0	$ 0

DEBT - Narrative (Details)

DEBT - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended	9 Months Ended
	Aug. 31, 2018	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	May 21, 2018	Dec. 31, 2017	Sep. 30, 2016	Jul. 31, 2016
Debt Instrument [Line Items]
Accrued interest (less than)		$ 0	$ 0			$ 6,200,000
Cash paid for interest			9,200,000	$ 600,000
Debt issuance costs, net		$ 25,000	$ 25,000
Maximum borrowing capacity, percentage of accounts receivable		85.00%	85.00%
Revenue, threshold			$ 130,800,000
Debt instrument, required cash balance		$ 5,000,000	5,000,000
Repayments of lines of credit			52,475,000	74,000
2016 Line of Credit and 2016 Term Loan
Debt Instrument [Line Items]
Debt issuance costs, net					$ 100,000
Lines of credit
Debt Instrument [Line Items]
Maximum borrowing capacity		30,000,000	$ 30,000,000
Proceeds from lines of credit		27,400,000
Debt issuance costs					$ 100,000
Debt instrument, interest rate					4.50%
Commitment fee percentage			0.15%
Debt Instrument, success fee			$ 75,000
Revenue threshold, trailing four quarter revenue		200,000,000	200,000,000
Debt instrument, collateral amount		$ 20,000,000	$ 20,000,000
Debt instrument, interest rate increase event of default		3.00%	3.00%
Repayments of lines of credit	$ 700,000
Line of credit facility, remaining borrowing capacity		$ 3,100,000	$ 3,100,000
Lines of credit | Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate			(0.75%)
Lines of credit | Loan Facility, Threshold One
Debt Instrument [Line Items]
Line of credit, deposit threshold		40,000,000	$ 40,000,000
Lines of credit | Loan Facility, Threshold One | Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate			(0.75%)
Lines of credit | Loan Facility, Threshold Two | Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate			(0.50%)
Lines of credit | Loan Facility, Threshold Three
Debt Instrument [Line Items]
Line of credit, deposit threshold		20,000,000	$ 20,000,000
Lines of credit | 2016 Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity							$ 50,000,000
Loss on extinguishment of debt		$ 100,000
Term loans
Debt Instrument [Line Items]
Debt instrument, face amount					$ 20,000,000
Debt instrument, interest rate		2.50%	2.50%
Term loans | Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate			(2.75%)
Term loans | 2016 Term Loan
Debt Instrument [Line Items]
Debt instrument, face amount								$ 24,000,000
Loss on extinguishment of debt		$ 800,000
Convertible Promissory Notes
Debt Instrument [Line Items]
Accrued interest on convertible promissory notes				$ 1,701,000
Convertible Promissory Notes | Convertible Promissory Notes
Debt Instrument [Line Items]
Debt instrument, face amount		50,700,000	$ 50,700,000
Paid-in-king interest			1,700,000
Revolving Credit Facility | Lines of credit
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 30,000,000
Maximum | Lines of credit | Loan Facility, Threshold Two
Debt Instrument [Line Items]
Line of credit, deposit threshold		40,000,000	40,000,000
Minimum | Lines of credit | Loan Facility, Threshold Two
Debt Instrument [Line Items]
Line of credit, deposit threshold		$ 20,000,000	$ 20,000,000

DEBT - Future Payments (Details

DEBT - Future Payments (Details) $ in Thousands	Sep. 30, 2018USD ($)
Debt
2018 (remainder of year)	$ 0
2,019	0
2,020	46,777
2,021	0
Total principal payments	46,777
Less unamortized debt issuance costs	(25)
Less unamortized debt discount	0
Total debt	46,752
Capital leases
2018 (remainder of year)	6
2,019	20
2,020	24
2,021	13
Total principal payments	63
Total debt
2018 (remainder of year)	6
2,019	20
2,020	46,801
2,021	13
Total principal payments	46,840
Less unamortized debt issuance costs	(25)
Less unamortized debt discount	0
Total debt	$ 46,815

STOCK-BASED COMPENSATION - Narr

STOCK-BASED COMPENSATION - Narrative (Details) $ / shares in Units, user in Millions, $ in Millions

Feb. 08, 2018$ / sharesshares

Nov. 13, 2018USD ($)shares

Aug. 31, 2018shares

Feb. 28, 2018USD ($)

Sep. 30, 2018USD ($)usershares

Jun. 30, 2018USD ($)shares

Mar. 31, 2018trancheshares

Sep. 30, 2018USD ($)user$ / sharesshares

Sep. 30, 2017USD ($)$ / shares

Dec. 31, 2016USD ($)

Jan. 31, 2018shares

Dec. 31, 2017shares

May 31, 2017shares

May 30, 2017shares

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

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%

5.00%

Award vesting period

4 years

Expiration period

10 years

Weighted-average grant date fair value (in usd per share) | $ / shares

$ 3.91

$ 10

$ 12.11

Options vested in period, fair value | $

$ 5

$ 3.2

Compensation not yet recognized | $

$ 7.6

$ 7.6

Common stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Compensation cost not yet recognized

2 years 2 months 12 days

Restricted stock units

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Granted (in shares)

1,269,000

Unvested PSU (in shares)

1,200,000

1,200,000

0

Compensation not yet recognized, awards other than options | $

$ 12.6

$ 12.6

Awards granted | $

$ 1

Compensation cost not yet recognized

1 year 1 month 24 days

Restricted stock units | Share-based Compensation Award, Tranche One

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

4 years

4 years

Granted (in shares)

26,590

32,070

335,562

Performance-based restricted share unit

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Granted (in shares)

437,500

Number of tranches | tranche

2

Unvested PSU (in shares)

875,000

875,000

Compensation cost, modification | $

$ 10.7

Performance-based restricted share unit | Share-based Compensation Award, Tranche One

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award, performance conditions | user

70

70

RSU, performance condition, period

3 years

Performance-based restricted share unit | Share-based Compensation Award, Tranche Two

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award, performance conditions | user

85

85

RSU, performance condition, period

5 years

Restricted securities units

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

RSU, service condition period

6 years

Award period for sale of company or IPO

5 years

Stock option expense | $

$ 0.5

Stock issued during period, RSU (in shares)

37,406

ESPP

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of shares authorized (in shares)

375,000

375,000

ESPP, purchase price percentage

85.00%

85.00%

ESPP, number of shares authorized, annual percentage increase

1.00%

1.00%

ESPP, number of shares authorized, annual increase (in shares)

500,000

500,000

2008 Stock Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of shares authorized (in shares)

4,020,000

3,495,000

3,120,000

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

Compensation not yet recognized, awards other than options | $

$ 0.8

Subsequent Event | Restricted stock units | Share-based Compensation Award, Tranche One

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Granted (in shares)

40,155

STOCK-BASED COMPENSATION - Allo

STOCK-BASED COMPENSATION - Allocation of Stock-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 5,723	$ 1,482	$ 16,968	$ 3,707
Delivery costs
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	203	62	471	146
Sales and marketing expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	1,939	524	5,550	1,390
Research and development expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	915	281	3,141	691
General and administration expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation expense	$ 2,666	$ 615	$ 7,806	$ 1,480

STOCK-BASED COMPENSATION - Summ

STOCK-BASED COMPENSATION - Summary of Common Stock Option Activity (Details) - $ / shares shares in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Shares
Beginning balance (in shares)	2,514	2,137
Granted (in shares)	29	799
Exercised (in shares)	(329)	(154)
Forfeited (in shares)	(154)	(145)
Canceled (in shares)	(198)	(104)
Ending balance (in shares)	1,862	2,533
Weighted-Average Exercise Price
Beginning balance (in usd per share)	$ 18.42	$ 15
Granted (in usd per share)	24.24	23.80
Exercised (in usd per share)	6.27	3.84
Forfeited (in usd per share)	24.99	17.68
Canceled (in usd per share)	15.87	11.29
Ending balance (in usd per share)	$ 20.38	$ 18.44

STOCK-BASED COMPENSATION - Su_2

STOCK-BASED COMPENSATION - Summary of RSU Activity (Details) - Restricted stock units shares in Thousands	9 Months Ended
	Sep. 30, 2018$ / sharesshares
Shares
Unvested — Beginning balance (in shares) | shares	0
Granted (in shares) | shares	1,269
Vested (in shares) | shares	0
Forfeited (in shares) | shares	(69)
Canceled (in shares) | shares	0
Unvested — Ending balance (in shares) | shares	1,200
Weighted-Average Grant Date Fair Value
Unvested — Beginning balance (in usd per share) | $ / shares	$ 0
Granted (in usd per share) | $ / shares	20.61
Vested (in usd per share) | $ / shares	0
Forfeited (in usd per share) | $ / shares	18.07
Canceled (in usd per share) | $ / shares	0
Unvested — Ending balance (in usd per share) | $ / shares	$ 20.75

REDEEMABLE CONVERTIBLE PREFER_3

REDEEMABLE CONVERTIBLE PREFERRED STOCK - Outstanding Stock (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	Aug. 31, 2018	Sep. 30, 2018	Sep. 30, 2017
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance		$ 196,437
Conversion of preferred stock to common stock		(196,594)	$ (24,392)
Ending balance		$ 0
Series G’ Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)		1,296,000
Beginning balance		$ 44,672
Accretion of redeemable convertible preferred stock		$ 0
Conversion of preferred stock to common stock (in shares)		(1,296,000)
Conversion of preferred stock to common stock		$ (44,672)
Ending balance (in shares)		0
Ending balance		$ 0
Series G Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)		346,000
Beginning balance		$ 5,110
Accretion of redeemable convertible preferred stock		$ 108
Conversion of preferred stock to common stock (in shares)	(792,434)	(346,000)
Conversion of preferred stock to common stock		$ (5,218)
Ending balance (in shares)		0
Ending balance		$ 0
Series F-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)		1,199,000
Beginning balance		$ 58,449
Accretion of redeemable convertible preferred stock		$ 38
Conversion of preferred stock to common stock (in shares)		(1,199,000)
Conversion of preferred stock to common stock		$ (58,487)
Ending balance (in shares)		0
Ending balance		$ 0
Series E-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)		795,000
Beginning balance		$ 29,972
Accretion of redeemable convertible preferred stock		$ 1
Conversion of preferred stock to common stock (in shares)		(795,000)
Conversion of preferred stock to common stock		$ (29,973)
Ending balance (in shares)		0
Ending balance		$ 0
Series D-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)		1,396,000
Beginning balance		$ 32,728
Accretion of redeemable convertible preferred stock		$ 7
Conversion of preferred stock to common stock (in shares)		(1,396,000)
Conversion of preferred stock to common stock		$ (32,735)
Ending balance (in shares)		0
Ending balance		$ 0
Series C-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)		1,508,000
Beginning balance		$ 18,366
Accretion of redeemable convertible preferred stock		$ 3
Conversion of preferred stock to common stock (in shares)		(1,508,000)
Conversion of preferred stock to common stock		$ (18,369)
Ending balance (in shares)		0
Ending balance		$ 0
Series B-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)		2,247,000
Beginning balance		$ 5,288
Accretion of redeemable convertible preferred stock		$ 0
Conversion of preferred stock to common stock (in shares)		(2,247,000)
Conversion of preferred stock to common stock		$ (5,288)
Ending balance (in shares)		0
Ending balance		$ 0
Series A-R Stock
Increase (Decrease) in Temporary Equity [Roll Forward]
Beginning balance (in shares)		1,857,000
Beginning balance		$ 1,852
Accretion of redeemable convertible preferred stock		$ 0
Conversion of preferred stock to common stock (in shares)		(1,857,000)
Conversion of preferred stock to common stock		$ (1,852)
Ending balance (in shares)		0
Ending balance		$ 0

REDEEMABLE CONVERTIBLE PREFER_4

REDEEMABLE CONVERTIBLE PREFERRED STOCK - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 08, 2018	Aug. 31, 2018	May 31, 2017	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 26, 2018	Dec. 31, 2017	Feb. 28, 2017	May 31, 2013
Temporary Equity [Line Items]
Shares authorized (in shares)			96,131,002				25,000,000		82,683,212
Shares authorized (in shares)			83,000,000		100,000,000		100,000,000	83,000,000
Redeemable convertible preferred stock, par value (in usd per share)							$ 0.0001
Issuance costs					$ 1,949	$ 2,190
Conversion of stock, shares converted (in shares)			801,329
Shares issued (in shares)					21,411,000			3,439,000
Exercise price of warrants (in usd per share)										$ 23.64
Proceeds from issuance of Series G preferred stock					$ 0	$ 11,940
Series G Stock
Temporary Equity [Line Items]
Shares authorized (in shares)					0			1,385,000
Issuance of Series G and Series G’ Stock		$ 15,300	$ 11,900
Issuance of Series G and Series G’ Stock (in shares)			346,334
Redeemable convertible preferred stock, par value (in usd per share)			$ 0.0001		$ 0			$ 0.0001
Shares issued (in usd per share)			$ 34.4758
Issuance costs			$ 100
Shares issued (in shares)			346,334
Class of warrant, numerator input value (in usd per share)			$ 68.9516
Number of trading days			30 days
Number of days following prospectus	180 days
Number of days prior to sale of company	10 days
Exercise price of warrants (in usd per share)	$ 0.0004	$ 0.0004
Exercise of common stock warrants (in shares)		792,434
Conversion of securities to common stock (in shares)		792,434			346,000
Proceeds from issuance of Series G preferred stock			$ 11,900
Redeemable convertible preferred stock, residual value			4,500
Deemed dividend related to beneficial conversion feature			$ 6,100
Deemed dividend related to beneficial conversion feature				$ 4,500
Series G’ Stock
Temporary Equity [Line Items]
Shares authorized (in shares)					0			5,339,000
Redeemable convertible preferred stock, par value (in usd per share)			$ 0.1000		$ 0			$ 0.0001
Shares issued (in usd per share)			$ 27.58
Conversion of stock, shares converted (in shares)			1,295,746
Conversion of securities to common stock (in shares)					1,296,000
Additional Paid-In Capital | Series G Stock
Temporary Equity [Line Items]
Beneficial conversion feature of Series G stock			$ 4,500

FAIR VALUE MEASUREMENTS - Finan

FAIR VALUE MEASUREMENTS - Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability	$ 0	$ 10,230
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Common stock warrants	0	0
Total liabilities	0	10,230
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Common stock warrants	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Common stock warrants	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Common stock warrants	0	0
Total liabilities	0	10,230
Preferred Stock Warrants | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability	0	2,285
Preferred Stock Warrants | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability	0	0
Preferred Stock Warrants | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability	0	0
Preferred Stock Warrants | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability	0	2,285
Common Stock Warrants | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability	0	7,945
Common Stock Warrants | Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability	0	0
Common Stock Warrants | Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability	0	0
Common Stock Warrants | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term warrant liability	$ 0	$ 7,945

FAIR VALUE MEASUREMENTS - Instr

FAIR VALUE MEASUREMENTS - Instruments Recorded at Fair Value Using Level 3 Inputs (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Preferred Stock Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 2,285	$ 2,197
Exercise/Conversion to common stock	(1,736)
Accrued interest on convertible promissory notes		0
Changes in fair value	(549)	(119)
Fair value, ending balance	0	2,078
Common Stock Warrants
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	7,945	0
Exercise/Conversion to common stock	(15,254)
Accrued interest on convertible promissory notes		0
Issuance of stock		7,452
Changes in fair value	7,309	531
Fair value, ending balance	0	7,983
Convertible Promissory Notes
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	0	72,332
Exercise/Conversion to common stock	0
Accrued interest on convertible promissory notes		1,701
Changes in fair value	0	(4,969)
Fair value, ending balance	$ 0	0
Convertible Promissory Notes | Series G’ Stock
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Exercise/Conversion to common stock		(44,672)
Convertible Promissory Notes | Common Stock
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Exercise/Conversion to common stock		$ (24,392)

FAIR VALUE MEASUREMENTS - Fair

FAIR VALUE MEASUREMENTS - Fair Value Assumptions (Details)	Sep. 30, 2017
Weighted-average cost of capital applicable to preferred stock warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.21
Discount for lack of marketability | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.07
Discount for lack of marketability | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.13
Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.55
Risk-free interest rate | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.012
Risk-free interest rate | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Measurement input	0.014

FAIR VALUE MEASUREMENTS - Prefe

FAIR VALUE MEASUREMENTS - Preferred Stock Warrants (Details) - $ / shares	Sep. 30, 2018	Dec. 31, 2017	May 31, 2013
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)			$ 23.64
Class of warrant (in shares)	0	110,000	644,365
Series B-R Stock | Grant One
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)	$ 2.36
Class of warrant (in shares)	0	59,000
Series D-R Stock | Grant One
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)	$ 23.64
Class of warrant (in shares)	0	38,000
Series D-R Stock | Grant Two
Class of Stock [Line Items]
Exercise price of warrants (in usd per share)	$ 23.64
Class of warrant (in shares)	0	13,000

FAIR VALUE MEASUREMENTS - Narra

FAIR VALUE MEASUREMENTS - Narrative (Details) $ / shares in Units, $ in Thousands	Aug. 08, 2018$ / shares	Aug. 31, 2018USD ($)$ / sharesshares	Feb. 28, 2018USD ($)	May 31, 2017USD ($)$ / sharesshares	May 31, 2013$ / sharesshares	Sep. 30, 2018USD ($)$ / sharesshares	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)$ / sharesshares	Sep. 30, 2017USD ($)	Feb. 08, 2018$ / shares	Dec. 31, 2017USD ($)$ / sharesshares	Dec. 31, 2016USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value per share (in usd per share) | $ / shares										$ 13
Shares issued (in shares) | shares						21,411,000		21,411,000			3,439,000
Exercise price of warrants (in usd per share) | $ / shares					$ 23.64
Change in fair value of warrant liabilities, net						$ 801	$ 1,381	$ (6,760)	$ (412)
Class of warrant (in shares) | shares					644,365	0		0			110,000
Warrant, term					10 years
Common Stock Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability value						$ 0	7,983	$ 0	7,983		$ 7,945	$ 0
Changes in fair value, loss								7,309	531
Change in fair value of warrant liabilities, net						800	1,200
Convertible promissory notes (converted into Series G' Stock in May 2017)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability value						$ 0	$ 0	0	0		$ 0	$ 72,332
Changes in fair value, loss								$ 0	$ (4,969)
Series G Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Shares issued (in shares) | shares				346,334
Class of warrant, numerator input value (in usd per share) | $ / shares				$ 68.9516
Number of trading days				30 days
Number of days following prospectus	180 days
Number of days prior to sale of company	10 days
Exercise price of warrants (in usd per share) | $ / shares	$ 0.0004	$ 0.0004
Liability value				$ 7,500
Exercise of common stock warrants (in shares) | shares		792,434
Conversion of securities to common stock (in shares) | shares		792,434						346,000
Issuance of Series G and Series G’ Stock		$ 15,300		$ 11,900
Series B-R Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value per share (in usd per share) | $ / shares						$ 20.18		$ 20.18			$ 26.80
Conversion of securities to common stock (in shares) | shares								2,247,000
Series D-R Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value per share (in usd per share) | $ / shares						$ 10.57		$ 10.57			$ 13.63
Conversion of securities to common stock (in shares) | shares								1,396,000
Common Stock Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stock option expense			$ 2,500
Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant inputs										0.50
Volatility | Series G Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant inputs				0.59
Discount for lack of marketability | Series G Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Significant inputs					0.11

FAIR VALUE MEASUREMENTS - Perfo

FAIR VALUE MEASUREMENTS - Performance-based Warrants (Details)	Feb. 08, 2018$ / shares	Sep. 30, 2018$ / shares	Sep. 30, 2017$ / shares
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Weighted-average grant date fair value (in usd per share)	$ 3.91	$ 10	$ 12.11
Value of common stock (in usd per share)	$ 13
Expected term	5 years 3 months 18 days
Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant inputs	0.50
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant inputs	0.020
Dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Significant inputs	0

RELATED PARTIES - Narrative (De

RELATED PARTIES - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			9 Months Ended
	Feb. 28, 2018	May 31, 2017	May 31, 2013	Sep. 30, 2018	Sep. 30, 2017	Aug. 31, 2018	Aug. 08, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Proceeds from issuance of Series G preferred stock				$ 0	$ 11,940
Conversion of stock, shares converted (in shares)		801,329
Warrant, term			10 years
Class of warrant (in shares)			644,365	0				110,000
Exercise price of warrants (in usd per share)			$ 23.64
Series G Stock
Related Party Transaction [Line Items]
Proceeds from issuance of Series G preferred stock		$ 11,900
Issuance of Series G and Series G’ Stock (in shares)		346,334
Exercise price of warrants (in usd per share)						$ 0.0004	$ 0.0004
Series G’ Stock
Related Party Transaction [Line Items]
Conversion of stock, shares converted (in shares)		1,295,746
Series E
Related Party Transaction [Line Items]
Issuance of Series G and Series G’ Stock (in shares)			397,515
Common Stock Warrants
Related Party Transaction [Line Items]
Stock option expense	$ 2,500
Stockholders' Equity | Shareholder Concentration Risk
Related Party Transaction [Line Items]
Concentration risk				5.00%

RELATED PARTIES - Series G _ Se

RELATED PARTIES - Series G / Series G’ (Details) - $ / shares	1 Months Ended
	May 31, 2017	Sep. 30, 2018	Dec. 31, 2017	May 31, 2013
Related Party Transaction [Line Items]
Shares outstanding (in shares)		21,411,000	3,439,000
Class of warrant (in shares)		0	110,000	644,365
Series G Stock
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0	346,000
Class of warrant, numerator input value (in usd per share)	$ 68.9516
Number of trading days	30 days
Series G’ Stock
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0	1,296,000
Aimia Inc. | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		801,000
Class of warrant (in shares)		0
Aimia Inc. | Series G Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Aimia Inc. | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		382,000
Polaris Venture Partners | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Class of warrant (in shares)		66,000
Polaris Venture Partners | Series G Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		29,000
Polaris Venture Partners | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		212,000
Canaan VIII L.P. | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Class of warrant (in shares)		123,000
Canaan VIII L.P. | Series G Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		54,000
Canaan VIII L.P. | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		260,000
Discovery Capital | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Class of warrant (in shares)		0
Discovery Capital | Series G Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Discovery Capital | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		106,000
Scott D. Grimes | Scott D. Grimes
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Class of warrant (in shares)		0
Scott D. Grimes | Series G Stock | Scott D. Grimes
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Scott D. Grimes | Series G’ Stock | Scott D. Grimes
Related Party Transaction [Line Items]
Shares outstanding (in shares)		26,000
Lynne M. Laube | Lynne M. Laube
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Class of warrant (in shares)		0
Lynne M. Laube | Series G Stock | Lynne M. Laube
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Lynne M. Laube | Series G’ Stock | Lynne M. Laube
Related Party Transaction [Line Items]
Shares outstanding (in shares)		14,000
Entities affiliated with Mark A. Johnson | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Class of warrant (in shares)		80,000
Entities affiliated with Mark A. Johnson | Series G Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		35,000
Entities affiliated with Mark A. Johnson | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		15,000
Mark A. Johnson | Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)		13,273
Mark A. Johnson | Series G Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		5,801
John Klinck | Director
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Class of warrant (in shares)		13,000
John Klinck | Series G Stock | Director
Related Party Transaction [Line Items]
Shares outstanding (in shares)		6,000
John Klinck | Series G’ Stock | Director
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
David Adams | Director
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Class of warrant (in shares)		7,000
David Adams | Series G Stock | Director
Related Party Transaction [Line Items]
Shares outstanding (in shares)		3,000
David Adams | Series G’ Stock | Director
Related Party Transaction [Line Items]
Shares outstanding (in shares)		0
Aeroplan Holdings Europe Sàrl | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		159,207
Aimia EMEA Limited | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		801,329
Aimia EMEA Limited | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		223,020
Polaris Venture Partners V, L.P. | Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)		64,038
Polaris Venture Partners V, L.P. | Series G Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		27,988
Polaris Venture Partners V, L.P. | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		205,020
Polaris Venture Partners Entrepreneurs’ Fund V, L.L. | Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)		1,247
Polaris Venture Partners Entrepreneurs’ Fund V, L.L. | Series G Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		545
Polaris Venture Partners Entrepreneurs’ Fund V, L.L. | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		3,995
Polaris Venture Partners Founders’ Fund V, L.P. | Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)		438
Polaris Venture Partners Founders’ Fund V, L.P. | Series G Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		191
Polaris Venture Partners Founders’ Fund V, L.P. | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		1,404
Polaris Venture Partners Special Founders’ Fund V, L.P. | Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)		641
Polaris Venture Partners Special Founders’ Fund V, L.P. | Series G Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		280
Polaris Venture Partners Special Founders’ Fund V, L.P. | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		2,050
Discovery Opportunity Master Fund, Ltd. | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		95,272
Discovery Global Opportunity Master Fund, Ltd. | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		11,072
TTP Fund II, L.P. | Series G’ Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		15,045
TTV Ivy Holdings, LLC | Affiliated Entity
Related Party Transaction [Line Items]
Class of warrant (in shares)		66,365
TTV Ivy Holdings, LLC | Series G Stock | Affiliated Entity
Related Party Transaction [Line Items]
Shares outstanding (in shares)		29,005

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2018
Loss Contingencies [Line Items]
Amounts not yet paid to FI	$ 3.5			$ 3.5
FI share, expense			$ 3
Non-cash gain on financial institution share	0.8	$ 3		0.8
Financial Institution Share Commitment
Loss Contingencies [Line Items]
FI share commitment	$ 10			$ 10

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Deferred FI Implementation Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Deferred Financial Institution Costs [Roll Forward]
Beginning balance	$ 12,425	$ 8,754	$ 13,625	$ 8,451
Deferred costs	3,500	3,650	5,750	6,650
Recoveries through FI Share	(1,344)	(1,185)	(4,036)	(3,137)
Amortization	(378)	(365)	(1,136)	(1,110)
Ending balance	$ 14,203	$ 10,854	$ 14,203	$ 10,854

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - shares shares in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Redeemable convertible preferred stock | Series A-R Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	1,857
Redeemable convertible preferred stock | Series B-R Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	2,247
Redeemable convertible preferred stock | Series C-R Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	1,508
Redeemable convertible preferred stock | Series D-R Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	1,396
Redeemable convertible preferred stock | Series E-R Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	795
Redeemable convertible preferred stock | Series F-R Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	1,199
Redeemable convertible preferred stock | Series G Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	346
Redeemable convertible preferred stock | Series G’ Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	1,296
Common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,862	2,533
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	868	1,245
Common stock warrants | Series G’ Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	639
Redeemable convertible preferred stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	110
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,200	0
Common stock issuable pursuant to the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	151	0

SEGMENTS - Narrative (Details)

SEGMENTS - Narrative (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)segment	Sep. 30, 2017USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	3
Capital expenditures	$ 3,190	$ 971
United Kingdom
Segment Reporting Information [Line Items]
Capital expenditures	$ 100	$ 300

SEGMENTS - Revenue by Segment (

SEGMENTS - Revenue by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Adjusted contribution	$ 16,978	$ 17,242	$ 47,371	$ 41,323
Plus: FI Share and other third-party costs	17,604	14,164	55,494	49,776
Revenues	34,582	31,406	102,865	91,099
Non-cash gain on financial institution share	800	3,000	800
Cardlytics Direct
Segment Reporting Information [Line Items]
Adjusted contribution	16,906	16,805	47,368	37,673
Plus: FI Share and other third-party costs	17,514	13,409	54,271	45,942
Revenues	34,420	30,214	101,639	83,615
Other Platform Solutions
Segment Reporting Information [Line Items]
Adjusted contribution	72	437	3	3,650
Plus: FI Share and other third-party costs	90	755	1,223	3,834
Revenues	$ 162	$ 1,192	$ 1,226	$ 7,484

SEGMENTS - Adjusted Contributio

SEGMENTS - Adjusted Contribution Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting [Abstract]
Adjusted contribution	$ 16,978	$ 17,242	$ 47,371	$ 41,323
Non-cash equity expense included in FI Share	0	0	2,519	0
Amortization of deferred FI implementation costs	378	365	1,136	1,110
Delivery costs	3,007	1,646	7,509	5,095
Sales and marketing expense	9,452	8,302	27,915	23,454
Research and development expense	4,097	3,421	12,444	9,527
General and administration expense	7,925	5,276	23,486	14,738
Depreciation and amortization expense	777	771	2,471	2,303
Total other income (expense)	(290)	(65)	11,367	681
Loss before income taxes	$ (8,368)	$ (2,474)	$ (41,476)	$ (15,585)

SEGMENTS - Geographical Informa

SEGMENTS - Geographical Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 34,582	$ 31,406	$ 102,865	$ 91,099
Property and equipment	9,273		9,273		$ 7,319
United States
Segment Reporting Information [Line Items]
Revenues	30,884	26,841	90,606	80,606
Property and equipment	8,955		8,955		6,813
United Kingdom
Segment Reporting Information [Line Items]
Revenues	3,698	$ 4,565	12,259	$ 10,493
Property and equipment	$ 318		$ 318		$ 506