Rocket Fuel 10-Q 10 May 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	Apr. 30, 2016
Document and Entity Information
Entity Registrant Name	Rocket Fuel Inc.
Entity Central Index Key	1,477,200
Document Type	10-Q
Document Period End Date	Mar. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		43,858,580
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current Assets:
Cash and cash equivalents	$ 67,392	$ 78,560
Accounts receivable, net	109,821	124,998
Deferred tax assets, net	722	718
Prepaid expenses	4,474	3,803
Other current assets	2,987	2,081
Total current assets	184,674	209,442
Property, equipment and software, net	75,715	82,781
Restricted cash	2,002	2,141
Intangible assets, net	46,792	50,919
Other assets	1,059	1,053
Total assets	310,964	347,054
Current Liabilities:
Accounts payable	59,999	71,292
Accrued and other current liabilities	34,596	40,734
Deferred revenue	1,642	2,116
Current portion of capital leases	8,723	8,602
Revolving credit facility, net	61,957	45,720
Total current liabilities	166,917	168,464
Debt —Less current portion	0	17,617
Capital leases—Less current portion	9,793	11,855
Deferred rent—Less current portion	14,866	14,042
Other liabilities	1,143	1,176
Total liabilities	$ 192,719	$ 213,154
Commitments and contingencies (Note 10)
Stockholders’ Equity:
Common stock, $0.001 par value— 1,000,000,000 authorized as of March 31, 2016 and December 31, 2015; 43,709,562 and 43,567,016 issued and outstanding as of March 31, 2016 and December 31, 2015, respectively	$ 44	$ 44
Additional paid-in capital	458,631	453,338
Accumulated other comprehensive loss	(326)	(151)
Accumulated deficit	(340,104)	(319,331)
Total stockholders’ equity	118,245	133,900
Total liabilities and stockholders’ equity	$ 310,964	$ 347,054

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	43,709,562	43,567,016
Common stock, shares outstanding	43,709,562	43,567,016

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Statement [Abstract]
Revenue	$ 104,745	$ 104,334
Costs and expenses:
Media costs	42,559	45,561
Other cost of revenue	20,085	19,956
Research and development	10,639	11,323
Sales and marketing	36,840	42,878
General and administrative	14,321	17,574
Restructuring	(199)	0
Total costs and expenses	124,245	137,292
Operating loss	(19,500)	(32,958)
Interest expense	1,237	1,340
Other (income) expense, net	(194)	2,208
Loss before income taxes	(20,543)	(36,506)
Income tax provision	230	357
Net loss	$ (20,773)	$ (36,863)
Basic and diluted net loss per share attributable to common stockholders (in dollars per share)	$ (0.48)	$ (0.88)
Basic and diluted weighted-average shares used to compute net loss per share attributable to common stockholders (shares)	43,601	41,981

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net loss		$ (20,773)	$ (36,863)
Other comprehensive income (loss):
Foreign currency translation adjustments	[1]	(173)	(109)
Comprehensive loss		$ (20,946)	$ (36,972)
[1]	Reclassifications out of Other comprehensive income (loss) into Net loss were not significant.

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
OPERATING ACTIVITIES:
Net loss	$ (20,773)	$ (36,863)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	12,264	11,866
Accelerated amortization of leasehold improvements	3,533	0
Stock-based compensation expense	4,810	7,447
Other non-cash adjustments, net	1,350	794
Changes in operating assets and liabilities:
Accounts receivable	14,103	22,549
Prepaid expenses and other assets	(1,796)	5,379
Accounts payable	(10,846)	(14,812)
Accrued and other liabilities	(1,851)	(4,271)
Deferred rent	(3,074)	1,184
Deferred revenue	(474)	2,530
Net cash used in operating activities	(2,754)	(4,197)
Investing Activities:
Purchases of property, equipment and software	(1,787)	(5,519)
Capitalized internal-use software development costs	(2,924)	(3,076)
Proceeds from Sale of Property, Plant, and Equipment	293	0
Changes in restricted cash	39	636
Net cash used in investing activities	(4,379)	(7,959)
Financing Activities:
Proceeds from employee stock plans, net	28	189
Tax withholdings related to net share settlements of restricted stock units	(241)	0
Repayment of capital lease obligations	(2,092)	(1,090)
Proceeds from debt facilities, net of issuance costs	22,350	(242)
Repayment of debt	(24,000)	(1,500)
Net cash used in financing activities	(3,955)	(2,643)
Effect of Exchange Rate Changes on Cash and Cash Equivalents	(80)	(202)
Change in Cash and Cash Equivalents	(11,168)	(15,001)
Cash and Cash Equivalents—Beginning of period	78,560	107,056
Cash and Cash Equivalents—End of period	67,392	92,055
SUPPLEMENTAL DISCLOSURES OF OTHER CASH FLOW INFORMATION:
Cash paid for income taxes, net of refunds	351	205
Cash paid for interest	1,021	914
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Purchases of property, equipment and software recorded in accounts payable and accruals	563	623
Property, equipment and software acquired under capital lease obligations	151	325
Vesting of early exercised options	25	53
Stock-based compensation capitalized in internal-use software costs	$ 711	$ 494

NATURE OF BUSINESS AND SUMMARY

NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE 1. NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Rocket Fuel Inc. (the “Company”) was incorporated as a Delaware corporation on March 25, 2008. The Company is a provider of artificial-intelligence digital advertising solutions headquartered in Redwood City. The accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) and the applicable rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in Consolidated Financial Statements prepared in accordance with GAAP have been condensed or omitted in accordance with such rules and regulations. The Condensed Consolidated Balance Sheet data as of December 31, 2015 was derived from audited financial statements, but does not include all disclosures required by GAAP. In the opinion of management, the accompanying unaudited Condensed Consolidated Financial Statements reflect all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of our financial position and our results of operations and cash flows. These Condensed Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and notes thereto included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2015. The significant accounting policies and recent accounting pronouncements were described in Note 1 to the Consolidated Financial Statements included in the 2015 Annual Report on Form 10-K for the fiscal year ended December 31, 2015. There have been no significant changes in or updates to the accounting policies since December 31, 2015. Recently Issued and Adopted Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Codification (“ASC”) 842 (“ASC 842”), “Leases” which replaces the existing guidance in ASC 840, Leases. The amendment is effective for the Company for fiscal years, and interim periods within those years, beginning after December 15, 2018. ASC 842 requires a dual approach for lessee accounting under which a lessee would account for leases as finance leases or operating leases. Both finance leases and operating leases will result in the lessee recognizing a right-of-use ("ROU") asset and a corresponding lease liability. For finance leases the lessee would recognize interest expense and amortization of the ROU asset and for operating leases the lessee would recognize a straight-line total lease expense. The Company is evaluating the impact of the adoption on the consolidated financial statements. In March 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-09 ("ASU 2016-09"), which simplifies several aspects of the accounting for employee share-based payment transactions for both public and nonpublic entities, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. For public business entities, ASU 2016-09 is effective for annual reporting periods beginning after December 15, 2016, including interim periods within those annual reporting periods. The Company is currently evaluating the impact of this ASU and expects no material modifications to its financial statements. With the exception of the new standard discussed above, there have been no other recent accounting pronouncements or changes in accounting pronouncements during the three months ended March 31, 2016 that are of significance or potential significance to the Company, as compared to the recent accounting pronouncements described in Note 1 of the Company’s Annual Report on Form 10-K for the year ended December 31, 2015.

PROPERTY, EQUIPMENT AND SOFTWAR

PROPERTY, EQUIPMENT AND SOFTWARE, NET	3 Months Ended
	Mar. 31, 2016
Property, Plant and Equipment [Abstract]
PROPERTY, EQUIPMENT AND SOFTWARE, NET	NOTE 2. PROPERTY, EQUIPMENT AND SOFTWARE, NET Property, equipment and software, net as of March 31, 2016 and December 31, 2015 , consisted of the following (in thousands): March 31, December 31, 2016 2015 Capitalized internal-use software costs $ 42,518 $ 38,879 Computer hardware and software 57,973 57,827 Furniture and fixtures 13,108 13,619 Leasehold improvements 37,789 39,956 Total 151,388 150,281 Accumulated depreciation and amortization (75,673 ) (67,500 ) Total property, equipment and software, net $ 75,715 $ 82,781 Refer to Note 4 for details of the Company's capital leases. The Company capitalized internal-use software development costs of $3.6 million and $3.3 million for the three months ended March 31, 2016 and 2015 , respectively. Amortization expense of internal-use software costs was $2.3 million and $1.6 million for the three months ended March 31, 2016 and 2015 , respectively. Total depreciation and amortization expense related to property, equipment and software, exclusive of the amortization of capitalized internal-use software costs, was $5.8 million and $6.0 million for the three months ended March 31, 2016 and 2015 , respectively. In addition, in the three months ended March 31, 2016 , the Company recorded an accelerated amortization of leasehold assets of $3.5 million related to its terminated office lease in New York in connection with its restructuring activities. Refer to Note 5 for details of the Company's restructuring costs.

BUSINESS COMBINATIONS

BUSINESS COMBINATIONS	3 Months Ended
	Mar. 31, 2016
Business Combinations [Abstract]
BUSINESS COMBINATION	NOTE 3. BUSINESS COMBINATIONS Acquisitions in Fiscal Year 2014 On September 5, 2014, the Company acquired X Plus Two Solutions, Inc., a Delaware corporation (“X Plus Two”), which wholly owns X Plus One Solutions, Inc. known in the industry as [x+1] ("[x+1]"). The acquisition of [x+1] significantly expanded the market opportunity and accelerated the Company’s entry into the digital marketing enterprise software-as-a-service ("SaaS") market. The total purchase consideration is as follows (in thousands): Purchase consideration: Cash $ 98,045 Fair value of 5.3 million shares common stock transferred 82,421 Total purchase price $ 180,466 The acquisition of [x+1] was accounted for in accordance with the acquisition method of accounting for business combinations with the Company as the accounting acquiror. The Company expensed the acquisition-related transaction costs in the amount of $4.9 million in general and administrative expenses. The total purchase price as shown in the table above was allocated to the tangible and identifiable intangible assets acquired and liabilities assumed based on their estimated fair values as of September 5, 2014, as set forth below. The Company finalized its estimates of fair value for certain of the acquired current assets and liabilities resulting in an adjustment of $2.1 million which was recorded during the three months ended September 30, 2015. The total purchase price was allocated as follows (in thousands): Current assets $ 29,853 Non-current assets 3,999 Current liabilities (29,354 ) Non-current liabilities (16,253 ) Net acquired tangible assets (11,755 ) Identifiable intangible assets 74,700 Goodwill 117,521 Total purchase price $ 180,466 Due to a stock price decline during the third quarter of 2015, the Company’s market capitalization declined to a value below the net book value of the Company’s equity, triggering the Company to conduct a goodwill impairment test. The outcome of the goodwill impairment test resulted in a non-cash impairment of goodwill of $117.5 million , which was recorded in the third quarter of 2015. Identifiable intangible assets acquired are as follows: March 31, 2016 December 31, 2015 Estimated Useful Life (in years) Gross Accumulated Amortization Net Book Value Gross Accumulated Amortization Net Book Value Developed technology 3-4 $ 42,100 $ (18,192 ) $ 23,908 $ 42,100 $ (15,295 ) $ 26,805 Customer relationships 7-8 27,700 (5,440 ) 22,260 27,700 (4,573 ) 23,127 Trademarks 5 2,000 (2,000 ) — 2,000 (2,000 ) — Non-compete agreements 2 2,900 (2,276 ) 624 2,900 (1,913 ) 987 Total $ 74,700 (27,908 ) 46,792 $ 74,700 $ (23,781 ) $ 50,919 Total amortization expense related to intangible assets acquired in the business combination with [x+1] was $4.1 million and $4.2 million for the three months ended March 31, 2016 and 2015, respectively. During the third quarter of 2015, the Company accelerated the amortization of the trademark assets recording $1.6 million in additional amortization expense due to a change of its useful life.

CAPITAL LEASES

CAPITAL LEASES	3 Months Ended
	Mar. 31, 2016
Leases [Abstract]
CAPITAL LEASES	NOTE 4. CAPITAL LEASES Property, equipment and software includes hardware and software related to our data centers, which are acquired under capital lease agreements. The remaining future minimum lease payments under these non-cancelable capital leases as of March 31, 2016 were as follows (in thousands): Year ending December 31, Future Payments 2016 (remaining 9 months) $ 7,217 2017 7,862 2018 4,366 2019 414 2020 13 Total minimum lease payments $ 19,872 Less: amount representing interest and taxes (1,356 ) Less: current portion of minimum lease payments (8,723 ) Capital lease obligations, net of current portion $ 9,793

RESTRUCTURING COSTS

RESTRUCTURING COSTS	3 Months Ended
	Mar. 31, 2016
Restructuring and Related Activities [Abstract]
Restructuring Costs	NOTE 5. RESTRUCTURING COSTS In April 2015, the Company announced a restructuring plan intended to improve its operational efficiency, which included a reduction of its workforce, and sublease or termination of certain excess leased office space, among other cost reduction measures. During the three months ended March 31, 2016 , the Company recorded a $0.2 million restructuring net gain. This is comprised of $3.5 million accelerated amortization of leasehold assets related to its terminated office lease in New York, $0.4 million severance payouts, and an offsetting release of $4.1 million deferred rent liabilities related to our terminated office lease in New York.

DEBT

DEBT	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
DEBT	NOTE 6. DEBT Loan Facility —On December 31, 2014, the Company entered into a Second Amended and Restated Revolving Credit and Term Loan Agreement with certain lenders (the "2014 Loan Facility"). The 2014 Loan Facility amended and restated the Company's then-existing Amended and Restated Revolving Credit and Term Loan Agreement, dated as of December 20, 2013. Through March 10, 2016, the 2014 Loan Facility provided for an $80.0 million revolving credit facility which matures on December 31, 2017, with a $12.0 million letter of credit sub-facility, a $2.5 million swing-line sub-facility, and a $30.0 million secured term loan that matures on December 31, 2019. Revolving loans could be advanced under the revolving credit facility in amounts up to the lesser of (i) 85% of eligible accounts receivable and (ii) $80.0 million , less the then outstanding principal amount of the term loan. If at any time the aggregate amounts outstanding exceeded the allowable maximum advance, then the Company was required to make a repayment in an amount sufficient to eliminate the excess. On March 10, 2016, the Company amended the 2014 Loan Facility and terminated the term loan (as so amended, the "2016 Loan Facility"). The then-remaining balance of the term loan was repaid and refinanced by an additional draw down on the revolving credit facility of $22.5 million. In the amendment the minimum bank-defined EBITDA covenant and the liquidity ratio covenant were changed. The Company paid customary closing fees in connection with establishing and amending this facility, and pays customary commitment fees and letter of credit fees. Under the 2016 Loan Facility, as amended, the lenders have the right to use future cash collections from accounts receivable directly to reduce the outstanding balance of the revolving credit facility if the aggregated cash balances on deposit with the lenders and certain other domestic financial institutions fall below $40.0 million . The Company may repay revolving loans and term loans under the 2016 Loan Facility in whole or in part at any time without premium or penalty, subject to certain conditions. As of March 31, 2016 , $62.5 million under the revolving credit facility and letters of credit in the amount of $7.5 million were outstanding. Revolving loans bear interest, at the Company's option, at (i) a base rate determined pursuant to the terms of the 2016 Loan Facility, plus a spread of 1.625% to 2.125% , or (ii) a LIBOR rate determined pursuant to the terms of the 2016 Loan Facility, plus a spread of 2.625% to 3.125% . Term loans bear interest, at the Company's option, at (i) a base rate determined pursuant to the terms of the 2016 Loan Facility, plus a spread of 2.50% to 3.00% , or (ii) a LIBOR rate determined pursuant to the terms of the 2016 Loan Facility, plus a spread of 3.50% to 4.00% . In each case, the spread is based on the cash reflected on the Company’s balance sheet for the preceding fiscal quarter, plus an amount equal to the average unused portion of the revolving credit commitments during such fiscal quarter. The base rate is determined as the highest of (i) the prime rate announced by Comerica Bank, (ii) the federal funds rate plus a margin equal to 1.00% and (iii) the daily adjusted LIBOR rate plus a margin equal to 1.00% . Under certain circumstances, a default interest rate of 2.00% above the applicable interest rate will apply on all obligations during the existence of an event of default under the 2016 Loan Facility. The Company is required to maintain a minimum of $30.0 million of cash on deposit with the lenders and comply with certain financial covenants under the 2016 Loan Facility, including the following: Bank-defined EBITDA. The Company is required to maintain specified bank-defined EBITDA, which is defined for this purpose, with respect to any trailing twelve-month period, as an amount equal to the sum of (i) consolidated net income (loss) in accordance with GAAP, after eliminating all extraordinary non-recurring items of income, plus (ii) depreciation and amortization, income tax expense, total interest expense, non-cash expenses or losses, stock-based compensation expense, costs and expenses from permitted acquisitions up to certain limits;,costs and expenses in connection with the 2016 Loan Facility up to certain limits; certain legal fees up to certain limits incurred through December 2015, integration costs related to the [x+1] acquisition up to certain limits incurred through December 31, 2014 and any other expenses agreed with Comerica and the lenders, less (iii) all extraordinary and non-recurring revenues and gains (including income tax benefits). Liquidity ratio. Under the 2016 Loan Facility, the ratio of (i) the sum of all cash and accounts receivable to (ii) the sum of all accounts payable and all indebtedness owing to the lenders under the 2016 Loan Facility must be at least 1.00 to 1.00. The terms of the 2016 Loan Facility also require the Company to comply with certain other financial and non-financial covenants. As of March 31, 2016 , the Company was in compliance with all financial and non-financial covenants. As of March 31, 2016 , the $62.5 million balance outstanding under the 2016 Loan Facility had a maturity date of December 31, 2017, and because the Company has the option to draw upon the facility or repay borrowed funds at any time, the balance is shown as a current liability in the accompanying condensed consolidated balance sheets. The debt on the condensed consolidated balance sheets is shown net of $0.5 million in debt issuance costs.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	3 Months Ended
	Mar. 31, 2016
Stockholders' Equity Note [Abstract]
STOCKHOLDERS' EQUITY	NOTE 7. STOCKHOLDERS’ EQUITY The following table summarizes information pertaining to our stock-based compensation expense from stock options and stock awards, which are comprised of restricted stock awards and restricted stock units (in thousands, except grant-date fair value and recognition period): Three Months Ended March 31, Three Months Ended March 31, 2016 2015 Stock options: Outstanding at the beginning of the period 5,387 6,291 Options granted 1,631 208 Options exercised (41 ) (116 ) Options forfeited (1,544 ) (75 ) Outstanding at the end of the period 5,433 6,308 Total intrinsic value of options exercised $ 113 $ 858 Total unrecognized compensation expense at period-end $ 8,399 $ 23,190 Weighted-average remaining recognition period at period-end (in years) 3.0 2.2 Stock awards: Outstanding at the beginning of the period 3,612 2,515 Stock awards granted 490 348 Stock awards vested (179 ) (48 ) Stock awards canceled (268 ) (136 ) Outstanding at the end of the period 3,655 2,680 Weighted-average grant-date fair value $ 10.39 $ 16.74 Total unrecognized compensation expense at period-end $ 25,712 $ 41,131 Weighted-average remaining recognition period at period-end (in years) 2.6 3.4 2016 Inducement Equity Incentive Plan —Effective March 4, 2016, the Company's board of directors adopted the 2016 Inducement Equity Incentive Plan (the “2016 Plan”) pursuant to Nasdaq Listing Rule 5635(c)(4) (the "Listing Rule"). The Listing Rule permits a company to adopt a plan without stockholder approval if each grant is made to a new employee of the Company, or an employee returning to the Company after a bona fide period of non-employment, and in each case was offered the grant as a material inducement for the employee to join the Company. The 2016 Plan permits the grant of non-statutory stock options, restricted stock, restricted stock units, stock appreciation rights, performance units and performance shares to eligible participants. A total of 2,200,000 shares of common stock were reserved for issuance upon initial adoption of the 2016 Plan. The 2016 Plan has a term of one year from its effective date. The compensation committee of the board of directors has the authority to approve the employees to whom equity awards are granted and to determine the terms of each award, subject to the terms of the 2016 Plan. The compensation committee may determine the number of shares subject to an award. Options and stock appreciation rights granted under the 2016 Plan must have a per share exercise price equal to at least 100% of the fair market value of a shares of the Company's common stock as of the date of grant and may not expire later than 10 years from the date of grant. As of the three months ended March 31, 2016 , 0.4 million shares have been granted under the 2016 Plan. Employee Stock Purchase Plan —In August 2013, the Company’s board of directors adopted and the stockholders approved the Company’s 2013 Employee Stock Purchase Plan (the “ESPP”), which became effective upon adoption by the Company’s board of directors. The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations. The offering periods generally start on the first trading day on or after June 1 and December 1 of each year and end on the first trading day on or before November 30 and May 31 approximately six months later. The administrator may, in its discretion, modify the terms of future offering periods. At the end of each offering period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last trading day of the offering period. As of March 31, 2016 , total compensation costs, representing the fair value related to outstanding rights to purchase shares of common stock under the ESPP offering period ending on the first trading day on or before May 31, 2016, were approximately $0.7 million , which will be recognized over the offering period. Effective January 15, 2016, the compensation committee of the Company's board of directors adopted an amendment and restatement of the ESPP that will apply to offering periods beginning on and after June 1, 2016. Pursuant to the amendment, future offering periods will start on the first trading day on or after June 1 and December 1 of each year and terminate on the first trading day or before the May 31 and November 30 that occurs approximately 24 months later. Each twenty-four month offering period will generally have four purchase periods of approximately six months in length, with the first purchase period of an offering period commencing on the date the offering period commences. At the end of each purchase period, employees are able to purchase shares, subject to any plan limitations, at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last trading day of the purchase period. Offering periods may overlap. However, if the fair market value of the Company's stock has declined between the first date of an offering period and the end of a purchase period, the offering period will terminate on the purchase date that is at the end of that purchase period immediately after the purchase and participants in that offering period will automatically be re-enrolled in the immediately following offering period. Stock-based Compensation —The fair value of options on the date of grant is estimated based on the Black-Scholes option-pricing model using the single-option award approach with the weighted-average assumptions set forth below. Expected term represents the period that the Company’s stock-based awards are expected to be outstanding and is determined based on the simplified method. Due to the lack of historical exercise activity for the Company, the simplified method calculates the expected term as the mid-point between the vesting date and the contractual expiration date of the award. Volatility is estimated using comparable public company volatility for similar option terms until a sufficient amount of historical information regarding the volatility of the Company's share price becomes available. The risk-free interest rate is determined using a U.S. Treasury rate for the period that coincides with the expected term. As the Company has never paid cash dividends, and at present, has no intention to pay cash dividends in the future, expected dividends are zero . Expected forfeitures are based on the Company’s historical experience. The fair value of restricted stock unit awards is the grant date closing price of the Company's common stock. The Company uses the straight-line method for expense recognition over the vesting period of the award or option. The assumptions used to value options granted to employees were as follows: Three Months Ended March 31, 2016 2015 Expected term (years) 6.3 6.3 Volatility 55.0% 58.0% Risk-free interest rate 1.57% - 1.93% 1.57% Dividend yield — — The assumptions used to calculate our stock-based compensation for each stock purchase right granted under the ESPP were as follows: Three Months Ended March 31, 2016 2015 Expected term (years) 0.5 0.5 Volatility 65.0% 77.2% Risk-free interest rate 0.42% 0.08% Dividend yield — — Stock-based compensation allocation The following table summarizes the allocation of stock-based compensation, net of amounts capitalized for internal-use software development, in the accompanying condensed consolidated statements of operations (in thousands): Three Months Ended March 31, 2016 2015 Other cost of revenue $ 530 $ 625 Research and development 1,365 2,247 Sales and marketing 1,489 2,831 General and administrative 1,426 1,744 Total $ 4,810 $ 7,447

NET LOSS PER SHARE

NET LOSS PER SHARE	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
NET LOSS PER SHARE	NOTE 8. NET LOSS PER SHARE Basic net loss per share is calculated by dividing net loss by the weighted-average number of shares of common stock outstanding during the period, less shares subject to repurchase, and excludes any dilutive effects of employee stock-based awards. Because the Company had net losses for the three months ended March 31, 2016 and 2015 , all these potentially dilutive shares of common stock were determined to be anti-dilutive and accordingly were not included in the calculation of diluted net loss per share. The following table sets forth the computation of net loss per share of common stock (in thousands, except per share amounts): Three Months Ended March 31, 2016 2015 Net loss $ (20,773 ) $ (36,863 ) Weighted-average shares used to compute basic and diluted net loss per share 43,601 41,981 Basic and diluted net loss per share $ (0.48 ) $ (0.88 ) Common stock equivalents excluded from net loss per diluted share because their effect would have been anti-dilutive 9,521 9,387

INCOME TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2016
Income Tax Disclosure [Abstract]
INCOME TAXES	NOTE 9. INCOME TAXES The Company is subject to income tax in the United States as well as other tax jurisdictions in which it conducts business. Earnings from non-U.S. activities are subject to local country income tax. The Company does not provide for federal income taxes on the undistributed earnings of its foreign subsidiaries as such earnings are intended to be reinvested indefinitely. The Company recorded income tax provisions of $0.2 million and $0.4 million for the three months ended March 31, 2016 and 2015 , respectively. The tax provision for the three months ended March 31, 2016 and March 31, 2015 are primarily due to foreign and state income taxes. Due to uncertainty as to the realization of benefits from deferred tax assets, including net operating loss carry-forwards, research and development and other tax credits, the Company has provided valuation allowances against such assets as of March 31, 2016 and December 31, 2015 .

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	NOTE 10. COMMITMENTS AND CONTINGENCIES Operating Leases —The Company has operating lease agreements for office space for administrative, research and development and sales and marketing activities in the United States that expire at various dates through 2026. The Company recognizes rent expense on a straight-line basis over the lease term and records the difference between cash rent payments and the recognition of rent expense as a deferred rent liability. Rent expense was $4.3 million and $4.0 million for the three months ended March 31, 2016 and 2015 , respectively. The approximate remaining future minimum cash lease payments under these non-cancelable operating leases as of March 31, 2016 were as follows (in thousands): Year ending December 31, Future Payments 2016 (remaining 9 months) $ 12,786 2017 16,324 2018 15,128 2019 16,473 2020 7,247 Thereafter 21,301 $ 89,259 Please refer to Note 4 for details of the Company's capital lease commitments as of March 31, 2016 . Letters of Credit Bank Guarantees and Restricted Cash —As of March 31, 2016 and December 31, 2015 , the Company had irrevocable letters of credit for facilities leases of $7.7 million and $6.3 million , respectively. The letters of credit have various expiration dates, with the latest being June 2025. As of March 31, 2016 and December 31, 2015, the Company had $2.0 million and $2.1 million , respectively, in cash reserved to support bank guarantees for certain office lease agreements. These amounts are classified as restricted cash on the Company's condensed consolidated balance sheets. Indemnification Agreements —In the ordinary course of business, the Company enters into agreements providing for indemnification of varying scope and terms to customers, vendors, lessors, business partners, and other parties with respect to certain matters, including, but not limited to, losses arising out of breach of such agreements, services to be provided by the Company or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with directors and certain officers and employees that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors, officers or employees. No demands have been made upon the Company to provide indemnification under such agreements, and thus there are no claims that the Company is aware of that could have a material effect on the Company’s condensed consolidated balance sheets, condensed consolidated statements of operations, condensed consolidated statements of comprehensive loss, or condensed consolidated statements of cash flows. Legal Proceedings —The Company is involved from time to time in claims, proceedings, and litigation, including the following: On September 3, 2014 and September 10, 2014, respectively, two purported class actions were filed in the Northern District of California against the Company and certain of its officers and directors at the time. The actions are Shah v. Rocket Fuel Inc., et al. , Case No. 4:14-cv-03998, and Mehrotra v. Rocket Fuel Inc., et al. , Case No. 4:14-cv-04114. The underwriters in the initial public offering on September 19, 2013 (the "IPO") and the secondary offering on February 5, 2014 (the "Secondary Offering") were also named as defendants. These actions were consolidated and a consolidated complaint, In re Rocket Fuel Securities Litigation , was filed on February 27, 2015. The consolidated complaint alleged that the defendants made false and misleading statements about the ability of the Company's technology to detect and eliminate fraudulent web traffic, and about Rocket Fuel’s future prospects. The consolidated complaint also alleged that the Company’s registration statements and prospectuses for the IPO and the Secondary Offering contained false and misleading statements on these topics. The consolidated complaint purported to assert claims for violations of Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and SEC Rule 10b-5 (the "Exchange Act" claims), and for violations of Sections 11 and 15 of the Securities Act of 1933, as amended (the "Securities Act" claims), on behalf of those who purchased the Company’s common stock between September 20, 2013 and August 5, 2014, inclusive, as well as those who purchased stock in the IPO, and a claim for violation of Section 12(a)(2) of the Securities Act in connection with the Secondary Offering. The consolidated complaint sought monetary damages in an unspecified amount. All defendants moved to dismiss the consolidated complaint and on December 23, 2015, the court granted in part and denied in part the defendants’ motions to dismiss. The court dismissed the Securities Act claims and all but one of the statements on which the Exchange Act claims were based. The court also dismissed all claims against the outside directors and the underwriters of the Company’s public offerings. On March 23, 2015, a purported shareholder derivative complaint for breach of fiduciary duty, waste of corporate assets, and unjust enrichment was filed in San Mateo, California Superior Court against certain of the then-current and former officers and the Company’s board of directors at that time. The action is Davydov v. George H. John , et.al, Case No. CIV 53304. This state court action has been stayed pending the resolution of the Victor Veloso v. George H. John et al. action described below. On October 6, 2015, a purported verified shareholder derivative complaint was filed in the Northern District of California. The action is Victor Veloso v. George H. John et al. , Case No. 4:15-cv-04625-PJH. Beginning in January 2016, three substantially similar related cases, Gervat v. Wootton et al. , 4:16-cv-00332-PJH, Pack v. John et al. , 4:16-cv-00608-EDL, and McCawley v. Wootton et al ., Case No. 4:16-cv-00812, also were filed in the Northern District of California on January 21, 2016, February 4, 2016 and February 18, 2016, respectively. The complaints in these related actions are based on substantially the same facts as the In re Rocket Fuel Securities Litigation, and name as defendants the Company’s board of directors at the time of filing and certain then-current and former executives. The Veloso action has been related to the In re Rocket Fuel Securities Litigation and motions to relate the other actions are pending. The four purported verified shareholder derivative complaints were consolidated by the Court in March 2016, and a compliant in the consolidated action, titled In re Rocket Fuel, Inc. Derivative Litigation, Case No. 4:15-cv-4625-PJH, was filed on April 14, 2016. On January 27, 2016, a purported shareholder derivative complaint was filed in the Delaware Court of Chancery. The action was Gee v. Wootton et al. , Case No. 11940-VCL. The plaintiff voluntarily dismissed this action on February 9, 2016. On March 29, 2016, a purported shareholder derivative complaint for breach of fiduciary duty and violation of California corporations code section 25402 was filed in San Francisco, California Superior Court against certain of the Company's current and former officers and certain of the Company's current and former directors. The action is Lunam v. William Ericson, et. al., Case No. CGC-16-551209. The Company intends to vigorously defend itself against these actions. The outcomes of the legal proceedings are inherently unpredictable, subject to significant uncertainties, and could be material to the Company's operating results and cash flows for a particular period. Legal fees are expensed in the period in which they are incurred.

SEGMENTS

SEGMENTS	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
SEGMENTS	NOTE 11. SEGMENTS The Company considers operating segments to be components of the Company's business for which separate financial information is available that is evaluated regularly by the Company’s chief operating decision maker in deciding how to allocate resources and in assessing performance. The chief operating decision maker for the Company is the Chief Executive Officer. The Chief Executive Officer reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. The Company has one business activity, and there are no segment managers who are held accountable for operations, operating results or plans for levels or components below the consolidated unit level. Accordingly, the Company has determined that it has a single operating and reportable segment. The following table summarizes total revenue generated through sales personnel located in the respective locations (in thousands): Three Months Ended March 31, 2016 2015 United States $ 81,397 $ 86,151 All Other Countries (1) 23,348 18,183 Total revenue $ 104,745 $ 104,334 (1) No individual country, other than disclosed above, exceeded 10% of our total revenue for any period presented. The following table summarizes total carrying values of long-lived assets in the respective locations (in thousands): March 31, December 31, 2016 2015 North America $ 70,601 $ 77,038 All Other Countries 5,114 5,743 Total long-lived assets $ 75,715 $ 82,781

GOODWILL

GOODWILL	3 Months Ended
	Mar. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL	NOTE 12. GOODWILL Due to a stock price decline during fiscal year 2015, the Company’s market capitalization declined to a value below the net book value of the Company’s equity, triggering the Company to test its goodwill for impairment. The Company first tested its intangible assets (other than goodwill) and determined that these assets were not impaired. Goodwill is tested for impairment in a two-step process. The first step is to determine if there is an indication of impairment by comparing the estimated fair value of the reporting unit to its carrying value including goodwill. Goodwill is considered impaired if the reporting unit’s carrying value exceeds its estimated fair value. Upon indication of impairment, a second step is performed to determine the amount of the impairment by comparing the implied fair value of the reporting unit’s goodwill with the carrying value of the goodwill. Since the Company operates its business in one reporting unit, goodwill is tested for impairment at the enterprise level. In the first step of the goodwill impairment test, the Company estimated the fair value of its reporting unit using the market approach. Under the market approach, the Company utilized the market capitalization of its publicly-traded shares and comparable company information to determine revenue multiples which were used to determine the fair value of the reporting unit. Based on this approach, the Company determined that there is an indication of impairment as the carrying value including goodwill exceeded the estimated fair value of the reporting unit. In the second step of the goodwill impairment test the Company estimated the fair value of its assets and liabilities to determine the implied fair value of goodwill, and then compared the implied fair value of the goodwill to its carrying value. The outcome of this second step resulted in a non-cash impairment of goodwill of $117.5 million , which was recorded during the third quarter of fiscal year 2015. The inputs used to measure the estimated fair value of goodwill are classified as a Level 3 fair value measurement due to the significance of unobservable inputs based on company specific information.

RELATED PARTY TRANSACTIONS (Not

RELATED PARTY TRANSACTIONS (Notes)	3 Months Ended
	Mar. 31, 2016
Related Party Transaction [Line Items]
Related Party Transactions Disclosure [Text Block]	NOTE 13. RELATED PARTY TRANSACTIONS John J. Lewis, Global President of Nielsen Holding Plc ("Nielsen"), joined the Board of Directors of Rocket Fuel Inc. on January 19, 2016. Mr. Lewis was also appointed to the Audit Committee of the Board. Nielsen is one of the Company's data vendors. Total expense recognized for services delivered by Nielsen and its affiliates during the three months ended March 31, 2016 was $0.4 million . Total accounts payable as of March 31, 2016 were $1.2 million .

SUBSEQUENT EVENTS (Notes)

SUBSEQUENT EVENTS (Notes)	3 Months Ended
	Mar. 31, 2016
Subsequent Event [Line Items]
Subsequent Events [Text Block]	NOTE 14. SUBSEQUENT EVENTS On May 10, 2016, we filed a shelf registration statement on Form S-3 with the SEC (the “Registration Statement”). The Registration Statement contains a base prospectus that covers (i) the offering, issuance and sale by the Company of up to a maximum aggregate offering price of $50.0 million of the Company’s common stock, preferred stock, warrants, debt securities, subscription rights and/or units and (ii) a sales agreement prospectus supplement along with an accompanying base prospectus covering the offering, issuance and sale by the Company up to a maximum aggregate offering price of $30.0 million of the Company’s common stock that may be issued and sold from time to time under a sales agreement with Cantor Fitzgerald & Co. The up to $30.0 million of common stock that may be issued and sold under the sales agreement prospectus supplement is included in the $50.0 million of securities that may be offered and sold under the base prospectus. The Registration Statement has not yet been declared effective by the SEC.

NATURE OF BUSINESS AND SUMMAR21

NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Recently Issued and Adopted Accounting Pronouncements	Recently Issued and Adopted Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Codification (“ASC”) 842 (“ASC 842”), “Leases” which replaces the existing guidance in ASC 840, Leases. The amendment is effective for the Company for fiscal years, and interim periods within those years, beginning after December 15, 2018. ASC 842 requires a dual approach for lessee accounting under which a lessee would account for leases as finance leases or operating leases. Both finance leases and operating leases will result in the lessee recognizing a right-of-use ("ROU") asset and a corresponding lease liability. For finance leases the lessee would recognize interest expense and amortization of the ROU asset and for operating leases the lessee would recognize a straight-line total lease expense. The Company is evaluating the impact of the adoption on the consolidated financial statements. In March 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2016-09 ("ASU 2016-09"), which simplifies several aspects of the accounting for employee share-based payment transactions for both public and nonpublic entities, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. For public business entities, ASU 2016-09 is effective for annual reporting periods beginning after December 15, 2016, including interim periods within those annual reporting periods. The Company is currently evaluating the impact of this ASU and expects no material modifications to its financial statements. With the exception of the new standard discussed above, there have been no other recent accounting pronouncements or changes in accounting pronouncements during the three months ended March 31, 2016 that are of significance or potential significance to the Company, as compared to the recent accounting pronouncements described in Note 1 of the Company’s Annual Report on Form 10-K for the year ended December 31, 2015.

PROPERTY, EQUIPMENT AND SOFTW22

PROPERTY, EQUIPMENT AND SOFTWARE, NET (Tables)	3 Months Ended
	Mar. 31, 2016
Property, Plant and Equipment [Abstract]
Schedule of property, equipment and software	Property, equipment and software, net as of March 31, 2016 and December 31, 2015 , consisted of the following (in thousands): March 31, December 31, 2016 2015 Capitalized internal-use software costs $ 42,518 $ 38,879 Computer hardware and software 57,973 57,827 Furniture and fixtures 13,108 13,619 Leasehold improvements 37,789 39,956 Total 151,388 150,281 Accumulated depreciation and amortization (75,673 ) (67,500 ) Total property, equipment and software, net $ 75,715 $ 82,781

BUSINESS COMBINATIONS BUSINESS

BUSINESS COMBINATIONS BUSINESS COMBINATIONS (Tables)	3 Months Ended
	Mar. 31, 2016
Business Combinations [Abstract]
Schedule of Consideration For Business Acquisitions	The total purchase consideration is as follows (in thousands): Purchase consideration: Cash $ 98,045 Fair value of 5.3 million shares common stock transferred 82,421 Total purchase price $ 180,466
Schedule of the Total Purchase Price Allocation	The total purchase price was allocated as follows (in thousands): Current assets $ 29,853 Non-current assets 3,999 Current liabilities (29,354 ) Non-current liabilities (16,253 ) Net acquired tangible assets (11,755 ) Identifiable intangible assets 74,700 Goodwill 117,521 Total purchase price $ 180,466
Schedule of Finite-Lived Intangible Assets Acquired	March 31, 2016 December 31, 2015 Estimated Useful Life (in years) Gross Accumulated Amortization Net Book Value Gross Accumulated Amortization Net Book Value Developed technology 3-4 $ 42,100 $ (18,192 ) $ 23,908 $ 42,100 $ (15,295 ) $ 26,805 Customer relationships 7-8 27,700 (5,440 ) 22,260 27,700 (4,573 ) 23,127 Trademarks 5 2,000 (2,000 ) — 2,000 (2,000 ) — Non-compete agreements 2 2,900 (2,276 ) 624 2,900 (1,913 ) 987 Total $ 74,700 (27,908 ) 46,792 $ 74,700 $ (23,781 ) $ 50,919

CAPITAL LEASES (Tables)

CAPITAL LEASES (Tables)	3 Months Ended
	Mar. 31, 2016
Leases [Abstract]
Schedule of approximate remaining future minimum lease payments under non-cancelable capital leases	The remaining future minimum lease payments under these non-cancelable capital leases as of March 31, 2016 were as follows (in thousands): Year ending December 31, Future Payments 2016 (remaining 9 months) $ 7,217 2017 7,862 2018 4,366 2019 414 2020 13 Total minimum lease payments $ 19,872 Less: amount representing interest and taxes (1,356 ) Less: current portion of minimum lease payments (8,723 ) Capital lease obligations, net of current portion $ 9,793

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	3 Months Ended
	Mar. 31, 2016
Stockholders' Equity Note [Abstract]
Summary of option award activity	The following table summarizes information pertaining to our stock-based compensation expense from stock options and stock awards, which are comprised of restricted stock awards and restricted stock units (in thousands, except grant-date fair value and recognition period): Three Months Ended March 31, Three Months Ended March 31, 2016 2015 Stock options: Outstanding at the beginning of the period 5,387 6,291 Options granted 1,631 208 Options exercised (41 ) (116 ) Options forfeited (1,544 ) (75 ) Outstanding at the end of the period 5,433 6,308 Total intrinsic value of options exercised $ 113 $ 858 Total unrecognized compensation expense at period-end $ 8,399 $ 23,190 Weighted-average remaining recognition period at period-end (in years) 3.0 2.2 Stock awards: Outstanding at the beginning of the period 3,612 2,515 Stock awards granted 490 348 Stock awards vested (179 ) (48 ) Stock awards canceled (268 ) (136 ) Outstanding at the end of the period 3,655 2,680 Weighted-average grant-date fair value $ 10.39 $ 16.74 Total unrecognized compensation expense at period-end $ 25,712 $ 41,131 Weighted-average remaining recognition period at period-end (in years) 2.6 3.4
Schedule of assumptions used to value stock-based awards granted to employees	The assumptions used to value options granted to employees were as follows: Three Months Ended March 31, 2016 2015 Expected term (years) 6.3 6.3 Volatility 55.0% 58.0% Risk-free interest rate 1.57% - 1.93% 1.57% Dividend yield — —
Schedule of assumptions used to calculate stock-based compensation for each stock purchase right granted under the ESPP	The assumptions used to calculate our stock-based compensation for each stock purchase right granted under the ESPP were as follows: Three Months Ended March 31, 2016 2015 Expected term (years) 0.5 0.5 Volatility 65.0% 77.2% Risk-free interest rate 0.42% 0.08% Dividend yield — — Stock-based compensation allocation The following table summarizes the allocation of stock-based compensation, net of amounts capitalized for internal-use software development, in the accompanying condensed consolidated statements of operations (in thousands): Three Months Ended March 31, 2016 2015 Other cost of revenue $ 530 $ 625 Research and development 1,365 2,247 Sales and marketing 1,489 2,831 General and administrative 1,426 1,744 Total $ 4,810 $ 7,447 The assumptions used to calculate our stock-based compensation for each stock purchase right granted under the ESPP were as follows: Three Months Ended March 31, 2016 2015 Expected term (years) 0.5 0.5 Volatility 65.0% 77.2% Risk-free interest rate 0.42% 0.08% Dividend yield — —

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	3 Months Ended
	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Schedule of future minimum lease payments under non-cancelable operating leases	The approximate remaining future minimum cash lease payments under these non-cancelable operating leases as of March 31, 2016 were as follows (in thousands): Year ending December 31, Future Payments 2016 (remaining 9 months) $ 12,786 2017 16,324 2018 15,128 2019 16,473 2020 7,247 Thereafter 21,301 $ 89,259

SEGMENTS (Tables)

SEGMENTS (Tables)	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
Schedule of total revenue generated through sales personnel located in the respective locations	The following table summarizes total revenue generated through sales personnel located in the respective locations (in thousands): Three Months Ended March 31, 2016 2015 United States $ 81,397 $ 86,151 All Other Countries (1) 23,348 18,183 Total revenue $ 104,745 $ 104,334
Schedule of total long-lived assets in the respective locations	The following table summarizes total carrying values of long-lived assets in the respective locations (in thousands): March 31, December 31, 2016 2015 North America $ 70,601 $ 77,038 All Other Countries 5,114 5,743 Total long-lived assets $ 75,715 $ 82,781

NATURE OF BUSINESS AND SUMMAR28

NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Millions	3 Months Ended				12 Months Ended
	Mar. 31, 2016agency	Mar. 31, 2016customer	Mar. 31, 2016advertiser	Mar. 31, 2015agency	Dec. 31, 2015USD ($)agencyadvertiser	Dec. 31, 2013customer
Money market funds (included in cash and cash equivalents) | Level 1
Concentration of credit risk
Assets, fair value disclosure					$ 22.9
Accounts receivable | Customer concentration
Concentration of credit risk
Number of customers	2		0	2	0
Revenue | Customer concentration
Concentration of credit risk
Number of customers	2	0			2	0

PROPERTY, EQUIPMENT AND SOFTW29

PROPERTY, EQUIPMENT AND SOFTWARE, NET (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Property, equipment and software
Property, equipment, and software, gross	$ 151,388		$ 150,281
Accumulated depreciation and amortization	(75,673)		(67,500)
Total property, equipment and software, net	75,715		82,781
Amortization expense	3,600	$ 3,300
Amortization	2,300	1,600
Depreciation and Amortization Expense Excluding Amortization of Internal Use Software Costs	5,800	6,000
Accelerated amortization of leasehold improvements	3,533	$ 0
Capitalized internal-use software costs
Property, equipment and software
Property, equipment, and software, gross	42,518		38,879
Computer hardware and software
Property, equipment and software
Property, equipment, and software, gross	57,973		57,827
Furniture and fixtures
Property, equipment and software
Property, equipment, and software, gross	13,108		13,619
Leasehold improvements
Property, equipment and software
Property, equipment, and software, gross	$ 37,789		$ 39,956

BUSINESS COMBINATIONS - Narrati

BUSINESS COMBINATIONS - Narrative (Details) - USD ($) $ in Thousands	Sep. 05, 2014	Mar. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill, Impairment Loss			$ 117,500
x Plus 1
Business Acquisition [Line Items]
Cash payment	$ 98,045
Acquisition costs	$ 4,900
x Plus 1 | Trademarks
Business Acquisition [Line Items]
Amortization of Intangible Assets		$ 1,600

BUSINESS COMBINATIONS - Purchas

BUSINESS COMBINATIONS - Purchase Consideration (Details) - x Plus 1 $ in Thousands	Sep. 05, 2014USD ($)
Business Acquisition [Line Items]
Cash	$ 98,045
Fair value of 5.3 million shares common stock transferred	82,421
Total purchase price	$ 180,466

BUSINESS COMBINATIONS - Schedul

BUSINESS COMBINATIONS - Schedule of Purchase Price Allocation (Details) - x Plus 1 $ in Thousands	Sep. 05, 2014USD ($)
Business Acquisition [Line Items]
Current assets	$ 29,853
Non-current assets	3,999
Current liabilities	(29,354)
Non-current liabilities	(16,253)
Net acquired tangible assets	(11,755)
Identifiable intangible assets	74,700
Goodwill	117,521
Total preliminary purchase price	$ 180,466

BUSINESS COMBINATIONS - Sched33

BUSINESS COMBINATIONS - Schedule of Acquired Finite-Lived Intangible Assets (Details) - x Plus 1 - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Preliminary Fair Value	$ 74,700	$ 74,700
Accumulated Amortization	(27,908)	(23,781)
Net Book Value	46,792	50,919
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Preliminary Fair Value	42,100	42,100
Accumulated Amortization	(18,192)	(15,295)
Net Book Value	$ 23,908	26,805
Developed technology | Minimum
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	3 years
Developed technology | Maximum
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	4 years
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Preliminary Fair Value	$ 27,700	27,700
Accumulated Amortization	(5,440)	(4,573)
Net Book Value	$ 22,260	23,127
Customer relationships | Minimum
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	7 years
Customer relationships | Maximum
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	8 years
Trademarks
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	5 years
Preliminary Fair Value	$ 2,000	2,000
Accumulated Amortization	(2,000)	(2,000)
Net Book Value	$ 0	0
Non-compete agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated Useful Life	2 years
Preliminary Fair Value	$ 2,900	2,900
Accumulated Amortization	(2,276)	(1,913)
Net Book Value	$ 624	$ 987

CAPITAL LEASES (Details)

CAPITAL LEASES (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Approximate remaining future minimum lease payments under non-cancelable capital leases
2016 (remaining 9 months)	$ 7,217
2,016	7,862
2,017	4,366
2,018	414
2,019	13
Total minimum lease payments	19,872
Less: amount representing interest and taxes	(1,356)
Less: current portion of minimum lease payments	(8,723)	$ (8,602)
Capital lease obligations, net of current portion	$ 9,793	$ 11,855

RESTRUCTURING COSTS (Details)

RESTRUCTURING COSTS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring	$ (199)	$ 0
Accelerated amortization of leasehold improvements	3,533	$ 0
Restructuring and Related Cost, Expected Cost Remaining	3,500
One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	400
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4,100
Restructuring and Related Cost, Expected Cost Remaining	$ 4,100

DEBT (Details)

DEBT (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Debt
Amount outstanding	$ 62,500,000
Applicable margin over variable rate basis (as a percent)	2.00%
Future principal payments of long-term debt
Term loan, net of current portion	$ 0	$ 17,617,000
Unamortized discounts	$ 500,000
Federal funds rate
Debt
Applicable margin over variable rate basis (as a percent)	1.00%
Daily adjusting LIBOR rate
Debt
Applicable margin over variable rate basis (as a percent)	1.00%
Revolving line of credit, as amended in June 2013
Debt
Revolving credit facility, net	$ 80,000,000
Maximum amount available for borrowing expressed as a percentage of certain eligible accounts	85.00%
Amount outstanding	$ 62,500,000
Letter of credit subfacility
Debt
Revolving credit facility, net	12,000,000
Aggregate minimum cash on deposit	40,000,000
Amount outstanding	7,500,000
Debt Instrument, Required Cash on Deposit	30,000,000
Swing line subfacility
Debt
Revolving credit facility, net	2,500,000
Revolving line of credit amended in March 2012
Debt
Revolving credit facility, net	$ 30,000,000
Revolving line of credit | Base rate
Debt
Applicable margin over variable rate basis (as a percent)	2.125%
Revolving line of credit | Base rate | Minimum
Debt
Applicable margin over variable rate basis (as a percent)	1.625%
Revolving line of credit | LIBOR | Minimum
Debt
Applicable margin over variable rate basis (as a percent)	2.625%
Revolving line of credit | LIBOR | Maximum
Debt
Applicable margin over variable rate basis (as a percent)	3.125%
Term loans | Base rate | Minimum
Debt
Applicable margin over variable rate basis (as a percent)	2.50%
Term loans | Base rate | Maximum
Debt
Applicable margin over variable rate basis (as a percent)	3.00%
Term loans | LIBOR | Minimum
Debt
Applicable margin over variable rate basis (as a percent)	3.50%
Term loans | LIBOR | Maximum
Debt
Applicable margin over variable rate basis (as a percent)	4.00%

STOCKHOLDERS' EQUITY - Schedul

STOCKHOLDERS' EQUITY - Schedule of Share-based Compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2014
Additional Disclosures [Abstract]
Total unrecognized compensation expense at period-end	$ 700
Options
Number of Shares Outstanding
Balance at the beginning of the period (in shares)	5,387	6,291
Options granted (shares)	1,631	208
Options exercised (in shares)	(41)	(116)
Options forfeited (in shares)	(1,544)	(75)
Balance at the end of the period (in shares)	5,433	6,308
Additional Disclosures [Abstract]
Total intrinsic value of options exercised	$ 113	$ 858
Total unrecognized compensation expense at period-end	$ 8,399		$ 23,190
Weighted-average remaining recognition period at period-end (in years)	3 years 5 days	2 years 2 months 19 days
Restricted stock units (RSUs) and restricted stock awards (RSAs)
Number of Shares Outstanding
Balance at the beginning of the period (in shares)	3,612	2,515
Options granted (shares)	490	348
Options exercised (in shares)	(179)	(48)
Options forfeited (in shares)	(268)	(136)
Balance at the end of the period (in shares)	3,655	2,680
Additional Disclosures [Abstract]
Weighted-average grant-date fair value (dollars per share)	$ 10.39	$ 16.74
Total unrecognized compensation expense at period-end	$ 25,712		$ 41,131
Weighted-average remaining recognition period at period-end (in years)	2 years 7 months 19 days	3 years 4 months 28 days

- Additional Information (Detai

- Additional Information (Details)	3 Months Ended
	Mar. 31, 2016USD ($)shares
STOCKHOLDERS' EQUITY (DEFICIT)
Common Stock, Capital Shares Reserved for Future Issuance | shares	2,200,000
Total unrecognized compensation expense at period-end | $	$ 700,000
Expected dividend payments | $	$ 0
2016 Inducement Equity Incentive Plan [Member]
STOCKHOLDERS' EQUITY (DEFICIT)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross | shares	400,000
Purchase price of common stock, percent	100.00%
Employee stock purchase plan
STOCKHOLDERS' EQUITY (DEFICIT)
Maximum employee subscription rate	15.00%
Purchase price of common stock, percent	85.00%

STOCKHOLDERS' EQUITY - Valuati

STOCKHOLDERS' EQUITY - Valuation Assumptions (Details)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Employee stock purchase plan
Assumptions used to calculate stock-based compensation for each stock purchase right granted under the Employee Stock Purchase Plan (ESPP)
Expected volatility rate, minimum	65.00%	77.20%
Expected volatility rate, maximum	65.00%	77.20%
Risk free interest rate, minimum	0.42%	0.08%
Risk free interest rate, maximum	0.42%	0.08%
Dividend yield	0.00%	0.00%
Options
Assumptions used to calculate stock-based compensation for each stock purchase right granted under the Employee Stock Purchase Plan (ESPP)
Expected volatility rate, minimum	55.00%	58.00%
Expected volatility rate, maximum	55.00%	58.00%
Risk free interest rate, minimum	1.57%	1.57%
Risk free interest rate, maximum	1.93%	1.57%
Dividend yield	0.00%	0.00%
Minimum | Employee stock purchase plan
Assumptions used to calculate stock-based compensation for each stock purchase right granted under the Employee Stock Purchase Plan (ESPP)
Expected term (years)	6 months	6 months
Minimum | Options
Assumptions used to calculate stock-based compensation for each stock purchase right granted under the Employee Stock Purchase Plan (ESPP)
Expected term (years)	6 years 3 months 18 days	6 years 3 months 18 days
Maximum | Employee stock purchase plan
Assumptions used to calculate stock-based compensation for each stock purchase right granted under the Employee Stock Purchase Plan (ESPP)
Expected term (years)	6 months	6 months
Maximum | Options
Assumptions used to calculate stock-based compensation for each stock purchase right granted under the Employee Stock Purchase Plan (ESPP)
Expected term (years)	6 years 3 months 18 days	6 years 3 months 18 days

STOCKHOLDERS' EQUITY - Sched40

STOCKHOLDERS' EQUITY - Schedule of Allocated Share-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Allocation of stock-based compensation and restricted stock for employees and non-employees
Allocated share-based compensation expense	$ 4,810	$ 7,447
Other cost of revenue
Allocation of stock-based compensation and restricted stock for employees and non-employees
Allocated share-based compensation expense	530	625
Research and development
Allocation of stock-based compensation and restricted stock for employees and non-employees
Allocated share-based compensation expense	1,365	2,247
Sales and marketing
Allocation of stock-based compensation and restricted stock for employees and non-employees
Allocated share-based compensation expense	1,489	2,831
General and administrative
Allocation of stock-based compensation and restricted stock for employees and non-employees
Allocated share-based compensation expense	$ 1,426	$ 1,744

NET LOSS PER SHARE (Details)

NET LOSS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Computation of net loss per common share
Net loss	$ (20,773)	$ (36,863)
Weighted-average shares used to compute basic and diluted net loss per share (shares)	43,601	41,981
Basic and diluted net loss per share (in dollars per share)	$ (0.48)	$ (0.88)
Anti-dilutive securities that were excluded from the calculation of diluted net loss per share attributable to common stockholders (in shares)	9,521	9,387

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income tax provision	$ 230	$ 357

COMMITMENTS AND CONTINGENCIES43

COMMITMENTS AND CONTINGENCIES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Operating Leases
Rent expense	$ 4,300	$ 4,000
Future minimum lease payments under non-cancelable operating leases
2016 (remaining 9 months)	12,786
2,016	16,324
2,017	15,128
2,018	16,473
2,019	7,247
Thereafter	21,301
Total future payments	89,259
Letters of Credit and Bank Guarantees
Irrevocable letters of credit outstanding	7,700		$ 6,300
Bank guarantees for security deposits	$ 2,002		$ 2,141

SEGMENTS (Details)

SEGMENTS (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016USD ($)managerbusiness_activity	Mar. 31, 2015USD ($)	Dec. 31, 2015USD ($)
Segments
Number of business activities | business_activity	1
Number of segment managers held accountable for operations, operating results or plans for levels or components below the consolidated unit level | manager	0
Total revenue	$ 104,745	$ 104,334
Total long-lived assets	75,715		$ 82,781
North America
Segments
Total revenue	81,397	86,151
Total long-lived assets	70,601		77,038
All Other Countries
Segments
Total revenue	23,348	$ 18,183
Total long-lived assets	$ 5,114		$ 5,743

RELATED PARTY TRANSACTIONS (Det

RELATED PARTY TRANSACTIONS (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	$ 0.4
Accounts Payable, Related Parties	$ 1.2

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - Subsequent Event [Member]	May. 10, 2016USD ($)
Subsequent Event [Line Items]
Sale of Stock, Consideration Received on Transaction	$ 50,000,000
Cantor Fitzgerald & Co. [Member] | Sales Agreement [Member]
Subsequent Event [Line Items]
Sale of Stock, Consideration Received on Transaction	$ 30,000,000