Wayfair (W) 10-Q 9 May 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	Apr. 30, 2017
Document and Entity Information
Entity Registrant Name	Wayfair Inc.
Entity Central Index Key	1,616,707
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Amendment Flag	false
Class A common stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		51,717,925
Class B common stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		34,909,163

CONSOLIDATED AND CONDENSED BALA

CONSOLIDATED AND CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 212,408	$ 279,840
Short-term investments	64,277	68,743
Accounts receivable, net of allowance of $2,857 and $3,115 at March 31, 2017 and December 31, 2016, respectively	21,770	19,113
Inventories	14,457	18,550
Prepaid expenses and other current assets	119,450	90,845
Total current assets	432,362	477,091
Property and equipment, net	263,315	239,354
Goodwill and intangible assets, net	3,949	4,230
Long-term investments	33,242	30,967
Other noncurrent assets	9,255	10,041
Total assets	742,123	761,683
Current liabilities
Accounts payable	362,719	379,493
Accrued expenses	70,629	67,807
Deferred revenue	88,325	65,892
Other current liabilities	44,911	44,028
Total current liabilities	566,584	557,220
Lease financing obligation	41,542	28,900
Other liabilities	97,535	96,179
Total liabilities	705,661	682,299
Commitments and contingencies
Convertible preferred stock, $0.001 par value per share: 10,000,000 shares authorized and none issued at March 31, 2017 and December 31, 2016	0	0
Stockholders’ equity:
Additional paid-in capital	431,812	409,225
Accumulated deficit	(395,191)	(329,940)
Accumulated other comprehensive (loss) gain	(245)	13
Total stockholders’ equity	36,462	79,384
Total liabilities and stockholders’ equity	742,123	761,683
Class A common stock
Stockholders’ equity:
Common stock	51	50
Class B common stock
Stockholders’ equity:
Common stock	$ 35	$ 36

CONSOLIDATED AND CONDENSED BAL3

CONSOLIDATED AND CONDENSED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accounts receivable allowance	$ 2,857	$ 3,115
Convertible redeemable preferred units, par value (in dollars per share)	$ 0.001	$ 0.001
Convertible redeemable preferred units, shares authorized (in shares)	10,000,000	10,000,000
Convertible redeemable preferred units, shares issued (in shares)	0	0
Class A common stock
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares outstanding (in shares)	50,971,401	49,945,202
Common stock, shares issued (in shares)	50,971,401	49,945,202
Class B common stock
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	164,000,000	164,000,000
Common stock, shares outstanding (in shares)	35,475,888	35,885,692
Common stock, shares issued (in shares)	35,475,888	35,885,692

CONSOLIDATED AND CONDENSED STAT

CONSOLIDATED AND CONDENSED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Net revenue	$ 960,825	$ 747,348
Cost of goods sold	723,942	568,292
Gross profit	236,883	179,056
Operating expenses:
Customer service and merchant fees	35,058	27,350
Advertising	118,265	97,677
Merchandising, marketing and sales	50,794	37,856
Operations, technology, general and administrative	88,972	58,282
Total operating expenses	293,089	221,165
Loss from operations	(56,206)	(42,109)
Interest (expense) income, net	(299)	552
Other income, net	176	669
Loss before income taxes	(56,329)	(40,888)
Provision for income taxes	210	317
Net loss	$ (56,539)	$ (41,205)
Net loss per share, basic and diluted (in dollars per share)	$ (0.66)	$ (0.49)
Weighted average number of common stock outstanding used in computing per share amounts, basic and diluted (in shares)	86,036	84,445

CONSOLIDATED AND CONDENSED STA5

CONSOLIDATED AND CONDENSED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (56,539)	$ (41,205)
Other comprehensive loss:
Foreign currency translation adjustments	(281)	(333)
Net unrealized gain on available-for-sale investments	23	497
Comprehensive loss	$ (56,797)	$ (41,041)

CONSOLIDATED AND CONDENSED STA6

CONSOLIDATED AND CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities
Net loss	$ (56,539)	$ (41,205)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	20,352	10,487
Equity based compensation	13,629	9,715
Other non-cash adjustments	(246)	(156)
Changes in operating assets and liabilities:
Accounts receivable	(2,651)	(1,941)
Inventories	4,094	2,142
Prepaid expenses and other current assets	(28,200)	(8,643)
Accounts payable and accrued expenses	(22,412)	(29,097)
Deferred revenue and other liabilities	25,930	7,926
Other assets	(55)	(432)
Net cash used in operating activities	(46,098)	(51,204)
Cash flows from investing activities
Purchase of short-term and long-term investments	(16,225)	(28,489)
Sale and maturities of short-term investments	18,275	29,620
Purchase of property and equipment	(11,952)	(23,927)
Site and software development costs	(10,920)	(5,451)
Net cash used in investing activities	(20,822)	(28,247)
Cash flows from financing activities
Taxes paid related to net share settlement of equity awards	(592)	(6,621)
Net proceeds from exercise of stock options	54	51
Net cash used in financing activities	(538)	(6,570)
Effect of exchange rate changes on cash and cash equivalents	26	643
Net decrease in cash and cash equivalents	(67,432)	(85,378)
Cash and cash equivalents
Beginning of period	279,840	334,176
End of period	212,408	248,798
Supplemental disclosure of non-cash investing activities
Purchase of property and equipment included in accounts payable and accrued expenses and in other liabilities	11,524	19,186
Construction costs capitalized under finance lease obligation and other leases	$ 8,389	$ 13,077

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation Wayfair Inc. (the “Company”) is one of the world's largest online destinations for the home. Through its e-commerce business model, the Company offers visually inspired browsing, compelling merchandising, easy product discovery and attractive prices for over eight million products from over 10,000 suppliers. The consolidated and condensed financial statements and other disclosures contained in this Quarterly Report on Form 10-Q are those of the Company. The consolidated and condensed balance sheet data as of December 31, 2016 was derived from audited financial statements. The accompanying consolidated and condensed balance sheet as of March 31, 2017 , the consolidated and condensed statements of operations, consolidated and condensed statements of comprehensive loss, and consolidated and condensed statements of cash flows for the periods ended March 31, 2017 and 2016 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the audited consolidated financial statements and in the opinion of management, reflect all adjustments, consisting of only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2017 and statements of operations, comprehensive loss, and cash flows for the periods ended March 31, 2017 and 2016 . The financial data and the other information disclosed in these notes to the consolidated and condensed financial statements related to these periods are unaudited. The consolidated and condensed statements of operations, comprehensive loss, and cash flows for the period ended March 31, 2017 are not necessarily indicative of the results of operations and cash flows that may be expected for the year ending December 31, 2017 , or for any other period.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies The Company has identified the significant accounting policies that are critical to understanding its business and results of operations. The Company believes that there have been no significant changes during the three months ended March 31, 2017 to the items disclosed in Note 2, Summary of Significant Accounting Policies , included in Part II, Item 8, Financial Statements and Supplementary Data , of the Company’s Annual Report on Form 10-K for the year ended December 31, 2016 .

Marketable Securities and Fair

Marketable Securities and Fair Value Measurements	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Marketable Securities and Fair Value Measurements	Marketable Securities and Fair Value Measurements Marketable Securities As of March 31, 2017 and December 31, 2016 , all of the Company’s marketable securities were classified as available-for-sale and their estimated fair values were $97.5 million and $99.7 million , respectively. The Company periodically reviews its available-for-sale securities for other-than-temporary impairment. The Company considers factors such as the duration, severity and the reason for the decline in value, the potential recovery period, and its intent to sell. As of March 31, 2017 , the Company’s available-for-sale securities primarily consisted of corporate bonds and other government obligations that are priced at fair value. During the three months ended March 31, 2017 and 2016 , the Company did not recognize any other-than-temporary impairment loss. The maturities of the Company’s long-term marketable securities generally range from one to three years. The cost basis of a marketable security sold is determined by the Company using the specific identification method. During the three months ended March 31, 2017 and 2016 , we did not have any realized gains or losses. The following tables present details of the Company’s marketable securities as of March 31, 2017 and December 31, 2016 (in thousands): March 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Short-term: Investment securities $ 61,044 $ 8 $ (16 ) $ 61,036 Commercial paper 3,241 1 (1 ) 3,241 Long-term: Investment securities 33,262 18 (38 ) 33,242 Total $ 97,547 $ 27 $ (55 ) $ 97,519 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Short-term: Investment securities $ 63,135 $ 7 $ (39 ) $ 63,103 Commercial paper 5,641 1 (2 ) 5,640 Long-term: Investment securities 30,985 16 (34 ) 30,967 Total $ 99,761 $ 24 $ (75 ) $ 99,710 Fair Value Measurements The Company's financial assets and liabilities are measured at fair value, which 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 (exit price). The three levels of inputs used to measure fair value are as follows: ▪ Level 1—Unadjusted quoted prices in active markets for identical assets or liabilities ▪ Level 2—Unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or inputs other than quoted prices that are observable or can be corroborated by observable market data for substantially the full-term of the asset or liability ▪ Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the asset or liability This hierarchy requires the Company to use observable market data, when available, and to minimize the use of unobservable inputs when determining fair value. The Company measures its cash equivalents and short-term and long-term investments at fair value. The Company classifies its cash equivalents and restricted cash within Level 1 because the Company values these investments using quoted market prices. The fair value of the Company's Level 1 financial assets is based on quoted market prices of the identical underlying security. The Company classifies short-term and long-term investments within Level 2 because unadjusted quoted prices for identical or similar assets in markets are not active. The Company does not have any assets or liabilities classified as Level 3 financial assets. The following tables set forth the fair value of the Company’s financial assets measured at fair value on a recurring basis as of March 31, 2017 and December 31, 2016 based on the three-tier value hierarchy (in thousands): March 31, 2017 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 113,588 $ — $ — $ 113,588 Short-term investments: Investment securities — 61,036 — 61,036 Commercial paper — 3,241 — 3,241 Restricted cash: Certificate of deposit 5,000 — — 5,000 Long-term: Investment securities — 33,242 — 33,242 Total $ 118,588 $ 97,519 $ — $ 216,107 December 31, 2016 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 200,867 $ — $ — $ 200,867 Short-term investments: Investment securities — 63,103 — 63,103 Commercial paper — 5,640 — 5,640 Restricted cash: Certificate of deposit 5,000 — — 5,000 Long-term: Investment securities — 30,967 — 30,967 Total $ 205,867 $ 99,710 $ — $ 305,577

Intangible Assets and Goodwill

Intangible Assets and Goodwill	3 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets and Goodwill	Intangible Assets and Goodwill The following table summarizes intangible assets as of March 31, 2017 and December 31, 2016 (in thousands): Weighted - Average Amortization Period (Years) March 31, 2017 Gross Carrying Amount Accumulated Amortization Net Book Value Trademarks 5 $ 1,900 $ (1,393 ) $ 507 Technology 3 1,453 (282 ) 1,171 Customer relationships 5 1,300 (953 ) 347 Total $ 4,653 $ (2,628 ) $ 2,025 Weighted - Average Amortization Period (Years) December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Book Value Trademarks 5 $ 1,900 $ (1,298 ) $ 602 Technology 3 1,453 (161 ) 1,292 Customer relationship 5 1,300 (888 ) 412 Total $ 4,653 $ (2,347 ) $ 2,306 Amortization expense related to intangible assets was $0.3 million and $0.2 million for the three months ended March 31, 2017 and 2016 , respectively. Goodwill as of March 31, 2017 was $1.9 million , unchanged from December 31, 2016 .

Property and Equipment, net

Property and Equipment, net	3 Months Ended
	Mar. 31, 2017
Property, Plant and Equipment [Abstract]
Property and Equipment, net	Property and Equipment, net The following table summarizes property and equipment, net as of March 31, 2017 and December 31, 2016 (in thousands): March 31, December 31, Furniture and computer equipment $ 149,258 $ 133,297 Site and software development costs 87,139 77,429 Leasehold improvements 65,652 62,090 Construction in progress 46,808 47,013 Buildings (leased - Note 6) 42,498 29,856 391,355 349,685 Less accumulated depreciation and amortization (128,040 ) (110,331 ) Property and equipment, net $ 263,315 $ 239,354 Property and equipment depreciation and amortization expense was $20.1 million and $10.3 million for the three months ended March 31, 2017 and 2016 , respectively.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Leases The Company leases office and warehouse spaces under non-cancelable leases. These leases expire at various dates through 2027 and include discounted rental periods and fixed escalation clauses, which are amortized straight-line over the terms of the lease. Rent expense under operating leases was $11.6 million and $7.1 million in the three months ended March 31, 2017 and 2016 , respectively. The Company has issued letters of credit for approximately $11.4 million and $10.6 million as security for these lease agreements as of March 31, 2017 and December 31, 2016 , respectively. As of December 31, 2016 , the future minimum rental commitments under non-cancelable leases with initial or remaining terms in excess of one year totaled $568.7 million . Subsequent to December 31, 2016 , the Company entered into additional non-cancelable leases in the United States ("U.S.") with initial or remaining terms in excess of one year with total future minimum lease commitments of $ 50.2 million . Future lease payments have not been reduced by minimum sublease rentals of $9.3 million due to the Company in the future under non-cancelable subleases through 2020 . The Company establishes assets and liabilities for the estimated construction costs incurred under lease arrangements where the Company is considered the owner for accounting purposes only, or build-to-suit leases, to the extent the Company is involved in the construction of structural improvements or takes construction risk prior to commencement of a lease. Upon occupancy of facilities under build-to-suit leases, the Company assesses whether these arrangements qualify for sales recognition under the sale-leaseback accounting guidance. If the Company continues to be the deemed owner, the facilities are accounted for as financing leases. The construction of one warehouse lease arrangement was completed during the three months ended June 30, 2016, and because the Company concluded it had a letter of credit of $1.2 million , the Company did not meet the sale-leaseback criteria for derecognition of the building asset and liability. Another warehouse lease arrangement was completed in the three months ended March 31, 2017, and because the Company concluded it had a letter of credit of $0.8 million , the Company did not meet the sale-leaseback criteria for derecognition of the building asset and liability. Accordingly, these leases were accounted for as financing obligations and $28.9 million and $12.6 million was recorded in "Lease financing obligation" in the Company’s unaudited consolidated and condensed balance sheets as of June 30, 2016 and March 31, 2017, respectively. The monthly rent payments made to the lessor under the lease agreement are recorded in the Company’s financial statements as land lease expense and principal and interest on the financing obligation. Interest expense on the lease financing obligation reflects the portion of the Company's monthly lease payments that is allocated to interest expense. For the three months ended March 31, 2017 , land lease expense was $0.1 million and interest expense on lease financing obligations was $0.9 million . As of March 31, 2017 , future minimum commitments related to the financing obligations were $3.5 million and $19.2 million for principal and interest, respectively, through March 31, 2022. Collection of Sales or Other Similar Taxes Based on the location of the Company’s current operations, it collects and remits sales tax. The Company does not currently collect sales or other similar taxes for the sale of goods in states where no obligation to collect these taxes is required under applicable law. Several states have presented the Company with assessments, alleging that it is required to collect and remit sales or other similar taxes. The aggregate amount of claims from these states, not including taxes allegedly owed for periods subsequent to such assessments or interest and penalties after the date the Company last received such assessments, is approximately $21.9 million . The Company does not believe that it was obligated to collect and remit such taxes, and intends to vigorously defend its position. At this time, the Company believes any losses that may arise from these assessments would be immaterial; however, no assurance can be given as to the outcome of these assessments. Legal Matters In September 2016, a putative class action complaint was filed against the Company in the Superior Court of the province of Quebec (Naomi Zouzout v. Wayfair LLC, Case No. PQ 500-06-000809-166) by an individual on behalf of herself and on behalf of all other similarly situated individuals alleging violations of various Canadian consumer protection statutes. Among other remedies, this lawsuit seeks compensatory and punitive money damages, costs, and various fees. The Company intends to defend the lawsuit vigorously. At this time, based on available information regarding this litigation, the Company is unable to reasonably assess the ultimate outcome of this case or determine an estimate, or a range of estimates, of potential losses. From time to time the Company is involved in claims that arise during the ordinary course of business. Although the results of litigation and claims cannot be predicted with certainty, the Company does not currently believe that the outcome of any of these other legal matters will have a material adverse effect on the Company's results of operation or financial condition. Regardless of the outcome, litigation can be costly and time consuming, as it can divert management’s attention from important business matters and initiatives, negatively impacting the Company's overall operations. In addition, the Company may also find itself at greater risk to outside party claims as it increases its operations in jurisdictions where the laws with respect to the potential liability of online retailers are uncertain, unfavorable, or unclear.

Equity-Based Compensation

Equity-Based Compensation	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity-Based Compensation	Equity-Based Compensation The board of directors of the Company adopted the 2014 Incentive Award Plan ("2014 Plan") to grant cash and equity incentive awards to eligible service providers in order to attract, motivate and retain the talent for which the Company competes. The 2014 Plan is administered by the board of directors of the Company with respect to awards to non-employee directors and by the compensation committee with respect to other participants and provides for the issuance of stock options, SARs, restricted stock, restricted stock units ("RSUs"), performance shares, stock payments, cash payments, dividend awards and other incentives. Prior to the adoption of the 2014 Plan, Wayfair LLC issued certain equity awards pursuant to the Wayfair LLC Amended and Restated Common Unit Plan (the “2010 Plan”), which was administered by the board of directors of Wayfair LLC. Awards issued under this plan that remain outstanding currently represent Class A or Class B common stock of the Company. 8,603,066 shares of Class A common stock were initially available for issuance under awards granted pursuant to the 2014 Plan. The 2014 Plan also contains an evergreen provision whereby the shares available for future grant are increased on the first day of each calendar year beginning January 1, 2016 and ending on and including January 1, 2024. As of January 1, 2017, 8,389,750 shares of Class A common stock were available for future grant under the 2014 Plan. Shares or RSUs forfeited, withheld for minimum statutory tax obligations, and unexercised stock option lapses from the 2010 and 2014 Plans are available for grants of awards under the 2014 Plan. All equity awards granted prior to the initial public offering ("IPO") were subject to two vesting conditions: (i) a service period (typically five years ) and (ii) a performance condition (a liquidity event in the form of either a change of control or an IPO, each as defined in the 2010 Plan). Employees were able to retain provisionally vested stock options and shares upon departure. The Company determined that a liquidity event was not probable until the closing of its IPO on October 7, 2014, and as such, no expense was recognized until that date. After the IPO, awards for employees still providing service continue to vest over the remaining service period. Any future grants of awards are expected to vest over the service period. The Company adopted Financial Accounting Standards Board ("FASB") Accounting Standards Update ("ASU") No. 2016-09, "Compensation - Stock Compensation" ("ASU 2016-09") as of January 1, 2017. For additional information, refer to Note 13, Recent Accounting Pronouncements . The following table presents activity relating to stock options for the three months ended March 31, 2017 : Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (Years) Outstanding at December 31, 2016 209,759 $ 2.98 4.5 Options exercised (17,981 ) $ 2.90 Outstanding and exercisable at March 31, 2017 191,778 $ 2.99 4.2 Intrinsic value of stock options exercised was $0.7 million for the three months ended March 31, 2017 . Aggregate intrinsic value of stock options outstanding and currently exercisable is $7.2 million . All stock options were fully vested at March 31, 2017 . The following table presents activity relating to restricted common stock for the three months ended March 31, 2017 : Shares Weighted- Average Grant Date Fair Value Outstanding at December 31, 2016 60,000 $ 35.05 Unvested and expected to vest at March 31, 2017 60,000 $ 40.49 Aggregate intrinsic value of restricted common stock unvested is $2.4 million as of March 31, 2017 . Unrecognized equity based compensation expense related to restricted common stock expected to vest over time is $2.0 million with a weighted average remaining vesting term of 1.8 years as of March 31, 2017 . The following table presents activity relating to RSUs for the three months ended March 31, 2017 : Shares Weighted- Average Grant Date Fair Value Outstanding at December 31, 2016 6,986,776 $ 34.21 RSUs granted 720,706 $ 41.10 RSUs vested (610,079 ) $ 31.26 RSUs forfeited/canceled (169,726 ) $ 36.57 Outstanding and expected to vest at March 31, 2017 6,927,677 $ 35.13 The intrinsic value of RSUs vested was $23.2 million for the three months ended March 31, 2017 . Aggregate intrinsic value of RSUs outstanding is $280.5 million as of March 31, 2017 . Unrecognized equity based compensation expense related to RSUs expected to vest over time is $209.1 million with a weighted average remaining vesting term of 1.8 years at March 31, 2017 .

Segment and Geographic Informat

Segment and Geographic Information	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Segment and Geographic Information	Segment and Geographic Information Operating segments are defined as components of an enterprise for which separate financial information is available that is evaluated on a regular basis by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its Chief Executive Officer. Beginning the fourth quarter of 2016, the Company changed its operating and reportable segments to U.S. and International. These segments reflect changes in the way the CODM allocates resources and evaluates financial performance, which is based upon each segment's Adjusted EBITDA. Adjusted EBITDA is defined as loss before depreciation and amortization, equity-based compensation and related taxes, interest and other income and expense, provision for income taxes, and non-recurring items. These charges are excluded from evaluation of segment performance because it facilitates reportable segment performance comparisons on a period-to-period basis. Refer to Note 2, Summary of Significant Accounting Policies for the accounting policies of segments. The Company allocates certain operating expenses to the operating and reportable segments, including "Customer service and merchant fees," "Merchandising, marketing and sales," and "Operations, technology, general and administrative" based on the usage and relative contribution provided to the segments. It excludes from the allocations certain operating expense lines, including "Depreciation and amortization, "Equity based compensation and related taxes," "Interest (income), net," "Other (income) expense, net," and "Provision for income taxes." There are no revenue transactions between the Company's reportable segments. U.S. The U.S. segment primarily consists of amounts earned through product sales through the Company's sites in the U.S. and through sites operated by third parties in the U.S. International The International segment primarily consists of amounts earned through product sales through the Company's international sites. Revenue from external customers for each group of similar products and services are not reported to the CODM. Separate identification of this information for purposes of segment disclosure is impractical, as it is not readily available and the cost to develop it would be excessive. No individual country outside of the U.S. provided greater than 10% of total revenue. The following tables present Direct Retail and Other net revenues and Adjusted EBITDA attributable to the Company's reportable segments for the periods presented (in thousands): Three months ended March 31, 2017 2016 U.S. Direct Retail $ 837,556 $ 672,700 U.S. Other 20,473 33,221 U.S. segment net revenue 858,029 705,921 International Direct Retail 102,796 39,146 International Other — 2,281 International segment net revenue 102,796 41,427 Total net revenue $ 960,825 $ 747,348 Three months ended March 31, 2017 2016 Adjusted EBITDA U.S. $ 3,728 $ (1,039 ) International (24,624 ) (19,921 ) Total reportable segments Adjusted EBITDA (20,896 ) (20,960 ) Less: reconciling items (1) (35,643 ) (20,245 ) Net loss $ (56,539 ) $ (41,205 ) (1) Adjustments are made to reconcile total reportable segments Adjusted EBITDA to consolidated net loss including the following (in thousands): Three months ended March 31, 2017 2016 Depreciation and amortization $ 20,352 $ 10,487 Equity based compensation and related taxes 14,958 10,662 Interest expense (income), net 299 (552 ) Other (income), net (176 ) (669 ) Provision for income taxes 210 317 Total reconciling items $ 35,643 $ 20,245 The following table presents the activity related to the Company’s net revenue from Direct Retail sales derived through the Company’s sites and Other sales derived through sites operated by third parties and fees from third-party advertising distribution providers (in thousands): Three months ended March 31, 2017 2016 Net revenue Direct Retail $ 940,352 $ 711,846 Other 20,473 35,502 Net revenue $ 960,825 $ 747,348 The following table presents long-lived assets by segment (in thousands): March 31, December 31, Geographic long-lived assets U.S. $ 256,807 $ 233,099 International 6,508 6,255 Total $ 263,315 $ 239,354

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income tax expense was $0.2 million and $0.3 million for the three months ended March 31, 2017 and 2016 , respectively. The income tax expense recorded in the three months ended March 31, 2017 and 2016 is primarily related to various foreign income tax assessments, state income taxes and to a lesser extent the amortization of goodwill for tax purposes for which there is no corresponding book deduction. Deferred income taxes reflect the impact of temporary differences between the amounts of assets and liabilities for financial reporting purposes and such amounts as measured by tax laws. The Company has deferred tax assets related to its net operating loss carryforwards accumulated since the fourth quarter of 2014 and related to net operating loss carryforwards of certain of its foreign subsidiaries. A valuation allowance against net deferred tax assets is required if, based upon the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company reassesses the valuation allowance on a quarterly basis and has provided a valuation allowance for the full amount of its net deferred tax assets. The Company had no unrecognized tax benefits as of March 31, 2017 and December 31, 2016 . The Company’s policy is to recognize interest and penalties related to unrecognized tax benefits as a component of income tax expense.

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)	3 Months Ended
	Mar. 31, 2017
Equity [Abstract]
Stockholders' Equity (Deficit)	Stockholders’ Equity (Deficit) Preferred Stock The Company authorized 10,000,000 shares of undesignated preferred stock, $0.001 par value per share, for future issuance. As of March 31, 2017 , the Company had no shares of undesignated preferred stock issued or outstanding. Common Stock The Company authorized 500,000,000 shares of Class A common stock, $0.001 par value per share, and 164,000,000 shares of Class B common stock, $0.001 par value per share, of which 50,971,401 and 49,945,202 shares of Class A common stock and 35,475,888 and 35,885,692 shares of Class B common stock were outstanding as of March 31, 2017 and December 31, 2016 , respectively. The rights of the holders of Class A common stock and Class B common stock are identical, except with respect to voting and conversion rights. Each share of Class A common stock is entitled to one vote per share and each share of Class B common stock is entitled to ten votes per share. Each share of Class B common stock may be converted into one share of Class A common stock at the option of its holder and will be automatically converted into one share of Class A common stock upon transfer thereof, subject to certain exceptions. In addition, upon the date on which the outstanding shares of Class B common stock represent less than 10% of the aggregate number of shares of the then outstanding Class A common stock and Class B common stock, or in the event of the affirmative vote or written consent of holders of at least 66 2/3% of the outstanding shares of Class B common stock, all outstanding shares of Class B common stock shall convert automatically into Class A common stock. Subject to preferences that may apply to any shares of preferred stock outstanding at the time, the holders of common stock are entitled to receive dividends out of funds legally available if the Board, in its discretion, determines to issue dividends and then only at the times and in the amounts that the Board may determine. Since the IPO through March 31, 2017 , 35,220,479 shares of Class B common stock were converted to Class A common stock.

Credit Agreement

Credit Agreement	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Credit Agreement	Credit Agreement On February 22, 2017, the Company entered into a $40 million credit card program and a credit agreement consisting of a $100 million secured revolving credit facility (the "Revolver") with Citibank, N.A. ("Citibank"). The Citibank credit facility replaced the Company's existing credit facility with Bank of America, N.A. ("Bank of America"), which was terminated on February 22, 2017 as described below. The Citibank Revolver has a $40 million letter of credit sublimit and a $10 million swing line sublimit, and a final maturity date of February 21, 2020. Wayfair LLC is the borrower (the "Borrower") under the Citibank credit agreement. Subject to certain conditions, the Borrower has the right to increase the Revolver by $25 million . Borrowings under the Revolver will bear interest through maturity at a variable rate based upon, at the Borrower’s option, either the Eurodollar rate or the base rate (which is the highest of (x) Citibank's prime rate, (y) one-half of 1.00% in excess of the federal funds effective rate, and (z) 1.00% in excess of the one-month Eurodollar rate), plus, in each case an applicable margin. From closing until September 30, 2019, the applicable margin for Eurodollar rate loans is 1.75% per annum and the applicable margin for base rate loans is 0.75% per annum. After September 30, 2019, the applicable margin is subject to specified changes depending on the applicable consolidated leverage ratio. Any amounts outstanding under the Revolver are due at maturity. In addition, subject to the terms and conditions set forth in the credit agreement, the Borrower is required to make certain mandatory prepayments prior to maturity. The Citibank credit agreement contains affirmative and negative covenants customarily applicable to senior secured credit facilities, including covenants that, among other things, will limit or restrict the ability of the Company and its subsidiaries, subject to negotiated exceptions, to incur additional indebtedness and additional liens on their assets, engage in mergers or acquisitions or dispose of assets, pay dividends or make other distributions, voluntarily prepay other indebtedness, enter into transactions with affiliated persons, make investments, and change the nature of their businesses. In addition, the Citibank credit agreement requires the Company to maintain certain financial ratios. As of March 31, 2017 , the Company was in compliance with its covenants under the Revolver. The Company previously had a credit agreement with Bank of America, which was replaced by the Citibank credit agreement on February 22, 2017. The Bank of America credit agreement provided the Company with a $20.0 million revolving line of credit to support direct borrowings and letters of credit, provided that a maximum of $5.0 million could be applied to direct borrowings under the revolving line of credit, plus an additional $45.0 million credit card program (which the Company continued to utilize on a transitional basis as of March 31, 2017), for a maximum aggregate commitment of $65.0 million . Subject to the terms and conditions of the Bank of America credit agreement, advances under the line of credit, if any, would bear interest at the LIBOR rate, plus 1.75% . The Bank of America credit agreement also required the Company to maintain certain covenants, including debt service coverage, tangible net worth and unencumbered liquid assets. The Company did not borrow any amounts under the Revolver or the Bank of America credit agreement during the three months ended March 31, 2017 and the year ended December 31, 2016 .

Net Loss per Share

Net Loss per Share	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Net Loss per Share	Net Loss per Share Basic and diluted net loss per share is presented using the two class method required for participating securities: Class A and Class B common stock. The rights of the holders of Class A and Class B common stock are identical, except with respect to voting and conversion. Each share of Class A common stock is entitled to one vote per share and each share of Class B common stock is entitled to ten votes per share. Each share of Class B common stock may be converted into one share of Class A common stock at any time at the option of the stockholder, and will be automatically converted into one share of Class A common stock upon a sale or transfer, subject to certain limited exceptions. In addition, upon the date on which the outstanding shares of Class B common stock represent less than 10% of the aggregate number of shares of the then outstanding Class A common stock and Class B common stock, or in the event of the affirmative vote or written consent of at least 66 2/3% of the outstanding shares of Class B common stock, all outstanding shares of Class B common stock will automatically convert into Class A common stock. Basic net loss per share attributable to common stockholders is computed using the weighted-average number of shares of common stock outstanding during the period. Diluted net loss per share attributable to common stockholders is computed using the weighted-average number of shares of common stock and, if dilutive, common stock equivalents outstanding during the period. The Company's common stock equivalents consist of shares issuable upon the release of restricted stock units, and to a lesser extent, the incremental shares of common stock issuable upon the exercise of stock options and unvested restricted stock. The dilutive effect of these common stock equivalents is reflected in diluted earnings per share by application of the treasury stock method. The Company's basic and diluted net loss per share are the same because the Company has generated net loss attributable to common stockholders and common stock equivalents are excluded from diluted net loss per share because they have an antidilutive impact. The Company allocates undistributed earnings between the classes on a one-to-one basis when computing net loss per share. As a result, basic and diluted net loss per Class A and Class B shares are equivalent. The following table presents the calculation of basic and diluted net loss per share (in thousands, except per share data): Three months ended March 31, 2017 2016 Net loss $ (56,539 ) $ (41,205 ) Weighted average common shares used for basic and diluted net loss per share computation 86,036 84,445 Net loss per share: Basic and Diluted $ (0.66 ) $ (0.49 ) The following have been excluded from the computation of basic and diluted net loss per share as their effect would have been antidilutive: Three months ended March 31, 2017 2016 Stock options 191,778 262,819 Restricted stock 60,000 — Restricted stock units 6,927,677 6,170,820 Total 7,179,455 6,433,639

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2017
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Stock Compensation In March 2016, the FASB issued ASU No. 2016-09, "Compensation - Stock Compensation" ("ASU 2016-09"). This ASU revises the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and an option to recognize gross stock compensation expense with actual forfeitures recognized as they occur, as well as certain classifications on the statement of cash flows. This ASU is effective for annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting year, and early adoption is permitted. The Company adopted ASU 2016-09 as of January 1, 2017 using a modified retrospective approach with the option to recognize gross stock compensation expense with actual forfeitures recognized as they occur, with a cumulative-effect adjustment to retained earnings recognized as of January 1, 2017 of $8.7 million . The adoption of ASU 2016-09 also requires all income tax adjustments to be recorded in the consolidated and condensed statements of operations. Revenue Recognition In May 2014, the FASB issued ASU No. 2014-09, "Revenue from Contracts with Customers" ("ASU 2014-09"). This ASU is a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. This ASU was originally effective for annual reporting periods beginning after December 15, 2016 and early adoption was not permitted. In August 2015, the FASB issued ASU No. 2015-14, "Revenue from Contracts with Customers – Deferral of the Effective Date" (ASU-2015-14), which defers the effective date of ASU 2014-09 for one year and permits early adoption as early as the original effective date of ASU 2014-09. Accordingly, ASU 2014-09 is now effective for annual reporting periods beginning after December 15, 2017 and early adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting year. In March 2016, the FASB issued ASU No. 2016-08, "Revenue from Contracts with Customers - Principal versus Agent Considerations" ("ASU 2016-08"). This ASU clarifies the implementation guidance for principal versus agent considerations in ASU 2014-09. This ASU is effective at the same period as ASU 2015-14 and ASU 2014-09. Management expects to adopt ASU 2014-09, ASU 2015-14, and ASU 2016-08 (collectively, the "Revenue Recognition Accounting Pronouncements") for annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting year. While management is still in its assessment process, management generally expects to identify substantially similar performance obligations after adoption of the Revenue Recognition Accounting Pronouncements as compared with deliverables and separate units of accounting under previous revenue recognition guidance. Therefore, the Company generally does not expect the impact of the adoption of the Revenue Recognition Accounting Pronouncements to be significant to its consolidated financial statements. Management expects to apply the Revenue Recognition Accounting Pronouncements retrospectively with the cumulative effect of initially applying the Revenue Recognition Accounting Pronouncements recognized at the date of initial application recorded as an adjustment to retained earnings, referred to as the "Modified Retrospective Approach." Leases In February 2016, the FASB issued ASU No. 2016-02, "Leases" ("ASU 2016-02"). This ASU revises the accounting related to leases by requiring lessees to recognize a lease liability and a right-of-use asset for all leases. The new lease guidance also simplifies the accounting for sale and leaseback transactions. This ASU is effective for annual reporting periods beginning after December 15, 2018 and early adoption is permitted. Management expects to adopt ASU 2016-02 for annual reporting periods beginning after December 15, 2018. Management is currently evaluating the impact of the adoption of this ASU on the Company’s consolidated financial statements, and expects it will have a material impact on our consolidated financial statements, primarily the consolidated balance sheets and related disclosures.

Recent Accounting Pronounceme20

Recent Accounting Pronouncements (Policies)	3 Months Ended
	Mar. 31, 2017
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Stock Compensation In March 2016, the FASB issued ASU No. 2016-09, "Compensation - Stock Compensation" ("ASU 2016-09"). This ASU revises the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and an option to recognize gross stock compensation expense with actual forfeitures recognized as they occur, as well as certain classifications on the statement of cash flows. This ASU is effective for annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting year, and early adoption is permitted. The Company adopted ASU 2016-09 as of January 1, 2017 using a modified retrospective approach with the option to recognize gross stock compensation expense with actual forfeitures recognized as they occur, with a cumulative-effect adjustment to retained earnings recognized as of January 1, 2017 of $8.7 million . The adoption of ASU 2016-09 also requires all income tax adjustments to be recorded in the consolidated and condensed statements of operations. Revenue Recognition In May 2014, the FASB issued ASU No. 2014-09, "Revenue from Contracts with Customers" ("ASU 2014-09"). This ASU is a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. This ASU was originally effective for annual reporting periods beginning after December 15, 2016 and early adoption was not permitted. In August 2015, the FASB issued ASU No. 2015-14, "Revenue from Contracts with Customers – Deferral of the Effective Date" (ASU-2015-14), which defers the effective date of ASU 2014-09 for one year and permits early adoption as early as the original effective date of ASU 2014-09. Accordingly, ASU 2014-09 is now effective for annual reporting periods beginning after December 15, 2017 and early adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting year. In March 2016, the FASB issued ASU No. 2016-08, "Revenue from Contracts with Customers - Principal versus Agent Considerations" ("ASU 2016-08"). This ASU clarifies the implementation guidance for principal versus agent considerations in ASU 2014-09. This ASU is effective at the same period as ASU 2015-14 and ASU 2014-09. Management expects to adopt ASU 2014-09, ASU 2015-14, and ASU 2016-08 (collectively, the "Revenue Recognition Accounting Pronouncements") for annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting year. While management is still in its assessment process, management generally expects to identify substantially similar performance obligations after adoption of the Revenue Recognition Accounting Pronouncements as compared with deliverables and separate units of accounting under previous revenue recognition guidance. Therefore, the Company generally does not expect the impact of the adoption of the Revenue Recognition Accounting Pronouncements to be significant to its consolidated financial statements. Management expects to apply the Revenue Recognition Accounting Pronouncements retrospectively with the cumulative effect of initially applying the Revenue Recognition Accounting Pronouncements recognized at the date of initial application recorded as an adjustment to retained earnings, referred to as the "Modified Retrospective Approach." Leases In February 2016, the FASB issued ASU No. 2016-02, "Leases" ("ASU 2016-02"). This ASU revises the accounting related to leases by requiring lessees to recognize a lease liability and a right-of-use asset for all leases. The new lease guidance also simplifies the accounting for sale and leaseback transactions. This ASU is effective for annual reporting periods beginning after December 15, 2018 and early adoption is permitted. Management expects to adopt ASU 2016-02 for annual reporting periods beginning after December 15, 2018. Management is currently evaluating the impact of the adoption of this ASU on the Company’s consolidated financial statements, and expects it will have a material impact on our consolidated financial statements, primarily the consolidated balance sheets and related disclosures.

Marketable Securities and Fai21

Marketable Securities and Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of Marketable Securities	The following tables present details of the Company’s marketable securities as of March 31, 2017 and December 31, 2016 (in thousands): March 31, 2017 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Short-term: Investment securities $ 61,044 $ 8 $ (16 ) $ 61,036 Commercial paper 3,241 1 (1 ) 3,241 Long-term: Investment securities 33,262 18 (38 ) 33,242 Total $ 97,547 $ 27 $ (55 ) $ 97,519 December 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Short-term: Investment securities $ 63,135 $ 7 $ (39 ) $ 63,103 Commercial paper 5,641 1 (2 ) 5,640 Long-term: Investment securities 30,985 16 (34 ) 30,967 Total $ 99,761 $ 24 $ (75 ) $ 99,710
Schedule of the Fair Value of the Company's Financial Assets Measured at Fair Value on a Recurring Basis Based on the Three-Tier Value Hierarchy	The following tables set forth the fair value of the Company’s financial assets measured at fair value on a recurring basis as of March 31, 2017 and December 31, 2016 based on the three-tier value hierarchy (in thousands): March 31, 2017 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 113,588 $ — $ — $ 113,588 Short-term investments: Investment securities — 61,036 — 61,036 Commercial paper — 3,241 — 3,241 Restricted cash: Certificate of deposit 5,000 — — 5,000 Long-term: Investment securities — 33,242 — 33,242 Total $ 118,588 $ 97,519 $ — $ 216,107 December 31, 2016 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 200,867 $ — $ — $ 200,867 Short-term investments: Investment securities — 63,103 — 63,103 Commercial paper — 5,640 — 5,640 Restricted cash: Certificate of deposit 5,000 — — 5,000 Long-term: Investment securities — 30,967 — 30,967 Total $ 205,867 $ 99,710 $ — $ 305,577

Intangible Assets and Goodwill

Intangible Assets and Goodwill (Tables)	3 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets	The following table summarizes intangible assets as of March 31, 2017 and December 31, 2016 (in thousands): Weighted - Average Amortization Period (Years) March 31, 2017 Gross Carrying Amount Accumulated Amortization Net Book Value Trademarks 5 $ 1,900 $ (1,393 ) $ 507 Technology 3 1,453 (282 ) 1,171 Customer relationships 5 1,300 (953 ) 347 Total $ 4,653 $ (2,628 ) $ 2,025 Weighted - Average Amortization Period (Years) December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Book Value Trademarks 5 $ 1,900 $ (1,298 ) $ 602 Technology 3 1,453 (161 ) 1,292 Customer relationship 5 1,300 (888 ) 412 Total $ 4,653 $ (2,347 ) $ 2,306

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	3 Months Ended
	Mar. 31, 2017
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	The following table summarizes property and equipment, net as of March 31, 2017 and December 31, 2016 (in thousands): March 31, December 31, Furniture and computer equipment $ 149,258 $ 133,297 Site and software development costs 87,139 77,429 Leasehold improvements 65,652 62,090 Construction in progress 46,808 47,013 Buildings (leased - Note 6) 42,498 29,856 391,355 349,685 Less accumulated depreciation and amortization (128,040 ) (110,331 ) Property and equipment, net $ 263,315 $ 239,354

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Activity Relating to Stock Options	The following table presents activity relating to stock options for the three months ended March 31, 2017 : Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (Years) Outstanding at December 31, 2016 209,759 $ 2.98 4.5 Options exercised (17,981 ) $ 2.90 Outstanding and exercisable at March 31, 2017 191,778 $ 2.99 4.2
Summary of Activity Relating to Restricted Stock	The following table presents activity relating to restricted common stock for the three months ended March 31, 2017 : Shares Weighted- Average Grant Date Fair Value Outstanding at December 31, 2016 60,000 $ 35.05 Unvested and expected to vest at March 31, 2017 60,000 $ 40.49 The following table presents activity relating to RSUs for the three months ended March 31, 2017 : Shares Weighted- Average Grant Date Fair Value Outstanding at December 31, 2016 6,986,776 $ 34.21 RSUs granted 720,706 $ 41.10 RSUs vested (610,079 ) $ 31.26 RSUs forfeited/canceled (169,726 ) $ 36.57 Outstanding and expected to vest at March 31, 2017 6,927,677 $ 35.13

Segment and Geographic Inform25

Segment and Geographic Information (Tables)	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Activity Related to Net Revenue, Adjusted EBITDA and Long-Lived Assets by Segment	The following tables present Direct Retail and Other net revenues and Adjusted EBITDA attributable to the Company's reportable segments for the periods presented (in thousands): Three months ended March 31, 2017 2016 U.S. Direct Retail $ 837,556 $ 672,700 U.S. Other 20,473 33,221 U.S. segment net revenue 858,029 705,921 International Direct Retail 102,796 39,146 International Other — 2,281 International segment net revenue 102,796 41,427 Total net revenue $ 960,825 $ 747,348 Three months ended March 31, 2017 2016 Adjusted EBITDA U.S. $ 3,728 $ (1,039 ) International (24,624 ) (19,921 ) Total reportable segments Adjusted EBITDA (20,896 ) (20,960 ) Less: reconciling items (1) (35,643 ) (20,245 ) Net loss $ (56,539 ) $ (41,205 ) (1) Adjustments are made to reconcile total reportable segments Adjusted EBITDA to consolidated net loss including the following (in thousands): Three months ended March 31, 2017 2016 Depreciation and amortization $ 20,352 $ 10,487 Equity based compensation and related taxes 14,958 10,662 Interest expense (income), net 299 (552 ) Other (income), net (176 ) (669 ) Provision for income taxes 210 317 Total reconciling items $ 35,643 $ 20,245 The following table presents the activity related to the Company’s net revenue from Direct Retail sales derived through the Company’s sites and Other sales derived through sites operated by third parties and fees from third-party advertising distribution providers (in thousands): Three months ended March 31, 2017 2016 Net revenue Direct Retail $ 940,352 $ 711,846 Other 20,473 35,502 Net revenue $ 960,825 $ 747,348 The following table presents long-lived assets by segment (in thousands): March 31, December 31, Geographic long-lived assets U.S. $ 256,807 $ 233,099 International 6,508 6,255 Total $ 263,315 $ 239,354

Net Loss per Share (Tables)

Net Loss per Share (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Schedule of Calculation of Basic and Diluted Net Loss Per Share	The following table presents the calculation of basic and diluted net loss per share (in thousands, except per share data): Three months ended March 31, 2017 2016 Net loss $ (56,539 ) $ (41,205 ) Weighted average common shares used for basic and diluted net loss per share computation 86,036 84,445 Net loss per share: Basic and Diluted $ (0.66 ) $ (0.49 )
Schedule of Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders as their Effect Would Have Been Antidilutive	The following have been excluded from the computation of basic and diluted net loss per share as their effect would have been antidilutive: Three months ended March 31, 2017 2016 Stock options 191,778 262,819 Restricted stock 60,000 — Restricted stock units 6,927,677 6,170,820 Total 7,179,455 6,433,639

Basis of Presentation (Details)

Basis of Presentation (Details) supplier in Thousands, product in Millions	3 Months Ended
	Mar. 31, 2017productsupplier
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of products offered (more than) | product	8
Number of suppliers providing products offered (more than) | supplier	10

Marketable Securities and Fai28

Marketable Securities and Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated fair values	$ 97,519,000		$ 99,710,000
Other-than-temporary impairment loss	0	$ 0
Long-term marketable securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated fair values	$ 33,242,000		$ 30,967,000
Long-term marketable securities | Minimum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities term	1 year
Long-term marketable securities | Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Marketable securities term	3 years

Marketable Securities and Fai29

Marketable Securities and Fair Value Measurements - Schedule of Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Marketable securities and fair value measurements
Amortized Cost	$ 97,547	$ 99,761
Gross Unrealized Gains	27	24
Gross Unrealized Losses	(55)	(75)
Estimated Fair Value	97,519	99,710
Investment securities
Marketable securities and fair value measurements
Amortized Cost	61,044	63,135
Gross Unrealized Gains	8	7
Gross Unrealized Losses	(16)	(39)
Estimated Fair Value	61,036	63,103
Commercial paper
Marketable securities and fair value measurements
Amortized Cost	3,241	5,641
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(1)	(2)
Estimated Fair Value	3,241	5,640
Investment securities
Marketable securities and fair value measurements
Amortized Cost	33,262	30,985
Gross Unrealized Gains	18	16
Gross Unrealized Losses	(38)	(34)
Estimated Fair Value	$ 33,242	$ 30,967

Marketable Securities and Fai30

Marketable Securities and Fair Value Measurements - Schedule of the Fair Value of the Company's Financial Assets Measured at Fair Value on a Recurring Basis Based on the Three-Tier Value Hierarchy (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Marketable securities and fair value measurements
Total	$ 216,107	$ 305,577
Cash equivalents
Marketable securities and fair value measurements
Money market funds	113,588	200,867
Commercial paper	3,241	5,640
Short-term investments
Marketable securities and fair value measurements
Investment securities	61,036	63,103
Restricted cash
Marketable securities and fair value measurements
Certificate of deposit	5,000	5,000
Long-term marketable securities
Marketable securities and fair value measurements
Investment securities	33,242	30,967
Level 1
Marketable securities and fair value measurements
Total	118,588	205,867
Level 1 | Cash equivalents
Marketable securities and fair value measurements
Money market funds	113,588	200,867
Commercial paper	0	0
Level 1 | Short-term investments
Marketable securities and fair value measurements
Investment securities	0	0
Level 1 | Restricted cash
Marketable securities and fair value measurements
Certificate of deposit	5,000	5,000
Level 1 | Long-term marketable securities
Marketable securities and fair value measurements
Investment securities	0	0
Level 2
Marketable securities and fair value measurements
Total	97,519	99,710
Level 2 | Cash equivalents
Marketable securities and fair value measurements
Money market funds	0	0
Commercial paper	3,241	5,640
Level 2 | Short-term investments
Marketable securities and fair value measurements
Investment securities	61,036	63,103
Level 2 | Restricted cash
Marketable securities and fair value measurements
Certificate of deposit	0	0
Level 2 | Long-term marketable securities
Marketable securities and fair value measurements
Investment securities	33,242	30,967
Level 3
Marketable securities and fair value measurements
Total	0	0
Level 3 | Cash equivalents
Marketable securities and fair value measurements
Money market funds	0	0
Commercial paper	0	0
Level 3 | Short-term investments
Marketable securities and fair value measurements
Investment securities	0	0
Level 3 | Restricted cash
Marketable securities and fair value measurements
Certificate of deposit	0	0
Level 3 | Long-term marketable securities
Marketable securities and fair value measurements
Investment securities	$ 0	$ 0

Intangible Assets and Goodwil31

Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 4,653		$ 4,653
Accumulated Amortization	(2,628)		(2,347)
Net Book Value	2,025		$ 2,306
Amortization expense related to intangibles	300	$ 200
Goodwill	$ 1,900
Trademarks
Finite-Lived Intangible Assets [Line Items]
Weighted - Average Amortization Period (Years)	5 years		5 years
Gross Carrying Amount	$ 1,900		$ 1,900
Accumulated Amortization	(1,393)		(1,298)
Net Book Value	$ 507		$ 602
Technology
Finite-Lived Intangible Assets [Line Items]
Weighted - Average Amortization Period (Years)	3 years		3 years
Gross Carrying Amount	$ 1,453		$ 1,453
Accumulated Amortization	(282)		(161)
Net Book Value	$ 1,171		$ 1,292
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted - Average Amortization Period (Years)	5 years		5 years
Gross Carrying Amount	$ 1,300		$ 1,300
Accumulated Amortization	(953)		(888)
Net Book Value	$ 347		$ 412

Property and Equipment, net (De

Property and Equipment, net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Property and equipment, net
Property and equipment, gross	$ 391,355		$ 349,685
Less accumulated depreciation and amortization	(128,040)		(110,331)
Property and equipment, net	263,315		239,354
Depreciation and amortization	20,100	$ 10,300
Furniture and computer equipment
Property and equipment, net
Property and equipment, gross	149,258		133,297
Site and software development costs
Property and equipment, net
Property and equipment, gross	87,139		77,429
Leasehold improvements
Property and equipment, net
Property and equipment, gross	65,652		62,090
Construction in progress
Property and equipment, net
Property and equipment, gross	46,808		47,013
Buildings (leased - Note 6)
Property and equipment, net
Property and equipment, gross	$ 42,498		$ 29,856

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Jun. 30, 2016
Operating Leased Assets [Line Items]
Rental expense under operating leases	$ 11,600	$ 7,100
Letter of credit issued as security for lease agreements	11,400		$ 10,600
Future minimum lease payments for non-cancelable lease			568,700
Additional non-cancelable leases with initial or remaining terms in excess of one year	50,200
Minimum sublease rentals	9,300
Lease financing obligation	41,542		$ 28,900
Land lease expense	100
Interest expense	900
Future minimum commitments related to financing obligation, principal	3,500
Future minimum commitments related to financing obligation, interest	19,200
Collection of Sales or Other Similar Taxes
Operating Leased Assets [Line Items]
Aggregate amount of claims	21,900
Warehouse Lease Arrangement | Three Months Ended June 30, 2016
Operating Leased Assets [Line Items]
Letter of credit issued as security for lease agreements				$ 1,200
Lease financing obligation				$ 28,900
Warehouse Lease Arrangement | Three Months Ended March 31, 2017
Operating Leased Assets [Line Items]
Letter of credit issued as security for lease agreements	800
Lease financing obligation	$ 12,600

Equity-Based Compensation - Nar

Equity-Based Compensation - Narrative (Details) $ in Millions	Oct. 06, 2014vesting_trigger	Mar. 31, 2017USD ($)shares	Jan. 01, 2017shares
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value of stock options exercised		$ 0.7
Aggregate intrinsic value of stock options outstanding and repurchased		7.2
Restricted common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of stock unvested		2.4
Unrecognized share-based compensation		$ 2
Weighted average remaining vesting term for options expected to vest		1 year 9 months 2 days
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized share-based compensation		$ 209.1
Weighted average remaining vesting term for options expected to vest		1 year 283 days
Intrinsic value of stock vested		$ 23.2
Aggregate intrinsic value		$ 280.5
2014 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized | shares		8,603,066
Number of shares available for future grant | shares			8,389,750
Number of vesting triggers | vesting_trigger	2
Service period	5 years

Equity-Based Compensation - Sum

Equity-Based Compensation - Summary of Activity Relating to Stock Options (Details) - Stock options - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Shares
Outstanding at the beginning of the period (in shares)	209,759
Options exercised (in shares)	(17,981)
Outstanding at the end of the period (in shares)	191,778	209,759
Weighted- Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 2.98
Options exercised (in dollars per share)	2.90
Outstanding at the end of the period (in dollars per share)	$ 2.99	$ 2.98
Weighted- Average Remaining Contractual Term (Years)
Outstanding	4 years 82 days	4 years 6 months

Equity-Based Compensation - S36

Equity-Based Compensation - Summary of Activity Relating to Restricted Stock (Details)	3 Months Ended
	Mar. 31, 2017$ / sharesshares
Restricted stock
Shares
Outstanding at the beginning of the period (in shares) | shares	60,000
Outstanding and expected to vest at the end of the period (in shares) | shares	60,000
Weighted- Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 35.05
Outstanding and expected to vest at the end of the period (in dollars per share) | $ / shares	$ 40.49
RSUs
Shares
Outstanding at the beginning of the period (in shares) | shares	6,986,776
RSUs granted (in shares) | shares	720,706
RSUs vested (in shares) | shares	(610,079)
RSUs forfeited/canceled (in shares) | shares	(169,726)
Outstanding and expected to vest at the end of the period (in shares) | shares	6,927,677
Weighted- Average Grant Date Fair Value
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 34.21
RSUs granted (in dollars per share) | $ / shares	41.10
RSUs vested (in dollars per share) | $ / shares	31.26
RSUs forfeited/canceled (in dollars per share) | $ / shares	36.57
Outstanding and expected to vest at the end of the period (in dollars per share) | $ / shares	$ 35.13

Segment and Geographic Inform37

Segment and Geographic Information - Activity Related to Net Revenue and Adjusted EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Direct Retail	$ 940,352	$ 711,846
Other	20,473	35,502
Total net revenue	960,825	747,348
Adjusted EBITDA	(20,896)	(20,960)
Less: reconciling items	(35,643)	(20,245)
Net loss	(56,539)	(41,205)
Depreciation and amortization	20,352	10,487
Equity based compensation and related taxes	14,958	10,662
Interest expense (income), net	299	(552)
Other (income), net	(176)	(669)
Provision for income taxes	210	317
Total reconciling items	35,643	20,245
U.S.
Segment Reporting Information [Line Items]
Direct Retail	837,556	672,700
Other	20,473	33,221
Total net revenue	858,029	705,921
Adjusted EBITDA	3,728	(1,039)
International
Segment Reporting Information [Line Items]
Direct Retail	102,796	39,146
Other	0	2,281
Total net revenue	102,796	41,427
Adjusted EBITDA	$ (24,624)	$ (19,921)

Segment and Geographic Inform38

Segment and Geographic Information - Schedule of Long-Lived Assets by Segment (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Geographic revenue and long-lived assets
Geographic long-lived assets	$ 263,315	$ 239,354
U.S.
Geographic revenue and long-lived assets
Geographic long-lived assets	256,807	233,099
International
Geographic revenue and long-lived assets
Geographic long-lived assets	$ 6,508	$ 6,255

Income Taxes (Details)

Income Taxes (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income tax expense (less than)	$ 210,000	$ 317,000
Unrecognized tax benefits	$ 0	$ 0

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit) (Details)	3 Months Ended	30 Months Ended
	Mar. 31, 2017vote$ / sharesshares	Mar. 31, 2017$ / sharesshares	Dec. 31, 2016$ / sharesshares
Stockholders' Equity
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Class A common stock
Stockholders' Equity
Common stock, shares authorized (in shares)	500,000,000	500,000,000	500,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001	$ 0.001
Common stock, shares outstanding (in shares)	50,971,401	50,971,401	49,945,202
Number of votes each holder is entitled | vote	1
Class B common stock
Stockholders' Equity
Common stock, shares authorized (in shares)	164,000,000	164,000,000	164,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001	$ 0.001
Common stock, shares outstanding (in shares)	35,475,888	35,475,888	35,885,692
Number of votes each holder is entitled | vote	10
Conversion ratio following the completion of the offering	1
Conversion ratio upon transfer	1
Aggregate number of shares outstanding Class A common stock and Class B common stock that shall convert automatically (less than)	10.00%
Number of shares converted into Class A shares		35,220,479
Class B common stock | Maximum
Stockholders' Equity
Aggregate number of shares outstanding Class A common stock and Class B common stock that shall convert automatically (less than)	10.00%
Class B common stock | Minimum
Stockholders' Equity
Percentage of outstanding shares of Class B common stock that shall convert automatically in the event of the affirmative vote or written consent of holders	66.67%

Credit Agreement (Details)

Credit Agreement (Details) - USD ($)	Feb. 22, 2017	Dec. 31, 2016	Mar. 31, 2017
Bank of America
Line of Credit Facility [Line Items]
Amount borrowed under the agreement		$ 0	$ 0
Line of credit | Bank of America
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 65,000,000
Line of credit | LIBOR | Bank of America
Line of Credit Facility [Line Items]
Basis spread		1.75%
Credit Card Program
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 40,000,000
Credit Card Program | Line of credit | Bank of America
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 45,000,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity	100,000,000
Right to increase	$ 25,000,000
Amount borrowed under the agreement		0	$ 0
Revolving Credit Facility | Eurodollar
Line of Credit Facility [Line Items]
Basis spread	1.00%
Applicable margin	0.0175
Revolving Credit Facility | Base Rate
Line of Credit Facility [Line Items]
Applicable margin	0.0075
Revolving Credit Facility | Federal Funds Effective Rate
Line of Credit Facility [Line Items]
Basis spread	0.50%
Revolving Credit Facility | Line of credit | Bank of America
Line of Credit Facility [Line Items]
Maximum borrowing capacity		20,000,000
Revolving Credit Facility | Letter of Credit Sublimit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 40,000,000
Revolving Credit Facility | Swing Line Sublimit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 10,000,000
Revolving Credit Facility | Direct Borrowings | Line of credit | Bank of America
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 5,000,000

Net Loss per Share - Narrative

Net Loss per Share - Narrative (Details)	3 Months Ended
	Mar. 31, 2017vote
Class A common stock
Class of Stock [Line Items]
Number of votes each holder is entitled	1
Class B common stock
Class of Stock [Line Items]
Number of votes each holder is entitled	10
Conversion ratio to Class A	1
Conversion ratio upon transfer	1
Percentage of aggregate number of shares of outstanding (less than)	10.00%
Written consent percentage required	66.67%

Net Loss per Share - Calculatio

Net Loss per Share - Calculation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Net loss	$ (56,539)	$ (41,205)
Weighted average common shares used for basic and diluted net loss per share computation (in shares)	86,036	84,445
Net loss per share:
Basic and Diluted (in dollars per share)	$ (0.66)	$ (0.49)

Net Loss per Share - Computatio

Net Loss per Share - Computation of Basic and Diluted Net Loss Per Share as Their Effect Would Have Been Antidilutive (Details) - shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of antidilutive shares excluded from computation of basic and diluted net loss per share	7,179,455	6,433,639
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of antidilutive shares excluded from computation of basic and diluted net loss per share	191,778	262,819
Restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of antidilutive shares excluded from computation of basic and diluted net loss per share	60,000	0
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of antidilutive shares excluded from computation of basic and diluted net loss per share	6,927,677	6,170,820

Recent Accounting Pronounceme45

Recent Accounting Pronouncements (Details) $ in Millions	Dec. 31, 2016USD ($)
New Accounting Pronouncement, Early Adoption, Effect | Accounting Standards Update 2016-09, Forfeiture Rate Component | Retained Earnings
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cumulative-effect adjustment	$ 8.7