Magnite (MGNI) 10-Q 4 May 22 2022 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2022	Apr. 27, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2022
Document Transition Report	false
Entity File Number	001-36384
Entity Registrant Name	MAGNITE, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8881738
Entity Address, Address Line One	1250 Broadway,
Entity Address, Address Line Two	15th Floor
Entity Address, City or Town	New York,
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10001
City Area Code	212
Local Phone Number	243-2769
Title of 12(b) Security	Common stock, par value $0.00001 per share
Trading Symbol	MGNI
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		131,910,148
Entity Central Index Key	0001595974
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 204,589	$ 230,401
Accounts receivable, net	782,956	927,781
Prepaid expenses and other current assets	22,219	19,934
TOTAL CURRENT ASSETS	1,009,764	1,178,116
Property and equipment, net	34,986	34,067
Right-of-use lease asset	72,363	76,986
Internal use software development costs, net	20,837	20,093
Intangible assets, net	399,419	426,615
Goodwill	978,216	969,873
Other assets, non-current	6,877	6,862
TOTAL ASSETS	2,522,462	2,712,612
Current liabilities:
Accounts payable and accrued expenses	859,178	1,000,956
Lease liabilities, current	18,638	19,142
Debt, current	3,600	3,600
Other current liabilities	5,903	5,697
TOTAL CURRENT LIABILITIES	887,319	1,029,395
Long-term Debt, Excluding Current Maturities	720,710	720,023
Deferred tax liability, net	11,509	13,303
Lease liabilities, non-current	62,777	66,487
Other liabilities, non-current	2,237	2,647
TOTAL LIABILITIES	1,684,552	1,831,855
Commitments and contingencies (Note 12)
STOCKHOLDERS' EQUITY
Preferred stock, $0.00001 par value, 10,000 shares authorized at March 31, 2022 and December 31, 2021; 0 shares issued and outstanding at March 31, 2022 and December 31, 2021	0	0
Common stock, $0.00001 par value; 500,000 shares authorized at March 31, 2022 and December 31, 2021; 132,052 and 132,553 shares issued at March 31, 2022 and December 31, 2021, respectively, and 132,051 and 132,204 shares outstanding at March 31, 2022 and December 31, 2021, respectively	2	2
Additional paid-in capital	1,278,218	1,282,589
Accumulated other comprehensive loss	(1,266)	(1,376)
Treasury stock at cost, 0 and 349 shares outstanding at March 31, 2022 and December 31, 2021, respectively	0	(6,007)
Accumulated deficit	(439,044)	(394,451)
TOTAL STOCKHOLDERS' EQUITY	837,910	880,757
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 2,522,462	$ 2,712,612

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Preferred stock, par value (usd per share)	$ 0.00001	$ 0.00001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (usd per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares, issued (in shares)	132,052,000	132,553,000
Common stock, shares, outstanding (in shares)	132,052,000	132,204,000
Treasury stock outstanding (in shares)	0	349,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Statement [Abstract]
Revenue	$ 118,075	$ 60,715
Expenses:
Cost of revenue	59,396	20,756
Sales and marketing	50,000	22,589
Technology and development	23,043	14,266
General and administrative	18,704	14,158
Merger, acquisition, and restructuring costs	6,756	2,722
Total expenses	157,899	74,491
Loss from operations	(39,824)	(13,776)
Other (income) expense:
Interest expense, net	7,111	143
Other income	(1,263)	(1,223)
Foreign exchange loss, net	926	15
Total other (income) expense, net	6,774	(1,065)
Loss before income taxes	(46,598)	(12,711)
Provision (benefit) for income taxes	(2,005)	166
Net loss	$ (44,593)	$ (12,877)
Net loss per share:
Basic (usd per share)	$ (0.34)	$ (0.11)
Diluted (usd per share)	$ (0.34)	$ (0.11)
Weighted average shares used to compute net loss per share:
Basic (in shares)	132,236	115,296
Diluted (in shares)	132,236	115,296

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Net loss	$ (44,593)	$ (12,877)
Other comprehensive income (loss):
Foreign currency translation adjustments	110	(313)
Other comprehensive income (loss)	110	(313)
Comprehensive loss	$ (44,483)	$ (13,190)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated  Other Comprehensive Income (Loss)	Accumulated Deficit	Treasury Stock
Beginning Balance (in shares) at Dec. 31, 2020		114,029,000
Beginning Balance at Dec. 31, 2020	$ 381,613	$ 2	$ 777,084	$ (957)	$ (394,516)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		733,000
Exercise of common stock options	5,785		5,785
Issuance of common stock related to RSU vesting (in shares)		1,351,000
Stock-based compensation	7,108		7,108
Capped call options	(38,960)		(38,960)
Other comprehensive loss	(313)			(313)
Net loss	(12,877)				(12,877)
Ending Balance (in shares) at Mar. 31, 2021		116,113,000				0
Ending Balance at Mar. 31, 2021	$ 342,356	$ 2	751,017	(1,270)	(407,393)	$ 0
Beginning Balance (in shares) at Dec. 31, 2021	132,204,000	132,553,000				(349,000)
Beginning Balance at Dec. 31, 2021	$ 880,757	$ 2	1,282,589	(1,376)	(394,451)	$ (6,007)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)		311,000
Exercise of common stock options	1,107		1,107
Issuance of common stock related to RSU vesting (in shares)		783,000
Shares withheld related to net share settlement (in shares)		(315,000)
Shares withheld related to net share settlement	(4,260)		(4,260)
Purchase of treasury stock (in shares)						(931,000)
Purchase of treasury stock	(12,138)					$ (12,138)
Retirement of common stock (in shares)		(1,280,000)				1,280,000
Retirement of common stock			(18,145)			$ 18,145
Stock-based compensation	16,927		16,927
Other comprehensive loss	110			110
Net loss	$ (44,593)				(44,593)
Ending Balance (in shares) at Mar. 31, 2022	132,052,000	132,052,000				0
Ending Balance at Mar. 31, 2022	$ 837,910	$ 2	$ 1,278,218	$ (1,266)	$ (439,044)	$ 0

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)	Mar. 31, 2021USD ($)
OPERATING ACTIVITIES:
Net loss	$ (44,593)	$ (12,877)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	45,866	12,485
Stock-based compensation	16,589	6,993
Impairment of intangible assets	3,320	0
(Gain) loss on disposal of property and equipment	(2)	50
Provision for doubtful accounts	(571)	(159)
Amortization of debt discount and issuance costs	1,700	99
Non-cash lease expense	610	(652)
Deferred income taxes	(1,891)	62
Unrealized foreign currency (gains) losses, net	458	(375)
Changes in operating assets and liabilities, net of effect of business acquisitions:
Accounts receivable	146,241	70,252
Prepaid expenses and other assets	(2,279)	1,578
Accounts payable and accrued expenses	(141,312)	(80,074)
Other liabilities	(2,504)	1,392
Net cash provided by (used in) operating activities	21,632	(1,226)
INVESTING ACTIVITIES:
Purchases of property and equipment	(7,184)	(1,317)
Capitalized internal use software development costs	(3,382)	(1,955)
Mergers and acquisitions, net of cash acquired	(20,755)	0
Net cash used in investing activities	(31,321)	(3,272)
FINANCING ACTIVITIES:
Proceeds from Convertible Senior Notes offering	0	389,000
Payment for capped call options	0	(38,960)
Payment for debt issuance costs	0	(198)
Proceeds from exercise of stock options	1,107	5,785
Repayment of debt	(900)	0
Repayment of financing lease	(197)	0
Purchase of treasury stock	(12,138)	0
Taxes paid related to net share settlement	(4,260)	0
Net cash (used in) provided by financing activities	(16,388)	355,627
EFFECT OF EXCHANGE RATE CHANGES ON CASH, CASH EQUIVALENTS AND RESTRICTED CASH	268	(256)
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(25,809)	350,873
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — Beginning of period	230,693	117,731
CASH, CASH EQUIVALENTS AND RESTRICTED CASH — End of period	204,884	468,604
RECONCILIATION OF CASH, CASH EQUIVALENTS AND RESTRICTED CASH TO CONSOLIDATED BALANCE SHEETS
Cash and cash equivalents	204,589	468,550
Restricted cash included in prepaid expenses and other current assets	242	0
Restricted cash included in other assets, non-current	53	54
Total cash, cash equivalents and restricted cash	204,884	468,604
SUPPLEMENTAL DISCLOSURES OF OTHER CASH FLOW INFORMATION:
Cash paid for income taxes	338	226
Cash paid for interest	5,668	51
Capitalized assets financed by accounts payable and accrued expenses	372	6,050
Capitalized stock-based compensation	338	115
Purchase consideration - indemnification claims holdback	2,300	0
Debt issuance costs included in accrued expenses and other liabilities	0	1,349
Debt discount, non-cash	$ 0	$ 11,000

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Organization and Summary of Significant Accounting Policies	Organization and Summary of Significant Accounting Policies Company Overview Magnite, Inc. ("Magnite" or the "Company"), formerly known as The Rubicon Project, Inc., was formed in Delaware and began operations on April 20, 2007. On April 1, 2020, Magnite completed a stock-for-stock merger with Telaria, Inc. ("Telaria" and such merger the "Telaria Merger"), a leading sell-side advertising platform and provider of connected television ("CTV") technology. On April 30, 2021, the Company completed its acquisition of SpotX, Inc. ("SpotX" and such acquisition the "SpotX Acquisition"), a leading CTV and video advertising platform. On July 1, 2021, the Company completed its acquisition of SpringServe, LLC ("SpringServe" and such acquisition the "SpringServe Acquisition"), a leading ad serving platform for CTV. The Company operates a sell-side advertising platform that offers buyers and sellers of digital advertising a single partner for transacting globally across all channels, formats, and auction types. Magnite has its principal offices in New York City, Los Angeles, London, and Sydney, and additional offices in Europe, Asia, North America, and South America. The Company provides a technology solution to automate the purchase and sale of digital advertising inventory for buyers and sellers. The Company’s platform features applications and services for sellers of digital advertising inventory, or publishers, that own or operate websites, applications, CTV channels, and other digital media properties, to manage and monetize their inventory; applications and services for buyers, including advertisers, agencies, agency trading desks, and demand side platforms, to buy digital advertising inventory; and a transparent, independent marketplace that brings buyers and sellers together and facilitates intelligent decision making and automated transaction execution at scale. The Company's clients include many of the world's leading sellers and buyers of digital advertising inventory. Basis of Presentation and Summary of Significant Accounting Policies The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP, for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair statement of the results for the interim period presented have been included. Operating results for the three months ended March 31, 2022 are not necessarily indicative of the results that may be expected for any future interim period, the year ending December 31, 2022, or for any future year. The condensed consolidated balance sheet at December 31, 2021 has been derived from the audited financial statements at that date, but does not include all of the disclosures required by GAAP. The accompanying condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements and notes thereto for the year ended December 31, 2021 included in its 2021 Annual Report on Form 10-K. There have been no significant changes in the Company's accounting policies from those disclosed in its audited consolidated financial statements and notes thereto for the year ended December 31, 2021 included in its Annual Report on Form 10-K. Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported and disclosed financial statements and accompanying footnotes. Due to the economic uncertainty as a result of the COVID-19 pandemic, geopolitical events, including the conflict in Ukraine, and economic and macro-economic factors like labor shortages, supply chain disruptions, and inflation impacting the markets and communities in which our clients operate, it has become more difficult to apply certain assumptions and judgments into these estimates. The extent of the impact of these factors on the Company's operational and financial performance will depend on future developments, which are highly uncertain and cannot be predicted, including but not limited to the duration and how quickly and to what extent normal economic and operating conditions can resume. During the three months ended March 31, 2022, this uncertainty continued to result in a higher level of judgment related to its estimates and assumptions. As of the date of issuance of the condensed consolidated financial statements for the three months ended March 31, 2022, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, judgments, or revise the carrying value of its assets or liabilities. These estimates may change, as new events occur and additional information is obtained, and are recognized in the consolidated financial statements as soon as they become known. Actual results could differ materially from these estimates. Recently Adopted Accounting Standards In July 2021, the FASB issued Update No. 2021-05, Leases (Topic 842)— Lessors – Certain Leases with Variable Lease Payments ("ASU 2021-05"). ASU 2021-05 requires a lessor to classify a lease with variable lease payments that do not depend on an index or rate as an operating lease if specified criteria are met. The Company adopted ASU 2021-05 on January 1, 2022 on a prospective basis, which did not have a material impact on the Company’s condensed consolidated financial statements and related disclosures. Recent Accounting Pronouncements Not Yet Adopted In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805) – Accounting for Contract Assets and Contract Liabilities from Contracts with Customers ("ASU 2021-08"). ASU 2021-08 requires the recognition and measurement of contract assets and contract liabilities acquired in a business combination in accordance with ASC 606, Revenue from Contracts with Customers . Considerations to determine the amount of contract assets and contract liabilities to record at the acquisition date include the terms of the acquired contract, such as timing of payment, identification of each performance obligation in the contract and allocation of the contract transaction price to each identified performance obligation on a relative standalone selling price basis as of contract inception. ASU 2021-08 is effective for the Company beginning in the first quarter of 2023. ASU 2021-08 should be applied prospectively for acquisitions occurring on or after the effective date of the amendments. Early adoption of the proposed amendments would be permitted, including adoption in an interim period. The Company is currently assessing the impact this standard will have on the Company’s consolidated financial statements. The Company does not believe there are any other recently issued and effective or not yet effective pronouncements that would have or are expected to have any significant effect on the Company’s financial position, cash flows or results of operations.

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Net Loss Per Share	Net Loss Per Share The following table presents the basic and diluted net loss per share: Three Months Ended March 31, 2022 March 31, 2021 (in thousands, except per share data) Basic and Diluted Income (Loss) Per Share: Net loss $ (44,593) $ (12,877) Weighted-average common shares outstanding 132,236 115,296 Weighted-average common shares outstanding used to compute net loss per share 132,236 115,296 Basic and diluted net loss per share $ (0.34) $ (0.11) The following weighted-average shares have been excluded from the calculation of diluted net loss per share attributable to common stockholders for each period presented because they are anti-dilutive: Three Months Ended March 31, 2022 March 31, 2021 (in thousands) Options to purchase common stock 2,593 5,400 Unvested restricted stock units 2,415 7,496 Unvested performance stock units 152 197 ESPP shares — 90 Convertible Senior Notes 6,262 — Total shares excluded from net loss per share 11,422 13,183 For the three months ended March 31, 2022, outstanding performance stock units granted during April 2020, April 2021, August 2021, and February 2022 based on a current achievement level of 121%, 0%, 0%, and 51%, respectively, were excluded from the calculation of diluted net loss per share because they were anti-dilutive. For the three months ended March 31, 2021, outstanding performance stock units granted during April 2020, based on a current achievement level of 150%, were excluded from the calculation of diluted net loss per share because they were anti-dilutive. Refer to Note 9—"Stock-Based Compensation" for additional information related to performance stock units. For the three months ended March 31, 2022 and 2021, shares that would be issuable assuming conversion of all of the Convertible Senior Notes (as defined in Note 13) were excluded from the calculation of diluted net loss per share because they were anti-dilutive. Diluted earnings per share for the Convertible Senior Notes is calculated under the if-converted method in accordance with ASC 260, Earnings Per Share . The Convertible Senior Notes have an initial conversion rate of 15.6539 shares of common stock per $1,000 principal amount of the Convertible Senior Notes, which will be subject to anti-dilution adjustments in certain circumstances. As of March 31, 2022 and 2021, the number of shares that would be issuable assuming conversion of all of

Revenue

Revenue	3 Months Ended
	Mar. 31, 2022
Revenue from Contract with Customer [Abstract]
Revenue	Revenue For the majority of transactions on the Company's platforms, the Company reports revenue on a net basis as it does not act as the principal in the purchase and sale of digital advertising inventory because it does not have control of the digital advertising inventory and does not set prices agreed upon within the auction marketplace. For certain advertising campaigns that are transacted through insertion orders, the Company reports revenue on a gross basis, based primarily on its determination that the Company acts as the primary obligor in the delivery of advertising campaigns for buyers with respect to such transactions. For periods prior to the SpotX Acquisition, revenue reported on a gross basis was generally less than 3% of the Company's total revenue. As a result of the SpotX Acquisition, an increased percentage of the Company's revenue is reported on a gross basis. The following table presents our revenue recognized on a net basis and on a gross basis for the three months ended March 31, 2022 and March 31, 2021, respectively. Three Months Ended March 31, 2022 March 31, 2021 (in thousands, except percentages) Revenue: Net basis $ 100,076 85 % $ 58,996 97 % Gross basis 17,999 15 1,719 3 Total $ 118,075 100 % $ 60,715 100 % The following table presents our revenue by channel for the three months ended March 31, 2022 and 2021: Three Months Ended March 31, 2022 March 31, 2021 (in thousands, except percentages) Channel: CTV $ 51,440 44 % $ 11,976 20 % Desktop 27,606 23 20,851 34 Mobile 39,029 33 27,888 46 Total $ 118,075 100 % $ 60,715 100 % The following table presents the Company's revenue disaggregated by geographic location, based on the location of the Company's sellers: Three Months Ended March 31, 2022 March 31, 2021 (in thousands) United States $ 90,408 $ 42,611 International 27,667 18,104 Total $ 118,075 $ 60,715 Payment terms are specified in agreements between the Company and the buyers and sellers on its platform. The Company generally bills buyers at the end of each month for the full purchase price of impressions filled in that month. The Company recognizes volume discounts as a reduction of revenue as they are incurred. Specific payment terms may vary by agreement, but are generally seventy-five days or less. The Company's accounts receivable are recorded at the amount of gross billings to buyers, net of allowances for the amounts the Company is responsible to collect. The Company's accounts payable related to amounts due to sellers are recorded at the net amount payable to sellers (see Note 5). Accordingly, both accounts receivable and accounts payable appear large in relation to revenue reported on a net basis. Accounts receivable are recorded at the invoiced amount, are unsecured, and do not bear interest. The allowance for doubtful accounts is reviewed quarterly, requires judgment, and is based on the best estimate of the amount of probable credit losses in existing accounts receivable. The Company reviews the status of the then-outstanding accounts receivable on a customer-by-customer basis, taking into consideration the aging schedule of receivables, its historical collection experience, current information regarding the client, subsequent collection history, and other relevant data, in establishing the allowance for doubtful accounts. Accounts receivable is presented net of an allowance for doubtful accounts of $2.1 million at March 31, 2022, and $3.5 million at December 31, 2021. Accounts receivable are written off against the allowance for doubtful accounts when the Company determines amounts are no longer collectible. The Company reviews the associated payable to sellers for recovery of buyer receivable allowance and write-offs; in some cases, the Company can reduce the payable to sellers. The reduction of seller payables related to recovery of uncollected buyer receivables is netted against allowance expense. The contra seller payables related to recoveries were $1.2 million and $2.1 million as of March 31, 2022 and December 31, 2021, respectively. The following is a summary of activity in the allowance for doubtful accounts for the three months ended March 31, 2022 and 2021: Three Months Ended March 31, 2022 March 31, 2021 (in thousands) Allowance for doubtful accounts, beginning balance December 31 $ 3,475 $ 2,360 Write-offs — (4) Increase (decrease) in provision for expected credit losses (1,466) (877) Recoveries of previous write-offs 87 20 Allowance for doubtful accounts, ending balance March 31 $ 2,096 $ 1,499 During the three months ended March 31, 2022, the provision for expected credit losses associated with accounts receivable decreased by $1.5 million, offset by decreases of contra seller payables related to recoveries of uncollected buyer receivables of $0.9 million, which resulted in $0.6 million of bad debt expense. During the three months ended March 31, 2021, the provision for expected credit losses associated with accounts receivable decreased by $0.9 million and was offset by decreases of contra seller payables related to recoveries of uncollected buyer receivables of $0.7 million, which resulted in $0.2 million of bad debt expense during the period.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Recurring Fair Value Measurements Fair value represents the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Observable inputs are based on market data obtained from independent sources. The fair value hierarchy is based on the following three levels of inputs, of which the first two are considered observable and the last one is considered unobservable: • Level 1 – Quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. • Level 2 – Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. • Level 3 – Unobservable inputs. The table below sets forth a summary of financial instruments that are measured at fair value on a recurring basis at March 31, 2022: Total Quoted Prices in Significant Other Significant (in thousands) Cash equivalents $ 7,870 $ 7,870 $ — $ — The table below sets forth a summary of financial instruments that are measured at fair value on a recurring basis at December 31, 2021: Total Quoted Prices in Significant Other Significant (in thousands) Cash equivalents $ 7,869 $ 7,869 $ — $ — At March 31, 2022 and December 31, 2021, cash equivalents of $7.9 million and $7.9 million, respectively, consisted of money market funds and commercial paper, with original maturities of three months or less. The carrying amounts of cash equivalents are classified as Level 1 or Level 2 depending on whether or not their fair values are based on quoted market prices for identical securities that are traded in an active market. At March 31, 2022 and December 31, 2021, the Company had Convertible Senior Notes and Term Loan B Facility (as defined in Note 13) included in its balance sheets. The estimated fair value of the Company's Convertible Senior Notes was $292.5 million and $315.5 million as of March 31, 2022 and December 31, 2021, respectively. The estimated fair value of Convertible Senior Notes is based on market rates and the closing trading price of the Convertible Senior Notes as of March 31, 2022 and is classified as Level 2 in the fair value hierarchy. At March 31, 2022 and December 31, 2021, the estimated fair value of the Company's Term Loan B Facility approximates the carrying value based on borrowing rates currently available to the Company for financing with similar terms and is classified as Level 2 in the fair value hierarchy. There were no transfers between Level 1 and Level 2 fair value measurements during the three months ended March 31, 2022 and 2021.

Other Balance Sheet Amounts

Other Balance Sheet Amounts	3 Months Ended
	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Other Balance Sheet Amounts	Other Balance Sheet Amounts Accounts payable and accrued expenses included the following: March 31, 2022 December 31, 2021 (in thousands) Accounts payable—seller $ 821,848 $ 971,220 Accounts payable—trade 16,857 11,904 Accrued employee-related payables 16,575 16,230 Accrued holdback - indemnification claims 3,898 1,602 Total $ 859,178 $ 1,000,956 Restricted cash was $0.3 million at March 31, 2022 and December 31, 2021, which was included within prepaid expenses and other current assets and other assets, non-current.

Goodwill, Intangible Assets, an

Goodwill, Intangible Assets, and Capitalized Costs Incurred in Cloud Computing Arrangements	3 Months Ended
	Mar. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Intangible Assets, and Capitalized Costs Incurred in Cloud Computing Arrangements	Goodwill, Intangible Assets, and Capitalized Costs Incurred in Cloud Computing ArrangementsThe Company's goodwill balance as of March 31, 2022 and December 31, 2021 was $978.2 million and $969.9 million, respectively. The increase during the three months ended March 31, 2022 was a result of the Carbon Acquisition (see Note 7). The Company’s intangible assets as of March 31, 2022 and December 31, 2021 included the following: March 31, 2022 December 31, 2021 (in thousands) Amortizable intangible assets: Developed technology $ 390,378 $ 378,958 Customer relationships 172,500 173,950 In-process research and development 12,730 14,630 Non-compete agreements 2,400 2,270 Trademarks 900 1,400 Total identifiable intangible assets, gross 578,908 571,208 Accumulated amortization—intangible assets: Developed technology (93,579) (75,850) Customer relationships (82,390) (65,702) In-process research and development (1,695) (1,250) Non-compete agreements (1,600) (1,197) Trademarks (225) (594) Total accumulated amortization—intangible assets (179,489) (144,593) Total identifiable intangible assets, net $ 399,419 $ 426,615 Amortization of intangible assets for the three months ended March 31, 2022 and 2021 was $38.5 million and $7.6 million, respectively. During the three months ended March 31, 2022, the Company abandoned certain in-process research and development projects and technology intangible assets. The abandonment resulted in $3.3 million of impairment costs, which was included within merger, acquisition, and restructuring costs in the condensed consolidated statement of operations. The estimated remaining amortization expense associated with the Company's intangible assets was as follows as of March 31, 2022: Fiscal Year Amount (in thousands) Remaining 2022 $ 111,428 2023 104,924 2024 87,294 2025 70,647 2026 24,695 Thereafter 431 Total $ 399,419

Business Combinations

Business Combinations	3 Months Ended
	Mar. 31, 2022
Business Combination and Asset Acquisition [Abstract]
Business Combinations	Business Combinations 2021 Acquisition—SpotX On April 30, 2021, the Company completed the SpotX Acquisition, pursuant to a Stock Purchase Agreement, dated as of February 4, 2021 (the "Purchase Agreement"), by and between the Company and RTL US Holdings, Inc. ("RTL"). The initial purchase price for the SpotX Acquisition was $560 million in cash ("Cash Consideration") and 14,000,000 shares of the Company's common stock. Per the terms of the Purchase Agreement, at the completion of the Company’s offering of its Convertible Senior Notes, RTL elected to increase the Cash Consideration by an amount equal to 20% of the gross proceeds of the Convertible Senior Notes (which amount was equal to $80 million) and to reduce the number of shares of common stock it would otherwise receive by a number of shares of common stock equal to 20% of the gross proceeds of the proposed offering of notes ($80 million) divided by the closing price of a share of our common stock on the trading day immediately prior to the date of pricing of the proposed offering of notes ($49.21). As a result of this election, the adjusted purchase price was $1.1 billion, prior to customary working capital adjustments and other adjustments, consisting of $640.0 million in cash plus 12,374,315 shares of common stock (based on the fair value of the Company's common stock on April 30, 2021). The Cash Consideration was subject to customary working capital and other adjustments. The working capital was approximately $65.2 million, including cash balances acquired and other working capital adjustments, resulting in a total purchase price of $1.2 billion. The Company financed the Cash Consideration through borrowings under the Term Loan B Facility and the Convertible Senior Notes (Note 13). In accordance with ASC 805, the Company recorded the acquisition based on the fair value of the consideration transferred and then allocated the purchase price to the identifiable assets acquired and liabilities assumed based on their respective fair values as of the acquisition date. The excess of the value of consideration transferred over the aggregate fair value of those net assets was recorded as goodwill. Any identified definite lived intangible assets will be amortized over their estimated useful lives and any identified intangible assets with indefinite useful lives and goodwill will not be amortized but will be tested for impairment at least annually. All intangible assets and goodwill will be tested for impairment when certain indicators are present. Determining the fair value of assets acquired and liabilities assumed requires management to use significant judgment and estimates including the selection of valuation methodologies, estimates of future revenues and cash flows, discount rates, and selection of comparable companies. Management's purchase price allocation is preliminary and subject to change pending finalization of the valuation, including finalization of tax attributes and tax related liabilities. Under the acquisition method of accounting for business combinations, if the Company identifies changes to acquired deferred tax asset ("DTA") valuation allowances or liabilities related to uncertain tax positions during the measurement period, and they are related to new information obtained about facts and circumstances that existed as of the acquisition date, those changes are considered a measurement-period adjustment, and the Company will record the offset to goodwill. The Company records all other changes to DTA valuation allowances and liabilities related to uncertain tax positions in current- period income tax expense. For purposes of measuring the estimated fair value, where applicable, of the assets acquired and the liabilities assumed, the Company has applied the guidance in ASC 820, Fair Value Measurement, which establishes a framework for measuring fair value. In accordance with ASC 820, fair value is an exit price and 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." Under ASC 805, acquisition-related transaction costs and acquisition-related restructuring charges are not included as components of consideration transferred but are accounted for as expenses in the period in which the costs are incurred. The following table summarizes the total purchase consideration (in thousands): Cash Consideration $ 640,000 Stock Consideration (Fair Value of Shares of Magnite common stock) 495,591 Working capital adjustment 65,152 Total purchase consideration $ 1,200,743 The purchase consideration for the SpotX Acquisition included 12,374,315 shares of the Company's common stock with a fair value of approximately $495.6 million, based on the close price of the Company's common stock at closing on April 30, 2021, which was $40.05 per share, and working capital adjustment of $65.2 million, mainly consisting of cash balances acquired on the date of the SpotX Acquisition and other opening balance sheet adjustments. During the three months ended March 31, 2022, the Company adjusted the preliminary purchase price allocation for SpotX based on updated fair values associated with the acquired assets and liabilities. Adjustments impacted acquisition related accounts payable and tax accruals. The fair value of the purchase price was allocated to the identifiable assets acquired and liabilities assumed based upon their estimated fair values as of the date of the SpotX Acquisition as set forth below (in thousands): Cash $ 81,967 Restricted cash 199 Accounts receivable 199,649 Prepaid and other assets, current 12,308 Fixed assets 6,823 Intangible assets 429,600 Right-of-use lease asset 10,055 Goodwill 782,719 Total assets to be acquired 1,523,320 Accounts payable and accrued expenses 205,822 Other current liabilities 1,091 Lease liabilities 12,625 Deferred tax liability, net 103,039 Total liabilities to be assumed 322,577 Total purchase price $ 1,200,743 The Company believes the amount of goodwill resulting from the purchase price allocation is primarily attributable to expected synergies from the assembled workforce, an increase in development capabilities, increased offerings to customers, and enhanced opportunities for growth and innovation. Goodwill will not be amortized but instead will be tested for impairment at least annually or more frequently if certain indicators of impairment are present. In the event that goodwill has become impaired, the Company will record an expense for the amount impaired during the quarter in which the determination is made. The acquired intangibles and goodwill resulting from the SpotX Acquisition are not amortizable for tax purposes. The following table summarizes the components of the intangible assets and estimated useful lives as of the date of the SpotX Acquisition (dollars in thousands): Estimated Useful Life Technology $ 280,400 5 years Customer relationships 130,300 2 to 4 years Backlog 11,100 <1 year In-process research and development 5,800 3 years* Non-compete agreements 1,500 1 year Trademarks 500 <1 year Total intangible assets acquired $ 429,600 * In-process research and development consists of six projects with a weighted-average useful life of 3 years. Amortization begins once associated projects are completed and it is determined the projects have alternative future use. The fair value of the acquired technology and in-process research and development was valued using the Excess Earnings Method. This methodology included allocating future revenue projections to the existing technologies and applying decay rates and appropriate discount rates that reflect the respective intangible asset's relative risk profile when compared to other intangible assets as well as the discount rate for the overall business. The Company used the Loss‐of‐Revenue and Income Method in its valuation of the existing customer relationships and non-compete agreements. To the extent that future cash flows of the business would be negatively affected in the absence of these relationships and non-compete agreements, they would be deemed to have economic value. This method attempts to quantify the scenario whereby the owner loses the right to the intangible asset and the resulting losses of revenue and income. Under this analysis, the value of the cash flows with the intangible asset is compared to the value of the cash flows without the intangible asset and the difference represents the value of the intangible asset. This methodology included applying a discount rate and the expected timing it would take to further enhance customer relationships. The fair value of the backlog was based on the Excess Earnings Method, taking into consideration the existing contracts as of the date of the SpotX Acquisition and the respective cost to complete the servicing of the existing agreements. The resulting stream of after tax earnings were discounted to present value by applying an appropriate discount rate for the asset. The discount rate was selected based on the intangible asset’s relative risk profile when compared to the other intangible assets as well as the discount rate for the overall business. The fair value of the trademarks was based on the Income Approach, specifically the Relief‐from‐Royalty Method. Under this method, data is obtained regarding actual royalty payments made for similar intangible assets. After the appropriate royalty rate is determined, the reasonable royalty savings is then discounted to its present value over the remaining technological, economic, or legal life of the intangible asset. Intangible assets are generally amortized on a straight-line basis, which approximates the pattern in which the economic benefits are consumed, over their estimated useful lives. Amortization of developed technology is included in cost of revenues and the amortization of customer relationships, backlog, non-compete agreements, and trademarks is included in sales and marketing expenses in the condensed consolidated statements of operations. Once the projects associated with acquired in-process research and development are completed, amortization will be included in cost of revenues in the condensed consolidated statements of operations. The acquired intangible assets and goodwill resulting from the SpotX Acquisition are not tax deductible. As part of the SpotX Acquisition, deferred tax liabilities were established. As a result of the deferred tax liability balance created by the acquisition, the Company reduced its deferred tax asset valuation allowance by $56.2 million for the year ended December 31, 2021. Such reduction was recognized as an income tax benefit in the post-acquisition consolidated statements of operations for the year ended December 31, 2021. 2021 Acquisition—SpringServe On July 1, 2021, the Company, through its wholly-owned subsidiary, SpotX, completed the SpringServe Acquisition. As a result of the SpringServe Acquisition, SpringServe became a wholly-owned subsidiary of SpotX, and a wholly-owned indirect subsidiary of the Company. The following table summarizes the total estimated purchase consideration (in thousands): Cash Consideration $ 31,136 SpotX initial cash investment in SpringServe 2,075 Fair value appreciation of SpotX purchase right 7,450 Indemnification claims - holdback 1,409 Total purchase consideration $ 42,070 In 2020, SpotX made a minority investment of $2.1 million in SpringServe in conjunction with a strategic partnership agreement between the two companies, which included an option agreement to purchase SpringServe. At the time of Magnite's acquisition of SpotX, the fair value of SpotX's minority investment and purchase right were valued at a combined $7.5 million for a total minority investment and purchase right of $9.5 million. In connection with the SpringServe Acquisition, approximately $1.4 million of the purchase price was held back to cover possible indemnification claims, which is expected to be paid in cash one year after the acquisition. In accordance with ASC 805, the Company recorded the acquisition based on the fair value of the consideration transferred and then allocated the purchase price to the identifiable assets acquired and liabilities assumed based on their respective fair values as of the acquisition date. The excess of the value of consideration transferred over the aggregate fair value of those net assets was recorded as goodwill. Any identified definite lived intangible assets will be amortized over their estimated useful lives and any identified intangible assets with indefinite useful lives and goodwill will not be amortized but will be tested for impairment at least annually. All intangible assets and goodwill will be tested for impairment when certain indicators are present. Determining the fair value of assets acquired and liabilities assumed requires management to use significant judgment and estimates including the selection of valuation methodologies, estimates of future revenues and cash flows, discount rates, and selection of comparable companies. Management's purchase price allocation is preliminary and subject to change pending finalization of the valuation, including finalization of tax attributes and tax related liabilities. Under the acquisition method of accounting for business combinations, if the Company identifies changes to acquired DTA valuation allowances or liabilities related to uncertain tax positions during the measurement period, and they are related to new information obtained about facts and circumstances that existed as of the acquisition date, those changes are considered a measurement-period adjustment, and the Company will record the offset to goodwill. The Company records all other changes to DTA valuation allowances and liabilities related to uncertain tax positions in current- period income tax expense. For purposes of measuring the estimated fair value, where applicable, of the assets acquired and the liabilities assumed, the Company has applied the guidance in ASC 820, Fair Value Measurement, which establishes a framework for measuring fair value. In accordance with ASC 820, fair value is an exit price and 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." Under ASC 805, acquisition-related transaction costs and acquisition-related restructuring charges are not included as components of consideration transferred but are accounted for as expenses in the period in which the costs are incurred. The fair value of the purchase price was allocated to the identifiable assets acquired and liabilities assumed based upon their estimated fair values as of the date of the SpringServe Acquisition as set forth below (in thousands): Cash $ 1,062 Accounts receivable 3,234 Prepaid and other assets, current 157 Fixed assets 25 Intangible assets 23,400 Right-of-use lease asset 1,879 Goodwill 24,156 Total assets to be acquired 53,913 Accounts payable and accrued expenses 2,475 Other current liabilities 35 Lease liabilities 3,179 Deferred tax liability, net 6,154 Total liabilities to be assumed 11,843 Total preliminary purchase price $ 42,070 The Company believes the amount of goodwill resulting from the purchase price allocation is primarily attributable to expected synergies from the assembled workforce, an increase in development capabilities, increased offerings to customers, and enhanced opportunities for growth and innovation. Goodwill will not be amortized but instead will be tested for impairment at least annually or more frequently if certain indicators of impairment are present. In the event that goodwill has become impaired, the Company will record an expense for the amount impaired during the quarter in which the determination is made. The following table summarizes the components of the intangible assets and estimated useful lives as of the date of the SpringServe Acquisition (dollars in thousands): Estimated Useful Life Technology $ 15,500 5 years Customer relationships 5,700 2 years Trademarks and Trade Names 900 3 years In-process research and development 800 3 years* Non-compete agreements 500 2 years Total intangible assets acquired $ 23,400 * In-process research and development consists of two projects with a weighted-average useful life of 3 years. Amortization begins once associated projects are completed and it is determined the projects have alternative future use. The fair value of the acquired technology and in-process research and development was valued using the Excess Earnings Method. This methodology included allocating future revenue projections to the existing technologies and applying decay rates and appropriate discount rates that reflect the respective intangible asset's relative risk profile when compared to other intangible assets as well as considering the risk associated with the overall business. At the acquisition date, SpringServe had existing customer relationships. To the extent that future cash flows of the business would be negatively affected in the absence of these relationships, they would be deemed to have economic value. In addition, certain employees of SpringServe signed two year non-compete agreements. The Company used the Loss‐of‐Revenue and Income Method in its valuation of the existing customer relationships and non-compete agreements. This method attempts to quantify the scenario whereby the owner loses the right to the intangible asset and the resulting losses of revenue and income. Under this analysis, the value of the cash flows with the intangible asset is compared to the value of the cash flows without the intangible asset and the difference represents the value of the intangible asset. This methodology included applying a discount rate and the expected timing it would take to further enhance customer relationships. The fair value of the trademarks and trade names were based on the Income Approach, specifically the Relief‐from‐Royalty Method. Under this method, data is obtained regarding actual royalty payments made for similar intangible assets. After the appropriate royalty rate is determined, the reasonable royalty savings is then discounted to its present value over the remaining technological, economic, or legal life of the intangible asset. Intangible assets are generally amortized on a straight-line basis, which approximates the pattern in which the economic benefits are consumed, over their estimated useful lives. Amortization of developed technology is included in cost of revenues and the amortization of customer relationships, non-compete agreements, and trademarks is included in sales and marketing expenses in the condensed consolidated statements of operations. Once the projects associated with acquired in-process research and development are completed, amortization will be included in cost of revenues in the condensed consolidated statements of operations. The acquired intangibles and goodwill resulting from the SpringServe Acquisition are not tax deductible. As part of the SpringServe Acquisition, deferred tax liabilities were established. As a result of this and the SpotX deferred tax liability balance, the Company recognized an income tax benefit in the post-acquisition consolidated statements of operations for the year ended December 31, 2021. 2021 Acquisition—Nth Party The Company completed the acquisition of Nth Party, Ltd. ("Nth Party"), a developer of cryptographic software for secure audience data sharing and analysis, in December 2021 for a total purchase price of $9.0 million in cash. The Company acquired Nth Party as part of its strategy to further invest in the development and enhancement of industry leading identity and audience solutions. The allocation of purchase consideration resulted in approximately $5.4 million of developed technology intangible assets with an estimated useful life of 5 years, approximately $0.2 million non-compete intangible assets with an estimated useful life of 2 years, approximately $1.3 million of deferred tax liability, and goodwill of approximately $4.8 million, which is attributable to the workforce of Nth Party and revenue growth from the acquisition. Acquired intangibles and goodwill resulting from the Nth Party acquisition are not deductible for income tax purposes. Acquisition related costs associated with the 2021 acquisitions included in the "Merger, acquisition, and restructuring costs" in the Company's condensed consolidated statements of operations during the three months ended March 31, 2022 were immaterial. Unaudited Pro Forma Information The following table provides unaudited pro forma information as if the SpotX and SpringServe Acquisitions had been acquired by the Company as of January 1, 2020. The unaudited pro forma information reflects adjustments for additional amortization resulting from the fair value adjustments to assets acquired and liabilities assumed, adjustments for alignment of accounting policies, and transaction expenses as if the SpotX and SpringServe Acquisitions occurred on January 1, 2020. The pro forma results do not include any anticipated cost synergies or other effects of the combined companies. Accordingly, pro forma amounts are not necessarily indicative of the results that actually would have occurred had the SpotX and SpringServe Acquisitions been completed on the dates indicated, nor is it indicative of the future operating results of the combined company. Three Months Ended March 31, 2021 (in thousands) Pro Forma Revenue $ 111,277 Pro Forma Net Income (Loss) $ (36,876) 2022 Acquisition—Carbon The Company completed the acquisition of the business of Carbon (AI) Limited ("Carbon" and such acquisition the "Carbon Acquisition"), a platform that enables publishers to measure, manage, and monetize audience segments, in February 2022 for a total purchase price of $23.1 million in cash. Approximately $2.3 million of the purchase price was held back to cover possible indemnification claims, which is expected to be paid in cash one year after the acquisition. The Company acquired Carbon as part of its strategy to further invest in the development and enhancement of industry leading identity and audience solutions. The allocation of purchase consideration resulted in an estimated $14.2 million of developed technology intangible assets with an estimated useful life of 5 years, $0.2 million non-compete intangible assets with an estimated useful life of 2 years, $0.2 million of customer relationships with an estimated useful life of 0.5 years, and goodwill of $8.5 million, which is attributable to the workforce of Carbon and revenue growth from the acquisition. For tax purposes, the Carbon Acquisition was treated as an asset acquisition. The acquisition of identified intangibles results in tax deductible amortization pursuant to IRC Section 197. Acquisition related costs associated with the Carbon Acquisition included in the "Merger, acquisition, and restructuring costs" in the Company's condensed consolidated statements of operations during the three months ended March 31, 2022 were immaterial.

Merger, Acquisition, and Restru

Merger, Acquisition, and Restructuring Costs	3 Months Ended
	Mar. 31, 2022
Restructuring and Related Activities [Abstract]
Merger, Acquisition, and Restructuring Costs	Merger, Acquisition, and Restructuring Costs Merger, acquisition, and restructuring costs consist primarily of professional services fees and employee termination costs, including stock-based compensation charges, associated with the Telaria Merger, the SpotX Acquisition, and restructuring activities. The following table summarizes merger, acquisition, and restructuring cost activity (in thousands): Three Months Ended March 31, 2022 March 31, 2021 (in thousands) Professional services (investment banking advisory, legal and other professional services) $ 775 $ 2,226 Personnel related (severance and one-time termination benefit costs) 717 119 Non-cash stock-based compensation (double-trigger acceleration and severance) 1,944 377 Impairment costs of abandoned technology 3,320 — Total merger, acquisition, and restructuring costs $ 6,756 $ 2,722 During the three months ended March 31, 2022 and March 31, 2021, the Company incurred costs of $6.8 million and $2.7 million, respectively, primarily related to the acquisitions of SpotX and SpringServe. Accrued restructuring costs related to mergers and acquisitions were $2.8 million and $2.7 million at March 31, 2022 and December 31, 2021, respectively, and were primarily related to the SpotX Acquisition, the SpringServe Acquisition, and the Telaria Merger. Accrued restructuring costs associated with personnel costs are included within accounts payable and accrued expenses and accruals related to the assumed loss contracts are included within other current liabilities and other liabilities, non-current on the Company's condensed consolidated balance sheets. (in thousands) Accrued restructuring costs at December 31, 2021 $ 2,742 Restructuring costs, personnel related and non-cash stock-based compensation 2,661 Restructuring costs, impairments 3,320 Cash paid for restructuring costs (658) Non-cash impairments (3,320) Non-cash stock-based compensation (1,944) Accrued restructuring costs at March 31, 2022 $ 2,801

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2022
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation In connection with its IPO, the Company implemented its 2014 Equity Incentive Plan, which governs equity awards made to employees and directors of the Company since the IPO. Prior to the IPO, the Company granted equity awards under its 2007 Stock Incentive Plan, which governs equity awards made to employees and contractors prior to the IPO. In November 2014, the Company approved the 2014 Inducement Grant Equity Incentive Plan (the "Inducement Plan"), which governs certain equity awards made to certain employees in connection with commencement of employment. In connection with the Company's acquisitions of Chango Inc. ("Chango"), iSocket, Inc. ("iSocket"), and nToggle, Inc. ("nToggle") it assumed the existing employee equity award plans, the 2009 Chango Stock Option Plan (the "Chango Plan"), the iSocket 2009 Equity Incentive Plan (the "iSocket Plan"), and the nToggle 2014 Equity Incentive Plan (the "nToggle Plan"). In connection with the Merger with Telaria, the Company assumed Telaria's 2013 Equity Incentive Plan, as amended (the "Telaria Plan"); the 2008 Stock Plan, as amended (the "2008 Stock Plan"); and the ScanScout, Inc. 2009 Equity Incentive Plan, as amended (the "ScanScout Plan"). All compensatory equity awards outstanding at March 31, 2022 were issued pursuant to the 2014 Equity Incentive Plan, the iSocket Plan, the Chango Plan, the nToggle Plan, the Telaria Plan, the 2008 Stock Plan, the ScanScout Plan, the Inducement Plan, or the Company's 2007 Stock Incentive Plan. The Company’s equity incentive plans provide for the grant of equity awards, including non-statutory or incentive stock options, restricted stock awards ("RSAs"), restricted stock units ("RSUs"), and performance stock units ("PSUs"), to the Company's employees, officers, directors, and consultants. The Company's board of directors administers the plans. Options outstanding vest based upon continued service at varying rates, but generally over four years from issuance with 25% vesting after one year of service and the remainder vesting monthly thereafter. RSAs and RSUs vest at varying rates, typically approximately 25% vesting after approximately one year of service and the remainder vesting annually, semi-annually, or quarterly thereafter. The restricted stock units granted in 2022 included 0.2 million awards that vest 50% on each of the first and second anniversaries of the grant date. Options, RSAs, and RSUs granted under the plans accelerate under certain circumstances for certain participants upon a change in control, as defined in the governing plan. No further awards were granted under the iSocket Plan, the Chango Plan, or the nToggle Plan from the date of acquisition and no further awards were granted under the 2007 Stock Incentive Plan since the IPO. Available shares under the iSocket Plan, the Chango Plan, and the nToggle Plan were rolled into the available share pool under the 2014 Equity Incentive Plan at the time of acquisition of each company, and available shares under the 2007 Stock Incentive Plan were rolled into the available share pool under the 2014 Equity Incentive Plan at the time of the IPO. An aggregate of 13,212,745 shares remained available for future grants at March 31, 2022 under the plans. The 2014 Equity Incentive Plan has an evergreen provision pursuant to which the share reserve will automatically increase on January 1 st of each year in an amount equal to 5% of the total number of shares of capital stock outstanding on December 31 st of the preceding calendar year, although the Company’s board of directors may provide for a lesser increase, or no increase, in any year. The 2014 Inducement Grant Equity Incentive Plan has a provision pursuant to which the share reserve may be increased at the discretion of the Company's board of directors. Stock Options A summary of stock option activity for the three months ended March 31, 2022 is as follows: Shares Under Option Weighted- Average Exercise Price Weighted- Average Contractual Life Aggregate Intrinsic Value (in thousands) (in thousands) Outstanding at December 31, 2021 5,129 $ 7.25 Granted 699 $ 13.90 Exercised (311) $ 3.56 Expired (21) $ 15.24 Outstanding at March 31, 2022 5,496 $ 8.27 5.9 years $ 35,278 Exercisable at March 31, 2022 3,763 $ 5.76 4.6 years $ 29,168 The total intrinsic value of options exercised during the three months ended March 31, 2022 was $3.3 million. At March 31, 2022, the Company had unrecognized employee stock-based compensation expense relating to nonvested stock options of approximately $13.1 million, which is expected to be recognized over a weighted-average period of 2.7 years. Total fair value of options vested during the three months ended March 31, 2022 was $1.2 million. The Company estimates the fair value of stock options that contain service and/or performance conditions using the Black-Scholes option pricing model. The grant date fair value of options granted during the three months ended March 31, 2022 was $8.93 per share. The weighted-average input assumptions used by the Company were as follows: Three Months Ended March 31, 2022 March 31, 2021 Expected term (in years) 5.0 N/A Risk-free interest rate 1.63 % N/A Expected volatility 79 % N/A Dividend yield — % N/A Restricted Stock Units A summary of restricted stock unit activity for the three months ended March 31, 2022 is as follows: Number of Shares Weighted-Average Grant Date Fair Value (in thousands) Restricted stock units outstanding at December 31, 2021 6,634 $ 18.39 Granted 6,556 $ 13.87 Canceled (284) $ 17.95 Vested and released (783) $ 9.27 Restricted stock units outstanding at March 31, 2022 12,123 $ 16.54 Restricted stock units outstanding and unvested* 12,086 * $ 16.57 *At March 31, 2022, outstanding restricted stock units included 37,318 units that were vested but deferred. The weighted-average grant date fair value per share of restricted stock units granted during the three months ended March 31, 2022 was $13.87. The aggregate fair value of restricted stock units that vested during the three months ended March 31, 2022 was $10.6 million. At March 31, 2022, the intrinsic value of unvested restricted stock units was $159.6 million. At March 31, 2022, the Company had unrecognized stock-based compensation expense relating to unvested restricted stock units of approximately $172.3 million, which is expected to be recognized over a weighted-average period of 3.1 years. Performance Stock Units In April 2020, April 2021, and February 2022, the Company granted the Company's CEO 146,341, 26,291, and 86,806 performance stock units that vest based on share price metrics tied to total shareholder return over a three year period with a fair value of $0.9 million, $1.4 million, and $1.5 million, respectively. The grant date fair value per share of these grants was $6.15, $52.49, and $17.28, respectively, which was estimated using a Monte-Carlo lattice model. At March 31, 2022, the Company had unrecognized employee stock-based compensation expense for the April 2020, April 2021, and February 2022 grants of approximately $0.3 million, $0.9 million, and $1.4 million, which is expected to be recognized over the remaining 1 year, 2 years, and 2.8 years, respectively. Between 0% and 150% of the performance stock units will vest on the third anniversary of its grant date. In August 2021, the Company granted the Company's CEO 379,635 performance stock units, which are subject to both time-based and performance-based vesting conditions. The performance stock units consist of three equal tranches (each, a "Performance Tranche"), based on achievement of a share price condition if the Company achieves share price targets of $60.00, $80.00, and $100.00, respectively, over 60 consecutive trading days during a performance period commencing on August 26, 2022 and ending on August 26, 2026. To the extent any of the performance-based requirements are met, the Company's CEO must also provide continued service to the Company through at least August 26, 2024 to receive any shares of common stock underlying the grant and through August 26, 2026 to receive all of the shares of common stock underlying the performance units that have satisfied the applicable performance-based requirement. The fair value of each of the Performance Tranches was $3.0 million, $2.8 million, and $2.6 million, respectively, and have a grant date fair value per share of restricted stock of $23.94, $21.93, and $20.30, respectively, which was estimated using a Monte-Carlo lattice model. At March 31, 2022, the Company had unrecognized employee stock-based compensation expense of approximately $2.4 million, $2.4 million, and $2.3 million, which is expected to be recognized over the remaining 2.4 years, 3.4 years, and 4.4 years, respectively. Between 0% and 100% of the performance stock units will vest on each of the tranche dates. During the three months ended March 31, 2022 and 2021, the Company recognized $0.8 million and $0.3 million, respectively, of stock-based compensation related to these performance stock units based on a performance measurement of 100%. The compensation expense will not be reversed if the performance metrics are not met. Employee Stock Purchase Plan In November 2013, the Company adopted the Company's 2014 Employee Stock Purchase Plan ("ESPP"). The ESPP is designed to enable eligible employees to periodically purchase shares of the Company's common stock at a discount through payroll deductions of up to 10% of their eligible compensation, subject to any plan limitations. At the end of each six-month offering period, employees are able to purchase shares at a price per share equal to 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. Offering periods generally commence and end in May and November of each year. As of March 31, 2022, the Company has reserved 4,256,520 shares of its common stock for issuance under the ESPP. The ESPP has an evergreen provision pursuant to which the share reserve will automatically increase on January 1st of each year in an amount equal to 1% of the total number of shares of capital stock outstanding on December 31st of the preceding calendar year, although the Company’s board of directors may provide for a lesser increase, or no increase, in any year. Stock-Based Compensation Expense Total stock-based compensation expense recorded in the condensed consolidated statements of operations was as follows: Three Months Ended March 31, 2022 March 31, 2021 (in thousands) Cost of revenue $ 350 $ 85 Sales and marketing 5,341 2,461 Technology and development 4,717 1,826 General and administrative 4,237 2,244 Merger, acquisition, and restructuring costs 1,944 377 Total stock-based compensation expense $ 16,589 $ 6,993

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes In determining quarterly provisions for income taxes, the Company uses the annual estimated effective tax rate applied to the actual year-to-date income. The Company's annual estimated effective tax rate differs from the statutory rate primarily as a result of state taxes, foreign taxes, deductible stock option expenses, nondeductible executive compensation, and changes in the Company's valuation allowance. The Company recorded an income tax benefit of $2.0 million and expense of $0.2 million for the three months ended March 31, 2022 and 2021, respectively. The tax benefit for the three months ended March 31, 2022 is primarily the result of recognizing the benefit of deferred tax assets previously subject to the domestic valuation allowance and the foreign income tax provision. The net deferred tax liabilities recorded in connection with the prior year acquisitions and our current year taxable income provided additional sources of taxable income to support the realizability of pre-existing deferred tax assets. The Company continues to maintain a partial valuation allowance for the domestic deferred tax assets. Due to uncertainty as to the realization of benefits from the Company's domestic and certain international deferred tax assets, including net operating loss carryforwards and research and development tax credits, the Company has a partial valuation allowance reserved against such assets. The Company intends to continue to maintain a partial valuation allowance on the deferred tax assets until there is sufficient evidence to support the reversal of all or some additional portion of these allowances. Due to the net operating loss carryforwards, all of the Company's United States federal and a majority of its state returns are open to examination by the Internal Revenue Service and state jurisdictions for all years since inception. The 2017 U.S. Income Tax Return for Telaria, Inc. was under examination by the IRS, which was closed during the period ended June 30, 2021 with no change to tax as reported. For the Netherlands and the United Kingdom, all tax years remain open for examination by the local country tax authorities, for France only 2018 forward are open for examination, for Singapore 2017 and forward are open for examination, for Australia, Brazil, Canada, Germany, Italy, New Zealand, and Malaysia 2016 and forward are open for examination, and for Japan 2014 and forward remain open for examination. Pursuant to Section 382 of the Internal Revenue Code, the Company and Telaria, Inc. both underwent ownership changes for tax purposes (i.e. a more than 50% change in stock ownership in aggregated 5% shareholders) on April 1, 2020 due to the Telaria Merger. As a result, the use of our total domestic NOL carryforwards and tax credits generated prior to the ownership change will be subject to annual use limitations under Section 382 and Section 383 of the Code and comparable state income tax laws. The Company believes that the ownership change will not impact our ability to utilize substantially all of our NOLs and state research and development carryforward tax credits to the extent it will generate taxable income that can be offset by such losses. The Company reasonably expects its pre-2021 federal research and development carryforward tax credits will not be recovered prior to expiration. There was no material change to the Company's unrecognized tax benefits in the three months ended March 31, 2022 and the Company does not expect to have any material changes to unrecognized tax benefits through the end of the fiscal year.

Lease Obligations

Lease Obligations	3 Months Ended
	Mar. 31, 2022
Leases [Abstract]
Lease Obligations	Lease ObligationsFor the three months ended March 31, 2022 and 2021, the Company recognized $5.6 million and $3.8 million, respectively, of lease expense under ASC 842, which included operating lease expenses associated with leases included in the lease liability and right of use ("ROU") asset on the condensed consolidated balance sheets. In addition, for the three months ended March 31, 2022 and 2021, the Company recognized $0.3 million and $0.3 million, respectively, of lease expense related to short-term leases, and $11.0 million and $6.4 million during the three months ended March 31, 2022 and 2021, respectively, of variable and cloud-based services related to data centers that are not included in the ROU asset or lease liability balances. The Company also received rental income of $1.3 million and $1.2 million for real estate leases for which it subleases the property to third parties during the three months ended March 31, 2022 and 2021, respectively. As of March 31, 2022, a weighted average discount rate of 5.15% has been applied to the remaining lease payments to calculate the lease liabilities included within the condensed consolidated balance sheet. The lease terms of the Company’s operating leases generally range from one year to ten years, and the weighted average remaining lease term of leases included in the lease liability is 6.4 years as of March 31, 2022. The maturity of the Company's lease liabilities associated with leases included in the lease liability and ROU asset were as follows as of March 31, 2022 (in thousands): Fiscal Year Remaining 2022 $ 16,397 2023 19,406 2024 16,593 2025 8,783 2026 7,761 Thereafter 27,302 Total lease payments (undiscounted) 96,242 Less: imputed interest (14,827) Lease liabilities—total (discounted) $ 81,415 In addition to the lease liabilities included in these condensed consolidated financial statements at March 31, 2022, during the three months ended March 31, 2022, the Company entered into agreements for office leases in San Francisco and Toronto, which have not commenced as of March 31, 2022; therefore, they are not included in the lease liability on the balance sheet as of March 31, 2022. The Company has future commitments totaling $2.3 million and $0.6 million, over the course of 5.4 years, and 5.0 years, respectively for these office leases.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments The Company has commitments under non-cancelable operating leases for facilities, certain equipment, and its managed data center facilities (Note 11). As of March 31, 2022 and December 31, 2021, the Company had $5.3 million and $5.1 million, respectively, of letters of credit associated with office leases available for borrowing, of which there were no outstanding borrowings as of either date. Guarantees and Indemnification The Company’s agreements with sellers, buyers, and other third parties typically obligate the Company to provide indemnity and defense for losses resulting from claims of intellectual property infringement, damages to property or persons, business losses, or other liabilities. Generally, these indemnity and defense obligations relate to the Company’s own business operations, obligations, and acts or omissions. However, under some circumstances, the Company agrees to indemnify and defend contract counterparties against losses resulting from their own business operations, obligations, and acts or omissions, or the business operations, obligations, and acts or omissions of third parties. For example, because the Company’s business interposes the Company between buyers and sellers in various ways, buyers often require the Company to indemnify them against acts and omissions of sellers, and sellers often require the Company to indemnify them against acts and omissions of buyers. In addition, the Company’s agreements with sellers, buyers, and other third parties typically include provisions limiting the Company’s liability to the counterparty, and the counterparty’s liability to the Company. These limits sometimes do not apply to certain liabilities, including indemnity obligations. These indemnity and limitation of liability provisions generally survive termination or expiration of the agreements in which they appear. The Company has also entered into indemnification agreements with its directors, executive officers, and certain other officers 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 material demands have been made upon the Company to provide indemnification under such agreements and there are no claims that the Company is aware of that could have a material effect on the Company’s consolidated financial statements. Litigation The Company and its subsidiaries may from time to time be parties to legal or regulatory proceedings, lawsuits and other claims incident to their business activities and to the Company’s status as a public company. Such matters may include, among other things, assertions of contract breach or intellectual property infringement, claims for indemnity arising in the course of the Company’s business, regulatory investigations or enforcement proceedings, and claims by persons whose employment has been terminated. Such matters are subject to many uncertainties, and outcomes are not predictable with assurance. Consequently, management is unable to ascertain the ultimate aggregate amount of monetary liability, amounts which may be covered by insurance or recoverable from third parties, or the financial impact with respect to such matters as of March 31, 2022. However, based on management’s knowledge as of March 31, 2022, management believes that the final resolution of these matters known at such date, individually and in the aggregate, will not have a material adverse effect upon the Company’s consolidated financial position, results of operations or cash flows. Employment Contracts

Debt

Debt	3 Months Ended
	Mar. 31, 2022
Debt Disclosure [Abstract]
Debt	Debt Long term debt as of March 31, 2022 and December 31, 2021 consisted of the following: March 31, 2022 December 31, 2021 (in thousands) Convertible Senior Notes $ 400,000 $ 400,000 Less: Unamortized debt issuance cost (9,071) (9,643) Net 390,929 390,357 Term Loan B Facility 357,300 358,200 Less: Unamortized discount and debt issuance cost (23,919) (24,934) Net 333,381 333,266 Less: Current portion (3,600) (3,600) Total non-current debt $ 720,710 $ 720,023 Maturities of the principal amount of the Company's long-term debt as of March 31, 2022 are as follows (in thousands): Fiscal Year Remaining 2022 $ 2,700 2023 3,600 2024 3,600 2025 3,600 2026 403,600 Thereafter 340,200 Total $ 757,300 Amortization of the debt issuance cost and the discount associated with our indebtedness totaled $1.7 million for the three months ended March 31, 2022 and $0.1 million for the three months ended March 31, 2021. Amortization of debt issuance costs is computed using the effective interest method and is included in interest expense. Convertible Senior Notes and Capped Call Transactions In March 2021, the Company issued $400.0 million aggregate principal amount of 0.25% convertible senior notes in a private placement, including $50.0 million aggregate principal amount of such notes pursuant to the exercise in full of the over-allotment options of the initial purchasers (collectively, the "Convertible Senior Notes"). The Convertible Senior Notes will mature on March 15, 2026, unless earlier repurchased, redeemed or converted. The total net proceeds from the offering, after deducting debt issuance costs, paid by the Company, were approximately $388.6 million. The Company used approximately $39.0 million of the net proceeds from the offering to pay for the Capped Call Transactions (as described below). The Convertible Senior Notes are senior, unsecured obligations and (i) will be equal in right of payment with the existing and future senior, unsecured indebtedness; (ii) senior in right of payment to any of the Company’s future indebtedness that is expressly subordinated to the Convertible Senior Notes; (iii) effectively subordinated to the Company’s existing and future secured indebtedness, to the extent of the value of the collateral securing that indebtedness, including amounts outstanding under our Loan Agreement or our new Credit Agreement (see section below); and (iv) structurally subordinated to all existing and future indebtedness and other liabilities, including trade payables, and (to the extent we are not a holder thereof) preferred equity, if any, of the Company’s subsidiaries that do not guarantee the Convertible Senior Notes. The Convertible Senior Notes accrue interest at 0.25% per annum payable semi-annually in arrears on March 15 and September 15 of each year, beginning on September 15, 2021. The Convertible Senior Notes will mature on March 15, 2026 unless they are redeemed, repurchased or converted prior to such date. The Convertible Senior Notes are convertible at the option of holders only during certain periods and upon satisfaction of certain conditions. Holders will have the right to convert their notes (or any portion of a note in an authorized denomination), in the following circumstances: (i) during any calendar quarter commencing after the calendar quarter ending on June 30, 2021, if the last reported sale price per share of the Company’s common stock exceeds 130% of the conversion price for each of at least 20 trading days during the 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter; (ii) during the five consecutive business days immediately after any ten consecutive trading day period (such ten consecutive trading day period, the "measurement period") in which the trading price per $1,000 principal amount of notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price per share of the Company’s common stock on such trading day and the conversion rate on such trading day; (iii) upon the occurrence of certain corporate events or distributions on the Company’s common stock; (iv) if the Company calls such Convertible Senior Notes for redemption; and (v) on or after September 15, 2025, until the close of business on the second scheduled trading day immediately before the maturity date, holders of the Convertible Senior Notes may, at their option, convert all or a portion of their Convertible Senior Notes regardless of the foregoing conditions at any time from, and including, September 15, 2025 until the close of business on the second scheduled trading day immediately before the maturity date. Upon conversion, the Convertible Senior Notes may be settled in shares of the Company’s common stock, cash or a combination of cash and shares of the Company’s common stock, at the Company’s election. All conversions with a conversion date that occurs on or after September 15, 2025 will be settled using the same settlement method, and the Company will send notice of such settlement method to noteholders no later than the open of business on September 15, 2025. The Company may not redeem the Convertible Senior Notes at their option at any time before March 20, 2024. Subject to the terms of the indenture agreement, the Company has the right, at its election, to redeem all, or any portion (subject to the partial redemption limitation) in an authorized denomination, of the Convertible Senior Notes, at any time, and from time to time, on a redemption date on or after March 20, 2024 and on or before the 40th scheduled trading day immediately before the maturity date, for cash, but only if the "last reported sale price," as defined under the Offering Memorandum, per share of common stock exceeds 130% of the “conversion price” on (i) each of at least 20 trading days, during the 30 consecutive trading days ending on, and including, the trading day immediately before the date the Company sends the related redemption notice; and (ii) the trading day immediately before the date we send such notice. In addition, calling any note for redemption will constitute a "make-whole fundamental change" (as defined below) with respect to that note, in which case the conversion rate applicable to the conversion of that note will be increased in certain circumstances if it is converted after it is called for redemption. If the Company elects to redeem less than all of the outstanding notes, then the redemption will not constitute a make-whole fundamental change with respect to the notes not called for redemption, and holders of the notes not called for redemption will not be entitled to an increased conversion rate for such notes as described above on account of the redemption, except to the limited extent described further below. No sinking fund is provided for the Convertible Senior Notes, which means that the Company is not required to redeem or retire the Convertible Senior Notes periodically. If a fundamental change occurs, then each noteholder will have the right to require the Company to repurchase its notes (or any portion thereof in an authorized denomination) for cash on a date (the "fundamental change repurchase date") of the Company’s choosing, which must be a business day that is no more than 45, nor less than 20, business days after the date Magnite distributes the related fundamental change notice. If an event of default, other than a reporting default remedied by special interest as defined in the indenture agreement, occurs with respect to the Company or any guarantor, then the principal amount of, and all accrued and unpaid interest on, all of the notes then outstanding will immediately become due and payable without any further action or notice by any person. If an event of default (other than a reporting event of default described above with respect to Magnite or any guarantor and not solely with respect to a significant subsidiary of the Company’s or a guarantor, other than the Company or such guarantor) occurs and is continuing, then, the trustee, by notice to the Company, or noteholders of at least 25% of the aggregate principal amount of notes then outstanding, by written notice to the Company and the trustee, may declare the principal amount of, and all accrued and unpaid interest on, all of the notes then outstanding to become due and payable immediately. The Convertible Senior Notes have an initial conversion rate of 15.6539 shares of common stock per $1,000 principal amount of the Convertible Senior Notes, which will be subject to customary anti-dilution adjustments in certain circumstances. In connection with the pricing of the Convertible Senior Notes, the Company entered into privately negotiated capped call transactions with various financial institutions (the "Capped Call Transactions"). The Capped Call Transactions were entered into with third party broker-dealers to limit the potential dilution that would occur if the Company has to settle the conversion value in excess of the principal in shares. This exposure will be covered (i.e., the Company will receive as many shares as are required to be issued between the conversion price of $63.8818 and the maximum price of $91.2600). Any shares required to be issued by the Company over this amount would have net earnings per share dilution impact. By entering into the Capped Call Transactions, the Company expects to reduce the potential dilution to its common stock (or, in the event the conversion is settled in cash, to reduce its cash payment obligation) in the event that at the time of conversion its stock price exceeds the conversion price under the Convertible Senior Notes. The Company paid $39.0 million for the Capped Call Transactions, which was recorded as additional paid-in capital, using a portion of the gross proceeds from the sale of the Convertible Senior Notes. The cost of the Capped Call Transactions is not expected to be tax deductible as the Company did not elect to integrate the capped call into the Convertible Senior Notes for tax purposes. The cost of the Capped Call Transaction was recorded as a reduction of the Company’s additional paid-in capital in the accompanying condensed consolidated financial statements. The Company incurred debt issuance costs of $11.4 million in March 2021. The Convertible Senior Notes are presented net of issuance costs on the Company's condensed consolidated balance sheets. The debt issuance costs are amortized on an effective interest basis over the term of the Convertible Senior Notes and are included in interest expense and amortization of debt discount in the accompanying condensed consolidated statements of operations. The following table sets forth interest expense related to the Convertible Senior Notes for the three months ended March 31, 2022 and 2021: Three Months Ended March 31, 2022 March 31, 2021 (in thousands) Contractual interest expense $ 250 $ 36 Amortization of debt issuance costs 572 83 Total interest expense $ 822 $ 119 Effective interest rate 0.82 % 0.82 % Amortization expense for the Company's debt issuance costs related to the Convertible Senior Notes for the fiscal years 2022 through 2026 is as follows (in thousands): Fiscal Year Debt Issuance Costs Remaining 2022 $ 1,716 2023 2,288 2024 2,288 2025 2,288 2026 491 Total $ 9,071 Credit Agreement On April 30, 2021, the Company entered into a credit agreement (the "Credit Agreement") with Goldman Sachs Bank USA as administrative agent and collateral agent, and other lender parties thereto. The Credit Agreement provides for a $360.0 million seven-year senior secured term loan facility ("Term Loan B Facility") and a $52.5 million senior secured revolving credit facility (the "Revolving Credit Facility"). As part of the Term Loan B Facility, the Company received $325 million in proceeds, net of discounts and fees, which were used to finance the SpotX Acquisition and related transactions, and for general corporate purposes. Loans, if any, under the Revolving Credit Facility are expected to be used for general corporate purposes. The obligations under the Credit Agreement are secured by substantially all of the assets of the Company and those of its subsidiaries that are guarantors under the Credit Agreement. Amounts outstanding under the Credit Agreement accrue interest at a rate equal to either, (1) for the Term Loan B Facility, at the Company’s election, the Eurodollar Rate (as defined in the Credit Agreement) plus a margin of 5.00% per annum, or ABR (as defined in the Credit Agreement) plus a margin of 4.00%, and (2) for the Revolving Credit Facility, at the Company’s election, the Eurodollar Rate plus a margin of 4.25% to 4.75%, or ABR plus a margin of 3.25% to 3.75%, in each case, depending on the Company’s first lien net leverage ratio. As of March 31, 2022, the contractual interest rate related to the Term Loan B Facility was 5.80%. The covenants of the Credit Agreement include customary negative covenants that, among other things, restrict the Company’s ability to incur additional indebtedness, grant liens and make certain acquisitions, investments, asset dispositions and restricted payments. In addition, the Credit Agreement contains a financial covenant, tested on the last day of any fiscal quarter if utilization of the Revolving Credit Facility exceeds 35% of the total revolving commitments, that requires the Company to maintain a first lien net leverage ratio not greater than 3.25 to 1.00. As of March 31, 2022, the Company was in compliance with its debt covenants. The Credit Agreement includes customary events of default, and customary rights and remedies upon the occurrence of any event of default thereunder, including rights to accelerate the loans, terminate the commitments thereunder and realize upon the collateral securing the obligations under the Credit Agreement. The Credit Agreement calls for customary scheduled loan amortization payments of 0.25% of the initial principal balance payable quarterly (i.e. 1% in aggregate per year) as well as a provision that requires the Company to prepay the Term Loan B based on an annual calculation of cumulative free cash flow ("Excess Cash Flow") generated by the company as defined within the terms of the Agreement. The Company was not required to make any such mandatory prepayment required by the Excess Cash Flow provision for the period ended March 31, 2022. On June 28, 2021, the Company entered into an Incremental Assumption Agreement (the "Incremental Agreement") to the Credit Agreement. Pursuant to the terms of the Incremental Agreement, the Company’s existing revolving credit facility under the Credit Agreement was increased by $12.5 million (the "Incremental Revolver"), and the letter of credit sublimit under the Credit Agreement was increased by $5.0 million. The Incremental Revolver bears the same interest rate as the existing revolving credit facility and has the same maturity date as the existing revolving credit facility. No other terms of the Credit Agreement were amended. As a result, amounts available under the Revolving Credit Facility were $65.0 million. At March 31, 2022, amounts available under the Revolving Credit Facility were $59.7 million, net of letters of credit outstanding in the amount of $5.3 million. The following table summarizes the amount outstanding under the Term Loan B Facility at March 31, 2022 and December 31, 2021: March 31, 2022 December 31, 2021 (in thousands) Term Loan B Facility $ 357,300 $ 358,200 Unamortized debt discounts (9,342) (9,738) Unamortized debt issuance costs (14,577) (15,196) Debt, net of debt issuance costs $ 333,381 $ 333,266 The Company incurred debt issuance costs of $27.7 million in April 2021, of which $10.8 million were associated with debt discount netted against the proceeds and $16.9 million were associated with other deferred financing costs associated with the Term Loan B Facility. Debt outstanding under the Term Loan B Facility are presented net of issuance costs on the Company's condensed consolidated balance sheets. The debt issuance costs are amortized on an effective interest basis over the term of the Term Loan B Facility and are included in interest expense and amortization of debt discount in the accompanying condensed consolidated statements of operations. The following table sets forth interest expense related to the Term Loan B Facility for the three months ended March 31, 2022: Three Months Ended March 31, 2022 (in thousands) Contractual interest expense $ 5,163 Amortization of debt discount 397 Amortization of debt issuance costs 619 Total interest expense $ 6,179 Effective interest rate 6.98 % Amortization expense for the Term Loan B Facility debt discount and debt issuance costs for fiscal years 2022 through 2028 is as follows: Fiscal Year Debt Discount Debt Issuance Costs Remaining 2022 1,184 1,847 2023 1,564 2,441 2024 1,548 2,416 2025 1,532 2,391 2026 1,516 2,366 Thereafter 1,998 3,116 Total $ 9,342 $ 14,577

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsIn April 2022, the Company repurchased and retired 312,497 shares of common stock through open market purchases under the share repurchase program for $3.5 million at an average price of $11.28, which was also recorded as a reduction in additional paid in capital.

Organization and Summary of S_2

Organization and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Basis of Presentation and Summary of Significant Accounting Policies The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP, for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair statement of the results for the interim period presented have been included. Operating results for the three months ended March 31, 2022 are not necessarily indicative of the results that may be expected for any future interim period, the year ending December 31, 2022, or for any future year. The condensed consolidated balance sheet at December 31, 2021 has been derived from the audited financial statements at that date, but does not include all of the disclosures required by GAAP. The accompanying condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements and notes thereto for the year ended December 31, 2021 included in its 2021 Annual Report on Form 10-K. There have been no significant changes in the Company's accounting policies from those disclosed in its audited consolidated financial statements and notes thereto for the year ended December 31, 2021 included in its Annual Report on Form 10-K.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported and disclosed financial statements and accompanying footnotes. Due to the economic uncertainty as a result of the COVID-19 pandemic, geopolitical events, including the conflict in Ukraine, and economic and macro-economic factors like labor shortages, supply chain disruptions, and inflation impacting the markets and communities in which our clients operate, it has become more difficult to apply certain assumptions and judgments into these estimates. The extent of the impact of these factors on the Company's operational and financial performance will depend on future developments, which are highly uncertain and cannot be predicted, including but not limited to the duration and how quickly and to what extent normal economic and operating conditions can resume. During the three months ended March 31, 2022, this uncertainty continued to result in a higher level of judgment related to its estimates and assumptions. As of the date of issuance of the condensed consolidated financial statements for the three months ended March 31, 2022, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, judgments, or revise the carrying value of its assets or liabilities. These estimates may change, as new events occur and additional information is obtained, and are recognized in the consolidated financial statements as soon as they become known. Actual results could differ materially from these estimates.
Recently Adopted and Recent Accounting Pronouncements	Recently Adopted Accounting Standards In July 2021, the FASB issued Update No. 2021-05, Leases (Topic 842)— Lessors – Certain Leases with Variable Lease Payments ("ASU 2021-05"). ASU 2021-05 requires a lessor to classify a lease with variable lease payments that do not depend on an index or rate as an operating lease if specified criteria are met. The Company adopted ASU 2021-05 on January 1, 2022 on a prospective basis, which did not have a material impact on the Company’s condensed consolidated financial statements and related disclosures. Recent Accounting Pronouncements Not Yet Adopted In October 2021, the FASB issued ASU 2021-08, Business Combinations (Topic 805) – Accounting for Contract Assets and Contract Liabilities from Contracts with Customers ("ASU 2021-08"). ASU 2021-08 requires the recognition and measurement of contract assets and contract liabilities acquired in a business combination in accordance with ASC 606, Revenue from Contracts with Customers . Considerations to determine the amount of contract assets and contract liabilities to record at the acquisition date include the terms of the acquired contract, such as timing of payment, identification of each performance obligation in the contract and allocation of the contract transaction price to each identified performance obligation on a relative standalone selling price basis as of contract inception. ASU 2021-08 is effective for the Company beginning in the first quarter of 2023. ASU 2021-08 should be applied prospectively for acquisitions occurring on or after the effective date of the amendments. Early adoption of the proposed amendments would be permitted, including adoption in an interim period. The Company is currently assessing the impact this standard will have on the Company’s consolidated financial statements. The Company does not believe there are any other recently issued and effective or not yet effective pronouncements that would have or are expected to have any significant effect on the Company’s financial position, cash flows or results of operations.

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Schedule of Net Loss Per Share, Basic and Diluted	The following table presents the basic and diluted net loss per share: Three Months Ended March 31, 2022 March 31, 2021 (in thousands, except per share data) Basic and Diluted Income (Loss) Per Share: Net loss $ (44,593) $ (12,877) Weighted-average common shares outstanding 132,236 115,296 Weighted-average common shares outstanding used to compute net loss per share 132,236 115,296 Basic and diluted net loss per share $ (0.34) $ (0.11)
Schedule of Antidilutive Securities Excluded from Computation of Diluted Net Loss Per Share	The following weighted-average shares have been excluded from the calculation of diluted net loss per share attributable to common stockholders for each period presented because they are anti-dilutive: Three Months Ended March 31, 2022 March 31, 2021 (in thousands) Options to purchase common stock 2,593 5,400 Unvested restricted stock units 2,415 7,496 Unvested performance stock units 152 197 ESPP shares — 90 Convertible Senior Notes 6,262 — Total shares excluded from net loss per share 11,422 13,183

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2022
Revenue from Contract with Customer [Abstract]
Schedule of Revenue Recognized on a Net Basis and on a Gross Basis	The following table presents our revenue recognized on a net basis and on a gross basis for the three months ended March 31, 2022 and March 31, 2021, respectively. Three Months Ended March 31, 2022 March 31, 2021 (in thousands, except percentages) Revenue: Net basis $ 100,076 85 % $ 58,996 97 % Gross basis 17,999 15 1,719 3 Total $ 118,075 100 % $ 60,715 100 %
Summary of Disaggregation of Revenue	The following table presents our revenue by channel for the three months ended March 31, 2022 and 2021: Three Months Ended March 31, 2022 March 31, 2021 (in thousands, except percentages) Channel: CTV $ 51,440 44 % $ 11,976 20 % Desktop 27,606 23 20,851 34 Mobile 39,029 33 27,888 46 Total $ 118,075 100 % $ 60,715 100 % The following table presents the Company's revenue disaggregated by geographic location, based on the location of the Company's sellers: Three Months Ended March 31, 2022 March 31, 2021 (in thousands) United States $ 90,408 $ 42,611 International 27,667 18,104 Total $ 118,075 $ 60,715
Accounts Receivable, Allowance for Credit Loss	The following is a summary of activity in the allowance for doubtful accounts for the three months ended March 31, 2022 and 2021: Three Months Ended March 31, 2022 March 31, 2021 (in thousands) Allowance for doubtful accounts, beginning balance December 31 $ 3,475 $ 2,360 Write-offs — (4) Increase (decrease) in provision for expected credit losses (1,466) (877) Recoveries of previous write-offs 87 20 Allowance for doubtful accounts, ending balance March 31 $ 2,096 $ 1,499

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value, Assets Measured on Recurring Basis	The table below sets forth a summary of financial instruments that are measured at fair value on a recurring basis at March 31, 2022: Total Quoted Prices in Significant Other Significant (in thousands) Cash equivalents $ 7,870 $ 7,870 $ — $ — The table below sets forth a summary of financial instruments that are measured at fair value on a recurring basis at December 31, 2021: Total Quoted Prices in Significant Other Significant (in thousands) Cash equivalents $ 7,869 $ 7,869 $ — $ —

Other Balance Sheet Amounts (Ta

Other Balance Sheet Amounts (Tables)	3 Months Ended
	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Accounts Payable and Accrued Expenses	Accounts payable and accrued expenses included the following: March 31, 2022 December 31, 2021 (in thousands) Accounts payable—seller $ 821,848 $ 971,220 Accounts payable—trade 16,857 11,904 Accrued employee-related payables 16,575 16,230 Accrued holdback - indemnification claims 3,898 1,602 Total $ 859,178 $ 1,000,956

Goodwill, Intangible Assets, _2

Goodwill, Intangible Assets, and Capitalized Costs Incurred in Cloud Computing Arrangements (Tables)	3 Months Ended
	Mar. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The Company’s intangible assets as of March 31, 2022 and December 31, 2021 included the following: March 31, 2022 December 31, 2021 (in thousands) Amortizable intangible assets: Developed technology $ 390,378 $ 378,958 Customer relationships 172,500 173,950 In-process research and development 12,730 14,630 Non-compete agreements 2,400 2,270 Trademarks 900 1,400 Total identifiable intangible assets, gross 578,908 571,208 Accumulated amortization—intangible assets: Developed technology (93,579) (75,850) Customer relationships (82,390) (65,702) In-process research and development (1,695) (1,250) Non-compete agreements (1,600) (1,197) Trademarks (225) (594) Total accumulated amortization—intangible assets (179,489) (144,593) Total identifiable intangible assets, net $ 399,419 $ 426,615
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The estimated remaining amortization expense associated with the Company's intangible assets was as follows as of March 31, 2022: Fiscal Year Amount (in thousands) Remaining 2022 $ 111,428 2023 104,924 2024 87,294 2025 70,647 2026 24,695 Thereafter 431 Total $ 399,419

Business Combinations (Tables)

Business Combinations (Tables)	3 Months Ended
	Mar. 31, 2022
Business Combination and Asset Acquisition [Abstract]
Unaudited Pro Forma Information	The following table provides unaudited pro forma information as if the SpotX and SpringServe Acquisitions had been acquired by the Company as of January 1, 2020. The unaudited pro forma information reflects adjustments for additional amortization resulting from the fair value adjustments to assets acquired and liabilities assumed, adjustments for alignment of accounting policies, and transaction expenses as if the SpotX and SpringServe Acquisitions occurred on January 1, 2020. The pro forma results do not include any anticipated cost synergies or other effects of the combined companies. Accordingly, pro forma amounts are not necessarily indicative of the results that actually would have occurred had the SpotX and SpringServe Acquisitions been completed on the dates indicated, nor is it indicative of the future operating results of the combined company. Three Months Ended March 31, 2021 (in thousands) Pro Forma Revenue $ 111,277 Pro Forma Net Income (Loss) $ (36,876)
Purchase Consideration	The following table summarizes the total purchase consideration (in thousands): Cash Consideration $ 640,000 Stock Consideration (Fair Value of Shares of Magnite common stock) 495,591 Working capital adjustment 65,152 Total purchase consideration $ 1,200,743 The following table summarizes the total estimated purchase consideration (in thousands): Cash Consideration $ 31,136 SpotX initial cash investment in SpringServe 2,075 Fair value appreciation of SpotX purchase right 7,450 Indemnification claims - holdback 1,409 Total purchase consideration $ 42,070
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The fair value of the purchase price was allocated to the identifiable assets acquired and liabilities assumed based upon their estimated fair values as of the date of the SpotX Acquisition as set forth below (in thousands): Cash $ 81,967 Restricted cash 199 Accounts receivable 199,649 Prepaid and other assets, current 12,308 Fixed assets 6,823 Intangible assets 429,600 Right-of-use lease asset 10,055 Goodwill 782,719 Total assets to be acquired 1,523,320 Accounts payable and accrued expenses 205,822 Other current liabilities 1,091 Lease liabilities 12,625 Deferred tax liability, net 103,039 Total liabilities to be assumed 322,577 Total purchase price $ 1,200,743 The fair value of the purchase price was allocated to the identifiable assets acquired and liabilities assumed based upon their estimated fair values as of the date of the SpringServe Acquisition as set forth below (in thousands): Cash $ 1,062 Accounts receivable 3,234 Prepaid and other assets, current 157 Fixed assets 25 Intangible assets 23,400 Right-of-use lease asset 1,879 Goodwill 24,156 Total assets to be acquired 53,913 Accounts payable and accrued expenses 2,475 Other current liabilities 35 Lease liabilities 3,179 Deferred tax liability, net 6,154 Total liabilities to be assumed 11,843 Total preliminary purchase price $ 42,070
Schedule of Intangible Assets Acquired and Estimated Useful Life as of the Acquisition Date	The following table summarizes the components of the intangible assets and estimated useful lives as of the date of the SpotX Acquisition (dollars in thousands): Estimated Useful Life Technology $ 280,400 5 years Customer relationships 130,300 2 to 4 years Backlog 11,100 <1 year In-process research and development 5,800 3 years* Non-compete agreements 1,500 1 year Trademarks 500 <1 year Total intangible assets acquired $ 429,600 * In-process research and development consists of six projects with a weighted-average useful life of 3 years. Amortization begins once associated projects are completed and it is determined the projects have alternative future use. The following table summarizes the components of the intangible assets and estimated useful lives as of the date of the SpringServe Acquisition (dollars in thousands): Estimated Useful Life Technology $ 15,500 5 years Customer relationships 5,700 2 years Trademarks and Trade Names 900 3 years In-process research and development 800 3 years* Non-compete agreements 500 2 years Total intangible assets acquired $ 23,400 * In-process research and development consists of two projects with a weighted-average useful life of 3 years. Amortization begins once associated projects are completed and it is determined the projects have alternative future use.

Merger, Acquisition, and Rest_2

Merger, Acquisition, and Restructuring Costs (Tables)	3 Months Ended
	Mar. 31, 2022
Restructuring and Related Activities [Abstract]
Merger and Restructuring Costs	The following table summarizes merger, acquisition, and restructuring cost activity (in thousands): Three Months Ended March 31, 2022 March 31, 2021 (in thousands) Professional services (investment banking advisory, legal and other professional services) $ 775 $ 2,226 Personnel related (severance and one-time termination benefit costs) 717 119 Non-cash stock-based compensation (double-trigger acceleration and severance) 1,944 377 Impairment costs of abandoned technology 3,320 — Total merger, acquisition, and restructuring costs $ 6,756 $ 2,722 (in thousands) Accrued restructuring costs at December 31, 2021 $ 2,742 Restructuring costs, personnel related and non-cash stock-based compensation 2,661 Restructuring costs, impairments 3,320 Cash paid for restructuring costs (658) Non-cash impairments (3,320) Non-cash stock-based compensation (1,944) Accrued restructuring costs at March 31, 2022 $ 2,801

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2022
Share-based Payment Arrangement [Abstract]
Schedule of Share-based Compensation, Stock Options, Activity	A summary of stock option activity for the three months ended March 31, 2022 is as follows: Shares Under Option Weighted- Average Exercise Price Weighted- Average Contractual Life Aggregate Intrinsic Value (in thousands) (in thousands) Outstanding at December 31, 2021 5,129 $ 7.25 Granted 699 $ 13.90 Exercised (311) $ 3.56 Expired (21) $ 15.24 Outstanding at March 31, 2022 5,496 $ 8.27 5.9 years $ 35,278 Exercisable at March 31, 2022 3,763 $ 5.76 4.6 years $ 29,168
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The weighted-average input assumptions used by the Company were as follows: Three Months Ended March 31, 2022 March 31, 2021 Expected term (in years) 5.0 N/A Risk-free interest rate 1.63 % N/A Expected volatility 79 % N/A Dividend yield — % N/A
Schedule of Nonvested Restricted Stock Units Activity	A summary of restricted stock unit activity for the three months ended March 31, 2022 is as follows: Number of Shares Weighted-Average Grant Date Fair Value (in thousands) Restricted stock units outstanding at December 31, 2021 6,634 $ 18.39 Granted 6,556 $ 13.87 Canceled (284) $ 17.95 Vested and released (783) $ 9.27 Restricted stock units outstanding at March 31, 2022 12,123 $ 16.54 Restricted stock units outstanding and unvested* 12,086 * $ 16.57 *At March 31, 2022, outstanding restricted stock units included 37,318 units that were vested but deferred.
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs for all Plans	Total stock-based compensation expense recorded in the condensed consolidated statements of operations was as follows: Three Months Ended March 31, 2022 March 31, 2021 (in thousands) Cost of revenue $ 350 $ 85 Sales and marketing 5,341 2,461 Technology and development 4,717 1,826 General and administrative 4,237 2,244 Merger, acquisition, and restructuring costs 1,944 377 Total stock-based compensation expense $ 16,589 $ 6,993

Lease Obligations (Tables)

Lease Obligations (Tables)	3 Months Ended
	Mar. 31, 2022
Leases [Abstract]
Schedule of Maturity of Lease Liabilities	The maturity of the Company's lease liabilities associated with leases included in the lease liability and ROU asset were as follows as of March 31, 2022 (in thousands): Fiscal Year Remaining 2022 $ 16,397 2023 19,406 2024 16,593 2025 8,783 2026 7,761 Thereafter 27,302 Total lease payments (undiscounted) 96,242 Less: imputed interest (14,827) Lease liabilities—total (discounted) $ 81,415

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2022
Debt Disclosure [Abstract]
Schedule of Long-term Debt	Long term debt as of March 31, 2022 and December 31, 2021 consisted of the following: March 31, 2022 December 31, 2021 (in thousands) Convertible Senior Notes $ 400,000 $ 400,000 Less: Unamortized debt issuance cost (9,071) (9,643) Net 390,929 390,357 Term Loan B Facility 357,300 358,200 Less: Unamortized discount and debt issuance cost (23,919) (24,934) Net 333,381 333,266 Less: Current portion (3,600) (3,600) Total non-current debt $ 720,710 $ 720,023
Schedule of Maturities of Long-term Debt	Maturities of the principal amount of the Company's long-term debt as of March 31, 2022 are as follows (in thousands): Fiscal Year Remaining 2022 $ 2,700 2023 3,600 2024 3,600 2025 3,600 2026 403,600 Thereafter 340,200 Total $ 757,300 Amortization of the debt issuance cost and the discount associated with our indebtedness totaled $1.7 million for the three months ended March 31, 2022 and $0.1 million for the three months ended March 31, 2021. Amortization of debt issuance costs is computed using the effective interest method and is included in interest expense. Amortization expense for the Company's debt issuance costs related to the Convertible Senior Notes for the fiscal years 2022 through 2026 is as follows (in thousands): Fiscal Year Debt Issuance Costs Remaining 2022 $ 1,716 2023 2,288 2024 2,288 2025 2,288 2026 491 Total $ 9,071 Amortization expense for the Term Loan B Facility debt discount and debt issuance costs for fiscal years 2022 through 2028 is as follows: Fiscal Year Debt Discount Debt Issuance Costs Remaining 2022 1,184 1,847 2023 1,564 2,441 2024 1,548 2,416 2025 1,532 2,391 2026 1,516 2,366 Thereafter 1,998 3,116 Total $ 9,342 $ 14,577
Interest Income and Interest Expense Disclosure	The following table sets forth interest expense related to the Convertible Senior Notes for the three months ended March 31, 2022 and 2021: Three Months Ended March 31, 2022 March 31, 2021 (in thousands) Contractual interest expense $ 250 $ 36 Amortization of debt issuance costs 572 83 Total interest expense $ 822 $ 119 Effective interest rate 0.82 % 0.82 % Three Months Ended March 31, 2022 (in thousands) Contractual interest expense $ 5,163 Amortization of debt discount 397 Amortization of debt issuance costs 619 Total interest expense $ 6,179 Effective interest rate 6.98 %
Schedule of Debt	The following table summarizes the amount outstanding under the Term Loan B Facility at March 31, 2022 and December 31, 2021: March 31, 2022 December 31, 2021 (in thousands) Term Loan B Facility $ 357,300 $ 358,200 Unamortized debt discounts (9,342) (9,738) Unamortized debt issuance costs (14,577) (15,196) Debt, net of debt issuance costs $ 333,381 $ 333,266

Net Loss Per Share - Basic and

Net Loss Per Share - Basic and Diluted Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Basic and Diluted Income (Loss) Per Share:
Net loss	$ (44,593)	$ (12,877)
Weighted-average common shares outstanding, basic (in shares)	132,236	115,296
Weighted average number of shares outstanding, diluted (in shares)	132,236	115,296
Basic net income (loss) per share (in shares)	$ (0.34)	$ (0.11)
Diluted net income (loss) per share (in shares)	$ (0.34)	$ (0.11)

Net Loss Per Share - Shares Exc

Net Loss Per Share - Shares Excluded From Calculation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net loss per share (in shares)	11,422	13,183
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net loss per share (in shares)	2,593	5,400
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net loss per share (in shares)	2,415	7,496
Unvested performance stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net loss per share (in shares)	152	197
ESPP shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net loss per share (in shares)	0	90
Convertible Senior Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net loss per share (in shares)	6,262	0

Net Loss Per Share - Narrative

Net Loss Per Share - Narrative (Details)	3 Months Ended
	Mar. 31, 2022share	Mar. 31, 2021
Convertible Senior Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of shares issuable assuming conversion	6,261,560
Convertible Senior Notes | Convertible Debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion ratio	0.0156539
Unvested performance stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Performance measurement percentage	100.00%
Performance Shares, Granted April 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Performance measurement percentage	121.00%	150.00%
Performance shares, Granted April 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Performance measurement percentage	0.00%
Performance shares, Granted August 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Performance measurement percentage	0.00%
Performance shares, Granted February 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Performance measurement percentage	51.00%

Revenue - Narrative (Details)

Revenue - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Percent of revenue (less than)	3.00%
Payment terms	75 days
Accounts receivable, allowance for credit loss	$ 2,096	$ 1,499	$ 3,475	$ 2,360
Contra seller payable	1,200		$ 2,100
Increase (decrease) in provision for expected credit losses	(1,466)	(877)
Increase (decrease) in contra seller payable	900	(700)
Provision for doubtful accounts	$ (571)	$ (159)

Revenue - Revenue Recognized on

Revenue - Revenue Recognized on a Gross and Net Basis (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 118,075	$ 60,715
Net basis
Disaggregation of Revenue [Line Items]
Revenue	100,076	58,996
Gross basis
Disaggregation of Revenue [Line Items]
Revenue	$ 17,999	$ 1,719
Revenue Benchmark | Concentration of Basis of Revenue Recognition
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	100.00%	100.00%
Revenue Benchmark | Concentration of Basis of Revenue Recognition | Net basis
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	85.00%	97.00%
Revenue Benchmark | Concentration of Basis of Revenue Recognition | Gross basis
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	15.00%	3.00%

Revenue - Revenue Disaggregated

Revenue - Revenue Disaggregated by Sales Distribution Channel (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 118,075	$ 60,715
CTV
Disaggregation of Revenue [Line Items]
Revenue	51,440	11,976
Desktop
Disaggregation of Revenue [Line Items]
Revenue	27,606	20,851
Mobile
Disaggregation of Revenue [Line Items]
Revenue	$ 39,029	$ 27,888
Product Concentration Risk | Revenue Benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	100.00%	100.00%
Product Concentration Risk | Revenue Benchmark | CTV
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	44.00%	20.00%
Product Concentration Risk | Revenue Benchmark | Desktop
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	23.00%	34.00%
Product Concentration Risk | Revenue Benchmark | Mobile
Disaggregation of Revenue [Line Items]
Concentration risk, percentage	33.00%	46.00%

Revenue - Revenue Disaggregat_2

Revenue - Revenue Disaggregated by Geographic Location (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 118,075	$ 60,715
United States
Disaggregation of Revenue [Line Items]
Revenue	90,408	42,611
International
Disaggregation of Revenue [Line Items]
Revenue	$ 27,667	$ 18,104

Revenue - Schedule of Allowance

Revenue - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for doubtful accounts, beginning balance December 31	$ 3,475	$ 2,360
Write-offs	0	(4)
Increase (decrease) in provision for expected credit losses	(1,466)	(877)
Recoveries of previous write-offs	87	20
Allowance for doubtful accounts, ending balance March 31	$ 2,096	$ 1,499

Fair Value Measurements - Finan

Fair Value Measurements - Financial Instruments (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 7,870	$ 7,869
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	7,870	7,869
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Significant Unobservable Inputs  (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 0	$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 7,870	$ 7,869
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Convertible notes	$ 292,500	$ 315,500

Other Balance Sheet Amounts - A

Other Balance Sheet Amounts - Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounts payable—seller	$ 821,848	$ 971,220
Accounts payable—trade	16,857	11,904
Accrued employee-related payables	16,575	16,230
Accrued holdback - indemnification claims	3,898	1,602
Total	$ 859,178	$ 1,000,956

Other Balance Sheet Amounts - N

Other Balance Sheet Amounts - Narrative (Details) $ in Millions	Mar. 31, 2022USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Restricted cash included in other assets, non-current	$ 0.3

Goodwill, Intangible Assets, _3

Goodwill, Intangible Assets, and Capitalized Costs Incurred in Cloud Computing Arrangements - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Acquired Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 978,216		$ 969,873
Amortization expense of intangible assets	38,500	$ 7,600
Prepaid Expenses and Other Current Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Capitalized cloud computing software, net	600		500
Other Noncurrent Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Capitalized cloud computing software, net	800		$ 700
Computer Software, Intangible Asset
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense of intangible assets	$ 0	$ 0

Goodwill, Intangible Assets, _4

Goodwill, Intangible Assets, and Capitalized Costs Incurred in Cloud Computing Arrangements - Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets, gross	$ 578,908	$ 571,208
Total accumulated amortization—intangible assets	(179,489)	(144,593)
Total	399,419	426,615
Developed technology
Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets, gross	390,378	378,958
Total accumulated amortization—intangible assets	(93,579)	(75,850)
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets, gross	172,500	173,950
Total accumulated amortization—intangible assets	(82,390)	(65,702)
In-process research and development
Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets, gross	12,730	14,630
Total accumulated amortization—intangible assets	(1,695)	(1,250)
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets, gross	2,400	2,270
Total accumulated amortization—intangible assets	(1,600)	(1,197)
Trademarks
Finite-Lived Intangible Assets [Line Items]
Total identifiable intangible assets, gross	900	1,400
Total accumulated amortization—intangible assets	$ (225)	$ (594)

Goodwill, Intangible Assets, _5

Goodwill, Intangible Assets, and Capitalized Costs Incurred in Cloud Computing Arrangements - Finite-Lived Intangible Assets, Future Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fiscal Year
Remaining 2022	$ 111,428
2023	104,924
2024	87,294
2025	70,647
2026	24,695
Thereafter	431
Total	$ 399,419	$ 426,615

Business Combinations - Narrati

Business Combinations - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Jul. 01, 2021	Apr. 30, 2021	Feb. 04, 2021	Feb. 28, 2022	Dec. 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2020	Apr. 29, 2021
Business Acquisition [Line Items]
Share Price (in USD per share)		$ 40.05							$ 49.21
Goodwill					$ 969,873	$ 978,216
Acquisition related costs						6,756	$ 2,722
SpotX, Inc | SpringServe
Business Acquisition [Line Items]
Prior investment								$ 2,100
Fair value of prior investment	$ 9,500	$ 7,500
SpotX, Inc
Business Acquisition [Line Items]
Cash Consideration		$ 640,000	$ 560,000
Issued in merger (in shares)		12,374,315	14,000,000
Cash consideration, elected increase, percent		20.00%
Cash consideration, elected increase, amount		$ 80,000
Shares issued, elected decrease, percent		20.00%
Shares issued, elected decrease, value		$ 80,000
Purchase price prior to working capital adjustments		1,100,000
Working capital adjustment		65,152
Purchase price		1,200,743	$ 1,200,000
Stock Consideration (Fair Value of Shares of Magnite common stock)		495,591
Deferred tax asset valuation allowance decrease						56,200
Intangible assets acquired		429,600
Deferred tax liability, net		103,039
Goodwill		$ 782,719
SpotX, Inc | Non-compete agreements
Business Acquisition [Line Items]
Estimated Useful Life		1 year
Intangible assets acquired		$ 1,500
SpotX, Inc | Technology
Business Acquisition [Line Items]
Estimated Useful Life		5 years
Intangible assets acquired		$ 280,400
SpotX, Inc | Customer relationships
Business Acquisition [Line Items]
Intangible assets acquired		$ 130,300
SpringServe
Business Acquisition [Line Items]
Cash Consideration	31,136
Purchase price held back to cover possible indemnification claims	1,400
Intangible assets acquired	23,400
Deferred tax liability, net	6,154
Goodwill	$ 24,156
Acquisition related costs						$ 0
SpringServe | Non-compete agreements
Business Acquisition [Line Items]
Estimated Useful Life	2 years
Intangible assets acquired	$ 500
SpringServe | Technology
Business Acquisition [Line Items]
Estimated Useful Life	5 years
Intangible assets acquired	$ 15,500
SpringServe | Customer relationships
Business Acquisition [Line Items]
Estimated Useful Life	2 years
Intangible assets acquired	$ 5,700
Nth Party, Ltd.
Business Acquisition [Line Items]
Purchase price					9,000
Deferred tax liability, net					1,300
Goodwill					$ 4,800
Nth Party, Ltd. | Non-compete agreements
Business Acquisition [Line Items]
Estimated Useful Life					2 years
Intangible assets acquired					$ 200
Nth Party, Ltd. | Technology
Business Acquisition [Line Items]
Estimated Useful Life					5 years
Intangible assets acquired					$ 5,400
Carbon (AI) Limited and Mode Technologies, Inc.
Business Acquisition [Line Items]
Purchase price				$ 23,100
Business combination, contingent consideration, liability				2,300
Goodwill				$ 8,500
Carbon (AI) Limited and Mode Technologies, Inc. | Non-compete agreements
Business Acquisition [Line Items]
Estimated Useful Life				2 years
Intangible assets acquired				$ 200
Carbon (AI) Limited and Mode Technologies, Inc. | Technology
Business Acquisition [Line Items]
Estimated Useful Life				5 years
Intangible assets acquired				$ 14,200
Carbon (AI) Limited and Mode Technologies, Inc. | Customer relationships
Business Acquisition [Line Items]
Estimated Useful Life				6 months
Intangible assets acquired				$ 200

Business Combinations - SpotX P

Business Combinations - SpotX Purchase Consideration (Details) - SpotX, Inc - USD ($) $ in Thousands	Apr. 30, 2021	Feb. 04, 2021
Business Acquisition [Line Items]
Cash Consideration	$ 640,000	$ 560,000
Stock Consideration (Fair Value of Shares of Magnite common stock)	495,591
Working capital adjustment	65,152
Total purchase consideration	$ 1,200,743	$ 1,200,000

Business Combinations - SpotX S

Business Combinations - SpotX Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Apr. 30, 2021
Business Acquisition [Line Items]
Goodwill	$ 978,216	$ 969,873
SpotX, Inc
Business Acquisition [Line Items]
Cash			$ 81,967
Restricted cash			199
Accounts receivable			199,649
Prepaid and other assets, current			12,308
Fixed assets			6,823
Intangible assets			429,600
Right-of-use lease asset			10,055
Goodwill			782,719
Total assets to be acquired			1,523,320
Accounts payable and accrued expenses			205,822
Other current liabilities			1,091
Lease liabilities			12,625
Deferred tax liability, net			103,039
Total liabilities to be assumed			322,577
Total purchase price			$ 1,200,743

Business Combinations - SpotX C

Business Combinations - SpotX Components of Intangible Assets and Estimated Useful Lives (Details) - SpotX, Inc $ in Thousands	Apr. 30, 2021USD ($)project
Business Acquisition [Line Items]
Intangible assets acquired	$ 429,600
Technology
Business Acquisition [Line Items]
Intangible assets acquired	$ 280,400
Estimated Useful Life	5 years
Customer relationships
Business Acquisition [Line Items]
Intangible assets acquired	$ 130,300
Customer relationships | Minimum
Business Acquisition [Line Items]
Estimated Useful Life	2 years
Customer relationships | Maximum
Business Acquisition [Line Items]
Estimated Useful Life	4 years
Backlog
Business Acquisition [Line Items]
Intangible assets acquired	$ 11,100
Estimated Useful Life	1 year
In-process research and development
Business Acquisition [Line Items]
Intangible assets acquired	$ 5,800
Number of projects | project	6
Estimated Useful Life	3 years
Non-compete agreements
Business Acquisition [Line Items]
Intangible assets acquired	$ 1,500
Estimated Useful Life	1 year
Trademarks
Business Acquisition [Line Items]
Intangible assets acquired	$ 500
Estimated Useful Life	1 year

Business Combinations - SpringS

Business Combinations - SpringServe Purchase Consideration (Details) - USD ($) $ in Thousands	Jul. 01, 2021	Mar. 31, 2022	Mar. 31, 2021
Business Acquisition [Line Items]
Indemnification claims - holdback		$ 2,300	$ 0
SpringServe
Business Acquisition [Line Items]
Cash Consideration	$ 31,136
SpotX initial cash investment in SpringServe	2,075
Fair value appreciation of SpotX purchase right	7,450
Indemnification claims - holdback	1,409
Total purchase consideration	$ 42,070

Business Combinations - Sprin_2

Business Combinations - SpringServe Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Jul. 01, 2021
Business Acquisition [Line Items]
Goodwill	$ 978,216	$ 969,873
SpringServe
Business Acquisition [Line Items]
Cash			$ 1,062
Accounts receivable			3,234
Prepaid and other assets, current			157
Fixed assets			25
Intangible assets			23,400
Right-of-use lease asset			1,879
Goodwill			24,156
Total assets to be acquired			53,913
Accounts payable and accrued expenses			2,475
Other current liabilities			35
Lease liabilities			3,179
Deferred tax liability, net			6,154
Total liabilities to be assumed			11,843
Total purchase price			$ 42,070

Business Combinations - Sprin_3

Business Combinations - SpringServe Components of Intangible Assets and Estimated Useful Lives (Details) - SpringServe $ in Thousands	Jul. 01, 2021USD ($)project
Business Acquisition [Line Items]
Intangible assets acquired	$ 23,400
Technology
Business Acquisition [Line Items]
Intangible assets acquired	$ 15,500
Estimated Useful Life	5 years
Customer relationships
Business Acquisition [Line Items]
Intangible assets acquired	$ 5,700
Estimated Useful Life	2 years
Trademarks and Trade Names
Business Acquisition [Line Items]
Intangible assets acquired	$ 900
Estimated Useful Life	3 years
In-process research and development
Business Acquisition [Line Items]
Intangible assets acquired	$ 800
Estimated Useful Life	3 years
Number of projects | project	2
Non-compete agreements
Business Acquisition [Line Items]
Intangible assets acquired	$ 500
Estimated Useful Life	2 years

Business Combinations - SpotX a

Business Combinations - SpotX and SpringServe Unaudited Pro Forma Information (Details) - SpotX and SpringServe $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Business Acquisition [Line Items]
Pro Forma Revenue	$ 111,277
Pro Forma Net Income (Loss)	$ (36,876)

Merger, Acquisition, and Rest_3

Merger, Acquisition, and Restructuring Costs - Merger and Restructuring Cost Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Restructuring Cost and Reserve [Line Items]
Professional services (investment banking advisory, legal and other professional services)	$ 775	$ 2,226
Non-cash stock-based compensation (double-trigger acceleration and severance)	1,944	377
Impairment costs of abandoned technology	3,320	0
Total merger, acquisition, and restructuring costs	6,756	2,722
Personnel related (severance and one-time termination benefit costs)
Restructuring Cost and Reserve [Line Items]
Personnel related (severance and one-time termination benefit costs)	$ 717	$ 119

Merger, Acquisition, and Rest_4

Merger, Acquisition, and Restructuring Costs - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Business Acquisition [Line Items]
Acquisition related costs	$ 6,756	$ 2,722
SpotX Acquisition, SpringServe Acquisition, And Telaria Merger
Business Acquisition [Line Items]
Accrued merger, acquisition, and restructuring costs	$ 2,800		$ 2,700

Merger, Acquisition, and Rest_5

Merger, Acquisition, and Restructuring Costs - Accrued Merger and Restructuring Cost Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Restructuring Reserve [Roll Forward]
Restructuring costs, impairments	$ 3,320
Non-cash impairments	(3,320)	$ 0
Non-cash stock-based compensation	(1,944)	$ (377)
SpotX and Telaria
Restructuring Reserve [Roll Forward]
Accrued restructuring costs at December 31, 2021	2,742
Restructuring costs, personnel related and non-cash stock-based compensation	2,661
Cash paid for restructuring costs	(658)
Non-cash stock-based compensation	(1,944)
Accrued restructuring costs at March 31, 2022	$ 2,801

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details)	3 Months Ended
	Mar. 31, 2022shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant (in shares)	13,212,745
Annual percentage increase	5.00%
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Stock Option | Tranche one
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
Award vesting rights, percentage	25.00%
RSAs and RSUs | Tranche one
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year
Award vesting rights, percentage	25.00%
Restricted Stock Units (RSUs) | Tranche two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage	50.00%
RSUs granted (in shares)	200,000

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Options Outstanding (Details) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)$ / sharesshares
Shares Under Option
Beginning balance (in shares) | shares	5,129
Granted (in shares) | shares	699
Exercised (in shares) | shares	(311)
Ending balance (in shares) | shares	5,496
Exercisable (in shares) | shares	3,763
Weighted- Average Exercise Price
Beginning balance (usd per share) | $ / shares	$ 7.25
Granted (usd per share) | $ / shares	13.90
Exercised (usd per share) | $ / shares	3.56
Ending balance (usd per share) | $ / shares	8.27
Exercisable (usd per share) | $ / shares	$ 5.76
Weighted- Average Contractual Life
Outstanding	5 years 10 months 24 days
Exercisable	4 years 7 months 6 days
Aggregate Intrinsic Value
Outstanding | $	$ 35,278
Exercisable | $	$ 29,168
Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period | shares	(21)
Expired (usd per share) | $ / shares	$ 15.24

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock Options Narrative (Details) - Stock Option $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2022USD ($)$ / shares
Number of Shares
Intrinsic values of options exercised	$ 3.3
Unrecognized employee stock-based compensation	$ 13.1
Unrecognized employee stock-based compensation, period for recognition	2 years 8 months 12 days
Fair value of options vested in period	$ 1.2
Grant date fair value of options granted (usd per share) | $ / shares	$ 8.93

Stock-Based Compensation - Valu

Stock-Based Compensation - Valuation Assumptions (Details) - Stock Option	3 Months Ended
	Mar. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years
Risk-free interest rate	1.63%
Expected volatility	79.00%
Dividend yield	0.00%

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Units Activity (Details) - Restricted Stock Units (RSUs)	3 Months Ended
	Mar. 31, 2022$ / sharesshares
Number of Shares
Beginning balance (in shares)	12,123,000
Granted (in shares)	6,556,000
Canceled (in shares)	(284,000)
Vested and released (in shares)	(783,000)
Ending balance (in shares)	6,634,000
Restricted stock units outstanding and unvested (in shares)	12,086,000
Vested but deferred (in shares)	37,318
Weighted-Average Grant Date Fair Value
Beginning balance (in dollars per share) | $ / shares	$ 18.39
Granted (in dollars per share) | $ / shares	13.87
Canceled (in dollars per share) | $ / shares	17.95
Vested and released (in dollars per share) | $ / shares	9.27
Ending balance (in dollars per share) | $ / shares	16.54
Restricted stock units outstanding and unvested (in dollars per share) | $ / shares	$ 16.57

Stock-Based Compensation - Re_2

Stock-Based Compensation - Restricted Stock Units Narrative (Details) - Restricted Stock Units (RSUs) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2022USD ($)$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share) | $ / shares	$ 13.87
Fair value of restricted stock vested	$ 10.6
Intrinsic value of nonvested unit	159.6
Unrecognized employee stock-based compensation	$ 172.3
Unrecognized employee stock-based compensation, period for recognition	3 years 1 month 6 days

Stock-Based Compensation - Perf

Stock-Based Compensation - Performance Stock Units Narrative (Details) $ / shares in Units, $ in Thousands	1 Months Ended				3 Months Ended
	Feb. 28, 2022USD ($)$ / sharesshares	Aug. 31, 2021USD ($)day$ / sharesshares	Apr. 30, 2021USD ($)$ / sharesshares	Apr. 30, 2020USD ($)$ / sharesshares	Mar. 31, 2022USD ($)	Mar. 31, 2021USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense					$ 16,589	$ 6,993
Performance Shares Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense					$ 800	$ 300
Performance measurement percentage					100.00%
Performance Shares Units | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares) | shares	86,806	379,635	26,291	146,341
Fair value of restricted stock vested	$ 1,500		$ 1,400	$ 900
Vested (in dollars per share) | $ / shares	$ 17.28		$ 52.49	$ 6.15
Trailing consecutive trading day performance period | day		60
Performance Shares Units | Tranche one | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of units granted		$ 3,000
Grant date fair value (in dollars per share) | $ / shares		$ 23.94
Unrecognized employee stock-based compensation					$ 2,400
Unrecognized employee stock-based compensation, period for recognition					2 years 4 months 24 days
Vesting period		3 years
Vesting, stock price trigger (in dollars per share) | $ / shares		$ 60
Performance Shares Units | Tranche two | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of units granted		$ 2,800
Grant date fair value (in dollars per share) | $ / shares		$ 21.93
Unrecognized employee stock-based compensation					$ 2,400
Unrecognized employee stock-based compensation, period for recognition					3 years 4 months 24 days
Vesting period		4 years
Vesting, stock price trigger (in dollars per share) | $ / shares		$ 80
Performance Shares Units | Tranche three | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of units granted		$ 2,600
Grant date fair value (in dollars per share) | $ / shares		$ 20.30
Unrecognized employee stock-based compensation					$ 2,300
Unrecognized employee stock-based compensation, period for recognition					4 years 4 months 24 days
Vesting period		5 years
Vesting, stock price trigger (in dollars per share) | $ / shares		$ 100
Performance Shares Units | Minimum | Vesting on third anniversary | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage					0.00%
Performance Shares Units | Minimum | Tranche one | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage					0.00%
Performance Shares Units | Minimum | Tranche two | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage					0.00%
Performance Shares Units | Minimum | Tranche three | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage					0.00%
Performance Shares Units | Maximum | Vesting on third anniversary | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage					150.00%
Performance Shares Units | Maximum | Tranche one | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage					100.00%
Performance Shares Units | Maximum | Tranche two | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage					100.00%
Performance Shares Units | Maximum | Tranche three | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage					100.00%
Performance Shares, Granted April 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance measurement percentage					121.00%	150.00%
Performance Shares, Granted April 2020 | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized employee stock-based compensation					$ 300
Unrecognized employee stock-based compensation, period for recognition					1 year
Performance shares, Granted April 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance measurement percentage					0.00%
Performance shares, Granted April 2021 | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized employee stock-based compensation					$ 900
Unrecognized employee stock-based compensation, period for recognition					2 years
Performance shares, Granted February 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance measurement percentage					51.00%
Performance shares, Granted February 2022 | Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized employee stock-based compensation					$ 1,400
Unrecognized employee stock-based compensation, period for recognition					2 years 9 months 18 days

Stock-Based Compensation - Empl

Stock-Based Compensation - Employee Stock Purchase Plan Narrative (Details) - shares	1 Months Ended	3 Months Ended
	Nov. 30, 2013	Mar. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved		13,212,745
Annual percentage increase		5.00%
2014 Employee Stock Purchase Plan | Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum employee subscription rate	10.00%
Offering period	6 months
Purchase price of common stock, percent	85.00%
Number of shares reserved		4,256,520
Annual percentage increase	1.00%

Stock-Based Compensation - St_3

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 16,589	$ 6,993
Cost of revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	350	85
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	5,341	2,461
Technology and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	4,717	1,826
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	4,237	2,244
Merger, acquisition, and restructuring costs
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,944	$ 377

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Provision (benefit) for income taxes	$ (2,005)	$ 166

Lease Obligations - Narrative (

Lease Obligations - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Lessee, Lease, Description [Line Items]
Lease expense	$ 5,600	$ 3,800
Short-term lease expense	300	300
Sublease income	$ 1,300	1,200
Weighted average discount rate	5.15%
Weighted average remaining lease term	6 years 4 months 24 days
Minimum
Lessee, Lease, Description [Line Items]
Term of lease contract	1 year
Maximum
Lessee, Lease, Description [Line Items]
Term of lease contract	10 years
Data centers for cloud-based services
Lessee, Lease, Description [Line Items]
Variable lease cost	$ 11,000	$ 6,400
Company Office, San Francisco CA
Lessee, Lease, Description [Line Items]
Operating lease not yet commenced, amount	$ 2,300
Operating lease not yet commenced, term of contract	5 years 4 months 24 days
Company Office, Toronto CA
Lessee, Lease, Description [Line Items]
Operating lease not yet commenced, amount	$ 600
Operating lease not yet commenced, term of contract	5 years

Lease Obligations - Schedule of

Lease Obligations - Schedule of Lease Liability Maturities (Details) $ in Thousands	Mar. 31, 2022USD ($)
Fiscal Year
Remaining 2022	$ 16,397
2023	19,406
2024	16,593
2025	8,783
2026	7,761
Thereafter	27,302
Total lease payments (undiscounted)	96,242
Less: imputed interest	(14,827)
Lease liabilities—total (discounted)	$ 81,415

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Financial Standby Letter of Credit
Other Commitments [Line Items]
Letters of credit outstanding, amount	$ 5.3	$ 5.1

Debt - Schedule of Long-term De

Debt - Schedule of Long-term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Net	$ 757,300
Less: Current portion	(3,600)	$ (3,600)
Total non-current debt	720,710	720,023
Convertible Senior Notes | Convertible Debt
Debt Instrument [Line Items]
Long-term debt, gross	400,000	400,000
Debt instrument, unamortized discount and debt issuance costs	(9,071)	(9,643)
Net	390,929	390,357
Term Loan B Facility | Secured Debt
Debt Instrument [Line Items]
Long-term debt, gross	357,300	358,200
Debt instrument, unamortized discount and debt issuance costs	(23,919)	(24,934)
Net	333,381	333,266
Total non-current debt	$ 333,381	$ 333,266

Debt - Maturities of Principle

Debt - Maturities of Principle Amount of Long-Term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Remaining 2022	$ 2,700
2023	3,600
2024	3,600
2025	3,600
2026	403,600
Thereafter	340,200
Total	757,300
Convertible Senior Notes | Convertible Debt
Debt Instrument [Line Items]
Total	390,929	$ 390,357
Term Loan B Facility | Secured Debt
Debt Instrument [Line Items]
Total	$ 333,381	$ 333,266

Debt - Convertible Senior Notes

Debt - Convertible Senior Notes and Capped Call Transactions Narrative (Details)	1 Months Ended	3 Months Ended
	Mar. 31, 2021USD ($)day$ / shares	Mar. 31, 2022USD ($)	Mar. 31, 2021USD ($)$ / shares	Apr. 30, 2021USD ($)
Debt Instrument [Line Items]
Net proceeds		$ 0	$ 389,000,000
Capped calls, transaction costs	$ 39,000,000
Debt issuance costs, gross	11,400,000		$ 11,400,000	$ 27,700,000
Convertible Senior Notes
Debt Instrument [Line Items]
Capped calls, transaction costs	$ 39,000,000
Percent of outstanding balance holders able to call debt in the event of default	25.00%		25.00%
Convertible Senior Notes | Maximum
Debt Instrument [Line Items]
Conversion price (in USD per share) | $ / shares	$ 91.2600		$ 91.2600
Convertible Senior Notes | Minimum
Debt Instrument [Line Items]
Conversion price (in USD per share) | $ / shares	$ 63.8818		$ 63.8818
Convertible Senior Notes | Convertible Debt
Debt Instrument [Line Items]
Aggregate principle amount	$ 400,000,000		$ 400,000,000
Interest rate	0.25%		0.25%
Over-allotment options	$ 50,000,000		$ 50,000,000
Net proceeds	$ 388,600,000
Conversion ratio		0.0156539
Convertible Senior Notes | Convertible Debt | Maximum
Debt Instrument [Line Items]
Make-whole fundamental change period	45 days
Convertible Senior Notes | Convertible Debt | Minimum
Debt Instrument [Line Items]
Make-whole fundamental change period	20 days
Convertible Senior Notes | Convertible Debt | Conversion Term (i)
Debt Instrument [Line Items]
Threshold percent of stock price trigger	130.00%
Threshold trading days | day	20
Threshold consecutive trading days | day	30
Convertible Senior Notes | Convertible Debt | Conversion Term (ii)
Debt Instrument [Line Items]
Threshold percent of stock price trigger	98.00%
Threshold trading days | day	5
Threshold consecutive trading days | day	10
Convertible Senior Notes | Convertible Debt | Conversion Term (iv)
Debt Instrument [Line Items]
Threshold percent of stock price trigger	130.00%
Threshold trading days | day	20
Threshold consecutive trading days | day	30
Term Loan B Facility | Secured Debt
Debt Instrument [Line Items]
Aggregate principle amount				$ 360,000,000
Interest rate		5.80%

Debt - Interest Expense Related

Debt - Interest Expense Related to the Convertible Senior Notes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Debt Instrument [Line Items]
Amortization of debt discount and issuance costs	$ 1,700	$ 99
Convertible Debt | Convertible Senior Notes
Debt Instrument [Line Items]
Contractual interest expense	250	36
Amortization of debt discount and issuance costs	572	83
Total interest expense	$ 822	$ 119
Effective interest rate	0.82%	0.82%

Debt - Amortization Expense for

Debt - Amortization Expense for Debt Issuance Costs (Details) - Convertible Debt - Convertible Senior Notes $ in Thousands	Mar. 31, 2022USD ($)
Debt Issuance Costs
Remaining 2022	$ 1,716
2023	2,288
2024	2,288
2025	2,288
2026	491
Total	$ 9,071

Debt - Credit Agreement Narrati

Debt - Credit Agreement Narrative (Details) - USD ($)	Apr. 30, 2021	Mar. 31, 2022	Jun. 28, 2021	Mar. 31, 2021
Line of Credit Facility [Line Items]
Debt issuance costs, gross	$ 27,700,000			$ 11,400,000
Term Loan B Facility | Secured Debt
Line of Credit Facility [Line Items]
Aggregate principle amount	$ 360,000,000
Long-term debt, term	7 years
Net proceeds	$ 325,000,000
Interest rate		5.80%
Term Loan B Facility | Secured Debt | Debt Discount
Line of Credit Facility [Line Items]
Debt issuance costs, gross	10,800,000
Term Loan B Facility | Secured Debt | Deferred Financing Costs
Line of Credit Facility [Line Items]
Debt issuance costs, gross	$ 16,900,000
Term Loan B Facility | Secured Debt | Eurodollar
Line of Credit Facility [Line Items]
Variable interest rate	5.00%
Term Loan B Facility | Secured Debt | Alternate Base Rate
Line of Credit Facility [Line Items]
Variable interest rate	4.00%
Senior Secured Revolving Credit Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Debt utilization triggering leverage ratio compliance, percent	35.00%
Leverage ratio maximum	3.25
Available borrowing capacity		$ 59,700,000
Senior Secured Revolving Credit Facility | Letter of Credit
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount		$ 5,300,000
Senior Secured Revolving Credit Facility | Eurodollar | Minimum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Variable interest rate	4.25%
Senior Secured Revolving Credit Facility | Eurodollar | Maximum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Variable interest rate	4.75%
Senior Secured Revolving Credit Facility | Alternate Base Rate | Minimum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Variable interest rate	3.25%
Senior Secured Revolving Credit Facility | Alternate Base Rate | Maximum | Revolving Credit Facility
Line of Credit Facility [Line Items]
Variable interest rate	3.75%
Senior Secured Revolving Credit Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 52,500,000		$ 65,000,000
Quarterly payments of principle balance (percent)	0.25%
Aggregate annual payments of principle balance (percent)	1.00%
Incremental Revolver | Revolving Credit Facility
Line of Credit Facility [Line Items]
Increase in maximum borrowing capacity			12,500,000
Incremental Revolver | Letter of Credit
Line of Credit Facility [Line Items]
Increase in maximum borrowing capacity			$ 5,000,000

Debt - Summary of Term Loan B F

Debt - Summary of Term Loan B Facility (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Long-term Debt, Excluding Current Maturities, Total	$ 720,710	$ 720,023
Secured Debt | Term Loan B Facility
Debt Instrument [Line Items]
Term Loan B Facility	357,300	358,200
Debt instrument, unamortized discount	(9,342)	(9,738)
Unamortized debt issuance costs	(14,577)	(15,196)
Long-term Debt, Excluding Current Maturities, Total	$ 333,381	$ 333,266

Debt - Interest Expense Relat_2

Debt - Interest Expense Related to the Term Loan B Facility (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Debt Instrument [Line Items]
Amortization of debt discount and issuance costs	$ 1,700	$ 99
Secured Debt | Term Loan B Facility
Debt Instrument [Line Items]
Contractual interest expense	5,163
Amortization of debt discount	397
Amortization of debt discount and issuance costs	619
Total interest expense	$ 6,179
Effective interest rate	6.98%

Debt - Amortization Expense f_2

Debt - Amortization Expense for the Term Loan B Facility Debt Discount and Issuance Costs (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Discount
2026	$ 1,998
Debt Issuance Costs
Amortization Of Debt Issuance Costs, Year Five	3,116
Secured Debt | Term Loan B Facility
Debt Discount
Remaining 2022	1,184
Remaining 2022	1,564
2023	1,548
2024	1,532
2025	1,516
Total	9,342	$ 9,738
Debt Issuance Costs
Remaining 2022	1,847
2023	2,441
2024	2,416
2025	2,391
2026	2,366
Total	$ 14,577	$ 15,196

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Apr. 30, 2022	Mar. 31, 2022
Subsequent Event [Line Items]
Purchase of treasury stock		$ 12,138
Subsequent Events
Subsequent Event [Line Items]
Treasury stock, shares acquired (in shares)	312,497
Treasury stock, shares retired (in shares)	312,497
Purchase of treasury stock	$ 3,500
Treasury stock acquired, average cost per share (in usd per share)	$ 11.28