Compass (COMP) 10-Q 12 Nov 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Nov. 09, 2021
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Registrant Name	Compass, Inc.
Entity Central Index Key	0001563190
Current Fiscal Year End Date	--12-31
Entity File Number	001-40291
Entity Tax Identification Number	30-0751604
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Trading Symbol	COMP
Security Exchange Name	NYSE
Title of 12(g) Security	Class A Common Stock, $0.00001 par value per share
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	90 Fifth Avenue, 3rd Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10011
City Area Code	212
Local Phone Number	913-9058
Entity Common Stock, Shares Outstanding		406,777,033

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 791.4	$ 440.1
Accounts receivable, net of allowance of $7.8 and $8.1, respectively	55.5	54.8
Compass Concierge receivables, net of allowance of $20.0 and $17.2, respectively	49.4	49.5
Other current assets	84.4	54.9
Total current assets	980.7	599.3
Property and equipment, net	151.3	141.7
Operating lease right-of-use assets	458.9	426.6
Intangible assets, net	127.5	45.6
Goodwill	182.6	119.8
Other non-current assets	46.2	32.1
Total assets	1,947.2	1,365.1
Current liabilities
Accounts payable	35.3	36.6
Commissions payable	73	62
Accrued expenses and other current liabilities	215.7	106.8
Current lease liabilities	80.2	68.1
Concierge credit facility	18.7	8.4
Total current liabilities	422.9	281.9
Non-current lease liabilities	457.8	435.9
Other non-current liabilities	36.6	23.5
Total liabilities	917.3	741.3
Commitments and contingencies (Note 6)
Convertible preferred stock, $0.00001 par value, 0 and 246,430,170 shares authorized at September 30, 2021 and December 31, 2020, respectively; 0 and 237,047,550 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	0	1,486.7
Stockholders' equity (deficit)
Common stock, $0.00001 par value, 13,850,000,000 and 700,754,910 shares authorized at September 30, 2021 and December 31, 2020, respectively; 399,082,563 and 125,221,900 shares issued at September 30, 2021 and December 31, 2020, respectively; 399,082,563 and 122,971,900 shares outstanding at September 30, 2021 and December 31, 2020, respectively	0	0
Additional paid-in capital	2,445.4	238
Accumulated deficit	(1,420.2)	(1,100.9)
Total Compass, Inc. stockholders' equity (deficit)	1,025.2	(862.9)
Non-controlling interest	4.7	0
Total stockholders' equity (deficit)	1,029.9	(862.9)
Total liabilities, convertible preferred stock and stockholders' equity (deficit)	$ 1,947.2	$ 1,365.1

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Allowance for credit loss on accounts receivable current	$ 7.8	$ 8.1
Allowance for credit loss on financing receivable current	$ 20	$ 17.2
Convertible preferred stock par or stated value per share	$ 0.00001	$ 0.00001
Convertible preferred stock shares authorized	0	246,430,170
Convertible preferred stock shares issued	0	237,047,550
Convertible preferred stock shares outstanding	0	237,047,550
Common stock par or stated value per share	$ 0.00001	$ 0.00001
Common stock shares authorized	13,850,000,000	700,754,910
Common stock shares issued	399,082,563	125,221,900
Common stock shares outstanding	399,082,563	122,971,900

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Revenue	$ 1,743.6	$ 1,188.5	$ 4,808.9	$ 2,490.5
Operating expenses
Commissions and other related expense	1,430.6	979.4	3,963.2	2,047.2
Sales and marketing	130.6	99.7	366.2	297
Operations and support	97	53.3	263.7	158.9
Research and development	89.7	33.7	259.8	106.7
General and administrative	79.5	22.7	231.8	75.7
Depreciation and amortization	16.7	13	45.1	38.1
Total operating expenses	1,844.1	1,201.8	5,129.8	2,723.6
Loss from operations	(100.5)	(13.3)	(320.9)	(233.1)
Investment income, net	0.1		0.1	2
Interest expense	(0.7)	(0.2)	(1.8)	(0.2)
Loss before income taxes	(101.1)	(13.5)	(322.6)	(231.3)
Benefit from income taxes	1.3		3.3	0.9
Net loss	$ (99.8)	$ (13.5)	$ (319.3)	$ (230.4)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.25)	$ (0.12)	$ (1.06)	$ (2.11)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	392,979,596	110,447,900	300,303,264	109,448,680

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment [Member]	Noncontrolling Interest [Member]	Parent [Member]	Parent [Member]Cumulative Effect, Period of Adoption, Adjustment [Member]	Convertible Preferred Stock [member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]	Accumulated Deficit [Member]Cumulative Effect, Period of Adoption, Adjustment [Member]
Beginning balance at Dec. 31, 2019	$ (681.6)			$ (681.6)		$ 1,525.7		$ 143.4	$ 0.1	$ (825.1)
Beginning balance, shares at Dec. 31, 2019						246,365,350	109,294,060
Net loss	(230.4)			(230.4)						(230.4)
Cumulative change in accounting principle (ASU 2016-13)		$ (5.6)			$ (5.6)						$ (5.6)
Unrealized loss on investments	(0.1)			(0.1)					$ (0.1)
Issuance of shares in connection with acquisitions	1.2			1.2				1.2
Issuance of shares in connection with acquisitions, Shares							401,310
Issuance of Series G convertible preferred stock, net of issuance costs						$ 1
Issuance of Series G convertible preferred stock, net of issuance costs, Shares						64,820
Issuance of stock for option exercises	6.7			6.7				6.7
Issuance of stock for option exercises, Shares							1,807,370
Stock-based compensation	30.2			30.2				30.2
Ending balance at Sep. 30, 2020	(879.6)			(879.6)		$ 1,526.7		181.5		(1,061.1)
Ending balance, shares at Sep. 30, 2020						246,430,170	111,502,740
Beginning balance at Jun. 30, 2020	(875.5)			(875.5)		$ 1,526.7		172.1		(1,047.6)
Beginning balance, shares at Jun. 30, 2020						246,430,170	110,645,490
Net loss	(13.5)			(13.5)						(13.5)
Issuance of stock for option exercises	3.3			3.3				3.3
Issuance of stock for option exercises, Shares							857,250
Stock-based compensation	6.1			6.1				6.1
Ending balance at Sep. 30, 2020	(879.6)			(879.6)		$ 1,526.7		181.5		(1,061.1)
Ending balance, shares at Sep. 30, 2020						246,430,170	111,502,740
Beginning balance at Dec. 31, 2020	(862.9)			(862.9)		$ 1,486.7		238		(1,100.9)
Beginning balance, shares at Dec. 31, 2020						237,047,550	122,971,900
Net loss	(319.6)		$ (0.3)	(319.3)						(319.3)
Capital contribution from non-controlling interest	5		5
Issuance of shares in connection with acquisitions	14.1			14.1				14.1
Issuance of shares in connection with acquisitions, Shares							9,185,720
Issuance of shares in connection with acquisitions	10.1			10.1				10.1
Issuance of shares in connection with acquisitions, Shares							855,740
Conversion of Series D convertible preferred stock	67.6			67.6		$ (67.6)		67.6
Conversion of Series D convertible preferred stock, Shares						(15,920,450)	15,920,450
Conversion of convertible preferred stock to common stock in connection with the initial public offering	1,419.1			1,419.1		$ (1,419.1)		1,419.1
Conversion of convertible preferred stock to common stock in connection with the initial public offering, Shares						(221,127,100)	223,033,725
Issuance of common stock in connection with the initial public offering, net of issuance costs	$ 438.7			438.7				438.7
Issuance of common stock in connection with the initial public offering, net of issuance costs, Shares							26,296,438
Issuance of stock for option exercises, Shares	6,224,067
Early exercise of stock options							818,590
Vesting of early exercised stock options	$ 3.8			3.8				3.8
Stock-based compensation	254			254				254
Ending balance at Sep. 30, 2021	1,029.9		4.7	1,025.2				2,445.4		(1,420.2)
Ending balance, shares at Sep. 30, 2021							399,082,563
Beginning balance at Jun. 30, 2021	1,075.5			1,075.5				2,395.9		(1,320.4)
Beginning balance, shares at Jun. 30, 2021							394,419,967
Net loss	(100.1)		(0.3)	(99.8)						(99.8)
Capital contribution from non-controlling interest	5		5
Issuance of shares in connection with acquisitions	2.9			2.9				2.9
Issuance of shares in connection with acquisitions, Shares							4,662,596
Vesting of early exercised stock options	1.3			1.3				1.3
Stock-based compensation	45.3			45.3				45.3
Ending balance at Sep. 30, 2021	$ 1,029.9		$ 4.7	$ 1,025.2				$ 2,445.4		$ (1,420.2)
Ending balance, shares at Sep. 30, 2021							399,082,563

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating Activities
Net loss	$ (319.3)	$ (230.4)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	45.1	38.1
Stock-based compensation	292.9	30.2
Change in acquisition related contingent consideration	(4.4)	5.5
Bad debt expense	8.9	12.7
Amortization of debt issuance costs	0.9	0.1
Changes in operating assets and liabilities:
Accounts receivable	1.6	(65.7)
Compass Concierge receivables	(7.1)	0.9
Other current assets	(29.6)	14.9
Other non-current assets	(13.4)	(2.8)
Operating lease right-of-use assets and operating lease liabilities	1.6	33.2
Accounts payable	(2.4)	(12.8)
Commissions payable	8.8	56.9
Accrued expenses and other liabilities	64.7	31.1
Net cash provided by (used in) operating activities	48.3	(88.1)
Investing Activities
Proceeds from sales and maturities of marketable securities		55.5
Capital expenditures	(33.6)	(34.8)
Payments for acquisitions, net of cash acquired	(127.3)	(0.8)
Net cash (used in) provided by investing activities	(160.9)	19.9
Financing Activities
Proceeds from issuance of convertible preferred stock, net of issuance costs		1
Proceeds from exercise and early exercise of stock options	19.1	6.8
Proceeds from drawdowns on Concierge credit facility	29.6	8.2
Repayments of drawdowns on Concierge credit facility	(19.3)
Payments of contingent consideration related to acquisitions	(8.2)	(3.2)
Payments of debt issuance costs for credit facilities	(1.9)
Proceeds from capital contribution of non-controlling interest in OriginPoint, LLC joint venture	5
Proceeds from issuance of common stock upon initial public offering, net of offering costs	439.6
Net cash provided by financing activities	463.9	12.8
Net increase (decrease) in cash and cash equivalents	351.3	(55.4)
Cash and cash equivalents at beginning of period	440.1	491.7
Cash and cash equivalents at end of period	791.4	436.3
Supplemental disclosures of cash flow information:
Cash paid for interest	0.7
Supplemental non-cash information:
Conversion of convertible preferred stock in connection with initial public offering	1,419.1
Conversion of Series D convertible preferred stock	67.6
Common Class A [Member]
Supplemental non-cash information:
Issuance of common stock for acquisitions	$ 10.1	$ 1.2

Business and Basis of Presentat

Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Basis of Presentation	1. Business and Basis of Presentation Description of the Business Compass, Inc. (the “Company”) was incorporated in Delaware on October 4, 2012 under the name Urban Compass, Inc. On January 8, 2021, the board of directors of the Company approved a change to the Company’s name from Urban Compass, Inc. to Compass, Inc. The Company provides an end-to-end The Company’s agents are independent contractors who affiliate their real estate licenses with the Company, operating their businesses on the Company’s platform and under the Compass brand. The Company generates revenue from clients through its agents by assisting home sellers and buyers in listing, marketing, selling and finding homes as well as through the provision of services adjacent to the transaction, like title and escrow services, which comprise a smaller portion of the Company’s revenue to date. The Company currently generates substantially all of its revenue from commissions paid by clients at the time that a home is transacted. Stock Split In March 2021, the Company’s board of directors and the stockholders of the Company approved a ten-for-one ten-for-one Initial Public Offering On April 6, 2021, the Company completed its initial public offering (“IPO”) and the Company’s Class A common stock began trading on the New York Stock Exchange on April 1, 2021 under the symbol “COMP”. In connection with the IPO, the Company issued and sold 26,296,438 shares of its common stock at a public offering price of $18.00 per share. The Company received aggregate proceeds of $438.7 million from the IPO, net of the underwriting discount and offering costs of approximately $11.0 million (of which $0.9 million were paid in 2020). Offering costs, including the legal, accounting, printing and other IPO-related paid-in paid-in-capital. On March 31, 2021, in connection with the effectiveness of the Company’s IPO registration statement, the Company recognized $148.5 million in stock-based compensation expense for (i) certain RSUs that contained both service-based and liquidity event-based vesting conditions as the liquidity event-based vesting condition was satisfied upon effectiveness of the registration statement and (ii) certain stock options and RSU awards with service, performance and market-based vesting conditions that include stock price targets to be met after the listing of the Company’s stock on a public exchange. In April 2021, the Company adopted a restated certificate of incorporation and changed its authorized capital stock to consist of 12,500,000,000 shares of Class A common stock, 1,250,000,000 shares of Class B common stock, 100,000,000 shares of Class C common stock and 25,000,000 shares of undesignated preferred stock. On March 31, 2021, in connection with the effectiveness of the Company’s IPO registration statement, 15,244,490 shares of Class A common stock held by the Company’s founder and Chief Executive Officer were exchanged for an equivalent number of shares of Class C common stock. In addition, any Class A common stock issued to the Company’s Chief Executive Officer from RSU awards granted prior to February 2021 are able to be exchanged for Class C common stock once the RSUs have been settled for the underlying Class A common stock. Basis of Presentation The condensed consolidated financial statements include the accounts of the Company and its subsidiaries. The activities of OriginPoint LLC (“OriginPoint”), a mortgage origination company and joint venture formed in July 2021 between the Company and Guaranteed Rate, Inc. (“Guaranteed Rate”), are consolidated within the accompanying condensed consolidated financial statements. OriginPoint is owned 49.9% by the Company and 50.1% by Guaranteed Rate and the activities of OriginPoint are consolidated since the Company has the power to direct those activities that will significantly affect the economic performance of the joint venture. The economic interests related to Guaranteed Rates’ 50.1% ownership interest are reflected as non-controlling The unaudited interim condensed consolidated financial statements and related disclosures have been prepared by management on a basis consistent with the annual consolidated financial statements and, in the opinion of management, include all adjustments necessary for a fair statement of the interim periods presented.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make judgments, estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and reported amounts of revenue and expenses during the reporting periods covered by the consolidated financial statements and accompanying notes. These judgments, estimates and assumptions are used for, but not limited to (i) valuation of the Company’s common stock and stock awards, (ii) fair value of acquired intangible assets and goodwill, (iii) contingent considerations in connection with business combinations, (iv) incremental borrowing rate used for the Company’s operating leases, (v) useful lives of long-lived assets, (vi) impairment of intangible assets and goodwill, (vii) allowance for Compass Concierge receivables and (viii) income taxes and certain deferred tax assets. The Company determines its estimates and judgments based on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, actual results could differ from these estimates and these differences may be material. There are many uncertainties regarding the ongoing coronavirus (“COVID-19”) COVID-19 COVID-19 Business Combinations Business combinations are accounted for under the acquisition method of accounting. This method requires, among other things, allocation of the fair value of purchase consideration to the tangible and intangible assets acquired and liabilities assumed at their estimated fair values on the acquisition date. The excess of the fair value of purchase consideration over the values of these identifiable assets and liabilities is recorded as goodwill. When determining the fair value of assets acquired and liabilities assumed, management makes significant estimates and assumptions, especially with respect to intangible assets. Management’s estimates of fair value are based upon assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates. During the measurement period, not to exceed one year from the date of acquisition, the Company may record adjustments to the assets acquired and liabilities assumed, with a corresponding offset to goodwill if new information is obtained related to facts and circumstances that existed as of the acquisition date. After the measurement period, any subsequent adjustments are reflected in the condensed consolidated statements of operations. Acquisition costs, consisting primarily of third-party legal and consulting fees, are expensed as incurred. Stock-Based Compensation The Company measures compensation expense for all stock-based awards based on the estimated fair value of the awards on the date of grant. Compensation expense is generally recognized as expense on a straight-line basis over the service period based on the vesting requirements. The Company recognizes forfeitures as they occur. For stock options, which the Company issues to employees and affiliated agents, the Company generally estimates the fair value using the Black- Scholes option pricing model, which requires the input of subjective assumptions, including (1) the fair value of common stock, (2) the expected stock price volatility, (3) the expected term of the award, (4) the risk-free interest rate and (5) expected dividends. The Company also issues RSUs to employees and affiliated agents. In addition to the issuance of RSUs to agents as equity compensation for the provision of services, the Company offers RSUs to affiliated agents through its Agent Equity Program. The Agent Equity Program offers affiliated agents the ability to elect to have a portion of their commissions earned during a calendar year to be paid in the form of RSUs. RSUs issued in connection with the Agent Equity Program are granted at the beginning of the year following the calendar year in which the commissions were earned and are subject to the terms and conditions of the 2012 Stock Incentive Plan and the 2021 Equity Incentive Plan, as applicable. The Company’s RSUs granted prior to December 2020 generally vest based upon the satisfaction of both a service-based condition and a liquidity event-based condition. The service-based vesting condition for these awards is generally satisfied over four years, except for the RSUs associated with the 2020 Agent Equity Program which vested immediately on the date of issuance. The liquidity event-based vesting condition is satisfied on the occurrence of a qualifying event, generally defined as a change in control or the effective date of the registration statement for the Company’s IPO. The fair value of these RSUs is measured based on the fair value of the Company’s common stock on the grant date and will begin to be recognized as expense when both the required service-based vesting condition and the liquidity event-based vesting condition has been achieved using the accelerated attribution method. The liquidity event-based vesting requirement was met on March 31, 2021, the effective date of the Company’s registration statement, see Note 1—“Business and Basis of Presentation—Initial Public Offering.” Beginning in December 2020, the Company began issuing RSUs that vest upon the satisfaction of only a service-based vesting condition that is generally ranging from four For RSUs to be granted in connection with the 2021 Agent Equity Program, the Company determines the value of the stock-based compensation expense at the time the underlying commission is earned and begins to recognize the associated expense on a straight-line basis over the requisite service periods beginning on the closing date of the underlying real estate commission transactions. The stock-based compensation expense is recorded as a liability and will be reclassified to Additional paid-in On a limited basis, the Company has issued stock options and RSUs that contain service, performance and market-based vesting conditions that include stock price targets to be met after the listing of the Company’s stock on a public exchange. Such awards are valued using a Monte Carlo simulation and the underlying expense will be recognized as the associated vesting conditions are met. Deferred Offering Costs Deferred offering costs, consisting of legal, accounting and other fees and costs relating to the IPO, are capitalized and recorded on the condensed consolidated balance sheets. As of December 31, 2020, $1.8 million of deferred offering costs were capitalized in Other non-current nine September paid-in New Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes Income Taxes step-up In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2021
Business Combinations [Abstract]
Acquisitions	3. Acquisitions During the nine months ended September 30, 2021, the Company completed several business acquisitions including the acquisition of 100% of the ownership interests in KVS Title, LLC, a title insurance and escrow settlement services company, Glide Labs, Inc., a real estate technology company, Randall Family of Companies, a group of Southern Coastal New England residential real-estate brokerage entities, four additional small real estate brokerages and one additional small title insurance and escrow settlement services company. The purpose of these acquisitions was to expand the Company’s title and escrow offerings, to grow the Company’s transaction management tools included in its end-to-end Total Consideration The total consideration for acquisitions completed during the nine months ended September 30, 2021 comprised $148.5 million of cash, net of cash acquired, $5.8 million in Class A Common Stock of the Company and up to $5.4 million of additional cash that may be paid contingent on certain earnings-based targets being met through 2023. During the nine months ended September 30, 2021, $127.3 million in cash was paid in connection with these acquisitions, net of cash acquired, and up to an aggregate of $21.2 million will be paid once certain indemnification matters and pre-acquisition These future cash payments were recorded as Accrued expenses and other current liabilities in the condensed consolidated balance sheet. The fair value of the assets acquired and the liabilities assumed primarily resulted in the recognition of: broker relationships of $82.7 million; trademark intangible assets of $11.4 million; acquired technology of $5.5 million; operating lease right-of-use non-current non-current Approximately $22.0 million of the goodwill recorded during the nine months ended September 30, 2021 is deductible for tax purposes. The amount of tax-deductible The Company has recorded the preliminary purchase price allocation as of the acquisition dates and expects to finalize its analysis within the measurement period (up to one year from the acquisition date) of the respective transaction. Any adjustments during the measurement period would have a corresponding offset to goodwill. Upon conclusion of the measurement period or final determination of the values of assets acquired or liabilities assumed, any subsequent adjustments are recorded to the consolidated statements of operations. Pro forma revenue and earnings for 2021 acquisitions have not been presented because they are not material to the Company’s consolidated revenue and results of operations, either individually or in the aggregate. Contingent Consideration Contingent consideration represents obligations of the Company to transfer cash and common stock to the sellers of certain acquired busin e $28.2 million. Changes in contingent consideration measured at fair value on a recurring basis were as follows (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Opening balance $ 33.0 $ 15.3 $ 39.8 $ 16.4 Acquisitions 0.7 — 5.4 — Payments and issuances (2.7 ) (2.4 ) (13.7 ) (5.4 ) Fair value (gains) losses included in net loss (3.9 ) 3.6 (4.4 ) 5.5 Closing Balance $ 27.1 $ 16.5 $ 27.1 $ 16.5 Other Acquisition Related Compensation In connection with the Company’s acquisitions, certain amounts paid or to be paid to selling shareholders are subject to clawback and forfeiture dependent on certain employees and agents providing continued service to the Company. These retention-based payments are accounted for as compensation for future services and the Company recognizes the expenses over the service period. As of September 30, 2021, the maximum was $ 57.7 During the nine months ended September 30, 2021, the Company granted 277,776 shares of common stock to sellers in accordance with arrangements where vesting of the shares is contingent on such sellers providing continued service to the Company. Accordingly, these share-based payments will be accounted for as stock-based compensation expense over the underlying retention periods. As a result, the Company recognized $0.7 million stock-based compensation expense related to these compensation arrangements during the three and nine months ended September 30, 2021.

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities	4. Fair Value of Financial Assets and Liabilities The Company’s cash and cash equivalents of $789.6 million and $440.1 million as of September 30, 2021 and December 31, 2020, respectively, are held in cash and money market funds which are classified as Level 1 within the fair value hierarchy because they are valued using quoted prices in active markets. These are the Company’s only Level 1 financial instruments. The Company does not hold any Level 2 financial instruments. The Company’s contingent consideration liabilities of $27.1 million and $39.8 million as of September 30, 2021 and December 31, 2020, respectively, are the Company’s only Level 3 financial instruments. See Note 3 – “Acquisitions” for changes in contingent consideration for the three and nine months ended September 30, 2021 and 2020. The following table presents the balances of contingent consideration (in millions): September 30, 2021 December 31, 2020 Accrued expenses and other current liabilities $ 12.1 $ 19.1 Other non-current 15.0 20.7 Total contingent consideration $ 27.1 $ 39.8 There were no transfers of financial instruments between Level 1, Level 2 and Level 3 during the periods presented. Level 3 Financial Liabilities The Company’s Level 3 financial liabilities relate to acquisition-related contingent consideration arrangements. Contingent consideration represents obligations of the Company to transfer cash and common stock to the sellers of certain acquired entities in the event that certain targets and milestones are met. The Company estimated the fair value of the contingent consideration using a Monte Carlo simulation, which is based on significant inputs, primarily forecasted future results of the acquired businesses, not observable in the market, discount rates and earnings volatility measures. The changes in the fair value of Level 3 financial liabilities are included within Operations and support in the accompanying condensed consolidated statements of operations (see Note 3 – “Acquisitions”). The following tables present quantitative information regarding the significant unobservable inputs utilized by the Company in the fair value measurement of Level 3 liabilities, consisting of different contingent consideration agreements, measured at fair value on a recurring basis: September 30, December 31, Discount rate 0.0% - 2.0% 0.0% - 2.0% Weighted average discount rate 0.5% 1.3% Earnings volatility 0% - 15% 0% - 18% Weighted average earnings volatility 3.4% 6.9%

Debt

Debt	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Debt	5. Debt Concierge Credit Facility In July 2020, the Company entered into a Revolving Credit and Security Agreement (the “Concierge Facility”) with Barclays Bank PLC, as administrative agent, and the several lenders party thereto. The Concierge Facility provides for a $75.0 million revolving credit facility and is solely used to finance, in part, the Company’s Compass Concierge Program. The Concierge Facility is secured primarily by the Concierge Receivables and cash of the Compass Concierge Program. Prior to July 29, 2021 borrowings under the Concierge Facility accrued interest at rates equal to the adjusted London interbank offered rate (“LIBOR”) plus a margin of 3.00 % The Company has the option to repay the borrowings under the Concierge Facility without premium or penalty prior to maturity. The Concierge Facility contains customary affirmative covenants, such as financial statement reporting requirements, as well as covenants that restrict its ability to, among other things, incur additional indebtedness, sell certain receivables, declare dividends or make certain distributions, and undergo a merger or consolidation or certain other transactions. Additionally, in the event that the Company fails to comply with certain financial covenants that require the Company to meet certain liquidity-based measures, the commitments under the Concierge Facility will automatically be reduced to zero and the Company will be required to repay any outstanding loans under the Concierge Facility. As of September 30, 2021, the Company was in compliance with the covenants under the Concierge Facility. Revolving Credit Facility In March 2021, the Company entered into a Revolving Credit and Guaranty Agreement (the “Revolving Credit Facility”) with several lenders and issuing banks and Barclays Bank PLC, as administrative agent and as collateral agent. The Revolving Credit Facility provides for a $350.0 million revolving credit facility, which may be increased by the greater of $250.0 million and 18.5% of the Company’s consolidated total assets, plus such additional amount so long as the Company’s total net leverage ratio does not exceed 4.50:1.00 on a pro forma basis as of the most recent test period, subject to the terms of the Revolving Credit Facility. The Revolving Credit Facility also includes a letter of credit sublimit which is the lesser of (i) $125.0 million and (ii) the aggregate unused amount of the revolving commitments then in effect under the Revolving Credit Facility. The Company’s obligations under the Revolving Credit Facility are guaranteed by certain of the Company’s subsidiaries and are secured by a first priority security interest in substantially all of the Company’s assets and the Company’s subsidiary guarantors. Borrowings under the Revolving Credit Facility bear interest, at the Company’s option, at either (i) a floating rate per annum equal to the base rate plus a margin of 0.50% or (ii) a floating rate per annum equal to the rate at which dollar deposits are offered in the London interbank market plus a margin of 1.50%. In the Revolving Credit Facility, the base rate is defined as the highest of (a) the prime rate as quoted by The Wall Street Journal, (b) the federal funds effective rate plus 0.50%, (c) the rate at which dollar deposits are offered in the London interbank market for a one-month The Company is also obligated to pay other customary fees for a credit facility of this size and type, including a commitment fee on a quarterly basis based on amounts committed but unused under the Revolving Credit Facility of 0.175% per annum and fees associated with letters of credit. The principal amount, if any, is payable in full in March 2026, unless earlier terminated or extended. The Company has the option to repay the Company’s borrowings, and to permanently reduce the loan commitments whole or in part, under the Revolving Credit Facility without premium or penalty prior to maturity. As of September 30, 2021, there were no borrowings outstanding under the Revolving Credit Facility and outstanding letters of credit under the Revolving Credit Facility totaled approximately $16.3 million. The Revolving Credit Facility contains customary representations, warranties, financial covenants applicable to the Company and to the Company’s restricted subsidiaries, affirmative covenants, such as financial statement reporting requirements, and negative covenant which restrict its ability, among other things, to incur liens and indebtedness, make certain investments, declare dividends, dispose of, transfer or sell assets, make stock repurchases and consummate certain other matters, all subject to certain exceptions. The financial covenants require that the Company maintain certain liquidity-based measures and total revenue requirements. As of September 30, 2021, the Company was in compliance with the covenants under the Revolving Credit Facility. The Revolving Credit Facility includes customary events of default that include, among other things, nonpayment of principal, interest or fees, inaccuracy of representations and warranties, violation of certain covenants, cross default to certain other indebtedness, bankruptcy and insolvency events, material judgments, change of control and certain material ERISA events. The occurrence of an event of default could result in the acceleration of the obligations under the Revolving Credit Facility. The Company incurred debt issuance costs of $1.4 million in connection with the Revolving Credit Facility, which are included in Other current assets and Other non-current

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Legal Proceedings From time to time, the Company may be involved in disputes or regulatory inquiries that arise in the ordinary course of business. When the Company determines that a loss is both probable and reasonably estimable, a liability is recorded and disclosed if the amount is material to the Company’s business taken as a whole. When a material loss contingency is only reasonably possible, the Company does not record a liability, but instead discloses the nature and the amount of the claim and an estimate of the loss or range of loss, if such an estimate can reasonably be made. Legal costs related to the defense of loss contingencies are expensed as incurred. Claims or regulatory actions against the Company, whether meritorious or not, could have an adverse impact on the Company due to legal costs, diversion of management resources and other elements. Except as identified with respect to the matters below, the Company does not believe that the outcome of any individual existing legal or regulatory proceeding to which it is a party will have a material adverse effect on its results of operations, financial condition or overall business in each case, taken as a whole. Avi Dorfman v. Robert Reffkin and Urban Compass, Inc. In July 2014, Avi Dorfman (“Dorfman”) and RentJolt, Inc. (“RentJolt”) (collectively, “Plaintiffs”) filed suit against the Company and Robert Reffkin (“Defendants”), seeking compensation for certain services, trade secrets and other contributions allegedly provided in the formation of the Company. After miscellaneous motion practice, in June 2018, Defendants moved for summary judgment, the court held oral argument in October 2018 and ultimately denied the Defendants’ motion for summary judgment in October 2019. In November 2019, Defendants appealed portions of the court’s summary judgment ruling. In February 2020, the appellate court granted in part and denied in part Defendants’ appeal resulting in one plaintiff (RentJolt) voluntarily discontinuing its only remaining claim and leaving the case. Defendants have one motion in limine pending. A trial date has been set for January 2022. On October 25, 2021, the parties agreed to a settlement in principle. Once the settlement is finalized , $ million during the three and nine months ended September 30, 2021 in connection with the settlement within General and administrative expense in the accompanying condensed consolidated statements of operations. Realogy Holdings Corp., et al v. Urban Compass, Inc. and Compass Inc. In July 2019, Realogy Holdings Corp., NRT New York LLC (“Corcoran”) and many of its related entities (collectively, “Plaintiffs”) filed a complaint against the Company in the New York Supreme Court. The complaint alleges various violations of New York and California state law related to claims of unfair competition and seeks unspecified damages. The Company filed a Motion to Dismiss in September 2019. In September 2019, Plaintiffs filed an amended complaint, removing one claim and adding a claim for defamation. In November 2019, the Company moved to compel arbitration related to claims asserted by Corcoran and moved to dismiss all of the counts. In June 2020, the Court denied the motion to dismiss and denied the motion to compel arbitration as moot, granting Plaintiffs leave to amend the complaint as to claims asserted by Corcoran without prejudice to Defendants’ ability to move to compel or dismiss the Second Amended Complaint. On July 3, 2020, Plaintiffs filed their Second Amended Complaint. On December 18, 2020, the Court denied the Company’s motion to compel arbitration on Plaintiffs’ second amended complaint without prejudice. Defendants’ Answer to the Second Amended Complaint and Counterclaims were filed on January 28, 2021. Additionally, the Company filed its appeal of the lower Court’s denial of the Company’s motion to dismiss and motion to compel arbitration on February 1, 2021. On June 1, 2021, the First Department affirmed the lower Court’s denial of the Company’s motion to compel arbitration. Discovery is proceeding, with an end date set for October Letter of Credit Agreements The Company has irrevocable letters of credit with various financial institutions, primarily related to security deposits for leased facilities. As of September 30, 2021 and December 31, 2020, the Company was contingently liable for $51.7 million and $50.7 million, respectively, under these letters of credit. As of September 30, 2021, $16.3 million and $35.4 million of these letters of credit were collateralized by the Company’s Revolving Credit Facility and cash and cash equivalents, respectively. As of December 31, 2020, all letters of credit were collateralized by the Company’s cash and cash equivalents. Escrow and Trust Deposits As a service to its home buyers and home sellers, the Company administers escrow and trust deposits which represent undistributed amounts for the settlement of real estate transactions. The escrow and trust deposits totaled $205.7 million and $46.1 million, respectively as of September 30, 2021 and December 31, 2020. These deposits are not assets of the Company and therefore are excluded from the accompanying condensed consolidated balance sheets. However, the Company remains contingently liable for the disposition of these deposits.

Preferred Stock and Common stoc

Preferred Stock and Common stock	9 Months Ended
	Sep. 30, 2021
Stockholders' Equity Note [Abstract]
Preferred Stock and Common stock	7. Preferred Stock and Common Stock Convertible Preferred Stock In March 2020, the Company issued an additional 64,820 shares of its Series G convertible preferred stock for proceeds of $1.0 million. In March 2021, the holders of 15,920,450 shares of the Company’s Series D convertible preferred stock elected to convert such shares into an equal number of shares of Class A common stock. During April 2021, in connection with the IPO, all series of the Company’s convertible preferred stock then outstanding were converted into 223,033,725 shares of Class A common stock and the Company reclassified $1.4 billion of Convertible preferred stock to Additional paid-in-capital. Undesignated Preferred Stock In April 2021, the Company adopted a restated certificate of incorporation which provides for authorized undesignated preferred stock to 25,000,000. As of September 30, 2021, there are no shares of the Company’s preferred stock issued and outstanding. Common Stock In February 2021, the Company approved the establishment of Class C common stock and an agreement with the Company’s CEO to exchange his Class A common stock for Class C common stock. On March 31, 2021, in connection with the effectiveness of the registration statement for the Company’s IPO, 15,244,490 shares of Class A common stock held by the Company’s founder and CEO were automatically exchanged for an equivalent number of shares of Class C common stock. In addition, any Class A common stock issued to the Company’s Chief Executive Officer from RSU awards granted prior to February 2021 are able to be exchanged for Class C common stock. Each share of Class C common stock is entitled to twenty votes per share and will be convertible at any time into one share of Class A common stock and will automatically convert into Class A common stock under certain “sunset” provisions. Other than certain permitted transfers for estate planning purposes, upon a transfer of Class C common stock, the Class C common stock will convert into Class A common stock. In April 2021, the Company adopted a restated certificate of incorporation and changed its authorized capital stock to consist of 12,500,000,000 shares of Class A common stock, 1,250,000,000 shares of Class B common stock and 100,000,000 shares of Class C common stock. As of September 30, 2021, the Company had three classes of common stock: Class A common stock, Class B common stock and Class C common stock. Each class has par value of $0.00001. September 30, 2021 Shares Shares Issued Shares Class A common stock 12,500,000,000 383,838,073 383,838,073 Class B common stock 1,250,000,000 — — Class C common stock 100,000,000 15,244,490 15,244,490 Total 13,850,000,000 399,082,563 399,082,563 As of December 31, 2020, the Company had two classes of common stock: Class A common stock and Class B common stock. Each class has a par value of $0.00001. December 31, 2020 Shares Shares Issued Shares Class A common stock 530,136,050 118,549,390 116,299,390 Class B common stock 170,618,860 6,672,510 6,672,510 Total 700,754,910 125,221,900 122,971,900 Holders of Class A common stock are entitled to one vote per share. Holders of Class B common stock are not entitled to vote. Holders of Class C common stock are entitled to twenty votes per share. Each share of Class C common stock is convertible at any time of the option of the holder into one share of Class A common stock. Each share of Class C common stock will automatically convert into a share of Class A common stock upon sale or transfer, except for certain permitted transfers. On July 1, 2021, the board of directors of the Company approved the conversion of all outstanding shares of the Company’s Class B common stock into the same number of shares of the Company’s Class A common stock effective on that date. A description of all other rights, preferences and privileges of the holders of the Company’s common stock are included in the Company’s IPO prospectus on Form S-1 As of December 31, 2020, the Company had 2,250,000 shares of Class A common stock issued and held as treasury stock which were subsequently retired on July 1, 2021.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	8. Stock-Based Compensation 2012 Stock Incentive Plan In October 2012, the Company adopted the 2012 Stock Incentive Plan (the “2012 Plan”). Under the 2012 Plan, employees and non-employees ten-year approval. 2021 Equity Incentive Plan In February 2021, the Company’s board of directors and stockholders adopted and approved the 2021 Equity Incentive Plan (the “2021 Plan”), with an initial pool of 29,666,480 shares of common stock available for granting stock-based awards plus any reserved shares of common stock not issued or subject to outstanding awards granted under the Company’s 2012 Plan. In addition, on January 1st of each year beginning in 2022 and continuing through 2031, the aggregate number of shares of common stock authorized for issuance under the 2021 Plan shall be increased automatically by the number of shares equal to five percent (5%) of the total number of outstanding shares of all classes of common stock on the immediately preceding December 31st, although the Company’s board of directors or one of its committees may reduce the amount of such increase in any particular year. The 2021 Plan became effective on March 30, 2021 and as of that date, the Company ceased granting new awards under the 2012 Plan and all remaining shares available under the 2012 Plan were transferred to the 2021 Plan. As of September 30, 2021, there were 2021 Employee Stock Purchase Plan In February 2021, the Company’s board of directors and stockholders adopted and approved the 2021 Employee Stock Purchase Plan (the “ESPP”). The ESPP authorizes the issuance of 7,416,620 shares of common stock to purchase rights granted to the Company’s employees or to employees of its designated affiliates. In addition, on January 1st of each year beginning in 2022 and continuing through 2031, the aggregate number of shares of common stock authorized for issuance under the ESPP shall be increased automatically by the number of shares equal to one percent (1%) of the total number of outstanding shares of common stock and shares of preferred stock of the Company outstanding (on an as converted to common stock basis) on the immediately preceding December 31st, although the Company’s board of directors or one of its committees may reduce the amount of the increase in any particular year. No more than 150,000,000 shares of common stock may be issued over the term of the ESPP, subject to certain exceptions set forth in the ESPP. As of the date of this filing, no shares have been granted under the ESPP. Stock Options A summary of stock option activity under the 2012 Plan and the 2021 Plan, including 1,061,250 stock options that were granted outside of the 2012 Plan in 2019, is presented below (in millions, except share and per share amounts): Number of Shares Weighted Weighted Aggregate Balances as of December 31, 2020 62,827,150 $ 4.55 7.8 $ 1,208.0 Granted 3,262,457 13.93 Exercised (6,224,067 ) 3.08 Forfeited (1,377,408 ) 6.62 Balances as of September 30, 2021 58,488,132 $ 5.17 7.2 $ 478.7 Exercisable and vested at September 30, 2021 35,425,241 $ 3.75 6.3 $ 337.1 During the nine months ended September 30, 2021 and 2020, the intrinsic value of options exercised was $97.6 million and $4.8 million, respectively. Restricted Stock Units A summary of RSU activity under the 2012 Plan and the 2021 Plan is presented below: Number of S Weighted Average Balances as of December 31, 2020 32,556,160 $ 6.75 Granted 32,872,347 14.09 Vested and converted to common stock (3,786,513 ) 16.71 Forfeited (2,159,492 ) 13.06 Balances as of September 30, 2021 59,482,502 $ 9.94 Included in the table above are 8,611,810 RSUs granted to an executive employee during the three months ended March 31, 2021. These RSUs have service, performance and market-based vesting conditions that include stock price targets to be met after the listing of the Company’s stock on a public exchange. During the nine months ended September 30, 2021 and 2020, the fair value of restricted stock units that vested and converted to common stock was $51.1 million and $0, respectively. During October and November 2021, the Company net settled all RSUs that had vested as of October 31, 2021. In connection with these settlements, the Company issued an aggregate of 6.8 million shares of Class A common stock and withheld an aggregate of 4.7 million shares of Class A common stock to satisfy $60.3 million of tax withholding obligations on behalf of the Company’s employees. Stock-Based Compensation Expense Total stock-based compensation expense included in the condensed consolidated statements of operations for the three and nine months ended September 30, 2021 and 2020 is as follows (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Commissions and other related expense $ 26.3 $ 0.5 $ 82.6 $ 5.1 Sales and marketing 10.3 2.6 27.9 8.0 Operations and support 4.5 0.7 12.3 2.2 Research and development 13.2 0.3 76.2 1.1 General and administrative 16.8 2.0 93.9 13.8 Total stock-based compensation expense $ 71.1 $ 6.1 $ 292.9 $ 30.2 As more fully described in Note 1 – “Business and Basis of Presentation”, the Company recognized $ million in stock-based compensation expense in connection with the effectiveness of the Company’s IPO registration statement on March 31, 2021. one-time IPO Related Commissions and other related expense $ 41.7 Sales and marketing 1.8 Operations and support 3.1 Research and development 46.9 General and administrative 55.0 Total stock-based compensation expense $ 148.5 As of September 30, 2021, unrecognized stock-based compensation expense totaled $598.0 million and is expected to be recognized over a weighted-average period of 3.2 years. The Company has not recognized any tax benefits from stock-based compensation as a result of the full valuation allowance maintained on its deferred tax assets. Early Exercise of Stock Options A majority of the stock options granted under the 2012 Plan provide option holders the right to elect to exercise unvested options in exchange for restricted common stock. Shares received from such early exercises are subject to repurchase in the event of the optionee’s termination of service until the stock options are fully vested at the lesser of the original issuance price or the fair value the Company’s common stock. During the nine months ended September 30, 2021, 818,590 stock options were early exercised for total proceeds of $5.0 million. As of September 30, 2021, 1,181,720 shares of common stock received by holders from an early exercise were subject to repurchase. The cash proceeds received for unvested shares of common stock recorded within Accrued expenses and other current liabilities and Other non-current paid-in

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	9. Income Taxes The Company recognized a benefit from income taxes of $1.3 The Company continues to maintain a full valuation allowance on all domestic net deferred tax assets based on numerous factors including estimated future taxable income and historic profitability. The Company does not have any amount recorded related to uncertain tax positions as of the period ended September 30, 2021 nor does it expect a substantial increase in the next 12 months. If applicable, the Company recognizes interest and penalties related to uncertain tax positions in the income tax provision. The United States is the Company’s only material tax jurisdiction and as a result of net operating loss carryforwards, the Company is subject to audit for all years for US federal income tax purposes.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	10. Net Loss Per Share Attributable to Common Stockholders The Company computes net loss per share under the two-class The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in millions, except share and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Numerator: Net loss attributable to common stockholders $ (99.8 ) $ (13.5 ) $ (319.3 ) $ (230.4 ) Denominator: Weighted-average number of shares outstanding used to compute net loss per share attributable to common stockholders, basic and diluted 392,979,596 110,447,900 300,303,264 109,448,680 Net loss per share attributable to common stockholders, basic and diluted $ (0.25 ) $ (0.12 ) $ (1.06 ) $ (2.11 ) The following securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented, because including them would have been anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Convertible preferred stock — 248,336,668 — 248,336,668 Outstanding stock options 58,488,132 62,507,670 58,488,132 62,507,670 Outstanding RSUs 59,482,502 29,089,920 59,482,502 29,089,920 Unvested early exercised options 1,181,720 — 1,181,720 — Unvested common stock 574,926 754,710 574,926 754,710 Total 119,727,280 340,688,968 119,727,280 340,688,968

Compass Concierge Receivables a

Compass Concierge Receivables and Allowance for Credit Losses	9 Months Ended
	Sep. 30, 2021
Receivables [Abstract]
Compass Concierge Receivables and Allowance for Credit Losses	11. Compass Concierge Receivables and Allowance for Credit Losses In 2018, the Company launched the Compass Concierge Program for home sellers who have engaged Compass as their exclusive listing agent. The program, initially launched by the Company, is based on a services model (“Concierge Classic”) provided by Compass Concierge, LLC (“Compass Concierge”), which includes items such as consultation on suggested cosmetic updates or modifications to a specific property or guidance on securing licensed contractors or vendors to perform non-structural up-front In 2019, the Compass Concierge Program was expanded to include a loan program underwritten by an independent third-party lender (the “Lender”) through a commercial arrangement with Compass Concierge (“Concierge Capital”). Under the Concierge Capital program, the Lender originates and services unsecured consumer loans to home sellers following its independent underwriting process pursuant to program-level criteria provided by the Company. Pursuant to the Company’s agreement with the Lender, the consumer loans are unsecured, interest-free and have no associated fees except for late fees that the Lender may charge in its sole discretion. The Company has no right or obligation with respect to any individual consumer loan originated by the Lender. Under the agreement with the Lender, the Company has repayment rights against the Lender in connection with a corporate loan. Payment to the Company for these services under the Concierge Classic model or repayment of the loan funds under the Concierge Capital model is due upon the earlier of a successful home sale, the termination of the listing agreement, or one year from the date in which costs were originally funded. Compass Concierge receivables (“Concierge Receivables”) are stated at the amount advanced to the home sellers, net of an estimated allowance for credit losses (“ACL”). The Company does not recognize any revenue or earn any fees from the Compass Concierge Program. The Company incurs service fees payable to the Lender and incurs bad debt expense in connection with the Compass Concierge Program. The Company manages its credit risk by establishing a comprehensive credit policy for the approval of projects under the Concierge Classic program and new loans under the Concierge Capital program, while monitoring and reviewing the performance of its existing Concierge Receivables. Factors considered include but not limited to: • No negative liens or judgements on the property; • Seller’s available equity on the property; • Loan to listing price ratio; • FICO score (only for Concierge Capital program); and • Macroeconomic conditions. Credit Quality The Company monitors credit quality by evaluating various attributes and utilizes such information in its evaluation of the appropriateness of the ACL. Based on the Company’s experience, the key credit quality indicator is whether the underlying properties associated with the Concierge Receivables will be sold or not. Concierge Receivables associated with properties that are eventually sold have a lower credit risk than those that are associated with properties that are not sold. For Concierge Receivables where repayments have not been triggered (i.e., earlier of (i) sale of the pr o respectively. Allowance for credit losses The Company maintains an ACL for the expected credit losses over the contractual life of the Concierge Receivables. The amount of ACL is based on ongoing, quarterly assessments by management. Historical loss experience is generally the starting point when the Company estimates the expected credit losses. The Company then considers whether (i) current conditions, such as the impact of COVID-19 and related economic uncertainty surrounding the pandemic, (ii) future economic conditions and (iii) any potential changes in the Compass Concierge Program that are reasonable and supportable would impact on its ACL. Three Months Ended Nine Months Ended Beginning of period $ 19.3 $ 17.2 Allowances 2.5 7.2 Net write-offs and other (1.8 ) (4.4 ) End of period $ 20.0 $ 20.0 Aging Status The Company generally considers Concierge Receivables to be past due after being outstanding for over 30 days after initial billing. Changes in the Company’s estimate to the ACL is recorded through bad debt expense as Sales and marketing expense in the condensed consolidated statements of operations and individual accounts are charged against the allowance when all reasonable collection efforts are exhausted. The following tables present the aging analysis of Concierge Receivables as of September 30, 2021 (in millions): 31-90 days Over 90 days Total Current Total September 30, 2021 $ 0.6 $ 12.6 $ 13.2 $ 56.2 $ 69.4

Restructuring Activities and CO

Restructuring Activities and COVID-19 Update	9 Months Ended
	Sep. 30, 2021
Restructuring and Related Activities [Abstract]
Restructuring Activities and COVID-19 Update	12. Restructuring Activities and COVID-19 Beginning in March 2020, the onset of the COVID-19 shelter-in-place stay-at-home in-person COVID-19, COVID-19 stay-at-home The expenses resulting from these cost-saving measures were included in the consolidated statement of operations for the three and nine months ended September 30, 2020, as follows (in millions): Three Months Ended Nine Months Ended Severance Lease Total Severance Lease Total Sales and marketing $ — $ 1.2 $ 1.2 $ 1.5 $ 4.2 $ 5.7 Operations and support — — — 2.9 — 2.9 Research and development — — — 0.7 — 0.7 General and administrative — — — 0.9 — 0.9 Total $ — $ 1.2 $ 1.2 $ 6.0 $ 4.2 $ 10.2 The Company did not recognize any restructuring expenses during the nine months ended September 30, 2021. As of September 30, 2021 and December 31, 2020, the Company did not have any material remaining liabilities related to restructuring costs.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The condensed consolidated financial statements include the accounts of the Company and its subsidiaries. The activities of OriginPoint LLC (“OriginPoint”), a mortgage origination company and joint venture formed in July 2021 between the Company and Guaranteed Rate, Inc. (“Guaranteed Rate”), are consolidated within the accompanying condensed consolidated financial statements. OriginPoint is owned 49.9% by the Company and 50.1% by Guaranteed Rate and the activities of OriginPoint are consolidated since the Company has the power to direct those activities that will significantly affect the economic performance of the joint venture. The economic interests related to Guaranteed Rates’ 50.1% ownership interest are reflected as non-controlling The unaudited interim condensed consolidated financial statements and related disclosures have been prepared by management on a basis consistent with the annual consolidated financial statements and, in the opinion of management, include all adjustments necessary for a fair statement of the interim periods presented. The results of the interim periods presented are not necessarily indicative of the results expected for the full year. Certain information and notes normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted under the Securities and Exchange Commission’s rules and regulations. Accordingly, the unaudited condensed consolidated financial statements and notes included herein should be read in conjunction with the Company’s audited consolidated financial statements and the related notes for the year ended December 31, 2020, included in the final prospectus that forms a part of the Company’s IPO registration statement, dated as of March 31, 2021 and filed with the Securities and Exchange Commission on April 1, 2021 pursuant to Rule 424(b) under the Securities Act of 1933, as amended.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make judgments, estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and reported amounts of revenue and expenses during the reporting periods covered by the consolidated financial statements and accompanying notes. These judgments, estimates and assumptions are used for, but not limited to (i) valuation of the Company’s common stock and stock awards, (ii) fair value of acquired intangible assets and goodwill, (iii) contingent considerations in connection with business combinations, (iv) incremental borrowing rate used for the Company’s operating leases, (v) useful lives of long-lived assets, (vi) impairment of intangible assets and goodwill, (vii) allowance for Compass Concierge receivables and (viii) income taxes and certain deferred tax assets. The Company determines its estimates and judgments based on historical experience and on various other assumptions that it believes are reasonable under the circumstances. However, actual results could differ from these estimates and these differences may be material. There are many uncertainties regarding the ongoing coronavirus (“COVID-19”) COVID-19 COVID-19
Business Combinations	Business Combinations Business combinations are accounted for under the acquisition method of accounting. This method requires, among other things, allocation of the fair value of purchase consideration to the tangible and intangible assets acquired and liabilities assumed at their estimated fair values on the acquisition date. The excess of the fair value of purchase consideration over the values of these identifiable assets and liabilities is recorded as goodwill. When determining the fair value of assets acquired and liabilities assumed, management makes significant estimates and assumptions, especially with respect to intangible assets. Management’s estimates of fair value are based upon assumptions believed to be reasonable, but which are inherently uncertain and unpredictable and, as a result, actual results may differ from estimates. During the measurement period, not to exceed one year from the date of acquisition, the Company may record adjustments to the assets acquired and liabilities assumed, with a corresponding offset to goodwill if new information is obtained related to facts and circumstances that existed as of the acquisition date. After the measurement period, any subsequent adjustments are reflected in the condensed consolidated statements of operations. Acquisition costs, consisting primarily of third-party legal and consulting fees, are expensed as incurred.
Stock-Based Compensation	Stock-Based Compensation The Company measures compensation expense for all stock-based awards based on the estimated fair value of the awards on the date of grant. Compensation expense is generally recognized as expense on a straight-line basis over the service period based on the vesting requirements. The Company recognizes forfeitures as they occur. For stock options, which the Company issues to employees and affiliated agents, the Company generally estimates the fair value using the Black- Scholes option pricing model, which requires the input of subjective assumptions, including (1) the fair value of common stock, (2) the expected stock price volatility, (3) the expected term of the award, (4) the risk-free interest rate and (5) expected dividends. The Company also issues RSUs to employees and affiliated agents. In addition to the issuance of RSUs to agents as equity compensation for the provision of services, the Company offers RSUs to affiliated agents through its Agent Equity Program. The Agent Equity Program offers affiliated agents the ability to elect to have a portion of their commissions earned during a calendar year to be paid in the form of RSUs. RSUs issued in connection with the Agent Equity Program are granted at the beginning of the year following the calendar year in which the commissions were earned and are subject to the terms and conditions of the 2012 Stock Incentive Plan and the 2021 Equity Incentive Plan, as applicable. The Company’s RSUs granted prior to December 2020 generally vest based upon the satisfaction of both a service-based condition and a liquidity event-based condition. The service-based vesting condition for these awards is generally satisfied over four years, except for the RSUs associated with the 2020 Agent Equity Program which vested immediately on the date of issuance. The liquidity event-based vesting condition is satisfied on the occurrence of a qualifying event, generally defined as a change in control or the effective date of the registration statement for the Company’s IPO. The fair value of these RSUs is measured based on the fair value of the Company’s common stock on the grant date and will begin to be recognized as expense when both the required service-based vesting condition and the liquidity event-based vesting condition has been achieved using the accelerated attribution method. The liquidity event-based vesting requirement was met on March 31, 2021, the effective date of the Company’s registration statement, see Note 1—“Business and Basis of Presentation—Initial Public Offering.” Beginning in December 2020, the Company began issuing RSUs that vest upon the satisfaction of only a service-based vesting condition that is generally ranging from four For RSUs to be granted in connection with the 2021 Agent Equity Program, the Company determines the value of the stock-based compensation expense at the time the underlying commission is earned and begins to recognize the associated expense on a straight-line basis over the requisite service periods beginning on the closing date of the underlying real estate commission transactions. The stock-based compensation expense is recorded as a liability and will be reclassified to Additional paid-in On a limited basis, the Company has issued stock options and RSUs that contain service, performance and market-based vesting conditions that include stock price targets to be met after the listing of the Company’s stock on a public exchange. Such awards are valued using a Monte Carlo simulation and the underlying expense will be recognized as the associated vesting conditions are met.
Deferred Offering Costs	Deferred Offering Costs Deferred offering costs, consisting of legal, accounting and other fees and costs relating to the IPO, are capitalized and recorded on the condensed consolidated balance sheets. As of December 31, 2020, $1.8 million of deferred offering costs were capitalized in Other non-current nine September paid-in
New Accounting Pronouncements	New Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes Income Taxes step-up In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting

Acquisitions (Tables)

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2021
Business Combinations [Abstract]
Summary of Changes in Contingent Consideration Measured at Fair Value on a Recurring Basis	Changes in contingent consideration measured at fair value on a recurring basis were as follows (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Opening balance $ 33.0 $ 15.3 $ 39.8 $ 16.4 Acquisitions 0.7 — 5.4 — Payments and issuances (2.7 ) (2.4 ) (13.7 ) (5.4 ) Fair value (gains) losses included in net loss (3.9 ) 3.6 (4.4 ) 5.5 Closing Balance $ 27.1 $ 16.5 $ 27.1 $ 16.5

Fair Value of Financial Asset_2

Fair Value of Financial Assets and Liabilities (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Summary of Fair Value Measurements of Our Financial Instruments	See Note 3 – “Acquisitions” for changes in contingent consideration for the three and nine months ended September 30, 2021 and 2020. The following table presents the balances of contingent consideration (in millions): September 30, 2021 December 31, 2020 Accrued expenses and other current liabilities $ 12.1 $ 19.1 Other non-current 15.0 20.7 Total contingent consideration $ 27.1 $ 39.8
Summary of Fair Value Measurement Inputs and Valuation Techniques	The following tables present quantitative information regarding the significant unobservable inputs utilized by the Company in the fair value measurement of Level 3 liabilities, consisting of different contingent consideration agreements, measured at fair value on a recurring basis: September 30, December 31, Discount rate 0.0% - 2.0% 0.0% - 2.0% Weighted average discount rate 0.5% 1.3% Earnings volatility 0% - 15% 0% - 18% Weighted average earnings volatility 3.4% 6.9%

Preferred Stock and Common st_2

Preferred Stock and Common stock (Tables)	9 Months Ended
	Sep. 30, 2021
Stockholders' Equity Note [Abstract]
Summary of Stock by Class	As of September 30, 2021, the Company had three classes of common stock: Class A common stock, Class B common stock and Class C common stock. Each class has par value of $0.00001. September 30, 2021 Shares Shares Issued Shares Class A common stock 12,500,000,000 383,838,073 383,838,073 Class B common stock 1,250,000,000 — — Class C common stock 100,000,000 15,244,490 15,244,490 Total 13,850,000,000 399,082,563 399,082,563 As of December 31, 2020, the Company had two classes of common stock: Class A common stock and Class B common stock. Each class has a par value of $0.00001. December 31, 2020 Shares Shares Issued Shares Class A common stock 530,136,050 118,549,390 116,299,390 Class B common stock 170,618,860 6,672,510 6,672,510 Total 700,754,910 125,221,900 122,971,900

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Summary of Stock Option Activity	A summary of stock option activity under the 2012 Plan and the 2021 Plan, including 1,061,250 stock options that were granted outside of the 2012 Plan in 2019, is presented below (in millions, except share and per share amounts): Number of Shares Weighted Weighted Aggregate Balances as of December 31, 2020 62,827,150 $ 4.55 7.8 $ 1,208.0 Granted 3,262,457 13.93 Exercised (6,224,067 ) 3.08 Forfeited (1,377,408 ) 6.62 Balances as of September 30, 2021 58,488,132 $ 5.17 7.2 $ 478.7 Exercisable and vested at September 30, 2021 35,425,241 $ 3.75 6.3 $ 337.1
Summary of Restricted Stock Units Activity	A summary of RSU activity under the 2012 Plan and the 2021 Plan is presented below: Number of S Weighted Average Balances as of December 31, 2020 32,556,160 $ 6.75 Granted 32,872,347 14.09 Vested and converted to common stock (3,786,513 ) 16.71 Forfeited (2,159,492 ) 13.06 Balances as of September 30, 2021 59,482,502 $ 9.94
Summary of Share-based Payment Arrangement, Expensed and Capitalized, Amount	Total stock-based compensation expense included in the condensed consolidated statements of operations for the three and nine months ended September 30, 2021 and 2020 is as follows (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Commissions and other related expense $ 26.3 $ 0.5 $ 82.6 $ 5.1 Sales and marketing 10.3 2.6 27.9 8.0 Operations and support 4.5 0.7 12.3 2.2 Research and development 13.2 0.3 76.2 1.1 General and administrative 16.8 2.0 93.9 13.8 Total stock-based compensation expense $ 71.1 $ 6.1 $ 292.9 $ 30.2
IPO [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Summary of Share-based Payment Arrangement, Expensed and Capitalized, Amount	Stock-based compensation expense for the nine months ended September 30, 2021 includes the following amounts related to a one-time IPO Related Commissions and other related expense $ 41.7 Sales and marketing 1.8 Operations and support 3.1 Research and development 46.9 General and administrative 55.0 Total stock-based compensation expense $ 148.5

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Summary of Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders	The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in millions, except share and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Numerator: Net loss attributable to common stockholders $ (99.8 ) $ (13.5 ) $ (319.3 ) $ (230.4 ) Denominator: Weighted-average number of shares outstanding used to compute net loss per share attributable to common stockholders, basic and diluted 392,979,596 110,447,900 300,303,264 109,448,680 Net loss per share attributable to common stockholders, basic and diluted $ (0.25 ) $ (0.12 ) $ (1.06 ) $ (2.11 )
Summary of Computation of Diluted Net Loss Per Share Attributable to Common Stockholders	The following securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented, because including them would have been anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Convertible preferred stock — 248,336,668 — 248,336,668 Outstanding stock options 58,488,132 62,507,670 58,488,132 62,507,670 Outstanding RSUs 59,482,502 29,089,920 59,482,502 29,089,920 Unvested early exercised options 1,181,720 — 1,181,720 — Unvested common stock 574,926 754,710 574,926 754,710 Total 119,727,280 340,688,968 119,727,280 340,688,968

Compass Concierge Receivables_2

Compass Concierge Receivables and Allowance for Credit Losses (Tables)	9 Months Ended
	Sep. 30, 2021
Receivables [Abstract]
Summary of ACL for Concierge Receivables	The following table summarizes the activity of the ACL for Concierge Receivables for the three and nine months ended September 30, 2021 (in millions): Three Months Ended Nine Months Ended Beginning of period $ 19.3 $ 17.2 Allowances 2.5 7.2 Net write-offs and other (1.8 ) (4.4 ) End of period $ 20.0 $ 20.0
Summary of Aging Analysis of Concierge Receivables	The following tables present the aging analysis of Concierge Receivables as of September 30, 2021 (in millions): 31-90 days Over 90 days Total Current Total September 30, 2021 $ 0.6 $ 12.6 $ 13.2 $ 56.2 $ 69.4

Restructuring Activities and _2

Restructuring Activities and COVID-19 Update (Tables)	9 Months Ended
	Sep. 30, 2021
Restructuring and Related Activities [Abstract]
Summary of restructuring costs	The expenses resulting from these cost-saving measures were included in the consolidated statement of operations for the three and nine months ended September 30, 2020, as follows (in millions): Three Months Ended Nine Months Ended Severance Lease Total Severance Lease Total Sales and marketing $ — $ 1.2 $ 1.2 $ 1.5 $ 4.2 $ 5.7 Operations and support — — — 2.9 — 2.9 Research and development — — — 0.7 — 0.7 General and administrative — — — 0.9 — 0.9 Total $ — $ 1.2 $ 1.2 $ 6.0 $ 4.2 $ 10.2

Business and Basis of Present_2

Business and Basis of Presentation - Additional Information (Detail) $ / shares in Units, $ in Millions	Apr. 01, 2021USD ($)$ / sharesshares	Mar. 31, 2021shares	Mar. 19, 2021	Mar. 31, 2021USD ($)	Sep. 30, 2021USD ($)shares	Jul. 01, 2021	Apr. 30, 2021shares	Dec. 31, 2020shares	Apr. 01, 2020USD ($)
Date of incorporation					Oct. 4, 2012
Stock split ratio common stock			10
Sale of stock net proceeds received on the transaction | $					$ 439.6
Deferred offering costs | $					$ 0
Common stock shares authorized					13,850,000,000			700,754,910
Reclassification of convertible preferred stock into common stock	223,033,725
Reclassification of convertible preferred stock into common stock value | $					$ 1,419.1
OriginPoint LLC Joint Venture [Member]
Consolidated entity investment ownership percentage						49.90%
OriginPoint LLC Joint Venture [Member] | Guaranteed Rate [Member]
Consolidated entity investment ownership percentage						50.10%
Restricted Stock Units [Member] | Service Based And Liquidity Event Based [Member]
Allocated share based compensation | $				$ 148.5
Additional Paid-in Capital [Member]
Reclassification of convertible preferred stock into common stock value | $	$ 1,400
IPO [Member]
Stock shares issued during the period shares	26,296,438
Sale of stock issue price per share | $ / shares	$ 18
Sale of stock net proceeds received on the transaction | $	$ 438.7
Deferred offering costs | $									$ 0.9
Net offering costs | $	$ 11
Common Class A [Member]
Common stock shares authorized					12,500,000,000			530,136,050
Conversion of Stock, Shares Converted		15,244,490
Common Class A [Member] | Restated Certificate Of Incorporation [Member]
Common stock shares authorized							12,500,000,000
Common Class B [Member]
Common stock shares authorized					1,250,000,000			170,618,860
Common Class B [Member] | Restated Certificate Of Incorporation [Member]
Common stock shares authorized							1,250,000,000
Common Class C [Member]
Common stock shares authorized					100,000,000
Common Class C [Member] | Restated Certificate Of Incorporation [Member]
Common stock shares authorized							100,000,000
Undesignated Preferred Stock [Member] | Restated Certificate Of Incorporation [Member]
Preferred stock shares authorized							25,000,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Millions	Apr. 01, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Apr. 01, 2020
Accounting Policies [Line Items]
Deferred offering costs		$ 0		$ 0
Stock based compensation expense		$ 71.1	$ 6.1	292.9	$ 30.2
Other Noncurrent Assets [Member]
Accounting Policies [Line Items]
Deferred offering costs						$ 1.8
IPO [Member]
Accounting Policies [Line Items]
Deferred offering costs							$ 0.9
Net offering costs	$ 11
IPO [Member] | Additional Paid-in Capital [Member]
Accounting Policies [Line Items]
Net offering costs				11
Restricted Stock Units [Member]
Accounting Policies [Line Items]
Share based compensation by share based payment arrangement service based vesting period						4 years
Stock based compensation expense				$ 40.1
Restricted Stock Units [Member] | Maximum [Member]
Accounting Policies [Line Items]
Share based compensation by share based payment arrangement service based vesting period						5 years
Restricted Stock Units [Member] | Minimum [Member]
Accounting Policies [Line Items]
Share based compensation by share based payment arrangement service based vesting period						4 years

Acquisitions - Additional Infor

Acquisitions - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Business Acquisition [Line Items]
Business combination contingent consideration, Stock			$ 127.3	$ 0.8
Stock based compensation expense	$ 71.1	$ 6.1	292.9	30.2
Business Combinations contingent liabilities undiscounted maximum payment	28,200		28,200
Business combination contingent consideration fixed in value	13		$ 13
Maximum [Member]
Business Acquisition [Line Items]
Finite lived intangible assets acquired remaining useful lives			9 years
Minimum [Member]
Business Acquisition [Line Items]
Finite lived intangible assets acquired remaining useful lives			2 years
2021 Acquistions [Member]
Business Acquisition [Line Items]
Payment to acquire business			$ 148.5
Business combination contingent consideration	5.4		5.4
Business combination operating lease right of use assets acquired	9.7		9.7
Goodwill arising out of business combination acquisitions	62.7		62.7
Business acquistion compensation expenses	7.5	$ 0.4	18.9	$ 1.6
Business combination other current assets and non current assets	7.1		7.1
Business combination contingent consideration, Stock			127.3
Business combination other current and non current liabilities	9.7		9.7
Consideration of lease liability	9.7		9.7
Amount of Goodwill is deductible for tax purposes	22		22
Amount of tax-deductible goodwill may increase in the future,dependent on contingent consideration milestones being achieved			$ 61.7
Sharebased compensation arrangement, shares of common stock granted to sellers			277,776
Stock based compensation expense	0.7		$ 0.7
2021 Acquistions [Member] | Common Class A [Member]
Business Acquisition [Line Items]
Business combination contingent consideration, Stock			5.8
2021 Acquistions [Member] | Accrued Expenses And Other Current Liabilities [Member]
Business Acquisition [Line Items]
Business combination contingent consideration	21.2		21.2
2021 Acquistions [Member] | Maximum [Member]
Business Acquisition [Line Items]
Business Combination Future Compensation To Be Paid To The Acquires	$ 57.7		57.7
2021 Acquistions [Member] | Broker Relationships [Member]
Business Acquisition [Line Items]
Finite lived intangible assets acquired			82.7
2021 Acquistions [Member] | Trademarks [Member]
Business Acquisition [Line Items]
Finite lived intangible assets acquired			11.4
2021 Acquistions [Member] | Technology [Member]
Business Acquisition [Line Items]
Finite lived intangible assets acquired			$ 5.5

Acquisitions - Summary of Chang

Acquisitions - Summary of Changes in Contingent Consideration Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Business Combinations [Abstract]
Opening balance	$ 33	$ 15.3	$ 39.8	$ 16.4
Acquisitions	0.7		5.4
Payments and issuances	(2.7)	(2.4)	(13.7)	(5.4)
Fair value (gains) losses included in net loss	(3.9)	3.6	(4.4)	5.5
Closing Balance	$ 27.1	$ 16.5	$ 27.1	$ 16.5

Fair Value of Financial Asset_3

Fair Value of Financial Assets and Liabilities - Summary of Fair Value Measurements of Our Financial Instruments (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Accrued expenses and other current liabilities	$ 12.1		$ 19.1
Other non-current liabilities	15		20.7
Total contingent consideration	$ 27.1	$ 33	$ 39.8	$ 16.5	$ 15.3	$ 16.4

Fair Value of Financial Asset_4

Fair Value of Financial Assets and Liabilities - Summary of Fair Value Measurement Inputs and Valuation Techniques (Detail)	Sep. 30, 2021	Dec. 31, 2020
Measurement Input, Discount Rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Business combination contingent consideration liability measurement input	2	2
Measurement Input, Discount Rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Business combination contingent consideration liability measurement input	0	0
Measurement Input, Discount Rate [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Business combination contingent consideration liability measurement input	0.5	1.3
Measurement Input Earnings Volatility [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Business combination contingent consideration liability measurement input	15	18
Measurement Input Earnings Volatility [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Business combination contingent consideration liability measurement input	0	0
Measurement Input Earnings Volatility [Member] | Weighted Average [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Business combination contingent consideration liability measurement input	3.4	6.9

Fair Value of Financial Asset_5

Fair Value of Financial Assets and Liabilities - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Inputs, Level 3 [Member]
Business combination contingent consideration fair value disclosure	$ 27.1	$ 39.8
Cash And Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents fair value disclosure	$ 789.6	$ 440.1

Debt - Additional Information (

Debt - Additional Information (Detail) - USD ($) $ in Millions	Jul. 29, 2021	Jul. 31, 2020	Sep. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Debt [Line Items]
Letters of credit outstanding, amount			$ 51.7		$ 50.7
Concierge Revolving Credit Facility [Member]
Debt [Line Items]
Maximum borrowing capacity		$ 75
Interest rate basis	1.85	3.00
Unused capacity commitment fee percentage		0.50%
Line of credit facility expiration month and year			2023
Debt instrument interest rate			3.15%
Covenant compliance			the Company was in compliance with the covenants under the Concierge Facility.
Concierge Revolving Credit Facility [Member] | Concierge Facility Used Greater Than Fifty Percent [Member]
Debt [Line Items]
Unused capacity commitment fee percentage	0.35%
Concierge Revolving Credit Facility [Member] | Concierge Facility Used Less Than Fifty Percent [Member]
Debt [Line Items]
Unused capacity commitment fee percentage	0.50%
Revolving Credit Facility [Member]
Debt [Line Items]
Maximum borrowing capacity				$ 350
Interest rate basis			1.00
Unused capacity commitment fee percentage			0.175%
Line of credit facility expiration month and year			2026
Outstanding Borrowings			$ 0
Additional borrowing capacity				$ 250
Additional borrowing capacity percentage threshold to assets				18.50%
Net leverage ratio				4.50
Letters of credit				$ 125
Revolving Credit Facility [Member] | Other Current Assets [Member]
Debt [Line Items]
Covenant compliance			the Company was in compliance with the covenants under the Revolving Credit Facility.
Debt issuance costs			$ 1.4
Revolving Credit Facility [Member] | Base Rate [Member]
Debt [Line Items]
Interest rate basis			0.50
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt [Line Items]
Interest rate basis			1.50
Revolving Credit Facility [Member] | Federal Funds Effective Swap Rate [Member]
Debt [Line Items]
Interest rate basis			0.50
Revolving Credit Facility [Member] | London Interbank Offered Rate (LIBOR) Swap Rate [Member]
Debt [Line Items]
Interest rate basis			1.00
Revolving Credit Facility [Member] | Debt Default Interest Rate [Member]
Debt [Line Items]
Interest rate basis			2.0
Letter of Credit [Member]
Debt [Line Items]
Letters of credit outstanding, amount			$ 16.3

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
Escrow and trust deposits	$ 205.7	$ 205.7	$ 46.1
Letters of credit	51.7	51.7	$ 50.7
Revolving Credit Facility [Member]
Letters of credit outstanding		16.3
Cash and Cash Equivalents [Member]
Letters of credit outstanding		35.4
General and Administrative Expense [Member]
Litigation settlement, expense	$ 21.3	$ 21.3

Preferred Stock and Common st_3

Preferred Stock and Common stock - Additional Information (Detail) - USD ($) $ in Millions	Apr. 01, 2021	Mar. 31, 2021	Feb. 28, 2021	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Apr. 30, 2021	Dec. 31, 2020
Proceeds from Issuance of Convertible Preferred Stock							$ 1
Common stock shares authorized						13,850,000,000			700,754,910
Reclassification of convertible preferred stock into common stock value						$ 1,419.1
Preferred stock shares issued						0
Preferred stock shares outstanding						0
Additional Paid-in Capital [Member]
Reclassification of convertible preferred stock into common stock value	$ 1,400
Series D Convertible Preferred Stock [Member]
Conversion of Stock, Shares Converted				15,920,450
Series G Convertible Preferred Stock [Member]
Temporary Equity Stock Issued During Period Shares New Issues					64,820
Proceeds from Issuance of Convertible Preferred Stock					$ 1
Common Class A [Member]
Conversion of Stock, Shares Converted		15,244,490
Convertible Preferred Stock, Shares Issued upon Conversion	223,033,725
Treasury Stock, Common, Shares									2,250,000
Common stock shares authorized						12,500,000,000			530,136,050
Treasury stock, retired						Jul. 1, 2021
Common Class A [Member] | Restated Certificate Of Incorporation [Member]
Common stock shares authorized								12,500,000,000
Common Class C [Member]
Conversion of Stock, Shares Issued		15,244,490
Common Stock, Voting Rights			Each share of Class C common stock is entitled to twenty votes
Common stock shares authorized						100,000,000
Common Class C [Member] | Restated Certificate Of Incorporation [Member]
Common stock shares authorized								100,000,000
Common Class B [Member]
Common stock shares authorized						1,250,000,000			170,618,860
Common Class B [Member] | Restated Certificate Of Incorporation [Member]
Common stock shares authorized								1,250,000,000
Undesignated Preferred Stock [Member] | Restated Certificate Of Incorporation [Member]
Preferred stock shares authorized								25,000,000

Preferred Stock and Common st_4

Preferred Stock and Common stock - Schedule of Stock by Class (Detail) - shares	Sep. 30, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Shares Authorized	13,850,000,000	700,754,910
Shares Issued	399,082,563	125,221,900
Shares Outstanding	399,082,563	122,971,900
Class A common stock [Member]
Class of Stock [Line Items]
Shares Authorized	12,500,000,000	530,136,050
Shares Issued	383,838,073	118,549,390
Shares Outstanding	383,838,073	116,299,390
Class B common stock [Member]
Class of Stock [Line Items]
Shares Authorized	1,250,000,000	170,618,860
Shares Issued		6,672,510
Shares Outstanding		6,672,510
Class C common stock [Member]
Class of Stock [Line Items]
Shares Authorized	100,000,000
Shares Issued	15,244,490
Shares Outstanding	15,244,490

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ in Millions	Feb. 28, 2021	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted during the period					818,590		1,061,250
Intrinsic value of stock options exercised					$ 97.6	$ 4.8
Allocated share based compensation expense		$ 71.1		$ 6.1	292.9	30.2
Options unrecognized compensation		598			$ 598
Options unrecognized compensation period of recognition					3 years 2 months 12 days
Proceeds from exercise of stock options					$ 19.1	6.8
Share based compensation by share based payment arrangement stock options granted during the period					3,262,457
Other non-current liabilities		$ 36.6			$ 36.6			$ 23.5
Tax withholding obligations amount					$ 60.3
Common Class A [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of aggregate shares issued					6,800,000
Number of aggregate shares withheld					4,700,000
SHARES Granted Under Stock Plans Subject To Repurchase [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares subject to repurchase		1,181,720			1,181,720
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation expense					$ 40.1
Fair value of stock units vested and converted to common stock					51.1	$ 0
IPO Based Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation expense			$ 148.5
Performance Shares [Member] | Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share based payment award restricted stock units granted			8,611,810
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from exercise of stock options					5
Other non-current liabilities		$ 6.8			$ 6.8
2012 Stock Incentive Plan [Member] | Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term					10 years
2012 Stock Incentive Plan [Member] | Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term					7 years
2021 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant	29,666,480	27,437,628			27,437,628
2021 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	7,416,620
Share based compensation by share based payment arrangement increase in the shares authorised for issuance as a percentage of shares outstanding	1.00%
Share based compensation by share based payment arrangement stock options granted during the period	0
2021 Employee Stock Purchase Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	150,000,000

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Share-based Payment Arrangement, Additional Disclosure [Abstract]
Number of Shares, Opening Balance	62,827,150
Number of Shares, Granted	3,262,457
Number of Shares, Exercised	(6,224,067)
Number of Shares, Forfeited	(1,377,408)
Number of Shares, Ending Balance	58,488,132	62,827,150
Exercisable and vested	35,425,241
Weighted Average Exercise Price, Opening Balance	$ 4.55
Weighted Average Exercise Price,Granted	13.93
Weighted Average Exercise Price,Exercised	3.08
Weighted Average Exercise Price,Forfeited	6.62
Weighted Average Exercise Price, Ending Balance	5.17	$ 4.55
Weighted Average Exercise Price, Exercisable and vested	$ 3.75
Weighted Average Remaining Contract Term, December 31, 2020	7 years 2 months 12 days	7 years 9 months 18 days
Weighted Average Remaining Contract Term, September 30, 2021	7 years 2 months 12 days	7 years 9 months 18 days
Weighted Average Remaining Contract Term, Exercisable and vested	6 years 3 months 18 days
Aggregate Intrinsic Value	$ 478.7	$ 1,208
Aggregate Intrinsic Value, Exercisable and vested	$ 337.1

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Restricted Stock Units Activity (Detail)	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Share-based Payment Arrangement [Abstract]
Number of Shares, Opening Balance | shares	32,556,160
Number of Shares, Granted | shares	32,872,347
Number of Shares, Vested and converted to common stock | shares	(3,786,513)
Number of Shares, Forfeited | shares	(2,159,492)
Number of Shares, Ending Balance | shares	59,482,502
Weighted Average Grant Date Fair Value, Opening Balance | $ / shares	$ 6.75
Weighted Average Grant Date Fair Value, Granted | $ / shares	14.09
Weighted Average Grant Date Fair Value, Vested and converted to common stock | $ / shares	16.71
Weighted Average Grant Date Fair Value, Forfeited | $ / shares	13.06
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 9.94

Stock-Based Compensation - Shar

Stock-Based Compensation - Share-based Payment Arrangement, Expensed and Capitalized, Amount (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 71.1	$ 6.1	$ 292.9	$ 30.2
Commissions and other related expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	26.3	0.5	82.6	5.1
Sales and marketing [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	10.3	2.6	27.9	8
Operations and support [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	4.5	0.7	12.3	2.2
Research and development[Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	13.2	0.3	76.2	1.1
General and administrative [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 16.8	$ 2	93.9	$ 13.8
IPO Related Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense			148.5
IPO Related Expense [Member] | Commissions and other related expense
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense			41.7
IPO Related Expense [Member] | Sales and marketing [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense			1.8
IPO Related Expense [Member] | Operations and support [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense			3.1
IPO Related Expense [Member] | Research and development[Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense			46.9
IPO Related Expense [Member] | General and administrative [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense			$ 55

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Benefit from income taxes	$ 1.3		$ 3.3	$ 0.9

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Schedule of Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net loss attributable to common stockholders	$ (99.8)	$ (13.5)	$ (319.3)	$ (230.4)
Denominator:
Weighted-average number of shares outstanding used to compute net loss per share attributable to common stockholders, basic and diluted	392,979,596	110,447,900	300,303,264	109,448,680
Net loss per share attributable to common stockholders, basic and diluted	$ (0.25)	$ (0.12)	$ (1.06)	$ (2.11)

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Schedule of Computation of Diluted Net Loss Per Share Attributable to Common Stockholders (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Diluted net loss per share attributable to common stockholders	119,727,280	340,688,968	119,727,280	340,688,968
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Diluted net loss per share attributable to common stockholders		248,336,668		248,336,668
Outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Diluted net loss per share attributable to common stockholders	58,488,132	62,507,670	58,488,132	62,507,670
Outstanding RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Diluted net loss per share attributable to common stockholders	59,482,502	29,089,920	59,482,502	29,089,920
Unvested early exercised options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Diluted net loss per share attributable to common stockholders	1,181,720		1,181,720
Unvested common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Diluted net loss per share attributable to common stockholders	574,926	754,710	574,926	754,710

Compass Concierge Receivables_3

Compass Concierge Receivables and Allowance for Credit Losses - Additional Information (Detail)	Sep. 30, 2021	Dec. 31, 2020
Receivables [Abstract]
Percentage of financing receivables related to unsold properties	97.00%	93.00%

Compass Concierge Receivables_4

Compass Concierge Receivables and Allowance for Credit Losses - Summary of ACL for Concierge Receivables (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021
Accounting Policies [Abstract]
Beginning of period	$ 19.3	$ 17.2
Allowances	2.5	7.2
Net write-offs and other	(1.8)	(4.4)
End of period	$ 20	$ 20

Compass Concierge Receivables_5

Compass Concierge Receivables and Allowance for Credit Losses - Summary of Aging Analysis of Concierge Receivables (Detail) $ in Millions	Sep. 30, 2021USD ($)
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 69.4
Financing Receivables Overdue Up to Thirty One Days And Less Than Ninety Days [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0.6
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	12.6
Financial Asset, Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	13.2
Financial Asset, Not Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 56.2

Restructuring Activities and _3

Restructuring Activities and COVID -19 Update - Summary of restructuring costs (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 1.2	$ 10.2
Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		6
Lease Terminaion [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	1.2	4.2
Sales and marketing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	1.2	5.7
Sales and marketing [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		1.5
Sales and marketing [Member] | Lease Terminaion [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 1.2	4.2
Operations and support [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		2.9
Operations and support [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		2.9
Research and development[Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.7
Research and development[Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.7
General and administrative [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		0.9
General and administrative [Member] | Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 0.9

Restructuring Activities and _4

Restructuring Activities and COVID -19 Update - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Restructuring and Related Activities [Abstract]
Restructuring and Related Cost, Number of Positions Eliminated, Percent	15.00%
Liabilities related to restructuring costs	$ 0	$ 0