Stagwell (STGW) 10-Q 9 Nov 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Nov. 08, 2021	Oct. 28, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-13718
Entity Registrant Name	Stagwell Inc
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	86-1390679
Entity Address, Address Line One	One World Trade Center, Floor 65
Entity Address, City or Town	New York,
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10007
City Area Code	646
Local Phone Number	429-1800
Title of 12(b) Security	Class A Common Stock, par value $0.001 per share
Trading Symbol	STGW
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0000876883
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false
Common Class A
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		113,198,517
Common Class B
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding			3,946
Common Class C
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding			179,970,051

UNAUDITED CONDENSED CONSOLIDATE

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue:
Revenue	$ 466,634	$ 228,097	$ 857,436	$ 574,970
Operating expenses:
Cost of services	324,782	149,011	558,856	373,064
Office and general expenses	121,770	42,666	226,720	127,181
Depreciation and amortization	24,790	9,974	46,122	29,838
Impairment and other losses	14,926	0	14,926	0
Costs and Expenses, Total	486,268	201,651	846,624	530,083
Operating income (loss)	(19,634)	26,446	10,812	44,887
Other income (expense):
Interest expense, net	(11,912)	(1,778)	(15,197)	(4,665)
Foreign exchange, net	(893)	(856)	(1,955)	794
Gain on sale of business and other, net	45,621	263	46,806	948
Nonoperating Income (Expense), Total	32,816	(2,371)	29,654	(2,923)
Income before income taxes and equity in earnings of non-consolidated affiliates	13,182	24,075	40,466	41,964
Income tax expense	5,183	2,618	9,205	3,211
Income before equity in earnings of non-consolidated affiliates	7,999	21,457	31,261	38,753
Equity in losses (income) of non-consolidated affiliates	(76)	(35)	(75)	7
Net income	7,923	21,422	31,186	38,760
Net income attributable to noncontrolling and redeemable noncontrolling interests	(9,994)	(3,614)	(10,987)	(4,636)
Net income (loss) attributable to Stagwell Inc. common shareholders	$ (2,071)	$ 17,808	$ 20,199	$ 34,124
Basic and diluted
Earnings per share, basic	$ (0.06)		$ (0.06)
Earnings per share, diluted	$ (0.06)		$ (0.06)
Weighted Average Number of Common Shares Outstanding:
Weighted Average Number of Shares Outstanding, Basic	76,105,807		76,105,807
Diluted weighted average number of common shares outstanding (in shares)	76,105,807		76,105,807

UNAUDITED CONSOLIDATED STATEMEN

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Comprehensive income (loss)
Net income		$ 22,330		$ 41,455
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation adjustment	$ 12,537	3,231	$ 12,537	(1,749)
Net unrealized loss on available for sale investment	0	(28)	0	(5,024)
Other comprehensive income (loss)	12,537	3,203	12,537	(6,773)
Comprehensive income for the period	20,460	24,625	43,723	31,987
Comprehensive income attributable to the noncontrolling interests	(9,994)	(3,614)	(10,987)	(4,636)
Comprehensive income attributable to Stagwell Inc.	$ 10,466	$ 21,011	$ 32,736	$ 27,351

UNAUDITED CONDENSED CONSOLIDA_2

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current Assets
Cash and cash equivalents	$ 115,489	$ 92,457
Accounts receivable, net	669,612	225,733
Expenditures billable to clients	37,101	11,063
Other current assets	78,884	36,433
Total Current Assets	901,086	365,686
Fixed assets, net	118,526	35,614
Right-of-use lease assets - operating leases	334,867	57,752
Goodwill	1,619,272	351,725
Other intangible assets, net	945,081	186,035
Other assets	24,789	17,043
Total Assets	3,943,621	1,013,855
Current Liabilities
Accounts payable	277,385	147,826
Accruals and other liabilities	371,289	90,557
Advance billings	286,790	66,418
Current portion of lease liabilities - operating leases	74,162	19,579
Current portion of deferred acquisition consideration	60,951	12,579
Total Current Liabilities	1,070,577	336,959
Long-term debt	1,265,747	198,024
Long-term portion of deferred acquisition consideration	14,754	5,268
Long-term lease liabilities - operating leases	328,048	52,606
Deferred tax liabilities, net	134,288	16,050
Other liabilities	59,190	5,801
Total Liabilities	2,872,604	614,708
Redeemable Noncontrolling Interests	29,787	604
Commitments, Contingencies and Guarantees (Note 11)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Convertible preferred shares, 123,849,000 and 0 authorized, issued and outstanding at September 30, 2021 and December 31, 2020, respectively	209,980	0
Members' capital	0	358,756
Paid-in capital	169,537	0
Accumulated deficit	(6,153)	0
Accumulated other comprehensive income	12,537	0
Stagwell Inc. Shareholders' Equity	385,980	358,756
Noncontrolling interests	655,250	39,787
Total Shareholders' Equity	1,041,230	398,543
Liabilities and Equity, Total	3,943,621	1,013,855
Common Class A and Common Class B
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Common shares	77	0
Common Class C
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Common shares	$ 2	$ 0

UNAUDITED CONDENSED CONSOLIDA_3

UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - shares shares in Thousands	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preference shares, authorized (in shares)	123,849	0
Preference shares, issued (in shares)	123,849	0
Preference shares, outstanding (in shares)	123,849	0

UNAUDITED CONDENSED CONSOLIDA_4

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net income	$ 31,186	$ 38,760
Adjustments to reconcile net income to cash provided by (used in) operating activities:
Stock-based compensation	53,465	0
Depreciation and amortization	46,122	29,838
Impairment and other losses	14,926	0
Provision for bad debt	1,893	3,241
Deferred income taxes	2,710	(2,631)
Adjustment to deferred acquisition consideration	9,456	2,270
Other	6,998	(882)
Gain on sale of an asset	(43,440)	0
Changes in working capital:
Accounts receivable	(26,095)	6,951
Expenditures billable to clients	(9,230)	(12,225)
Other assets	(14,568)	(6,637)
Accounts payable	(37,435)	4,539
Accruals and other liabilities	(26,668)	11,128
Advance billings	16,598	18,832
Acquisition related payments	(5,772)	0
Net cash provided by operating activities	20,146	93,184
Cash flows from investing activities:
Capital expenditures	(13,666)	(8,977)
Proceeds from sale of assets	37,232	0
Acquisitions, net of cash acquired	130,155	(5,549)
Other	0	(1,895)
Net cash provided by (used in) investing activities	153,721	(16,421)
Repayment of borrowings under revolving credit facility
Repayment of borrowings under revolving credit facility	(535,472)	(108,744)
Proceeds from borrowings under revolving credit facility	408,369	167,000
Shares acquired and cancelled	(820)	0
Distributions to noncontrolling interests and other	(19,245)	(3,075)
Payment of deferred consideration and other	0	(1,500)
Contributions	0	1,576
Proceeds from issuance of the 5.625% Notes	1,100,000	0
Debt issuance costs	(15,365)	(319)
Distributions	(204,929)	(98,638)
Repurchase of 7.50% Senior Notes	884,398	0
Net cash used in financing activities	(151,860)	(43,700)
Effect of exchange rate changes on cash and cash equivalents	1,025	555
Net increase in cash and cash equivalents	23,032	33,618
Cash and cash equivalents at beginning of period	92,457	63,860
Cash and cash equivalents at end of period	115,489	97,478
Supplemental disclosures:
Cash income taxes paid	42,346	3,618
Cash interest paid	22,493	7,288
Non-cash investing and financing activities:
Acquisitions of business	426,396	23,720
Acquisitions of noncontrolling interest	37,559	0
Net unrealized (loss) gain on available for sale investment	0	5,024
Non-cash contributions included in Member’s equity	12,372	83,242
Non-cash distributions to Stagwell Media LP	13,000	0
Non-cash payment of deferred acquisition consideration	$ 7,080	$ 64,322

UNAUDITED CONDENSED CONSOLIDA_5

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' DEFICIT - USD ($) $ in Thousands	Total	Members' capital	Stagwell Inc. Shareholders' Equity	Convertible Preference Shares	Common Shares	Common SharesCommon Class A & B	Common SharesClass C	Paid-in Capital	Accumulated Deficit	Other Comprehensive Income	Noncontrolling Interests
Beginning balance at Dec. 31, 2019	$ 316,960
Balance (in shares) at Dec. 31, 2019				0		0	0
Balance at Dec. 31, 2019	348,537		$ 316,960	$ 0		$ 0	$ 0	$ 0	$ 0	$ 0	$ 31,577
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income prior to reorganization	34,124		34,124
Net income	41,455	$ 34,124	34,124								7,331
Other comprehensive income (loss)	(6,773)	(6,773)	(6,773)							0
Contributions	84,818	84,818	84,818					0
Distributions	(98,638)	(98,638)	(98,638)						0
Distributions to noncontrolling interests	(3,075)		0								(3,075)
Changes in redemption value	(193)	(193)	(193)						0
Purchases of NCI			0
Other	2	2	2					0	0	0	0
Ending balance at Sep. 30, 2020	330,686
Balance (in shares) at Sep. 30, 2020				0	0		0
Balance at Sep. 30, 2020	366,519		330,686	$ 0		$ 0	$ 0	0	0	0	35,833
Beginning balance at Jun. 30, 2020	314,598
Balance (in shares) at Jun. 30, 2020				0		0	0
Balance at Jun. 30, 2020	348,984		314,598	$ 0		$ 0	$ 0	0	0	0	34,386
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income prior to reorganization	17,808		17,808
Net income	22,330	17,808	17,808						0		4,522
Other comprehensive income (loss)	3,203	3,203	3,203							0
Distributions	(4,724)	(4,724)	(4,724)						0
Distributions to noncontrolling interests	(3,075)		0								(3,075)
Changes in redemption value	199	$ 199	199
Purchases of NCI			0
Other	0		0						0
Ending balance at Sep. 30, 2020	330,686
Balance (in shares) at Sep. 30, 2020				0	0		0
Balance at Sep. 30, 2020	366,519		330,686	$ 0		$ 0	$ 0	0	0	0	35,833
Beginning balance at Dec. 31, 2020	358,756
Balance (in shares) at Dec. 31, 2020				0		0	0
Balance at Dec. 31, 2020	398,543		358,756	$ 0		$ 0	$ 0	0	0	0	39,787
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income prior to reorganization	20,199		20,199
Other comprehensive income (loss)	12,537
Distributions	(191,900)
Changes in redemption value	1,680
Purchases of NCI			9,679
Ending balance at Sep. 30, 2021	0
Balance (in shares) at Sep. 30, 2021				123,849,000		78,983,906	179,970,051
Balance at Sep. 30, 2021	1,041,230		385,980	$ 209,980		$ 77	$ 2	169,537	(6,153)	12,537	655,250
Beginning balance at Jun. 30, 2021	350,395
Balance (in shares) at Jun. 30, 2021				0		0	0
Balance at Jun. 30, 2021	381,342		350,395	$ 0		$ 0	$ 0	0	0	0	30,947
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income prior to reorganization	(2,071)		(2,071)
Other comprehensive income (loss)	12,537
Distributions	(165,700)
Purchases of NCI			9,679
Ending balance at Sep. 30, 2021	0
Balance (in shares) at Sep. 30, 2021				123,849,000		78,983,906	179,970,051
Balance at Sep. 30, 2021	$ 1,041,230		$ 385,980	$ 209,980		$ 77	$ 2	$ 169,537	$ (6,153)	$ 12,537	$ 655,250

Basis of Presentation and Recen

Basis of Presentation and Recent Developments	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Recent Developments	Business and Basis of Presentation Stagwell Inc. (the “Company” or “Stagwell”), incorporated under the laws of Delaware, conducts its business through its networks and their Brands ("Brands"), which provide marketing and business solutions that realize the potential of combining data and creativity. Stagwell’s strategy is to build, grow and acquire market-leading businesses that deliver the modern suite of services that marketers need to thrive in a rapidly evolving business environment. The accompanying consolidated financial statements include the accounts of Stagwell and its subsidiaries. Stagwell has prepared the unaudited condensed consolidated interim financial statements included herein in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for reporting interim financial information on Form 10-Q. Accordingly, the financial statements have been condensed and do not include certain information and disclosures pursuant to these rules. The preparation of financial statements in conformity with GAAP requires us to make judgments, assumptions and estimates about current and future results of operations and cash flows that affect the amounts reported and disclosed. Actual results could differ from these estimates and assumptions. The consolidated results for interim periods are not necessarily indicative of results for the full year and should be read in conjunction with the Company’s other SEC filings. On December 21, 2020, MDC Partners Inc. (“MDC”) and Stagwell Media LP (“Stagwell Media”) announced that they had entered into the Transaction Agreement, providing for the combination of MDC with the operating businesses and subsidiaries of Stagwell Media (the “Stagwell Subject Entities”). The Stagwell Subject Entities comprised Stagwell Marketing Group LLC (“Stagwell Marketing”) and its direct and indirect subsidiaries. On August 2, 2021, we completed the previously announced combination of MDC Partners Inc. (“MDC”) and the operating businesses and subsidiaries of Stagwell Media LP. (“Stagwell Media”) and a series related transactions (such combination and transactions, the “Transactions”). The Transactions were treated as a reverse acquisition for financial reporting purposes, with MDC treated as the legal acquirer and Stagwell Marketing Group LLC (“Stagwell Marketing or SMG”) treated as the accounting acquirer. The results of MDC are included within the Unaudited Condensed Consolidated Statements of Operations for the period beginning on the date of the acquisition through the end of the respective period presented and the results of SMG are included for the entire period presented. See Note 4 for information in connection with the acquisition of MDC. While a recovery from the COVID-19 pandemic is underway, economic conditions will be volatile as long as COVID-19 remains a public health threat. The Company continues to monitor developments. We will continue to monitor the worldwide public health threat, government actions to combat COVID-19 and the impact such developments may have on the overall economy, our clients and operations. The impact of the pandemic and the corresponding actions are reflected in our judgments, assumptions and estimates in the preparation of the financial statements. The judgments, assumptions and estimates will be updated and could result in different results in the future depending on the continued impact of the COVID-19 pandemic. The accompanying financial statements reflect all adjustments, consisting of normally recurring accruals, which in the opinion of management are necessary for a fair presentation, in all material respects, of the information contained therein. Intercompany balances and transactions have been eliminated in consolidation. Certain reclassifications have been made to the prior year financial information to conform to the current year presentation. Recent Developments On September 23, 2021, the Company provided notices of conversion to each holder of record of each of the Company’s Series 6 and Series 8 Preferred Stock. See Note 12 for additional information in connection with the conversion of the Preferred Stock to Class A Common Stock. On October 1, 2021 (the "closing date"), the Company entered into an agreement to purchase the remaining 26.7% interest in Targeted Victory it did not previously own for a combination of cash and Class A Common Stock, up to 50% with certain exceptions, determined at the option of the Company. The agreement provides for the purchase of half of the remaining interest on the closing date and the other half on July 31, 2023 ("second purchase"). The total purchase price, which is capped at $135,000 with certain exceptions, is based on a formula taking a multiple of the two-year average of earnings that includes the year of and the year subsequent to the year of the purchase. The seller has the option to extend the measurement period for two years in connection with the second purchase.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies The Company’s significant accounting policies are summarized as follows: Principles of Consolidation . The accompanying consolidated financial statements include the accounts of Stagwell Inc. and its domestic and international controlled subsidiaries that are not considered variable interest entities, and variable interest entities for which the Company is the primary beneficiary. Intercompany balances and transactions have been eliminated in consolidation. Use of Estimates . The preparation of the consolidated financial statements in conformity with GAAP requires management to make judgments, estimates and assumptions. These estimates and assumptions affect the reported amounts of assets and liabilities including goodwill, intangible assets, contingent deferred acquisition consideration, redeemable noncontrolling interests, deferred tax assets, right-of-use assets and the amounts of revenue and expenses reported during the period. These estimates are evaluated on an ongoing basis and are based on historical experience, current conditions and various other assumptions believed to be reasonable under the circumstances. These estimates require the use of assumptions about future performance, which are uncertain at the time of estimation. To the extent actual results differ from the assumptions used, results of operations and cash flows could be materially affected. Fair Value . The Company applies the fair value measurement guidance for financial assets and liabilities that are required to be measured at fair value and for non-financial assets and liabilities that are not required to be measured at fair value on a recurring basis, including goodwill, right-of-use assets and other identifiable intangible assets. See Note 13 included herein for additional information regarding fair value measurements. Concentration of Credit Risk . The Company provides marketing communications services to clients who operate in most industry sectors. Credit is granted to qualified clients in the ordinary course of business. Due to the diversified nature of the Company’s client base, the Company does not believe that it is exposed to a concentration of credit risk. No client accounted for more than 10% of the Company’s consolidated accounts receivable as of September 30, 2021 or December 31, 2020. No sales to an individual client accounted for more than 10% of revenue for the three and nine months ended September 30, 2021 and 2020. Cash and Cash Equivalents . The Company’s cash equivalents are primarily comprised of investments in overnight interest-bearing deposits, money market instruments and other short-term investments with original maturity dates of three months or less at the time of purchase. The Company has a concentration of credit risk in that there are cash deposits in excess of federally insured amounts and international cash balances may not qualify for foreign government insurance programs. To date, the Company has not experienced any losses on cash and cash equivalents. Allowance for Doubtful Accounts . Trade receivables are stated at invoiced amounts less allowances for doubtful accounts. The allowances represent estimated uncollectible receivables associated with potential customer defaults usually due to customers’ potential insolvency. The allowances include amounts for certain customers where a risk of default has been specifically identified. The assessment of the likelihood of customer defaults is based on various factors, including the length of time the receivables are past due, historical experience and existing economic conditions. Allowance for doubtful accounts was $5,294 and $5,109 at September 30, 2021 and December 31, 2020, respectively. Expenditures Billable to Clients . Expenditures billable to clients consist principally of outside vendor costs incurred on behalf of clients when providing services that have not yet been invoiced to clients. Such amounts are invoiced to clients at various times over the course of the period. Fixed Assets . Fixed assets are stated at cost, net of accumulated depreciation. Computers, furniture and fixtures, and capitalized software are depreciated on a straight-line basis over periods of three Leases . Effective January 1, 2019, the Company adopted Accounting Standards Codification, Leases (“ASC 842”). The Company recognizes on the balance sheet at the time of lease commencement a right-of-use lease asset and a lease liability, initially measured at the present value of the lease payments. All right-of-use lease assets are reviewed for impairment. With the adoption of ASC 842, the Company elected to apply the package of practical expedients: (i) whether a contract is or contains a lease, (ii) the classification of existing leases, and (iii) whether previously capitalized costs continue to qualify as initial indirect costs. Additionally, the Company elected the practical expedient to not separate non-lease components from lease components for all operating leases. See Note 8 included herein for further information on leases. Impairment of Long-lived Assets . A long-lived asset or asset group is tested for recoverability whenever events or changes in circumstances indicate that its carrying amount may not be recoverable. When such events occur, the Company compares the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset or asset group to the carrying amount of such asset or asset group. If this comparison indicates that there is an impairment, the amount of the impairment is typically calculated using discounted expected future cash flows where observable fair values are not readily determinable. The discount rate applied to these cash flows is based on the Company’s weighted average cost of capital (“WACC”), risk adjusted where appropriate, or other appropriate discount rate. Goodwill . Goodwill (the excess of the acquisition cost over the fair value of the net assets acquired) acquired as a result of a business combination which is not subject to amortization is tested for impairment, at the reporting unit level, annually as of October 1st of each year, or more frequently if indicators of potential impairment exist. For the annual impairment test, the Company has the option of assessing qualitative factors to determine whether it is more likely than not that the carrying amount of a reporting unit exceeds its fair value or performing a quantitative goodwill impairment test. Qualitative factors considered in the assessment include industry and market considerations, the competitive environment, overall financial performance, changing cost factors such as labor costs, and other factors specific to each reporting unit such as change in management or key personnel. If the Company elects to perform the qualitative assessment and concludes that it is more likely than not that the fair value of the reporting unit is more than its carrying amount, then goodwill is not considered impaired and the quantitative impairment test is not necessary. For reporting units for which the qualitative assessment concludes that it is more likely than not that the fair value of the reporting unit is less than its carrying amount and for reporting units for which the qualitative assessment is not performed, the Company will perform the quantitative impairment test, which compares the fair value of the reporting unit to its carrying amount. If the fair value of the reporting unit exceeds the carrying amount of the net assets assigned to that reporting unit, goodwill is not considered impaired. However, if the fair value of the reporting unit is lower than the carrying amount of the net assets assigned to the reporting unit, an impairment charge is recognized equal to the excess of the carrying amount over the fair value. Determining the fair value of a reporting unit involves the use of significant estimates and assumptions. The Company uses a combination of the income approach, which incorporates the use of the discounted cash flow (“DCF”) method, and the market approach, which incorporates the use of earnings and revenue multiples based on market data. The Company generally applies an equal weighting to the income and market approaches for the impairment test. The income approach and the market approach both require the exercise of significant judgment, including judgment about the amount and timing of expected future cash flows, assumed terminal value and appropriate discount rates. The DCF estimates incorporate expected cash flows that represent a spectrum of the amount and timing of possible cash flows of each reporting unit from a market participant perspective. The expected cash flows are developed from the Company’s long-range planning process using projections of operating results and related cash flows based on assumed long-term growth rates, demand trends and appropriate discount rates based on a reporting unit’s WACC as determined by considering the observable WACC of comparable companies and factors specific to the reporting unit. The terminal value is estimated using a constant growth method which requires an assumption about the expected long-term growth rate. The estimates are based on historical data and experience, industry projections, economic conditions, and the Company’s expectations. Definite Lived Intangible Assets . Definite lived intangible assets are subject to amortization over their useful lives. A straight-line amortization method is used over the estimated useful life which is representative of the pattern of how the economic benefits of the specific intangible asset is consumed. Intangible assets that are subject to amortization are reviewed for potential impairment at least annually or whenever events or circumstances indicate that carrying amounts may not be recoverable. The Company uses an income approach, which incorporates the use of the discounted cash flow (“DCF”) method. Business Combinations. Business combinations are accounted for using the acquisition method and accordingly, the assets acquired (including identified intangible assets), the liabilities assumed and any noncontrolling interest in the acquired business are recorded at their acquisition date fair values. For each acquisition, the Company undertakes a detailed review to identify other intangible assets and a valuation is performed for all such identified assets. The Company uses several market participant measurements to determine the estimated value. This approach includes consideration of similar and recent transactions, as well as utilizing discounted expected cash flow methodologies. A substantial portion of the intangible assets value that the Company acquires is the specialized know-how of the workforce, which is treated as part of goodwill and is not required to be valued separately. The majority of the value of the identifiable intangible assets acquired is derived from customer relationships, including the related customer contracts, as well as tradenames and trademarks. Deferred Acquisition Consideration . Certain acquisitions include an initial payment at the time of closing and provide for future additional contingent purchase price payments. Contingent purchase price obligations for these transactions are recorded as deferred acquisition consideration liabilities on the balance sheet, at the acquisition date fair value and are remeasured at each reporting period. These liabilities are derived from the projected performance of the acquired entity. These arrangements may be dependent on future events, such as the growth rate of the earnings of the relevant subsidiary during the contractual period. At each reporting date, the Company models each business’ future performance, including revenue growth and free cash flows, to estimate the value of each deferred acquisition consideration liability. The liability is adjusted quarterly based on changes in current information affecting each subsidiary’s current operating results and the impact this information will have on future results included in the calculation of the estimated liability. These adjustments are recorded in the results of operations. In instances where such contingent payments require the sellers’ continuous employment with the Company after the transaction, they are recorded as compensation expense in the Unaudited Condensed Consolidated Statements of Operations. Redeemable Noncontrolling Interests . Many of the Company’s acquisitions include contractual arrangements where the noncontrolling shareholders have an option to purchase, or may require the Company to purchase, such noncontrolling shareholders’ incremental ownership interests under certain circumstances. The Company typically has similar call options under the same contractual terms. The amount of consideration under these contractual arrangements is not a fixed amount, but rather is dependent upon various valuation formulas, such as the average earnings of the relevant subsidiary through the date of exercise or the growth rate of the earnings of the relevant subsidiary during that period. In the event that an incremental purchase may be required by the Company, the amounts are recorded as redeemable noncontrolling interests in mezzanine equity on the Unaudited Condensed Consolidated Balance Sheets at their acquisition date fair value and adjusted for changes to their estimated redemption value through Retained earnings or Paid-in capital (when at an accumulated deficit) in the Unaudited Condensed Consolidated Balance Sheets (but not less than their initial redemption value), except for foreign currency translation adjustments. These adjustments will not impact the calculation of earnings (loss) per share if the redemption values are less than the estimated fair values. Subsidiary and Equity Investment Stock Transactions. Transactions involving the purchase, sale or issuance of interests of a subsidiary where control is maintained are recorded as a reduction in the redeemable noncontrolling interests or noncontrolling interests, as applicable. Any difference between the purchase price and noncontrolling interest is recorded to Common stock and other paid-in capital in the Unaudited Condensed Consolidated Balance Sheets. In circumstances where the purchase of shares of an equity investment results in obtaining control, the existing carrying value of the investment is remeasured to the acquisition date fair value and any gain or loss is recognized in the results of operations. Revenue Recognition . The Company’s revenue is recognized when control of the promised services are transferred to our clients, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. See Note 5 included herein for additional information. Cost of Services . Cost of services sold primarily consists of staff costs that are directly attributable to the Company’s client engagements, as well as third-party direct costs of production and delivery of services to its clients. Cost of services sold does not include depreciation, amortization, and other office and general expenses that are not directly attributable to the Company’s client engagements. Deferred Financing Costs . The Company uses the effective interest method to amortize deferred financing costs and any original issue premium or discount, if applicable. The Company also uses the straight-line method, which approximates the effective interest method, to amortize the deferred financing costs on the Credit Agreement. Income Taxes. We account for income taxes using the asset and liability method. Under the asset and liability method, deferred tax assets and liabilities are recognized based on the differences between the financial statement carrying value of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates and laws expected to be in effect when the differences are expected to reverse. The Company records associated interest and penalties as a component of income tax expense. The Company records a valuation allowance against deferred income tax assets when management believes it is more likely than not that some portion or all of the deferred income tax assets will not be realized. Management evaluates on a quarterly basis all available positive and negative evidence considering factors such as the reversal of deferred income tax liabilities, taxable income in eligible carryback years, projected future taxable income, the character of the income tax asset, tax planning strategies, changes in tax laws and other factors. The periodic assessment of the net carrying value of the Company’s deferred tax assets under the applicable accounting rules requires significant management judgment. A change to any of these factors could impact the estimated valuation allowance and income tax expense. Stock-Based Compensation . Under the fair value method, compensation cost is measured at fair value at the date of grant and is expensed over the service period, generally the award’s vesting period. The Company uses its historical volatility derived over the expected term of the award to determine the volatility factor used in determining the fair value of the award. The Company recognizes forfeitures as they occur. Stock-based awards that are settled in cash or equity at the option of the Company are recorded at fair value on the date of grant. The fair value measurement of the compensation cost for these awards is based on using the Black-Scholes option pricing-model or other acceptable method and is recorded in Operating income over the service period, in this case the award’s vesting period. The Company has adopted the straight-line attribution method for determining the compensation cost to be recorded during each accounting period. The Company commences recording compensation expense related to awards that are based on performance conditions under the straight-line attribution method when it is probable that such performance conditions will be met. Income (Loss) per Common Share . Basic income (loss) per common share is based upon the weighted average number of common shares outstanding during each period. Diluted income (loss) per common share is based on the above, in addition, if dilutive, common share equivalents, which include outstanding options, stock appreciation rights, and unvested restricted stock units. In periods of net loss, all potentially issuable common shares are excluded from diluted net loss per common share because they are anti-dilutive. Foreign Currency Translation . The functional and reporting currency of the Company is the US dollar. Generally, the Company’s subsidiaries use their local currency as their functional currency. Accordingly, the currency impacts of the translation of the Unaudited Condensed Consolidated Balance Sheets of the Company and its non-U.S. dollar based subsidiaries to U.S. dollar statements are included as cumulative translation adjustments in Accumulated other comprehensive income (loss). Translation of intercompany debt, which is not intended to be repaid, is included in cumulative translation adjustments. Cumulative translation adjustments are not included in net income (loss) unless they are actually realized through a sale or upon complete, or substantially complete, liquidation of the Company’s net investment in the foreign operation. Translation of current intercompany balances are included in net income (loss). The balance sheets of non-U.S. dollar based subsidiaries are translated at the period end rate. The Unaudited Condensed Consolidated Statements of Operations of the Company and its non-U.S. dollar based subsidiaries are translated at average exchange rates for the period. Gains and losses arising from the Company’s foreign currency transactions are reflected in Foreign exchange, net on the Consolidated Statements of Operations.

New Accounting Pronouncements

New Accounting Pronouncements	9 Months Ended
	Sep. 30, 2021
Accounting Standards Update and Change in Accounting Principle [Abstract]
New Accounting Pronouncements	New Accounting Pronouncements In October 2021, the FASB issued ASU 2021-08, Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, to improve the accounting for acquired revenue contracts with customers in a business combination by addressing diversity in practice and inconsistency related to the recognition of an acquired contract liability and other items. ASU 2021-08 is effective January 1, 2023; however, the Company has early adopted the standard and retrospectively applied it to the financial statements herein. In March 2020, the FASB issued ASU 2020-04, and in January subsequently issued ASU 2021-01, Facilitation of the Effects of Reference Rate Reform on Financial Reporting, to provide optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. ASU 2020-04 is effective upon issuance, through December 31, 2022. The Company is evaluating the impact of the adoption of this guidance on the Company's financial statements and disclosures.

Acquisitions and Dispositions

Acquisitions and Dispositions	9 Months Ended
	Sep. 30, 2021
Business Combinations [Abstract]
Acquisitions and Dispositions	Acquisitions and Dispositions 2021 Acquisition On December 21, 2020, MDC Partners Inc. (“MDC”) and Stagwell Media LP (“Stagwell Media”) announced that they had entered into the Transaction Agreement, providing for the combination of MDC with the operating businesses and subsidiaries of Stagwell Media (the “Stagwell Subject Entities”). The Stagwell Subject Entities comprised Stagwell Marketing Group LLC (“Stagwell Marketing or SMG”) and its direct and indirect subsidiaries. On August 2, 2021 (the “Closing Date”), we completed the combination of MDC and the Stagwell Subject Entities and a series of steps and related transactions (such combination and transactions, the “Transactions”). In connection with the Transactions, among other things, (i) MDC completed a series of transactions pursuant to which it emerged as a wholly owned subsidiary of the Company, converted into a Delaware limited liability company and changed its name to Midas OpCo Holdings LLC (“OpCo”); (ii) Stagwell Media contributed the equity interests of Stagwell Marketing and its direct and indirect subsidiaries to OpCo; and (iii) the Company converted into a Delaware corporation, succeeded MDC as the publicly-traded company and changed its name to Stagwell Inc. In respect of the Transactions, the acquired assets and assumed liabilities, together with acquired processes and employees, represent a business as defined in the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) 805, Business Combinations (“ASC 805”). The Transactions was accounted for as a reverse acquisition using the acquisition method of accounting, pursuant to FASB Topic 805-10, Business Combinations, with MDC treated as the legal acquirer and SMG treated as the accounting acquirer. In identifying SMG as the acquiring entity for accounting purposes, MDC and SMG took into account a number of factors, including the relative voting rights and the corporate governance structure of the Company. SMG is considered the accounting acquirer since Stagwell Media controls the board of directors of the Company following the Transactions and received an indirect ownership interest in the Company’s only operating subsidiary, OpCo, of 69.55% ownership of OpCo’s common units. However, no single factor was the sole determinant in the overall conclusion that Stagwell is the acquirer for accounting purposes; rather all factors were considered in arriving at such conclusion. Under the acquisition method of accounting, the assets and liabilities of MDC, as the accounting acquiree, were recorded at their respective fair value as of the date the Transactions were completed. On August 2, 2021, an aggregate of 179,970,051 shares of the Company’s Class C common stock were issued to Stagwell Media in exchange for $1,800 (the “Stagwell New MDC Contribution”). The Class C common stock does not participate in the earnings of the Company. Additionally, an aggregate of 179,970,051 OpCo common units were issued to Stagwell Media in exchange for the equity interests of the Stagwell Subject Entities (the “Stagwell OpCo Contribution”). The fair value of the purchase consideration is $426,396, consisting of approximately 80,000,000 shares of the Company’s Class A and B common stock and common stock equivalents based on a per share price of approximately $5.42, the closing stock price on the date of the combination. ASC 805 requires the allocation of the purchase price consideration to the fair value of the identified assets acquired and liabilities assumed upon consummation of a business combination. For this purpose, fair value shall be determined in accordance with the fair value concepts defined in ASC 820, “Fair Value Measurements and Disclosures,” (“ASC 820”). Fair value is defined in ASC 820 as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” Fair value measurements can be highly subjective and can involve a high degree of estimation. The total purchase price to acquire MDC has been allocated to the assets acquired and assumed liabilities based upon preliminary estimated fair values, with any excess purchase price allocated to goodwill. The fair value of the acquired assets and assumed liabilities as of the date of acquisition are based on preliminary estimates assisted, in part, by a third-party valuation expert. The estimates are subject to change upon the finalization of appraisals and other valuation analyses, which are expected to be completed no later than one year from the date of acquisition. Although the completion of the valuation activities may result in asset and liability fair values that are different from the preliminary estimates included herein, it is not expected that those differences would alter the understanding of the impact of this transaction on the consolidated financial position and results of operations of the Company. The preliminary purchase price allocation is as follows: Amount Cash and cash equivalents $ 130,155 Accounts receivable 419,742 Other current assets 44,508 Fixed Assets 80,047 Right-of-use lease assets - operating leases 293,034 Intangible assets 809,900 Other assets 16,928 Accounts payable (165,443) Accruals and other liabilities (308,757) Advance billings (211,687) Current portion of lease liabilities (55,878) Current portion of deferred acquisition consideration (53,054) Long-term debt (1,011,690) Long-term portion of deferred acquisition consideration (8,056) Long-term portion of lease liabilities (292,497) Other liabilities (131,897) Redeemable noncontrolling interests (30,830) Preferred shares (209,980) Noncontrolling interests (158,230) Net liabilities assumed (843,685) Goodwill 1,270,081 Purchase price consideration $ 426,396 The excess of purchase consideration over the fair value of the net assets acquired was recorded as goodwill, which is primarily attributed to the assembled workforce of MDC. Goodwill of $1,041,277, $166,658 and $62,146 was assigned to the Integrated Agencies Network, the Media Network and the Communications Network reportable segments, respectively. The majority of the goodwill is non-deductible for income tax purposes. Intangible assets consist of trade names and customer relationships. We amortize purchased intangible assets on a straight-line basis over their respective useful lives. The weighted average life of the total acquired identifiable intangible assets is 13 years. The following table presents the details of identifiable intangible assets acquired. Estimated Fair Value Estimated Useful Life in Years Trade Names $ 98,000 10 Customer Relationships 711,900 6-15 Total Acquired Intangible Assets $ 809,900 MDC operating results are included in the Condensed Consolidated Statements of Operations from the date of the acquisition through September 30, 2021 with revenue of $241,257 and a nominal net loss. Transaction expenses were approximately $15,000 for the nine months ended September 30, 2021. Pro Forma Financial Information (unaudited) The unaudited pro forma information for the periods set forth below gives effect to the acquisition as if it occurred as of January 1, 2020. The pro forma information is presented for informational purposes only and is not necessarily indicative of the results of operations that actually would have been achieved had the acquisitions been consummated as of that time. Nine Months Ended September 30, 2021 Nine Months Ended September 30, 2020 Revenue $ 1,612,399 $ 1,445,813 The proforma net loss was nominal for the nine months ended September 30, 2021 and 2020. 2020 Acquisitions On February 14, 2020, the Company acquired Sloane & Company (“Sloane”) from an affiliate of MDC for approximately $24,400 of total consideration. Total consideration included a cash payment of $18,900 made by Stagwell Media (Non-consolidated related party) which was accounted for as a non-cash contribution for the purposes of the Company’s Consolidated Statement of Cash Flows and Statement of Changes in Equity, the acquisition date fair value of the contingent deferred acquisition consideration of $4,800, and $700 of cash paid by the Company. Sloane is an industry-leading strategic communications firm, based out of New York. Sloane will extend SKDK’s current suite of services and allow for the expansion into the capital markets and special situations verticals. On August 14, 2020, the Company acquired Kettle Solutions, LLC (“Kettle”) for approximately $5,400 of total consideration. Total consideration included a cash payment of $4,900, plus an additional $500 due upon the finalization of Kettle’s working capital accounts, as outlined in the purchase agreement. The purchase agreement also offers the previous owners of Kettle an additional $11,900 in deferred consideration, and is dependent on Kettle reaching contractually defined operating goals in 2020, 2021, 2022 and 2023. Kettle is an industry recognized web design and content creation firm that assists its customers in developing and executing marketing campaigns, based out of New York. On October 30, 2020, the Company acquired Truelogic Software, LLC, Ramenu S.A., and Polar Bear Development S.R.L. (collectively referred to as “Truelogic”), for approximately $17,300 of total consideration. Total consideration included a cash payment of $8,900, the acquisition date fair value of the contingent deferred acquisition consideration of $7,900, and an additional $500 due upon the finalization of Truelogic’s working capital accounts, as outlined in the purchase agreement. Truelogic is a software development firm based in Buenos Aires that assists customers in sourcing top South American engineering talent and developing small-scale software projects. Truelogic is included in the Company’s Code and Theory Brand, which is part of its Digital - Marketing reportable segment. The following table summarizes the estimated fair values of the assets acquired and liabilities assumed as of the date of each acquisition (in thousands): 2020 Sloane Kettle Truelogic Total Cash, cash equivalents and restricted cash $ — $ 49 $ 90 $ 139 Accounts receivable and other current assets 2,768 2,732 2,958 8,458 Other noncurrent assets — 172 10 182 Intangible assets 5,900 1,930 9,500 17,330 Property and equipment 72 58 50 180 Right-of-use assets – operating leases — 533 201 734 Accounts payable and other current liabilities (469) (552) (1,063) (2,084) Advanced billings (130) (310) (429) (869) Operating lease liabilities — (533) (201) (734) Goodwill 16,275 1,323 6,184 23,782 Total net assets acquired $ 24,416 $ 5,402 $ 17,300 $ 47,118 Goodwill recognized on the Sloane, Kettle and Truelogic acquisitions is fully-deductible for income tax purposes. The following table reports the fair value of intangible assets acquired, including the corresponding weighted average amortization periods, as of the date of each acquisition (in thousands, except years): 2020 Weighted Average Amortization Period Sloane Kettle Truelogic Total Customer relationships 10 years $ 4,600 $ 1,600 $ 9,100 $ 15,300 Tradenames and trademarks 11 years 1,300 330 400 2,030 Total $ 5,900 $ 1,930 $ 9,500 $ 17,330 The following table summarizes the total revenue and net income included in the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) from the date of each acquisition (in thousands): Nine Months Ended September 30, 2020 Revenue $ 10,794 Net Income $ 1,199 Pro Forma Financial Information (unaudited) The unaudited pro forma information for the periods set forth below gives effect to the 2020 acquisitions as if they had occurred as of January 1, 2020. The pro forma information is presented for informational purposes only and is not necessarily indicative of the results of operations that actually would have been achieved had the acquisitions been consummated as of that time (in thousands): Nine Months Ended September 30, 2020 Revenue $ 587,343 Net Income $ 39,801 2021 Disposition On September 15, 2021, the Company sold Reputation Defender to a strategic buyer for approximately $40,000 resulting in a gain of approximately $43,000. The gain is recognized within the All Other category in Gain on sale of business and other, net within the Unaudited Condensed Consolidated Statements of Operations. Deferred acquisition consideration on the balance sheet consists of deferred obligations related to contingent and fixed purchase price payments, and to a lesser extent, contingent and fixed retention payments tied to continued employment of specific personnel. Contingent deferred acquisition consideration is recorded at the acquisition date fair value and adjusted at each reporting period through operating income. The Company accounts for certain retention payments through operating income as compensation expense over the required retention period. The following table presents changes in contingent deferred acquisition consideration, which is measured at fair value on a recurring basis using significant unobservable inputs, and a reconciliation to the amounts reported on the balance sheets as of September 30, 2021 and December 31, 2020: September 30, December 31, 2021 2020 Beginning Balance of Contingent Payments $ 17,847 $ 65,792 Payments (12,286) (66,235) Redemption value adjustments (1) 9,535 2,520 Additions (2) 61,110 15,717 Other (501) 53 Ending balance of contingent payments $ 75,705 $ 17,847 (1) Redemption value adjustments are fair value changes from the Company’s initial estimates of deferred acquisition payments. Redemption value adjustments are recorded within Office and general expenses on the Unaudited Condensed Consolidated Statements of Operations. (2) Additions in 2021 represent deferred acquisition consideration acquired in connection with the acquisition of MDC.

Revenue

Revenue	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue	Revenue The Company’s revenue recognition policies are established in accordance with ASC 606, and accordingly, revenue is recognized when control of the promised goods or services is transferred to our clients, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. The Stagwell network provides an extensive range of services to our clients, offering a variety of marketing and communication capabilities including strategy, creative and production for advertising campaigns across a variety of platforms (print, digital, social media, television broadcast), public relations services including strategy, editorial, crisis support or issues management, media training, influencer engagement and events management. We also provide media buying and planning across a range of platforms (out-of-home, paid search, social media, lead generation, programmatic, television broadcast), experiential marketing and application/website design and development. The primary source of the Company’s revenue is from agency arrangements in the form of fees for services performed, commissions, and from performance incentives or bonuses, depending on the terms of the client contract. In all circumstances, revenue is only recognized when collection is reasonably assured. Certain of the Company’s contractual arrangements have more than one performance obligation. For such arrangements, revenue is allocated to each performance obligation based on its relative stand-alone selling price. Stand-alone selling prices are determined based on the prices charged to clients or using expected cost plus margin. The determination of our performance obligations is specific to the services included within each contract. Based on a client’s requirements within the contract, and how these services are provided, multiple services could represent separate performance obligations or be combined and considered one performance obligation. Contracts that contain services that are not significantly integrated or interdependent, and that do not significantly modify or customize each other, are considered separate performance obligations. Typically, we consider media planning, media buying, creative (or strategy), production and experiential marketing services to be separate performance obligations if included in the same contract as each of these services can be provided on a stand-alone basis, and do not significantly modify or customize each other. Public relations services and application/website design and development are typically each considered one performance obligation as there is a significant integration of these services into a combined output. Certain of the Company’s contracts consist of a single performance obligation. In these instances, the Company does not consider the underlying activities as separate or distinct performance obligations because its services are highly interrelated, and the integration of the various components is essential to the overall promise to the Company’s customer. In certain of the Company’s client contracts, the performance obligation is a stand-ready obligation because the Company provides a constant level of similar services over the term of the contract. We typically satisfy our performance obligations over time, as services are performed. Fees for services are typically recognized using input methods (direct labor hours, materials and third-party costs) that correspond with efforts incurred to date in relation to total estimated efforts to complete the contract. To a lesser extent, revenue is recognized using output measures, such as impressions or ongoing reporting. For client contracts when the Company has a stand-ready obligation to perform services on an ongoing basis over the life of the contract, where the scope of these arrangements includes an undefined number of broad activities and there are no significant gaps in performing the services, the Company recognizes revenue ratably using a time-based measure. In addition, for client contracts where the Company is providing online subscription-based hosted services, it recognizes revenue ratably over the contract term. Point in time recognition primarily relates to certain commission-based contracts, which are recognized upon the placement of advertisements in various media when the Company has no further performance obligation. Revenue is recognized net of sales and other taxes due to be collected and remitted to governmental authorities. The Company’s contracts typically provide for termination by either party within 30 to 90 days. Although payment terms vary by client, they are typically within 30 to 60 days. In addition, the Company generally has the right to payment for all services provided through the end of the contract or termination date. Within each contract, we identify whether the Company is principal or agent at the performance obligation level. In arrangements where the Company has substantive control over the service before transferring it to the client, and is primarily responsible for integrating the services into the final deliverables, we act as principal. In these arrangements, revenue is recorded at the gross amount billed. Accordingly, for these contracts the Company has included reimbursed expenses in revenue. In other arrangements where a third-party supplier, rather than the Company, is primarily responsible for the integration of services into the final deliverables, and thus the Company is solely arranging for the third-party supplier to provide these services to our client, we generally act as agent and record revenue equal to the net amount retained, when the fee or commission is earned. The role of Stagwell’s agencies under a production services agreement is to facilitate a client’s purchasing of production capabilities from a third-party production company in accordance with the client’s strategy and guidelines. The obligation of Stagwell’s agencies under media buying services is to negotiate and purchase advertising media from a third-party media vendor on behalf of a client to execute its media plan. We do not obtain control prior to transferring these services to our clients; therefore, we primarily act as agent for production and media buying services. A small portion of the Company’s contractual arrangements with clients include performance incentive provisions, which allow the Company to earn additional revenues as a result of its performance relative to both quantitative and qualitative goals. Incentive compensation is primarily estimated using the most likely amount method and is included in revenue up to the amount that is not expected to result in a reversal of a significant amount of cumulative revenue recognized. We recognize revenue related to performance incentives as we satisfy the performance obligation to which the performance incentives are related. Disaggregated Revenue Data The Company provides a broad range of services to a large base of clients across the full spectrum of verticals globally. The primary source of revenue is from agency arrangements in the form of fees for services performed, commissions, and from performance incentives or bonuses. Certain clients may engage with the Company in various geographic locations, across multiple disciplines, and through multiple Brands. Representation of a client rarely means that Stagwell handles marketing communications for all brands or product lines of the client in every geographical location. The Company’s Brands often cooperate with one another through referrals and the sharing of both services and expertise, which enables Stagwell to service clients’ varied marketing needs by crafting custom integrated solutions. Additionally, the Company maintains separate, independent operating companies to enable it to effectively manage potential conflicts of interest by representing competing clients across the Stagwell network. The following table presents revenue disaggregated by lines of business for the three and nine months ended September 30, 2021 and 2020: Three Months Ended September 30, Nine Months Ended September 30, Lines of Business Reportable Segment 2021 2020 2021 2020 Public Relations Integrated Agencies Network, Communications Network, Other $ 67,497 $ 43,497 $ 118,380 $ 97,217 Creative Integrated Agencies Network 125,637 1,927 127,791 6,792 Digital All Segments 191,643 153,284 445,485 370,711 Experiential Integrated Agencies Network 14,413 — 14,413 — Media Media Network 10,819 — 10,819 — Research Integrated Agencies Network 46,363 24,863 117,467 78,242 Other Media Network, Integrated Agencies Network, Other 10,262 4,526 23,081 22,008 $ 466,634 $ 228,097 $ 857,436 $ 574,970 Stagwell has historically largely focused where the Company was founded in North America, the largest market for its services in the world. The Company has expanded its global footprint to support clients looking for help to grow their businesses in new markets. Stagwell’s Brands are located in the United States and United Kingdom, and an additional eighteen countries around the world. In the past, some clients have responded to weakening economic conditions with reductions to their marketing budgets, which included discretionary components that are easier to reduce in the short term than other operating expenses. The following table presents revenue disaggregated by geography for the three and nine months ended September 30, 2021 and 2020: Three Months Ended September 30, Nine Months Ended September 30, Geographical Location Reportable Segment 2021 2020 2021 2020 United States All $ 387,662 $ 208,045 $ 733,038 $ 515,403 United Kingdom All 32,218 4,904 62,416 18,658 Other All 46,754 15,148 61,982 40,909 $ 466,634 $ 228,097 $ 857,436 $ 574,970 Contract Assets and Liabilities Contract assets consist of fees and reimbursable outside vendor costs incurred on behalf of clients when providing advertising, marketing and corporate communications services that have not yet been invoiced to clients. Unbilled service fees were $137,938 and $30,570 at September 30, 2021 and December 31, 2020, respectively, and are included as a component of Accounts receivable on the Unaudited Condensed Consolidated Balance Sheets. Outside vendor costs incurred on behalf of clients which have yet to be invoiced were $37,101 and $11,063 at September 30, 2021 and December 31, 2020, respectively, and are included on the Unaudited Condensed Consolidated Balance Sheets as Expenditures billable to clients. Such amounts are invoiced to clients at various times over the course of providing services. Additions to contract assets of $99,853 were added during the period as a result of the acquisition of MDC. Contract liabilities consist of fees billed to clients in excess of fees recognized as revenue and are classified as Advance billings and also are included within Accruals and other liabilities on the Company’s Unaudited Condensed Consolidated Balance Sheets. In arrangements in which we are acting as an agent, the revenue recognition related to the contract liability is presented on a net basis within the Unaudited Condensed Consolidated Statements of Operations. Advance billings at September 30, 2021 and December 31, 2020 were $286,790 and $66,418, respectively. The increase in the Advance billings balance of $220,372 for the nine months ended September 30, 2021 was primarily driven by the acquisition of MDC, representing a $211,687 increase, and by cash payments received or due in advance of satisfying our performance obligations, offset by $45,432 of revenues recognized that were included in the Advance billings balances as of December 31, 2020 and reductions due to the incurrence of third-party costs. Contract liabilities classified within Accruals and other liabilities at September 30, 2021 and December 31, 2020 were $168,882 and $9,311, respectively. The increase in the balance of $159,571 for the nine months ended September 30, 2021 was primarily driven by was primarily driven by the acquisition of MDC, representing a $108,488 increase, and by cash payments received or due in advance of satisfying our performance obligations, offset by $9,311 of revenues recognized that were included in the balance as of December 31, 2020 and reductions due to the incurrence of third-party costs. Changes in the contract asset and liability balances during the nine months ended September 30, 2021 were not materially impacted by write offs, impairment losses or any other factors.

Income (Loss) Per Common Share

Income (Loss) Per Common Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Income (Loss ) Per Common Share	Income (Loss) Per Common Share The following table sets forth the computations of basic and diluted income (loss) per common share: Three Months Ended September 30, Nine Months Ended September 30, 2021 2021 Numerator: Net loss attributable to Stagwell Inc. common shareholders $ (4,545) $ (4,545) Denominator: Weighted average number of common shares outstanding 76,105,807 76,105,807 Earnings Per Share - Basic & Diluted $ (0.06) $ (0.06) Anti-dilutive: Class C shares 179,970,051 179,970,051 Stock Appreciation Rights and Restricted Awards 6,596,023 6,596,023 There were 123,849,000 Preferred Shares outstanding which were convertible into 33,035,446 of Class A common shares at September 30, 2021. These Preferred Shares were anti-dilutive for each period presented in the table above and are therefore excluded from the diluted earnings per share calculation. The combination of MDC and SMG was completed on August 2, 2021, which was treated as a reverse acquisition for financial reporting purposes. SMG was treated as the accounting acquirer and MDC was the accounting acquiree. Therefore, under applicable accounting principles, the historical financial results of SMG prior to August 2, 2021 are considered our historical financial results. Accordingly, historical information presented in this Form 10-Q for events occurring or periods ending before August 2, 2021 does not reflect the impact of the Transactions or the financial results of MDC and may not be comparable with historical information for events occurring or periods ending on or after August 2, 2021. SMG’s equity structure, prior to the combination with MDC, was a non-unitized single member limited liability company, resulting in all components of equity attributable to the member being reported within Members' Capital. Given that SMG was a non-unitized single member limited liability company, net income (loss) prior to the combination is not applicable for purposes of calculating earnings per share. Therefore, the net income (loss) in the table above includes the income or loss for the period beginning on the acquisition date through the end of the respective reporting period and as such will not reconcile to the respective amounts presented within the Unaudited Condensed Consolidated Statements of Operations.

Deferred Acquisition Considerat

Deferred Acquisition Consideration	9 Months Ended
	Sep. 30, 2021
Business Combinations [Abstract]
Deferred Acquisition Consideration	Acquisitions and Dispositions 2021 Acquisition On December 21, 2020, MDC Partners Inc. (“MDC”) and Stagwell Media LP (“Stagwell Media”) announced that they had entered into the Transaction Agreement, providing for the combination of MDC with the operating businesses and subsidiaries of Stagwell Media (the “Stagwell Subject Entities”). The Stagwell Subject Entities comprised Stagwell Marketing Group LLC (“Stagwell Marketing or SMG”) and its direct and indirect subsidiaries. On August 2, 2021 (the “Closing Date”), we completed the combination of MDC and the Stagwell Subject Entities and a series of steps and related transactions (such combination and transactions, the “Transactions”). In connection with the Transactions, among other things, (i) MDC completed a series of transactions pursuant to which it emerged as a wholly owned subsidiary of the Company, converted into a Delaware limited liability company and changed its name to Midas OpCo Holdings LLC (“OpCo”); (ii) Stagwell Media contributed the equity interests of Stagwell Marketing and its direct and indirect subsidiaries to OpCo; and (iii) the Company converted into a Delaware corporation, succeeded MDC as the publicly-traded company and changed its name to Stagwell Inc. In respect of the Transactions, the acquired assets and assumed liabilities, together with acquired processes and employees, represent a business as defined in the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) 805, Business Combinations (“ASC 805”). The Transactions was accounted for as a reverse acquisition using the acquisition method of accounting, pursuant to FASB Topic 805-10, Business Combinations, with MDC treated as the legal acquirer and SMG treated as the accounting acquirer. In identifying SMG as the acquiring entity for accounting purposes, MDC and SMG took into account a number of factors, including the relative voting rights and the corporate governance structure of the Company. SMG is considered the accounting acquirer since Stagwell Media controls the board of directors of the Company following the Transactions and received an indirect ownership interest in the Company’s only operating subsidiary, OpCo, of 69.55% ownership of OpCo’s common units. However, no single factor was the sole determinant in the overall conclusion that Stagwell is the acquirer for accounting purposes; rather all factors were considered in arriving at such conclusion. Under the acquisition method of accounting, the assets and liabilities of MDC, as the accounting acquiree, were recorded at their respective fair value as of the date the Transactions were completed. On August 2, 2021, an aggregate of 179,970,051 shares of the Company’s Class C common stock were issued to Stagwell Media in exchange for $1,800 (the “Stagwell New MDC Contribution”). The Class C common stock does not participate in the earnings of the Company. Additionally, an aggregate of 179,970,051 OpCo common units were issued to Stagwell Media in exchange for the equity interests of the Stagwell Subject Entities (the “Stagwell OpCo Contribution”). The fair value of the purchase consideration is $426,396, consisting of approximately 80,000,000 shares of the Company’s Class A and B common stock and common stock equivalents based on a per share price of approximately $5.42, the closing stock price on the date of the combination. ASC 805 requires the allocation of the purchase price consideration to the fair value of the identified assets acquired and liabilities assumed upon consummation of a business combination. For this purpose, fair value shall be determined in accordance with the fair value concepts defined in ASC 820, “Fair Value Measurements and Disclosures,” (“ASC 820”). Fair value is defined in ASC 820 as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” Fair value measurements can be highly subjective and can involve a high degree of estimation. The total purchase price to acquire MDC has been allocated to the assets acquired and assumed liabilities based upon preliminary estimated fair values, with any excess purchase price allocated to goodwill. The fair value of the acquired assets and assumed liabilities as of the date of acquisition are based on preliminary estimates assisted, in part, by a third-party valuation expert. The estimates are subject to change upon the finalization of appraisals and other valuation analyses, which are expected to be completed no later than one year from the date of acquisition. Although the completion of the valuation activities may result in asset and liability fair values that are different from the preliminary estimates included herein, it is not expected that those differences would alter the understanding of the impact of this transaction on the consolidated financial position and results of operations of the Company. The preliminary purchase price allocation is as follows: Amount Cash and cash equivalents $ 130,155 Accounts receivable 419,742 Other current assets 44,508 Fixed Assets 80,047 Right-of-use lease assets - operating leases 293,034 Intangible assets 809,900 Other assets 16,928 Accounts payable (165,443) Accruals and other liabilities (308,757) Advance billings (211,687) Current portion of lease liabilities (55,878) Current portion of deferred acquisition consideration (53,054) Long-term debt (1,011,690) Long-term portion of deferred acquisition consideration (8,056) Long-term portion of lease liabilities (292,497) Other liabilities (131,897) Redeemable noncontrolling interests (30,830) Preferred shares (209,980) Noncontrolling interests (158,230) Net liabilities assumed (843,685) Goodwill 1,270,081 Purchase price consideration $ 426,396 The excess of purchase consideration over the fair value of the net assets acquired was recorded as goodwill, which is primarily attributed to the assembled workforce of MDC. Goodwill of $1,041,277, $166,658 and $62,146 was assigned to the Integrated Agencies Network, the Media Network and the Communications Network reportable segments, respectively. The majority of the goodwill is non-deductible for income tax purposes. Intangible assets consist of trade names and customer relationships. We amortize purchased intangible assets on a straight-line basis over their respective useful lives. The weighted average life of the total acquired identifiable intangible assets is 13 years. The following table presents the details of identifiable intangible assets acquired. Estimated Fair Value Estimated Useful Life in Years Trade Names $ 98,000 10 Customer Relationships 711,900 6-15 Total Acquired Intangible Assets $ 809,900 MDC operating results are included in the Condensed Consolidated Statements of Operations from the date of the acquisition through September 30, 2021 with revenue of $241,257 and a nominal net loss. Transaction expenses were approximately $15,000 for the nine months ended September 30, 2021. Pro Forma Financial Information (unaudited) The unaudited pro forma information for the periods set forth below gives effect to the acquisition as if it occurred as of January 1, 2020. The pro forma information is presented for informational purposes only and is not necessarily indicative of the results of operations that actually would have been achieved had the acquisitions been consummated as of that time. Nine Months Ended September 30, 2021 Nine Months Ended September 30, 2020 Revenue $ 1,612,399 $ 1,445,813 The proforma net loss was nominal for the nine months ended September 30, 2021 and 2020. 2020 Acquisitions On February 14, 2020, the Company acquired Sloane & Company (“Sloane”) from an affiliate of MDC for approximately $24,400 of total consideration. Total consideration included a cash payment of $18,900 made by Stagwell Media (Non-consolidated related party) which was accounted for as a non-cash contribution for the purposes of the Company’s Consolidated Statement of Cash Flows and Statement of Changes in Equity, the acquisition date fair value of the contingent deferred acquisition consideration of $4,800, and $700 of cash paid by the Company. Sloane is an industry-leading strategic communications firm, based out of New York. Sloane will extend SKDK’s current suite of services and allow for the expansion into the capital markets and special situations verticals. On August 14, 2020, the Company acquired Kettle Solutions, LLC (“Kettle”) for approximately $5,400 of total consideration. Total consideration included a cash payment of $4,900, plus an additional $500 due upon the finalization of Kettle’s working capital accounts, as outlined in the purchase agreement. The purchase agreement also offers the previous owners of Kettle an additional $11,900 in deferred consideration, and is dependent on Kettle reaching contractually defined operating goals in 2020, 2021, 2022 and 2023. Kettle is an industry recognized web design and content creation firm that assists its customers in developing and executing marketing campaigns, based out of New York. On October 30, 2020, the Company acquired Truelogic Software, LLC, Ramenu S.A., and Polar Bear Development S.R.L. (collectively referred to as “Truelogic”), for approximately $17,300 of total consideration. Total consideration included a cash payment of $8,900, the acquisition date fair value of the contingent deferred acquisition consideration of $7,900, and an additional $500 due upon the finalization of Truelogic’s working capital accounts, as outlined in the purchase agreement. Truelogic is a software development firm based in Buenos Aires that assists customers in sourcing top South American engineering talent and developing small-scale software projects. Truelogic is included in the Company’s Code and Theory Brand, which is part of its Digital - Marketing reportable segment. The following table summarizes the estimated fair values of the assets acquired and liabilities assumed as of the date of each acquisition (in thousands): 2020 Sloane Kettle Truelogic Total Cash, cash equivalents and restricted cash $ — $ 49 $ 90 $ 139 Accounts receivable and other current assets 2,768 2,732 2,958 8,458 Other noncurrent assets — 172 10 182 Intangible assets 5,900 1,930 9,500 17,330 Property and equipment 72 58 50 180 Right-of-use assets – operating leases — 533 201 734 Accounts payable and other current liabilities (469) (552) (1,063) (2,084) Advanced billings (130) (310) (429) (869) Operating lease liabilities — (533) (201) (734) Goodwill 16,275 1,323 6,184 23,782 Total net assets acquired $ 24,416 $ 5,402 $ 17,300 $ 47,118 Goodwill recognized on the Sloane, Kettle and Truelogic acquisitions is fully-deductible for income tax purposes. The following table reports the fair value of intangible assets acquired, including the corresponding weighted average amortization periods, as of the date of each acquisition (in thousands, except years): 2020 Weighted Average Amortization Period Sloane Kettle Truelogic Total Customer relationships 10 years $ 4,600 $ 1,600 $ 9,100 $ 15,300 Tradenames and trademarks 11 years 1,300 330 400 2,030 Total $ 5,900 $ 1,930 $ 9,500 $ 17,330 The following table summarizes the total revenue and net income included in the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) from the date of each acquisition (in thousands): Nine Months Ended September 30, 2020 Revenue $ 10,794 Net Income $ 1,199 Pro Forma Financial Information (unaudited) The unaudited pro forma information for the periods set forth below gives effect to the 2020 acquisitions as if they had occurred as of January 1, 2020. The pro forma information is presented for informational purposes only and is not necessarily indicative of the results of operations that actually would have been achieved had the acquisitions been consummated as of that time (in thousands): Nine Months Ended September 30, 2020 Revenue $ 587,343 Net Income $ 39,801 2021 Disposition On September 15, 2021, the Company sold Reputation Defender to a strategic buyer for approximately $40,000 resulting in a gain of approximately $43,000. The gain is recognized within the All Other category in Gain on sale of business and other, net within the Unaudited Condensed Consolidated Statements of Operations. Deferred acquisition consideration on the balance sheet consists of deferred obligations related to contingent and fixed purchase price payments, and to a lesser extent, contingent and fixed retention payments tied to continued employment of specific personnel. Contingent deferred acquisition consideration is recorded at the acquisition date fair value and adjusted at each reporting period through operating income. The Company accounts for certain retention payments through operating income as compensation expense over the required retention period. The following table presents changes in contingent deferred acquisition consideration, which is measured at fair value on a recurring basis using significant unobservable inputs, and a reconciliation to the amounts reported on the balance sheets as of September 30, 2021 and December 31, 2020: September 30, December 31, 2021 2020 Beginning Balance of Contingent Payments $ 17,847 $ 65,792 Payments (12,286) (66,235) Redemption value adjustments (1) 9,535 2,520 Additions (2) 61,110 15,717 Other (501) 53 Ending balance of contingent payments $ 75,705 $ 17,847 (1) Redemption value adjustments are fair value changes from the Company’s initial estimates of deferred acquisition payments. Redemption value adjustments are recorded within Office and general expenses on the Unaudited Condensed Consolidated Statements of Operations. (2) Additions in 2021 represent deferred acquisition consideration acquired in connection with the acquisition of MDC.

Leases

Leases	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Leases	Leases The Company leases office space in North America, Europe, Asia, South America, and Australia. This space is primarily used for office and administrative purposes by the Company’s employees in performing professional services. These leases are classified as operating leases and expire between years 2021 through 2034. The Company’s finance leases are immaterial. The Company’s leasing policies are established in accordance with ASC 842, and accordingly, the Company recognizes on the balance sheet at the time of lease commencement a right-of-use lease asset and a lease liability, initially measured at the present value of the lease payments. Right-of-use lease assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. All right-of-use lease assets are reviewed for impairment. As the Company’s implicit rate in its leases is not readily determinable, in determining the present value of lease payments, the Company uses its incremental borrowing rate based on the information available at the commencement date. Lease payments included in the measurement of the lease liability are comprised of noncancelable lease payments, payments based upon an index or rate, payments for optional renewal periods where it is reasonably certain the renewal period will be exercised, and payments for early termination options unless it is reasonably certain the lease will not be terminated early. Lease costs are recognized in the Unaudited Condensed Consolidated Statements of Operations over the lease term on a straight-line basis. Leasehold improvements are depreciated on a straight-line basis over the lesser of the term of the related lease or the estimated useful life of the asset. Some of the Company’s leases contain variable lease payments, including payments based upon an index or rate. Variable lease payments based upon an index or rate are initially measured using the index or rate in effect at the lease commencement date and are included within the lease liabilities. Lease liabilities are not remeasured as a result of changes in the index or rate, rather changes in these types of payments are recognized in the period in which the obligation for those payments is incurred. In addition, some of our leases contain variable payments for utilities, insurance, real estate tax, repairs and maintenance, and other variable operating expenses. Such amounts are not included in the measurement of the lease liability and are recognized in the period when the facts and circumstances which the variable lease payments are based upon occur. Some of the Company’s leases include options to extend or renew the leases through 2044. The renewal and extension options are not included in the lease term as the Company is not reasonably certain that it will exercise its option. From time to time, the Company enters into sublease arrangements both with unrelated third-parties and with our partner agencies. These leases are classified as operating leases and expire between years 2021 through 2031. Sublease income is recognized over the lease term on a straight-line basis. Currently, the Company subleases office space in North America, Asia, Europe and Australia. As of September 30, 2021, the Company has entered into three operating leases for which the commencement date has not yet occurred as the premises are in the process of being prepared for occupancy by the landlord. Accordingly, these three leases represent an obligation of the Company that is not reflected within the Unaudited Condensed Consolidated Balance Sheets as of September 30, 2021. The aggregate future liability related to these leases is approximately $31,310. The discount rate used for leases accounted for under ASC 842 is the Company’s collateralized credit adjusted borrowing rate. The following table presents lease costs and other quantitative information for the three and nine months ended September 30, 2021 and 2020: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Lease Cost: Operating lease cost $ 13,502 $ 5,900 $ 27,779 $ 19,279 Variable lease cost 3,230 928 5,167 2,959 Sublease rental income (2,359) (938) (4,290) (2,818) Total lease cost $ 14,373 $ 5,890 $ 28,656 $ 19,420 Additional information: Cash paid for amounts included in the measurement of lease liabilities for operating leases Operating cash flows $ 16,490 $ 5,260 $ 29,854 $ 15,580 Right-of-use lease assets obtained in exchange for operating lease liabilities and other non-cash adjustments $ 353,984 $ 128 $ 353,984 $ 1,961 Weighted average remaining lease term (in years) - Operating leases 6.8 4.6 6.8 4.6 Weighted average discount rate - Operating leases 4.0 % 4.1 % 4.0 % 4.1 % Operating lease expense is included in office and general expenses in the Unaudited Condensed Consolidated Statements of Operations. The Company’s lease expense for leases with a term of 12 months or less is immaterial. The following table presents minimum future rental payments under the Company’s leases at September 30, 2021 and their reconciliation to the corresponding lease liabilities: Maturity Analysis Remaining 2021 $ 23,452 2022 84,730 2023 80,281 2024 65,242 2025 50,076 2026 and thereafter 161,462 Total 465,243 Less: Present value discount (63,033) Lease liability $ 402,210

Debt

Debt	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Debt	Debt As of September 30, 2021 and December 31, 2020, the Company’s indebtedness was comprised as follows: September 30, 2021 December 31, 2020 Revolving credit facility $ 181,112 $ 201,636 Term debt — 994 5.625% Notes 1,100,000 — Debt issuance costs (15,365) (3,612) Total debt $ 1,265,747 $ 199,018 Less: Current maturities of long-term debt $ — $ (994) Long-term debt $ 1,265,747 $ 198,024 Interest expense related to long-term debt included in Interest expense, net on the Unaudited Condensed Consolidated Statements of Operations for the nine months ended September 30, 2021 and 2020 was $15,560 and $4,317, respectively. The amortization of debt issuance costs included in Interest expense, net on the Unaudited Condensed Consolidated Statements of Operations for the nine months ended September 30, 2021 and 2020 was $2,092 and $396, respectively. Revolving Credit Agreement On November 18, 2019, the Company entered into a debt agreement (“JPM Syndicated Facility”) with a syndicate of banks led by JPMorgan Chase Bank, N.A (“JPM”). The JPM Syndicated Facility consisted of a five-year revolving credit facility of $265,000 (“JPM Revolver”) with the right to be increased by an additional $150,000. On March 18, 2020, the Company increased the commitments on the JPM Revolver by $60,000 to $325,000. On August 2, 2021, in connection with the closing of the acquisition of MDC, the Company entered into an amended and restated credit agreement (the “Combined Credit Agreement”) with a syndicate of banks led by JPM to increase commitments on the existing JPM Revolver. The Combined Credit Agreement consists of a $500,000 senior secured revolving credit facility with a five-year maturity. The Combined Credit Agreement contains sub-limits for revolving loans and letters of credit of $50,000 for loans denominated in pounds sterling or euros. It also includes an accordion feature under which the Company may request, subject to lender approval and certain conditions, to increase the amount of the commitments to an aggregate amount not to exceed $650,000. Borrowings under the Combined Credit Agreement bear interest at a rate equal to, at the Company’s option, (i) the greatest of (a) the prime rate of interest announced from time to time by JPM, (b) the federal funds effective rate from time to time plus 0.50% and (c) the LIBOR rate plus 1%, in each case, plus the applicable margin (calculated based on the Company’s total leverage ratio) at that time or (ii) the LIBOR rate plus the applicable margin (calculated based on the Company’s total leverage ratio) at that time. The Company is also required to pay an unused revolver fee to the lenders under the Combined Credit Agreement in respect of the unused commitments thereunder ranging from 0.15% to 0.30% of unused commitments depending on the total leverage ratio, as well as customary letter of credit fees. Advances under the Combined Credit Agreement may be prepaid in whole or in part from time to time without penalty or premium. The Combined Credit Agreement commitment may be reduced by the Company from time to time. Principal amounts outstanding under the Combined Credit Agreement are due and payable in full at maturity within five years of the date of the Combined Credit Agreement. If an event of default occurs under the Combined Credit Agreement or any future secured indebtedness, the holders of such secured indebtedness will have a prior right to our assets securing such indebtedness, to the exclusion of the holders of the 5.625% Notes (as defined below), even if we are in default with respect to the 5.625% Notes. In that event, our assets securing such indebtedness would first be used to repay in full all indebtedness and other obligations secured by them (including all amounts outstanding under the Combined Credit Agreement), resulting in all or a portion of our assets being unavailable to satisfy the claims of the holders of the 5.625% Notes and other unsecured indebtedness. The Combined Credit Agreement contains a number of financial and nonfinancial covenants and is guaranteed by substantially all of our present and future subsidiaries, subject to customary exceptions. The Company was in compliance with all covenants at September 30, 2021. A portion of the Combined Credit Agreement in an amount not to exceed $50,000 is available for the issuance of standby letters of credit. At September 30, 2021 and December 31, 2020, the Company had issued undrawn outstanding letters of credit of $25,628 and $5,500, respectively. Term Loan On November 13, 2020, the Company, JPM as administrative agent, and a group of lenders entered into a term loan agreement that provided the Company with a delayed draw term loan in an aggregate principal amount of $90,000 (“DD Term Loan A”) with a maturity date of November 13, 2023. In connection with the acquisition of MDC, the Company drew down on the full amount of the DD Term Loan A, repaid the amount with the Combined Credit Agreement, and terminated the agreement. Line of Credit On August 2, 2021, the Company entered into an unsecured uncommitted line of credit in the aggregate amount of $30,000 with JPM (the “Line of Credit”) to meet certain short-term working capital needs. The Line of Credit expired on August 20, 2021. Senior Notes In August 2021, the Company issued $1,100,000 aggregate principal amount of 5.625% senior notes ("5.625% Notes"). A portion of the proceeds from the issuance of the 5.625% Notes was used to redeem $870,300 aggregate principal amount of the outstanding 7.50% Senior Notes due 2024 (the “Existing Notes”) for a price of $904,200. This price is equal to 101.625% of the outstanding principal amount of the Existing Notes being redeemed, plus, accrued, and unpaid interest on the principal amount of such Existing Notes. The Company did not recognize a gain or loss on redemption. The 5.625% Notes are due August 15, 2029 and bear interest of 5.625% to be paid on February 15 and August 15 of each year, commencing on February 15, 2022. The 5.625% Notes are guaranteed on a senior unsecured basis by substantially all of the Company’s subsidiaries. The 5.625% Notes rank (i) equally in right of payment with all of the Company’s or any guarantor’s existing and future unsubordinated indebtedness, (ii) senior in right of payment to the Company’s or any guarantor’s existing and future subordinated indebtedness, (iii) effectively subordinated to any of the Company’s or any guarantor’s existing and future secured indebtedness to the extent of the collateral securing such indebtedness, including the Combined Credit Agreement, and (iv) structurally subordinated to all existing and future liabilities of the Company’s subsidiaries that are not guarantors. Our obligations under the 5.625% Notes are unsecured and are effectively junior to our secured indebtedness to the extent of the value of the collateral securing such secured indebtedness. Borrowings under the Combined Credit Agreement are secured by substantially all of the assets of the Company, and any existing and future subsidiary guarantors, including all of the capital stock of each restricted subsidiary. The Company may, at its option, redeem the 5.625% Notes in whole at any time or in part from time to time, on and after August 15, 2024 at a redemption price of 102.813% of the principal amount thereof if redeemed during the twelve-month period beginning on August 15, 2024, at a redemption price of 101.406% of the principal amount thereof if redeemed during the twelve-month period beginning on August 15, 2025 and at a redemption price of 100% of the principal amount thereof if redeemed on August 15, 2026 and thereafter. Prior to August 15, 2024, the Company may, at its option, redeem some or all of the 5.625% Notes at a price equal to 100% of the principal amount of the 5.625% Notes plus a “make whole” premium and accrued and unpaid interest. The Company may also redeem, at its option, prior to August 15, 2024, up to 40% of the 5.625% Notes with the net proceeds from one or more equity offerings at a redemption price of 105.625% of the principal amount thereof. If the Company experiences certain kinds of changes of control (as defined in the indenture), holders of the 5.625% Notes may require the Company to repurchase any 5.625% Notes held by them at a price equal to 101% of the principal amount of the 5.625% Notes plus accrued and unpaid interest. In addition, if the Company sells assets under certain circumstances, it must offer to repurchase the 5.625% Notes at a price equal to 100% of the principal amount of the 5.625% Notes plus accrued and unpaid interest. The indenture includes covenants that, among other things, restrict the Company’s ability and the ability of its restricted subsidiaries (as defined in the indenture) to incur or guarantee additional indebtedness; pay dividends on or redeem or repurchase the capital stock of the Company; make certain types of investments; create restrictions on the payment of dividends or other amounts from the Company’s restricted subsidiaries; sell assets; enter into transactions with affiliates; create liens; enter into sale and leaseback transactions; and consolidate or merge with or into, or sell substantially all of the Company’s assets to, another person. These covenants are subject to a number of important limitations and exceptions. The 5.625% Notes are also subject to customary events of default, including cross-payment default and cross-acceleration provisions. The Company was in compliance with all covenants at September 30, 2021. Interest Rate Swap The Company also owns an interest rate swap maturing April 2022 with Bank of America to convert $11,563 of its variable rate debt as of September 30, 2021 to a fixed rate of 2.7%. The fair value of the swap was $155 and $416 and is included in Accruals and other liabilities on the Unaudited Condensed Consolidated Balance Sheets as of September 30, 2021 and December 31, 2020, respectively.

Noncontrolling and Redeemable N

Noncontrolling and Redeemable Noncontrolling Interests	9 Months Ended
	Sep. 30, 2021
Noncontrolling Interest [Abstract]
Noncontrolling and Redeemable Noncontrolling Interests	Noncontrolling and Redeemable Noncontrolling Interests When acquiring less than 100% ownership of an entity, the Company may enter into agreements that give the Company an option to purchase, or require the Company to purchase, the incremental ownership interests under certain circumstances. Where the option to purchase the incremental ownership is within the Company’s control, the amounts are recorded as noncontrolling interests in the equity section of the Company’s Unaudited Condensed Consolidated Balance Sheets. Where the incremental purchase may be required of the Company, the amounts are recorded as redeemable noncontrolling interests in mezzanine equity at their estimated acquisition date redemption value and adjusted at each reporting period for changes to their estimated redemption value through Retained earnings (but not less than their initial redemption value), except for foreign currency translation adjustments. Changes in the Company’s ownership interests in our less than 100% owned subsidiaries during the three and nine months ended September 30, 2021 and 2020 were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Net income (loss) attributable to Stagwell Inc. common shareholders $ (2,071) $ 17,808 $ 20,199 $ 34,124 Transfers from the noncontrolling interest: Increase in Stagwell Inc. paid-in capital for purchase of redeemable noncontrolling interests and noncontrolling interests 9,679 — 9,679 — Net transfers from noncontrolling interests 9,679 — 9,679 — Change from net income (loss) attributable to Stagwell Inc. and transfers to noncontrolling interests $ 7,608 $ 17,808 $ 29,878 $ 34,124 Redeemable Noncontrolling Interests The following table presents changes in redeemable noncontrolling interests: September 30, December 31, 2021 2020 Beginning Balance $ 604 $ 3,603 Redemptions (2,831) — Acquisitions (1) 30,830 — Changes in redemption value 1,680 127 Net loss attributable to redeemable noncontrolling interests (956) (3,126) Other 460 — Ending Balance $ 29,787 $ 604 (1) Represents redeemable noncontrolling interests acquired in connection with the acquisition of MDC. The noncontrolling shareholders’ ability to exercise any such option right is subject to the satisfaction of certain conditions, including conditions requiring notice in advance of exercise and specific employment termination conditions. In addition, these rights cannot be exercised prior to specified staggered exercise dates. The exercise of these rights at their earliest contractual date would result in obligations of the Company to fund the related amounts during 2021 to 2025. It is not determinable, at this time, if or when the owners of these rights will exercise all or a portion of these rights. The redeemable noncontrolling interest of $29,787 as of September 30, 2021, consists of $14,847, assuming that the subsidiaries perform over the relevant periods at their current profit levels, $14,940 upon termination of such owner’s employment with the applicable subsidiary or death, and $0 representing the initial redemption value (required floor) recorded for certain acquisitions in excess of the amount the Company would have to pay should the Company acquire the remaining ownership interests for such subsidiaries. These adjustments will not impact the calculation of earnings (loss) per share if the redemption values are less than the estimated fair values. There is no related impact on the Company’s income per share calculations.

Commitments, Contingencies and

Commitments, Contingencies and Guarantees	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies and Guarantees	Commitments, Contingencies, and Guarantees Legal Proceedings. The Company’s operating entities are involved in legal proceedings of various types. While any litigation contains an element of uncertainty, the Company has no reason to believe that the outcome of such proceedings or claims will have a material adverse effect on the financial condition or results of operations of the Company. Deferred Acquisition Consideration and Options to Purchase. See Notes 7 and 10 of the Notes included herein for information regarding potential payments associated with deferred acquisition consideration and the acquisition of noncontrolling shareholders’ ownership interest in subsidiaries. Guarantees . Generally, the Company has indemnified the purchasers of certain assets in the event that a third party asserts a claim against the purchaser that relates to a liability retained by the Company. These types of indemnification guarantees typically extend for a number of years. Historically, the Company has not made any significant indemnification payments under such agreements and no amount has been accrued in the accompanying consolidated financial statements with respect to these indemnification guarantees. The Company continues to monitor the conditions that are subject to guarantees and indemnifications to identify whether it is probable that a loss has occurred and would recognize any such losses under any guarantees or indemnifications in the period when those losses are probable and estimable. Commitments. At September 30, 2021, the Company had $25,628 of undrawn letters of credit. The Company entered into 3 operating leases for which the commencement date has not yet occurred as of September 30, 2021. See Note 8 included herein for additional information.

Share Capital

Share Capital	9 Months Ended
	Sep. 30, 2021
Share Capital [Abstract]
Share Capital	Share Capital The authorized and outstanding share capital of the Company is below. See Note 1 for information regarding the Transactions. Class A Common Stock (“Class A Shares”) There are 1,000,000,000 shares of Class A common stock authorized. There were 78,979,960 Class A Shares issued and outstanding as of September 30, 2021. The Class A Shares are an unlimited number of subordinate voting shares, carrying one vote each, with a par value of $0.001 entitled to dividends equal to or greater than Class B Shares, convertible at the option of the holder into one Class B Share for each Class A Share after the occurrence of certain events related to an offer to purchase all Class B shares. Class B Common Stock (“Class B Shares”) There are 5,000 shares of Class B common stock authorized. There were 3,946 of Class B Shares issued and outstanding as of September 30, 2021. These are an unlimited number of voting shares, carrying twenty votes each, with a par value of $0, convertible at any time at the option of the holder into one Class A share for each Class B share. Class C Common Stock (“Class C Shares”) There are 250,000,000 shares of Class C common stock authorized. There were 179,970,051 Class C Shares issued and outstanding as of September 30, 2021. The Class C shares do not participate in the earnings of the Company. In addition, an aggregate of 179,970,051 OpCo common units were issued to Stagwell Media in exchange for the equity interests of the Stagwell Subject Entities. Each Class C Share, together with the related Class C unit in OpCo, is convertible at any time, at the option of the holder, into one Class A Share. Convertible Preferred Stock ("Preferred Shares") There are 50,000,000 Series 6 Preferred Shares (par value $0.001 per share) outstanding held by Stagwell Agency Holdings LLC (a third party with an ownership interest in the Company) and 73,849,000 Series 8 Preferred Shares (par value $0.001 per share) held by affiliates of The Goldman Sachs Group, Inc. ("Goldman") as of September 30, 2021. The Company entered into an agreement with Goldman and on August 4, 2021, redeemed $30,000 of liquidation value of the Series 8 Preferred Shares for $25,000, resulting in the redemption of 21,151,000 shares. The terms of the Preferred Shares provided the Company the option to convert the Preferred Shares to Class A Common Shares if Class A Common Shares traded above 125% of the $5.00 per share conversion price for 30 consecutive trading days. On September 23, 2021, the Company provided notices of conversion to each holder of record of each of the Company’s Series 6 and Series 8 Preferred Shares. Pursuant to the notices, the 50,000,000 issued and outstanding Series 6 Preferred Shares were converted into 12,086,700 Class A Common Shares, in the aggregate, on October 7, 2021 and the 73,849,000 issued and outstanding Series 8 Preferred Shares were converted into 20,948,746 Class A Common Shares, in the aggregate, on November 8, 2021. Subsequent to the conversion of the Series 6 and Series 8 preferred shares, the number of Class A Common Shares outstanding was 113,198,517 as of November 8, 2021.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements A fair value measurement assumes a transaction to sell an asset or transfer a liability occurs in the principal market for the asset or liability or, in the absence of a principal market, the most advantageous market for the asset or liability. In determining fair value, the Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible as well as considers counterparty credit risk in its assessment of fair value. The hierarchy for observable and unobservable inputs used to measure fair value into three broad levels are described below: • Level 1 - Quoted prices (unadjusted) in active markets that are accessible at the measurement date for assets or liabilities. The fair value hierarchy gives the highest priority to Level 1 inputs. • Level 2 - Observable prices that are based on inputs not quoted on active markets, but corroborated by market data. • Level 3 - Unobservable inputs are used when little or no market data is available. The fair value hierarchy gives the lowest priority to Level 3 inputs. Financial Instruments that are not Measured at Fair Value on a Recurring Basis The following table presents certain information for our financial liability that is not measured at fair value on a recurring basis at September 30, 2021 and December 31, 2020: September 30, 2021 December 31, 2020 Carrying Fair Value Carrying Fair Value 5.625% Notes 1,100,000 1,133,891 — — Our long-term debt includes fixed rate debt. The fair value of this instrument is based on quoted market prices in markets that are not active. Therefore, this debt is classified as Level 2 within the fair value hierarchy. Financial Instruments Measured at Fair Value on a Recurring Basis The following table presents certain information for our financial instruments that are measured at fair value on a recurring basis at September 30, 2021 and December 31, 2020: September 30, 2021 December 31, 2020 Carrying Fair Value Carrying Fair Value Interest Rate Swap $ 155 $ 155 $ 416 $ 416 Call Options — — 360 360 Preferred Shares — — 12,033 12,033 The interest rate swap and call options are classified as Level 3 within the fair value hierarchy. As of December 31, 2020, the Company owned preferred shares in a company called Finn Partners. The preferred shares had a cost basis of $10,000, accrued non-cash dividends, on a cost basis, at a rate of 6% annually. The shares were redeemable to cash in the amount of the cost-plus accrued interest at any time after February 28, 2021 or upon a liquidation event and were also were convertible to common shares of Finn Partners at any time until February 28, 2021 using a conversion ratio of 1% per $1,000 of preferred shares held including accrued dividends. The conversion feature was not bifurcated and was clearly and closely related to the host instrument, preferred shares. Management determined that the preferred shares were a debt-like financial instrument and should be accounted for as available-for-sale securities at their fair value at each reporting period. These preferred shares are considered to be a Level 3 fair value measurement since they utilize unobservable inputs for which there is little or no market data and which require the Company to develop its own assumptions. On March 11, 2021, the Company transferred all of its ownership in the preferred shares. The Company recognized a gain of $1,200 within Gain on sale of business and other, net on the Unaudited Condensed Consolidated Statements of Operations for the nine months ended September 31, 2021 related to this transaction. Contingent deferred acquisition consideration (Level 3 fair value measurement) is recorded at the acquisition date fair value and adjusted at each reporting period. The estimated liability is determined in accordance with models of each business' future performance, including revenue growth and free cash flows. These models are dependent upon significant assumptions, such as the growth rate of the earnings of the relevant subsidiary during the contractual period and the discount rate. These growth rates are consistent with the Company’s long-term forecasts. As of September 30, 2021, the discount rate used to measure these liabilities ranged from 3.5% to 5.1%. As these estimates require the use of assumptions about future performance, which are uncertain at the time of estimation, the fair value measurements presented on the Unaudited Condensed Consolidated Balance Sheets are subject to material uncertainty. See Note 7 included herein for additional information regarding contingent deferred acquisition consideration. At September 30, 2021 and December 31, 2020, the carrying amount of the Company’s financial instruments, including cash, cash equivalents, accounts receivable and accounts payable, approximated fair value because of their short-term maturity. Non-financial Assets and Liabilities that are Measured at Fair Value on a Nonrecurring Basis

Supplemental Information

Supplemental Information	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Information	Supplemental Information Stock-Based Compensation & Purchase of Noncontrolling Interests The Company recognized stock-based compensation expense of $53,465 for the three and nine months ended September 30, 2021, of which $45,986 was for SMG unit awards (consisting of one share of the Company’s Class C Common stock and one Opco Common Unit) issued in the third quarter of 2021. Immediately following the acquisition of MDC, the Company issued 12,131 SMG unit awards, of which 6,661 were fully vested and 5,470 vest over a 6-month service period. E ach SMG unit award is exchangeable into one share of the Company’s Class A Common Stock. The unit awards were issued from Stagwell Media's total 179,970,051 Class C common shares and Stagwell OpCo common units issued to it in the business combination. Class C common shares and Stagwell OpCo common units. Immediately following the acquisition of MDC, t he Company also purchased the remaining interest it did not already own in Code and Theory (8.5%) and Observatory (8.1%) and an incremental interest in Targeted Victory (13.3%). The acquired interests were also funded from Stagwell Media’s total 179,970,051 Class C common shares and Stagwell OpCo common units issued to it in the business. A total of 6,930 units with a value of $37,560 were exchanged for the above interests in accordance with the business combination transaction agreement. See Note 1 for information related to the purchase of the remaining noncontrolling interest in Targeted Victory. Impairment and Other Losses

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions In the ordinary course of business, the Company enters into transactions with related parties, including its affiliates. The transactions may range in the nature and value of services underlying the arrangements. Below are the related party transactions that are significant in nature: In August 2016, a Brand of the Company entered into an arrangement to provide technology development services to a client in which several of Brand's partners hold key leadership positions. Under the arrangement, the Brand is expected to receive from the client approximately $1,800, which is expected to be fully recognized as of October 31, 2022. During the three and nine months ended September 30, 2021, the Company recognized $200 and $300, respectively, in revenue related to this transaction. As of September 30, 2021, $200 was due from the client. In December 2018, a Brand entered into a continuous arrangement with a third-party in which the third-party was to perform marketing services. Several of the Company’s Brand partners hold key leadership positions in this entity. Under the arrangement, the Brand is expected to pay the affiliate based upon the success of their services with no minimum or maximum spend. During the three and nine months ended September 30, 2021, the Company incurred $400 and $1,200, respectively, in expenses related to this transaction. As of September 30, 2021, $700 was due to the vendor. In October 2020, a Brand entered into a continuous arrangement to provide marketing services to a client in which one of the Brands's partners holds a key leadership position. During the three and nine months ended September 30, 2021, the Company recognized $500 and $5,100, respectively, in revenue related to this transaction. As of September 30, 2021, no receivables remained outstanding related to this arrangement. In June 2021, a Brand entered into a continuous arrangement to provide marketing services to a client in which one of Brand's partners has an ownership interest. During the three and nine months ended September 30, 2021, the Company recognized $1,300 and $2,700, respectively, in revenue related to this transaction. As of September 30, 2021, $2,200 was due from the client. In December 2018, a Brand entered into a continuous arrangement to provide marketing services to a client in which a family member of one of the Brand's partners holds an executive leadership position. During the three and nine months ended September 30, 2021, the Company recognized $100 and $200, respectively, in revenue related to this transaction. As of September 30, 2021, $200 was due from the client. In March 2019, a Brand of the Company, entered into a loan agreement with a third-party who holds a minority interest in the Brand. The loan receivable of $3,800 and $3,400 due from the third-party is included within Other current assets in the Company's Unaudited Condensed Consolidated Balance Sheets as of September 30, 2021 and December 31, 2020, respectively. The Company recognized $200 and $300 of interest income within interest expense, net on its Unaudited Condensed Consolidated Statements of Operations for the three and nine months ended September 30, 2021, respectively. The Stagwell Group LLC, the registered investment advisor of Stagwell Media, engaged certain of its Brands to provide services for the Stagwell Group for interagency customers. The Company recorded $100 and $1,200 of related party revenue for the three and nine months ended September 30, 2020, respectively, and nil and $200 of cost of service paid to the Stagwell Group for the three and nine months ended September 30, 2020, respectively, in connection with such services. The Company did not recognize any related party revenue or cost of services paid to the Stagwell Group for the three and nine months ended September 30, 2021. Stagwell Media made noncash investments in the Company of $300 and nil, during the three months ended September 30, 2021 and 2020, respectively, and $12,400 and $83,200, during the nine months ended September 30, 2021 and 2020, respectively. Additionally, during the three and nine months ended September 30, 2021, the Company made cash investments of $1,600 On March 11, 2021, Stagwell Media received a Noncash distribution of $13,000 for the transfer of the Company’s ownership in the Finn Partners Preferred shares. Additionally, the Company made cash distributions to Stagwell Media of $165,700 and $4,700 for the three months ended September 30, 2021 and 2020, respectively, and $191,900 and $98,600 for the nine months ended September 30, 2021 and 2020, respectively.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2021
Segment Reporting [Abstract]
Segment Information	Segment Information The Company determines an operating segment if a component (i) engages in business activities from which it earns revenues and incurs expenses, (ii) has discrete financial information, and is (iii) regularly reviewed by the Chief Operating Decision Maker (“CODM”), who is Mark Penn, Chief Executive Officer and Chairman, to make decisions regarding resource allocation for the segment and assess its performance. Once operating segments are identified, the Company performs an analysis to determine if aggregation of operating segments is applicable. This determination is based upon a quantitative analysis of the expected and historic average long-term profitability for each operating segment, together with a qualitative assessment to determine if operating segments have similar operating characteristics. The CODM uses Adjusted EBITDA (defined below) as a key metric, to evaluate the operating and financial performance of a segment, identify trends affecting the segments, develop projections and make strategic business decisions. Adjusted EBITDA is defined as Net income excluding non-operating income or expense to achieve operating income, plus depreciation and amortization, stock-based compensation, deferred acquisition consideration adjustments, and other items. Other items include restructuring costs, acquisition-related expenses, and non-recurring items. The Company has three reportable segments as follows: “Integrated Agencies Network,” “Media Network” and the “Communications Network.” In addition, the Company combines and discloses operating segments that do not meet the aggregation criteria as “All Other.” The Company also reports corporate expenses, as further detailed below, as “Corporate.” All segments follow the same basis of presentation and accounting policies as those described throughout the Notes to the Unaudited Condensed Consolidated Financial Statements included herein. • The Integrated Agencies Network reportable segment is comprised of Constellation (72andSunny, Crispin Porter Bogusky, Instrument, Team Enterprises, Harris, and Redscout brands), the Anomaly Alliance (Anomaly, Concentric, Hunter, Mono, YML and Scout brands), the Doner Partner Network (Doner, 6 Degrees, KWT Global, Union, Bruce Mau Design, Vitro, Harris X, Northstar, Veritas and Yamamoto brands) and the Code & Theory Network (Code & Theory, Forsman & Bodenfors, National Research Group, Observatory, Hello Design, and Colle McVoy brands) operating segments. The Integrated Agencies Networks provide a range of services for their clients, primarily including strategy, creative and production for advertising campaigns across a variety of platforms (digital, social media, television broadcast and print) as well as public relations and communications services, experiential, social media and influencer marketing. These operating segments share similar characteristics related to (i) the nature of their services; (ii) the type of clients and the methods used to provide services; and (iii) the extent to which they may be impacted by global economic and geopolitical risks. In addition, these operating segments compete with each other for new business and from time to time have business move between them. • The Media Network reportable segment is comprised of a single operating segment that combines media buying and planning across a range of platforms (out-of-home, paid search, social media, lead generation, programmatic, television broadcast) with technology and data capabilities and includes the Assembly, GALE, MMI Agency, Ink, Multiview, and Kenna brands. • The Communications Network reportable segment is comprised of a single operating segment that provides advocacy, corporate communications, public relations and other services and includes SKDK, Allison & Partners, and Targeted Victory brands. • All Other consists of the Company’s our central innovations group, Reputation Defender (sold in September 2021) and infancy stage digital products such as Prophet. • Corporate consists of corporate office expenses incurred in connection with the strategic resources provided to the operating segments, as well as certain other centrally managed expenses that are not fully allocated to the operating segments. These office and general expenses include (i) salaries and related expenses for corporate office employees, including employees dedicated to supporting the operating segments, (ii) occupancy expenses relating to properties occupied by all corporate office employees, (iii) other office and general expenses including professional fees for the financial statement audits and other public company costs, and (iv) certain other professional fees managed by the corporate office. Additional expenses managed by the corporate office that are directly related to the operating segments are allocated to the appropriate reportable segment and the All Other category. Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Revenue: (Dollars in Thousands) Integrated Agencies Network $ 288,479 $ 55,293 $ 441,229 $ 163,540 Media Network 103,418 60,777 235,539 185,714 Communications Network 67,348 106,909 157,794 210,100 All Other $ 7,389 $ 5,118 $ 22,874 $ 15,616 Total Revenue $ 466,634 $ 228,097 $ 857,436 $ 574,970 Adjusted EBITDA: Integrated Agencies Network $ 68,356 $ 11,270 $ 100,960 $ 28,913 Media Network 15,371 8,131 29,789 14,993 Communications Network 10,312 20,231 28,302 39,139 All Other 419 (193) (1,316) (749) Corporate (6,940) (2,316) (7,656) (3,325) Total Adjusted EBITDA $ 87,518 $ 37,123 $ 150,079 $ 78,971 Depreciation and amortization $ (24,790) $ (9,974) $ (46,122) $ (29,838) Impairment and other losses (14,926) — (14,926) — Stock-based compensation (53,465) — (53,465) — Deferred acquisition consideration (3,422) (149) (9,456) (1,270) Other items, net (10,549) (554) (15,298) (2,976) Total Operating Income (Loss) $ (19,634) $ 26,446 $ 10,812 $ 44,887 Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (Dollars in Thousands) Other Income (expenses): Interest expense, net $ (11,912) $ (1,778) $ (15,197) $ (4,665) Foreign exchange, net (893) (856) (1,955) 794 Gain on sale of business and other, net 45,621 263 46,806 948 Income before income taxes and equity in earnings of non-consolidated affiliates 13,182 24,075 40,466 41,964 Income tax expense 5,183 2,618 9,205 3,211 Income before equity in earnings of non-consolidated affiliates 7,999 21,457 31,261 38,753 Equity in losses (income) of non-consolidated affiliates (76) (35) (75) 7 Net income 7,923 21,422 31,186 38,760 Net income attributable to noncontrolling and redeemable noncontrolling interests (9,994) (3,614) (10,987) (4,636) Net income (loss) attributable to Stagwell Inc. common shareholders $ (2,071) $ 17,808 $ 20,199 $ 34,124 Depreciation and amortization: Integrated Agencies Network $ 14,396 $ 2,292 $ 19,816 $ 6,715 Media Network 6,597 4,903 17,041 14,751 Communications Network 2,110 1,455 5,087 4,210 All Other 493 815 2,013 2,696 Corporate 1,194 509 2,165 1,466 Total $ 24,790 $ 9,974 $ 46,122 $ 29,838 Stock-based compensation: Integrated Agencies Network $ 32,443 $ — $ 32,443 $ — Media Network 2,608 — 2,608 — Communications Network 15,384 — 15,384 — All Other 16 — 16 — Corporate 3,014 — 3,014 — Total $ 53,465 $ — $ 53,465 $ — The Company’s CODM does not use segment assets to allocate resources or to assess performance of the segments and therefore, total segment assets have not been disclosed. See Note 5 of the Notes included herein for a summary of the Company’s revenue by geographic region for the three and nine months ended September 30, 2021 and 2020.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation . The accompanying consolidated financial statements include the accounts of Stagwell Inc. and its domestic and international controlled subsidiaries that are not considered variable interest entities, and variable interest entities for which the Company is the primary beneficiary. Intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates.  The preparation of the consolidated financial statements in conformity with GAAP requires management to make judgments, estimates and assumptions. These estimates and assumptions affect the reported amounts of assets and liabilities including goodwill, intangible assets, contingent deferred acquisition consideration, redeemable noncontrolling interests, deferred tax assets, right-of-use assets and the amounts of revenue and expenses reported during the period. These estimates are evaluated on an ongoing basis and are based on historical experience, current conditions and various other assumptions believed to be reasonable under the circumstances. These estimates require the use of assumptions about future performance, which are uncertain at the time of estimation. To the extent actual results differ from the assumptions used, results of operations and cash flows could be materially affected.
Fair Value	Fair Value . The Company applies the fair value measurement guidance for financial assets and liabilities that are required to be measured at fair value and for non-financial assets and liabilities that are not required to be measured at fair value on a recurring basis, including goodwill, right-of-use assets and other identifiable intangible assets. See Note 13 included herein for additional information regarding fair value measurements.
Concentration of Credit Risk	Concentration of Credit Risk.  The Company provides marketing communications services to clients who operate in most industry sectors. Credit is granted to qualified clients in the ordinary course of business. Due to the diversified nature of the Company’s client base, the Company does not believe that it is exposed to a concentration of credit risk. No client accounted for more than 10% of the Company’s consolidated accounts receivable as of September 30, 2021 or December 31, 2020. No sales to an individual client accounted for more than 10% of revenue for the three and nine months ended September 30, 2021 and 2020.
Cash and Cash Equivalents	Cash and Cash Equivalents . The Company’s cash equivalents are primarily comprised of investments in overnight interest-bearing deposits, money market instruments and other short-term investments with original maturity dates of three months or less at the time of purchase. The Company has a concentration of credit risk in that there are cash deposits in excess of federally insured amounts and international cash balances may not qualify for foreign government insurance programs. To date, the Company has not experienced any losses on cash and cash equivalents.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts . Trade receivables are stated at invoiced amounts less allowances for doubtful accounts. The allowances represent estimated uncollectible receivables associated with potential customer defaults usually due to customers’ potential insolvency. The allowances include amounts for certain customers where a risk of default has been specifically identified. The assessment of the likelihood of customer defaults is based on various factors, including the length of time the receivables are past due, historical experience and existing economic conditions. Allowance for doubtful accounts was $5,294 and $5,109 at September 30, 2021 and December 31, 2020, respectively.
Expenditures Billable To Clients	Expenditures Billable to Clients . Expenditures billable to clients consist principally of outside vendor costs incurred on behalf of clients when providing services that have not yet been invoiced to clients. Such amounts are invoiced to clients at various times over the course of the period.
Fixed Assets	Fixed Assets . Fixed assets are stated at cost, net of accumulated depreciation. Computers, furniture and fixtures, and capitalized software are depreciated on a straight-line basis over periods of three
Leases	Leases . Effective January 1, 2019, the Company adopted Accounting Standards Codification, Leases (“ASC 842”). The Company recognizes on the balance sheet at the time of lease commencement a right-of-use lease asset and a lease liability, initially measured at the present value of the lease payments. All right-of-use lease assets are reviewed for impairment. With the adoption of ASC 842, the Company elected to apply the package of practical expedients: (i) whether a contract is or contains a lease, (ii) the classification of existing leases, and (iii) whether previously capitalized costs continue to qualify as initial indirect costs. Additionally, the Company elected the practical expedient to not separate non-lease components from lease components for all operating leases. See Note 8 included herein for further information on leases.
Impairment of Long-lived Assets	Impairment of Long-lived Assets.  A long-lived asset or asset group is tested for recoverability whenever events or changes in circumstances indicate that its carrying amount may not be recoverable. When such events occur, the Company compares the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset or asset group to the carrying amount of such asset or asset group. If this comparison indicates that there is an impairment, the amount of the impairment is typically calculated using discounted expected future cash flows where observable fair values are not readily determinable. The discount rate applied to these cash flows is based on the Company’s weighted average cost of capital (“WACC”), risk adjusted where appropriate, or other appropriate discount rate.
Goodwill	Goodwill . Goodwill (the excess of the acquisition cost over the fair value of the net assets acquired) acquired as a result of a business combination which is not subject to amortization is tested for impairment, at the reporting unit level, annually as of October 1st of each year, or more frequently if indicators of potential impairment exist. For the annual impairment test, the Company has the option of assessing qualitative factors to determine whether it is more likely than not that the carrying amount of a reporting unit exceeds its fair value or performing a quantitative goodwill impairment test. Qualitative factors considered in the assessment include industry and market considerations, the competitive environment, overall financial performance, changing cost factors such as labor costs, and other factors specific to each reporting unit such as change in management or key personnel. If the Company elects to perform the qualitative assessment and concludes that it is more likely than not that the fair value of the reporting unit is more than its carrying amount, then goodwill is not considered impaired and the quantitative impairment test is not necessary. For reporting units for which the qualitative assessment concludes that it is more likely than not that the fair value of the reporting unit is less than its carrying amount and for reporting units for which the qualitative assessment is not performed, the Company will perform the quantitative impairment test, which compares the fair value of the reporting unit to its carrying amount. If the fair value of the reporting unit exceeds the carrying amount of the net assets assigned to that reporting unit, goodwill is not considered impaired. However, if the fair value of the reporting unit is lower than the carrying amount of the net assets assigned to the reporting unit, an impairment charge is recognized equal to the excess of the carrying amount over the fair value. Determining the fair value of a reporting unit involves the use of significant estimates and assumptions. The Company uses a combination of the income approach, which incorporates the use of the discounted cash flow (“DCF”) method, and the market approach, which incorporates the use of earnings and revenue multiples based on market data. The Company generally applies an equal weighting to the income and market approaches for the impairment test. The income approach and the market approach both require the exercise of significant judgment, including judgment about the amount and timing of expected future cash flows, assumed terminal value and appropriate discount rates.
Definite Lived Intangible Assets	Definite Lived Intangible Assets.  Definite lived intangible assets are subject to amortization over their useful lives. A straight-line amortization method is used over the estimated useful life which is representative of the pattern of how the economic benefits of the specific intangible asset is consumed. Intangible assets that are subject to amortization are reviewed for potential impairment at least annually or whenever events or circumstances indicate that carrying amounts may not be recoverable. The Company uses an income approach, which incorporates the use of the discounted cash flow (“DCF”) method.
Business Combinations	Business Combinations. Business combinations are accounted for using the acquisition method and accordingly, the assets acquired (including identified intangible assets), the liabilities assumed and any noncontrolling interest in the acquired business are recorded at their acquisition date fair values. For each acquisition, the Company undertakes a detailed review to identify other intangible assets and a valuation is performed for all such identified assets. The Company uses several market participant measurements to determine the estimated value. This approach includes consideration of similar and recent transactions, as well as utilizing discounted expected cash flow methodologies. A substantial portion of the intangible assets value that the Company acquires is the specialized know-how of the workforce, which is treated as part of goodwill and is not required to be valued separately. The majority of the value of the identifiable intangible assets acquired is derived from customer relationships, including the related customer contracts, as well as tradenames and trademarks.
Deferred Acquisition Consideration	Deferred Acquisition Consideration . Certain acquisitions include an initial payment at the time of closing and provide for future additional contingent purchase price payments. Contingent purchase price obligations for these transactions are recorded
Redeemable Noncontrolling Interest	Redeemable Noncontrolling Interests. Many of the Company’s acquisitions include contractual arrangements where the noncontrolling shareholders have an option to purchase, or may require the Company to purchase, such noncontrolling shareholders’ incremental ownership interests under certain circumstances. The Company typically has similar call options under the same contractual terms. The amount of consideration under these contractual arrangements is not a fixed amount, but rather is dependent upon various valuation formulas, such as the average earnings of the relevant subsidiary through the date of exercise or the growth rate of the earnings of the relevant subsidiary during that period. In the event that an incremental purchase may be required by the Company, the amounts are recorded as redeemable noncontrolling interests in mezzanine equity on the Unaudited Condensed Consolidated Balance Sheets at their acquisition date fair value and adjusted for changes to their estimated redemption value through Retained earnings or Paid-in capital (when at an accumulated deficit) in the Unaudited Condensed Consolidated Balance Sheets (but not less than their initial redemption value), except for foreign currency translation adjustments. These adjustments will not impact the calculation of earnings (loss) per share if the redemption values are less than the estimated fair values.
Subsidiary and Equity Investment Stock Transactions	Subsidiary and Equity Investment Stock Transactions. Transactions involving the purchase, sale or issuance of interests of a subsidiary where control is maintained are recorded as a reduction in the redeemable noncontrolling interests or noncontrolling interests, as applicable. Any difference between the purchase price and noncontrolling interest is recorded to Common stock and other paid-in capital in the Unaudited Condensed Consolidated Balance Sheets. In circumstances where the purchase of shares of an equity investment results in obtaining control, the existing carrying value of the investment is remeasured to the acquisition date fair value and any gain or loss is recognized in the results of operations.
Revenue Recognition	Revenue Recognition . The Company’s revenue is recognized when control of the promised services are transferred to our clients, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. See Note 5 included herein for additional information.
Cost of Services Sold	Cost of Services . Cost of services sold primarily consists of staff costs that are directly attributable to the Company’s client engagements, as well as third-party direct costs of production and delivery of services to its clients. Cost of services sold does not include depreciation, amortization, and other office and general expenses that are not directly attributable to the Company’s client engagements.
Interest Expense	.  The Company uses the effective interest method to amortize deferred financing costs and any original issue premium or discount, if applicable. The Company also uses the straight-line method, which approximates the effective interest method, to amortize the deferred financing costs on the Credit Agreement.
Income Taxes	Income Taxes. We account for income taxes using the asset and liability method. Under the asset and liability method, deferred tax assets and liabilities are recognized based on the differences between the financial statement carrying value of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates and laws expected to be in effect when the differences are expected to reverse. The Company records associated interest and penalties as a component of income tax expense. The Company records a valuation allowance against deferred income tax assets when management believes it is more likely than not that some portion or all of the deferred income tax assets will not be realized. Management evaluates on a quarterly basis all available positive and negative evidence considering factors such as the reversal of deferred income tax liabilities, taxable income in eligible carryback years, projected future taxable income, the character of the income tax asset, tax planning strategies, changes in tax laws and other factors. The periodic assessment of the net carrying value of the Company’s deferred tax assets under the applicable accounting rules requires significant management judgment. A change to any of these factors could impact the estimated valuation allowance and income tax expense.
Share-based Compensation	Stock-Based Compensation . Under the fair value method, compensation cost is measured at fair value at the date of grant and is expensed over the service period, generally the award’s vesting period. The Company uses its historical volatility derived over the expected term of the award to determine the volatility factor used in determining the fair value of the award. The Company recognizes forfeitures as they occur. Stock-based awards that are settled in cash or equity at the option of the Company are recorded at fair value on the date of grant. The fair value measurement of the compensation cost for these awards is based on using the Black-Scholes option
Income (Loss) per Common Share	Income (Loss) per Common Share . Basic income (loss) per common share is based upon the weighted average number of common shares outstanding during each period. Diluted income (loss) per common share is based on the above, in addition, if dilutive, common share equivalents, which include outstanding options, stock appreciation rights, and unvested restricted stock units. In periods of net loss, all potentially issuable common shares are excluded from diluted net loss per common share because they are anti-dilutive.
Foreign Currency Translation	Foreign Currency Translation . The functional and reporting currency of the Company is the US dollar. Generally, the Company’s subsidiaries use their local currency as their functional currency. Accordingly, the currency impacts of the translation of the Unaudited Condensed Consolidated Balance Sheets of the Company and its non-U.S. dollar based subsidiaries to U.S. dollar statements are included as cumulative translation adjustments in Accumulated other comprehensive income (loss). Translation of intercompany debt, which is not intended to be repaid, is included in cumulative translation adjustments. Cumulative translation adjustments are not included in net income (loss) unless they are actually realized through a sale or upon complete, or substantially complete, liquidation of the Company’s net investment in the foreign operation. Translation of current intercompany balances are included in net income (loss). The balance sheets of non-U.S. dollar based subsidiaries are translated at the period end rate. The Unaudited Condensed Consolidated Statements of Operations of the Company and its non-U.S. dollar based subsidiaries are translated at average exchange rates for the period. Gains and losses arising from the Company’s foreign currency transactions are reflected in Foreign exchange, net on the Consolidated Statements of Operations.
New Accounting Pronouncements	In October 2021, the FASB issued ASU 2021-08, Accounting for Contract Assets and Contract Liabilities from Contracts with Customers, to improve the accounting for acquired revenue contracts with customers in a business combination by addressing diversity in practice and inconsistency related to the recognition of an acquired contract liability and other items. ASU 2021-08 is effective January 1, 2023; however, the Company has early adopted the standard and retrospectively applied it to the financial statements herein. In March 2020, the FASB issued ASU 2020-04, and in January subsequently issued ASU 2021-01, Facilitation of the Effects of Reference Rate Reform on Financial Reporting, to provide optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. ASU 2020-04 is effective upon issuance, through December 31, 2022. The Company is evaluating the impact of the adoption of this guidance on the Company's financial statements and disclosures.

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables)	9 Months Ended
	Sep. 30, 2021
Business Combinations [Abstract]
Schedule of Business Acquisitions, by Acquisition	The preliminary purchase price allocation is as follows: Amount Cash and cash equivalents $ 130,155 Accounts receivable 419,742 Other current assets 44,508 Fixed Assets 80,047 Right-of-use lease assets - operating leases 293,034 Intangible assets 809,900 Other assets 16,928 Accounts payable (165,443) Accruals and other liabilities (308,757) Advance billings (211,687) Current portion of lease liabilities (55,878) Current portion of deferred acquisition consideration (53,054) Long-term debt (1,011,690) Long-term portion of deferred acquisition consideration (8,056) Long-term portion of lease liabilities (292,497) Other liabilities (131,897) Redeemable noncontrolling interests (30,830) Preferred shares (209,980) Noncontrolling interests (158,230) Net liabilities assumed (843,685) Goodwill 1,270,081 Purchase price consideration $ 426,396 The following table summarizes the estimated fair values of the assets acquired and liabilities assumed as of the date of each acquisition (in thousands): 2020 Sloane Kettle Truelogic Total Cash, cash equivalents and restricted cash $ — $ 49 $ 90 $ 139 Accounts receivable and other current assets 2,768 2,732 2,958 8,458 Other noncurrent assets — 172 10 182 Intangible assets 5,900 1,930 9,500 17,330 Property and equipment 72 58 50 180 Right-of-use assets – operating leases — 533 201 734 Accounts payable and other current liabilities (469) (552) (1,063) (2,084) Advanced billings (130) (310) (429) (869) Operating lease liabilities — (533) (201) (734) Goodwill 16,275 1,323 6,184 23,782 Total net assets acquired $ 24,416 $ 5,402 $ 17,300 $ 47,118
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination	The following table presents the details of identifiable intangible assets acquired. Estimated Fair Value Estimated Useful Life in Years Trade Names $ 98,000 10 Customer Relationships 711,900 6-15 Total Acquired Intangible Assets $ 809,900 The following table reports the fair value of intangible assets acquired, including the corresponding weighted average amortization periods, as of the date of each acquisition (in thousands, except years): 2020 Weighted Average Amortization Period Sloane Kettle Truelogic Total Customer relationships 10 years $ 4,600 $ 1,600 $ 9,100 $ 15,300 Tradenames and trademarks 11 years 1,300 330 400 2,030 Total $ 5,900 $ 1,930 $ 9,500 $ 17,330
Business Acquisition, Pro Forma Information	The pro forma information is presented for informational purposes only and is not necessarily indicative of the results of operations that actually would have been achieved had the acquisitions been consummated as of that time. Nine Months Ended September 30, 2021 Nine Months Ended September 30, 2020 Revenue $ 1,612,399 $ 1,445,813 The proforma net loss was nominal for the nine months ended September 30, 2021 and 2020. The following table summarizes the total revenue and net income included in the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) from the date of each acquisition (in thousands): Nine Months Ended September 30, 2020 Revenue $ 10,794 Net Income $ 1,199 Nine Months Ended September 30, 2020 Revenue $ 587,343 Net Income $ 39,801

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2021
By Location
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue	The following table presents revenue disaggregated by geography for the three and nine months ended September 30, 2021 and 2020: Three Months Ended September 30, Nine Months Ended September 30, Geographical Location Reportable Segment 2021 2020 2021 2020 United States All $ 387,662 $ 208,045 $ 733,038 $ 515,403 United Kingdom All 32,218 4,904 62,416 18,658 Other All 46,754 15,148 61,982 40,909 $ 466,634 $ 228,097 $ 857,436 $ 574,970
Industry Vertical
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue	The following table presents revenue disaggregated by lines of business for the three and nine months ended September 30, 2021 and 2020: Three Months Ended September 30, Nine Months Ended September 30, Lines of Business Reportable Segment 2021 2020 2021 2020 Public Relations Integrated Agencies Network, Communications Network, Other $ 67,497 $ 43,497 $ 118,380 $ 97,217 Creative Integrated Agencies Network 125,637 1,927 127,791 6,792 Digital All Segments 191,643 153,284 445,485 370,711 Experiential Integrated Agencies Network 14,413 — 14,413 — Media Media Network 10,819 — 10,819 — Research Integrated Agencies Network 46,363 24,863 117,467 78,242 Other Media Network, Integrated Agencies Network, Other 10,262 4,526 23,081 22,008 $ 466,634 $ 228,097 $ 857,436 $ 574,970

Income (Loss) Per Common Share

Income (Loss) Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Schedule of Calculation of Numerator and Denominator in Earnings Per Share	The following table sets forth the computations of basic and diluted income (loss) per common share: Three Months Ended September 30, Nine Months Ended September 30, 2021 2021 Numerator: Net loss attributable to Stagwell Inc. common shareholders $ (4,545) $ (4,545) Denominator: Weighted average number of common shares outstanding 76,105,807 76,105,807 Earnings Per Share - Basic & Diluted $ (0.06) $ (0.06) Anti-dilutive: Class C shares 179,970,051 179,970,051 Stock Appreciation Rights and Restricted Awards 6,596,023 6,596,023 There were 123,849,000 Preferred Shares outstanding which were convertible into 33,035,446 of Class A common shares at September 30, 2021. These Preferred Shares were anti-dilutive for each period presented in the table above and are therefore excluded from the diluted earnings per share calculation. The combination of MDC and SMG was completed on August 2, 2021, which was treated as a reverse acquisition for financial reporting purposes. SMG was treated as the accounting acquirer and MDC was the accounting acquiree. Therefore, under applicable accounting principles, the historical financial results of SMG prior to August 2, 2021 are considered our historical financial results. Accordingly, historical information presented in this Form 10-Q for events occurring or periods ending before August 2, 2021 does not reflect the impact of the Transactions or the financial results of MDC and may not be comparable with historical information for events occurring or periods ending on or after August 2, 2021. SMG’s equity structure, prior to the combination with MDC, was a non-unitized single member limited liability company, resulting in all components of equity attributable to the member being reported within Members' Capital. Given that SMG was a non-unitized single member limited liability company, net income (loss) prior to the combination is not applicable for purposes of calculating earnings per share. Therefore, the net income (loss) in the table above includes the income or loss for the period beginning on the acquisition date through the end of the respective reporting period and as such will not reconcile to the respective amounts presented within the Unaudited Condensed Consolidated Statements of Operations.

Deferred Acquisition Consider_2

Deferred Acquisition Consideration (Tables)	9 Months Ended
	Sep. 30, 2021
Business Combinations [Abstract]
Schedule of Changes in Contingent Deferred Acquisition Consideration	The following table presents changes in contingent deferred acquisition consideration, which is measured at fair value on a recurring basis using significant unobservable inputs, and a reconciliation to the amounts reported on the balance sheets as of September 30, 2021 and December 31, 2020: September 30, December 31, 2021 2020 Beginning Balance of Contingent Payments $ 17,847 $ 65,792 Payments (12,286) (66,235) Redemption value adjustments (1) 9,535 2,520 Additions (2) 61,110 15,717 Other (501) 53 Ending balance of contingent payments $ 75,705 $ 17,847 (1) Redemption value adjustments are fair value changes from the Company’s initial estimates of deferred acquisition payments. Redemption value adjustments are recorded within Office and general expenses on the Unaudited Condensed Consolidated Statements of Operations. (2) Additions in 2021 represent deferred acquisition consideration acquired in connection with the acquisition of MDC.

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Lease Costs and Other Quantitative Information	The following table presents lease costs and other quantitative information for the three and nine months ended September 30, 2021 and 2020: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Lease Cost: Operating lease cost $ 13,502 $ 5,900 $ 27,779 $ 19,279 Variable lease cost 3,230 928 5,167 2,959 Sublease rental income (2,359) (938) (4,290) (2,818) Total lease cost $ 14,373 $ 5,890 $ 28,656 $ 19,420 Additional information: Cash paid for amounts included in the measurement of lease liabilities for operating leases Operating cash flows $ 16,490 $ 5,260 $ 29,854 $ 15,580 Right-of-use lease assets obtained in exchange for operating lease liabilities and other non-cash adjustments $ 353,984 $ 128 $ 353,984 $ 1,961 Weighted average remaining lease term (in years) - Operating leases 6.8 4.6 6.8 4.6 Weighted average discount rate - Operating leases 4.0 % 4.1 % 4.0 % 4.1 %
Minimum Future Rental Payments	The following table presents minimum future rental payments under the Company’s leases at September 30, 2021 and their reconciliation to the corresponding lease liabilities: Maturity Analysis Remaining 2021 $ 23,452 2022 84,730 2023 80,281 2024 65,242 2025 50,076 2026 and thereafter 161,462 Total 465,243 Less: Present value discount (63,033) Lease liability $ 402,210

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Schedule of Debt	As of September 30, 2021 and December 31, 2020, the Company’s indebtedness was comprised as follows: September 30, 2021 December 31, 2020 Revolving credit facility $ 181,112 $ 201,636 Term debt — 994 5.625% Notes 1,100,000 — Debt issuance costs (15,365) (3,612) Total debt $ 1,265,747 $ 199,018 Less: Current maturities of long-term debt $ — $ (994) Long-term debt $ 1,265,747 $ 198,024

Noncontrolling and Redeemable_2

Noncontrolling and Redeemable Noncontrolling Interests (Tables)	9 Months Ended
	Sep. 30, 2021
Noncontrolling Interest [Abstract]
Noncontrolling Interest [Table Text Block]	Changes in the Company’s ownership interests in our less than 100% owned subsidiaries during the three and nine months ended September 30, 2021 and 2020 were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Net income (loss) attributable to Stagwell Inc. common shareholders $ (2,071) $ 17,808 $ 20,199 $ 34,124 Transfers from the noncontrolling interest: Increase in Stagwell Inc. paid-in capital for purchase of redeemable noncontrolling interests and noncontrolling interests 9,679 — 9,679 — Net transfers from noncontrolling interests 9,679 — 9,679 — Change from net income (loss) attributable to Stagwell Inc. and transfers to noncontrolling interests $ 7,608 $ 17,808 $ 29,878 $ 34,124
Redeemable Noncontrolling Interest [Table Text Block]	The following table presents changes in redeemable noncontrolling interests: September 30, December 31, 2021 2020 Beginning Balance $ 604 $ 3,603 Redemptions (2,831) — Acquisitions (1) 30,830 — Changes in redemption value 1,680 127 Net loss attributable to redeemable noncontrolling interests (956) (3,126) Other 460 — Ending Balance $ 29,787 $ 604 (1) Represents redeemable noncontrolling interests acquired in connection with the acquisition of MDC.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value of Financial Liability Measured on a Non-recurring Basis	The following table presents certain information for our financial liability that is not measured at fair value on a recurring basis at September 30, 2021 and December 31, 2020: September 30, 2021 December 31, 2020 Carrying Fair Value Carrying Fair Value 5.625% Notes 1,100,000 1,133,891 — —
Fair Value Measurements, Recurring and Nonrecurring	The following table presents certain information for our financial instruments that are measured at fair value on a recurring basis at September 30, 2021 and December 31, 2020: September 30, 2021 December 31, 2020 Carrying Fair Value Carrying Fair Value Interest Rate Swap $ 155 $ 155 $ 416 $ 416 Call Options — — 360 360 Preferred Shares — — 12,033 12,033

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2021
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Revenue: (Dollars in Thousands) Integrated Agencies Network $ 288,479 $ 55,293 $ 441,229 $ 163,540 Media Network 103,418 60,777 235,539 185,714 Communications Network 67,348 106,909 157,794 210,100 All Other $ 7,389 $ 5,118 $ 22,874 $ 15,616 Total Revenue $ 466,634 $ 228,097 $ 857,436 $ 574,970 Adjusted EBITDA: Integrated Agencies Network $ 68,356 $ 11,270 $ 100,960 $ 28,913 Media Network 15,371 8,131 29,789 14,993 Communications Network 10,312 20,231 28,302 39,139 All Other 419 (193) (1,316) (749) Corporate (6,940) (2,316) (7,656) (3,325) Total Adjusted EBITDA $ 87,518 $ 37,123 $ 150,079 $ 78,971 Depreciation and amortization $ (24,790) $ (9,974) $ (46,122) $ (29,838) Impairment and other losses (14,926) — (14,926) — Stock-based compensation (53,465) — (53,465) — Deferred acquisition consideration (3,422) (149) (9,456) (1,270) Other items, net (10,549) (554) (15,298) (2,976) Total Operating Income (Loss) $ (19,634) $ 26,446 $ 10,812 $ 44,887 Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (Dollars in Thousands) Other Income (expenses): Interest expense, net $ (11,912) $ (1,778) $ (15,197) $ (4,665) Foreign exchange, net (893) (856) (1,955) 794 Gain on sale of business and other, net 45,621 263 46,806 948 Income before income taxes and equity in earnings of non-consolidated affiliates 13,182 24,075 40,466 41,964 Income tax expense 5,183 2,618 9,205 3,211 Income before equity in earnings of non-consolidated affiliates 7,999 21,457 31,261 38,753 Equity in losses (income) of non-consolidated affiliates (76) (35) (75) 7 Net income 7,923 21,422 31,186 38,760 Net income attributable to noncontrolling and redeemable noncontrolling interests (9,994) (3,614) (10,987) (4,636) Net income (loss) attributable to Stagwell Inc. common shareholders $ (2,071) $ 17,808 $ 20,199 $ 34,124 Depreciation and amortization: Integrated Agencies Network $ 14,396 $ 2,292 $ 19,816 $ 6,715 Media Network 6,597 4,903 17,041 14,751 Communications Network 2,110 1,455 5,087 4,210 All Other 493 815 2,013 2,696 Corporate 1,194 509 2,165 1,466 Total $ 24,790 $ 9,974 $ 46,122 $ 29,838 Stock-based compensation: Integrated Agencies Network $ 32,443 $ — $ 32,443 $ — Media Network 2,608 — 2,608 — Communications Network 15,384 — 15,384 — All Other 16 — 16 — Corporate 3,014 — 3,014 — Total $ 53,465 $ — $ 53,465 $ —

Basis of Presentation and Rec_2

Basis of Presentation and Recent Developments (Details) $ in Thousands	Oct. 01, 2021USD ($)	Sep. 30, 2021USD ($)reportable_segment	Dec. 31, 2020USD ($)
Debt [Line Items]
Total debt		$ 1,265,747	$ 199,018
Number of reportable segments | reportable_segment		3
Subsequent Event [Member] | Targeted Victory
Debt [Line Items]
Remaining ownership interest acquired (percent)	26.70%
Maximum common stock purchase consideration, percentage	50.00%
Subsequent Event [Member] | Maximum | Targeted Victory
Debt [Line Items]
Aggregate purchase price	$ 135,000

Significant Accounting Polici_3

Significant Accounting Policies (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Allowance for doubtful accounts	$ 5,294	$ 5,109
Significant Accounting Policies [Line Items]
Fixed assets, accumulated depreciation	$ 39,357	$ 28,365
Minimum
Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	3 years
Maximum
Significant Accounting Policies [Line Items]
Property, plant and equipment, useful life	10 years

Acquisitions and Dispositions -

Acquisitions and Dispositions - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 02, 2021	Oct. 30, 2020	Aug. 14, 2020	Feb. 14, 2020	Sep. 30, 2021	Jun. 30, 2020	Sep. 30, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Net Income						$ 39,801
Goodwill					$ 1,619,272		$ 1,619,272	$ 351,725
Revenue						$ 10,794
Stagwell Media
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash	$ 1,800
MDC
Business Acquisition [Line Items]
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	$ 80,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	13 years
Goodwill	$ 1,270,081
Business Acquisition, Share Price	$ 5.42
Revenue					$ 241,257
Transaction expenses							$ 15,000
MDC | Common Class C | Stagwell Media
Business Acquisition [Line Items]
Stock Issued During Period, Shares, Acquisitions	179,970,051
MDC | Common Units | Stagwell OpCo
Business Acquisition [Line Items]
Remaining ownership interest acquired (percent)	69.55%
MDC | Integrated Agencies Network
Business Acquisition [Line Items]
Goodwill	$ 1,041,277
MDC | Media Network
Business Acquisition [Line Items]
Goodwill	166,658
MDC | Communications Network
Business Acquisition [Line Items]
Goodwill	$ 62,146
MDC | Trade Names
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years
Sloane and Company LLC
Business Acquisition [Line Items]
Aggregate purchase price				$ 24,400
Closing cash payment				700
Goodwill				16,275
Business Combination, Consideration Transferred, Liabilities Incurred				4,800
Sloane and Company LLC | Stagwell Media
Business Acquisition [Line Items]
Closing cash payment				$ 18,900
Kettle
Business Acquisition [Line Items]
Aggregate purchase price			$ 5,400
Closing cash payment			4,900
Deferred acquisition consideration			11,900
Goodwill			1,323
Business Combination, Consideration Transferred, Liabilities Incurred			$ 500
Truelogic
Business Acquisition [Line Items]
Aggregate purchase price		$ 17,300
Closing cash payment		8,900
Deferred acquisition consideration		500
Goodwill		6,184
Business Combination, Consideration Transferred, Liabilities Incurred		$ 7,900

Acquisitions and Dispositions_2

Acquisitions and Dispositions - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Aug. 02, 2021	Dec. 31, 2020	Oct. 30, 2020	Aug. 14, 2020	Feb. 14, 2020
Business Acquisition [Line Items]
Goodwill	$ 1,619,272		$ 351,725
2020 Acquisitions
Business Acquisition [Line Items]
Fixed Assets			180
Right-of-use lease assets - operating leases			734
Intangible assets			17,330
Other assets			182
Advance billings			(869)
Long-term portion of lease liabilities			(734)
Goodwill			23,782
Purchase price consideration			47,118
Cash, cash equivalents and restricted cash			139
Accounts receivable and other current assets			8,458
Accounts payable and other current liabilities			$ (2,084)
MDC
Business Acquisition [Line Items]
Cash and cash equivalents		$ 130,155
Accounts receivable		419,742
Other current assets		44,508
Fixed Assets		80,047
Right-of-use lease assets - operating leases		293,034
Intangible assets		809,900
Other assets		16,928
Accounts payable		(165,443)
Accruals and other liabilities		(308,757)
Advance billings		(211,687)
Current portion of lease liabilities		(55,878)
Current portion of deferred acquisition consideration		(53,054)
Long-term debt		(1,011,690)
Long-term portion of deferred acquisition consideration		(8,056)
Long-term portion of lease liabilities		(292,497)
Other liabilities		(131,897)
Redeemable noncontrolling interests		(30,830)
Preferred shares		(209,980)
Noncontrolling interests		(158,230)
Net liabilities assumed		(843,685)
Goodwill		1,270,081
Purchase price consideration		$ 426,396
Sloane and Company LLC
Business Acquisition [Line Items]
Fixed Assets						$ 72
Right-of-use lease assets - operating leases						0
Intangible assets						5,900
Other assets						0
Advance billings						(130)
Long-term portion of lease liabilities						0
Goodwill						16,275
Purchase price consideration						24,416
Cash, cash equivalents and restricted cash						0
Accounts receivable and other current assets						2,768
Accounts payable and other current liabilities						$ (469)
Kettle
Business Acquisition [Line Items]
Fixed Assets					$ 58
Right-of-use lease assets - operating leases					533
Intangible assets					1,930
Other assets					172
Advance billings					(310)
Long-term portion of lease liabilities					(533)
Goodwill					1,323
Purchase price consideration					5,402
Cash, cash equivalents and restricted cash					49
Accounts receivable and other current assets					2,732
Accounts payable and other current liabilities					$ (552)
Truelogic
Business Acquisition [Line Items]
Fixed Assets				$ 50
Right-of-use lease assets - operating leases				201
Intangible assets				9,500
Other assets				10
Advance billings				(429)
Long-term portion of lease liabilities				(201)
Goodwill				6,184
Purchase price consideration				17,300
Cash, cash equivalents and restricted cash				90
Accounts receivable and other current assets				2,958
Accounts payable and other current liabilities				$ (1,063)

Acquisitions and Dispositions_3

Acquisitions and Dispositions - Intangible Assets Acquired (Details) - USD ($) $ in Thousands	Aug. 02, 2021	Dec. 31, 2020	Oct. 30, 2020	Aug. 14, 2020	Feb. 14, 2020
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 809,900	$ 17,330
Trade Names
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	98,000
Customer Relationships
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	$ 711,900	$ 15,300
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		10 years
Trademarks and Trade Names
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles		$ 2,030
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		11 years
MDC
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	13 years
MDC | Trade Names
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years
MDC | Customer Relationships | Minimum
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years
MDC | Customer Relationships | Maximum
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	15 years
Sloane and Company LLC
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					$ 5,900
Sloane and Company LLC | Customer Relationships
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					4,600
Sloane and Company LLC | Trademarks and Trade Names
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					$ 1,300
Kettle
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles				$ 1,930
Kettle | Customer Relationships
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles				1,600
Kettle | Trademarks and Trade Names
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles				$ 330
Truelogic
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			$ 9,500
Truelogic | Customer Relationships
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			9,100
Truelogic | Trademarks and Trade Names
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles			$ 400

Acquisitions and Dispositions_4

Acquisitions and Dispositions - Pro Forma (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2020	Sep. 30, 2021	Dec. 31, 2020
Business Combinations [Abstract]
Revenue	$ 587,343	$ 1,612,399	$ 1,445,813
Net Income	39,801
Revenue	10,794
Net Income	$ 1,199

Acquisitions and Dispositions_5

Acquisitions and Dispositions - Purchase Price (Details) - USD ($) $ in Thousands	Oct. 30, 2020	Aug. 14, 2020	Feb. 14, 2020
Sloane and Company LLC
Business Acquisition [Line Items]
Aggregate purchase price			$ 24,400
Kettle
Business Acquisition [Line Items]
Aggregate purchase price		$ 5,400
Truelogic
Business Acquisition [Line Items]
Aggregate purchase price	$ 17,300

Acquisitions and Dispositions_6

Acquisitions and Dispositions - Disposition (Details) - Reputation Defender - Disposed of by Sale $ in Thousands	Sep. 15, 2021USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received	$ 40,000
Other, net
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposition of business	$ 43,000

Revenue - Additional Informatio

Revenue - Additional Information (Details)	9 Months Ended
	Sep. 30, 2021country
Non-US And Canada [Member]
Disaggregation of Revenue [Line Items]
Number of countries in which entity operates	18
Minimum
Disaggregation of Revenue [Line Items]
Payment period	30 days
Termination period	30 days
Maximum
Disaggregation of Revenue [Line Items]
Payment period	60 days
Termination period	90 days

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 466,634	$ 228,097	$ 857,436	$ 574,970
United States
Disaggregation of Revenue [Line Items]
Revenue	387,662	208,045	733,038	515,403
United Kingdom
Disaggregation of Revenue [Line Items]
Revenue	32,218	4,904	62,416	18,658
Other
Disaggregation of Revenue [Line Items]
Revenue	46,754	15,148	61,982	40,909
Public Relations
Disaggregation of Revenue [Line Items]
Revenue	67,497	43,497	118,380	97,217
Creative
Disaggregation of Revenue [Line Items]
Revenue	125,637	1,927	127,791	6,792
Digital
Disaggregation of Revenue [Line Items]
Revenue	191,643	153,284	445,485	370,711
Experiential
Disaggregation of Revenue [Line Items]
Revenue	14,413	0	14,413	0
Media
Disaggregation of Revenue [Line Items]
Revenue	10,819	0	10,819	0
Research
Disaggregation of Revenue [Line Items]
Revenue	46,363	24,863	117,467	78,242
Other
Disaggregation of Revenue [Line Items]
Revenue	$ 10,262	$ 4,526	$ 23,081	$ 22,008

Revenue - Contract Assets and L

Revenue - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Unbilled service fees		$ 137,938	$ 30,570
Unbilled outside vendor costs, billable to clients		37,101	11,063
Advance billings		286,790	66,418
Increase (Decrease) in Contract with Customer, Liability		220,372
Contract with Customer, Liability, Increase (Decrease) for Contract Acquired in Business Combination		211,687
Contract with Customer, Liability, Revenue Recognized	$ 9,311	45,432
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, amount		$ 8,498
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period		1 year
Revenue, Remaining Performance Obligation, Percentage		35.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period		1 year
Revenue, Remaining Performance Obligation, Percentage		60.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Percentage		4.00%
Accrued Expenses and Other Current Liabilities
Disaggregation of Revenue [Line Items]
Advance billings		$ 168,882	$ 9,311
Increase (Decrease) in Contract with Customer, Liability		159,571
Contract with Customer, Liability, Increase (Decrease) for Contract Acquired in Business Combination		$ 108,488

Income (Loss) Per Common Shar_2

Income (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021
Numerator
Net loss attributable to Stagwell Inc. common shareholders	$ (4,545)	$ (4,545)
Denominator
Basic weighted average number of common shares outstanding (in shares)	76,105,807	76,105,807
Basic (in dollars per share)	$ (0.06)	$ (0.06)
Diluted weighted average number of common shares outstanding (in shares)	76,105,807	76,105,807
Diluted (in dollars per share)	$ (0.06)	$ (0.06)
Anti-dilutive stock awards	179,970,051	179,970,051

Income (Loss) Per Common Shar_3

Income (Loss) Per Common Share (Details Textual) - shares	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (shares)	179,970,051	179,970,051
Convertible Preference Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares outstanding (shares)	123,849,000	123,849,000	0	0	0	0	0
Series 4 Convertible Preferred Stock | Convertible Preference Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Convertible preferred stock, common shares issuable upon conversion (shares)	33,035,446	33,035,446

Deferred Acquisition Consider_3

Deferred Acquisition Consideration (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance of contingent payments	$ 17,847	$ 65,792
Payments	12,286	66,235
Redemption value adjustments	9,535	2,520
Additions	61,110	15,717
Foreign translation adjustment	(501)	53
Ending balance of contingent payments	$ 75,705	$ 17,847

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	Sep. 30, 2021USD ($)lease
Leases [Abstract]
Number of leases not yet commenced | lease	3
Leases not yet commenced, liability | $	$ 31,310

Leases - Lease Costs and Other

Leases - Lease Costs and Other Quantitative Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Operating lease cost	$ 13,502	$ 5,900	$ 27,779	$ 19,279
Variable lease cost	3,230	928	5,167	2,959
Sublease rental income	(2,359)	(938)	(4,290)	(2,818)
Total lease cost	14,373	5,890	28,656	19,420
Operating cash flows	16,490	5,260	29,854	15,580
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 353,984	$ 128	$ 353,984	$ 1,961
Weighted average remaining lease term (in years) - Operating leases	6 years 9 months 18 days	4 years 7 months 6 days	6 years 9 months 18 days	4 years 7 months 6 days
Weighted average discount rate - Operating leases	4000000.00%	4100000.00%	4000000.00%	4100000.00%

Leases - Minimum Future Rental

Leases - Minimum Future Rental Payments (Details) $ in Thousands	Sep. 30, 2021USD ($)
Leases [Abstract]
Remaining 2021	$ 23,452
2022	84,730
2022	80,281
2023	65,242
2024	50,076
2026 and thereafter	161,462
Total	465,243
Less: Present value discount	(63,033)
Lease liability	$ 402,210

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt [Line Items]
Debt issuance costs	$ (15,365)	$ (3,612)
Total debt	1,265,747	199,018
Less: Current maturities of long-term debt	0	(994)
Long-term debt	1,265,747	198,024
Combined Credit Agreement
Debt [Line Items]
Long-term Debt, Gross	181,112	201,636
Term debt
Debt [Line Items]
Long-term Debt, Gross	0	994
5.625% Notes | Senior Notes
Debt [Line Items]
Long-term Debt, Gross	$ 1,100,000	$ 0

Debt - Additional Information (

Debt - Additional Information (Details) - USD ($) $ in Thousands	Aug. 20, 2021	Aug. 02, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Nov. 13, 2020	Mar. 18, 2020	Nov. 18, 2019
Debt [Line Items]
Interest expense, long-term debt			$ 15,560	$ 4,317
Amortization of debt issuance costs			2,092	$ 396
Redemption price	$ 904,200
Interest Rate Swap
Debt [Line Items]
Amount of hedged item			$ 11,563
Fixed interest rate			2.70%
Interest Rate Swap | Accrued Expenses and Other Current Liabilities
Debt [Line Items]
Fair value			$ 155		$ 416
Term debt | JPMorgan Chase Bank, N.A
Debt [Line Items]
Aggregate principal amount						$ 90,000
Line of Credit
Debt [Line Items]
Maximum borrowing capacity		$ 30,000
Line of Credit | JPM Revolver | JPMorgan Chase Bank, N.A
Debt [Line Items]
Long-term debt, term								5 years
Maximum borrowing capacity							$ 325,000	$ 265,000
Right for additional borrowing capacity								$ 150,000
Additional borrowing capacity							$ 60,000
Secured Debt | Combined Credit Agreement | Revolving Credit Facility
Debt [Line Items]
Long-term debt, term		5 years
Maximum borrowing capacity		$ 500,000
Higher borrowing capacity option		$ 650,000
Secured Debt | Combined Credit Agreement | Revolving Credit Facility | Minimum
Debt [Line Items]
Commitment fee percentage		0.15%
Secured Debt | Combined Credit Agreement | Revolving Credit Facility | Maximum
Debt [Line Items]
Commitment fee percentage		0.30%
Secured Debt | Combined Credit Agreement | Revolving Credit Facility | Federal Funds
Debt [Line Items]
Variable rate		0.50%
Secured Debt | Combined Credit Agreement | Revolving Credit Facility | LIBOR
Debt [Line Items]
Variable rate		1.00%
Letter of Credit | Combined Credit Agreement | Revolving Credit Facility
Debt [Line Items]
Maximum borrowing capacity			$ 25,628		$ 5,500
Higher borrowing capacity option		$ 50,000
Standby Letters of Credit | Combined Credit Agreement | Revolving Credit Facility
Debt [Line Items]
Maximum borrowing capacity		$ 50,000
Senior Notes | 5.625% Notes
Debt [Line Items]
Aggregate principal amount	$ 1,100,000
Interest rate, stated percentage	5.625%
Percentage of principal amount redeemed	40.00%
Percentage of redemption price, change in ownership controllatest for redemption at face amount	101.00%
Percentage of redemption price, sale of certain assets	100.00%
Senior Notes | 5.625% Notes | Debt Instrument, Redemption, Period Two
Debt [Line Items]
Redemption price, percentage	102.813%
Senior Notes | 5.625% Notes | Debt Instrument, Redemption, Period Three
Debt [Line Items]
Redemption price, percentage	101.406%
Senior Notes | 5.625% Notes | Debt Instrument, Redemption, Period Four
Debt [Line Items]
Redemption price, percentage	100.00%
Senior Notes | 5.625% Notes | Debt Instrument, Redemption, Period One
Debt [Line Items]
Redemption price, percentage	100.00%
Senior Notes | 5.625% Notes | Debt Instrument, Redemption With Equity Offering proceeds, Period One
Debt [Line Items]
Redemption price, percentage	105.625%
Senior Notes | 7.50% Senior Notes
Debt [Line Items]
Aggregate principal amount	$ 870,300
Interest rate, stated percentage	7.50%
Redemption price, percentage	101.625%

Noncontrolling and Redeemable_3

Noncontrolling and Redeemable Noncontrolling Interests (Details Textual) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Fair Value	$ 29,787	$ 604	$ 3,603
Vesting over period [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Fair Value	14,847
Termination, disability, or death [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Fair Value	14,940
Acquisition Value in excess of Redemption Value [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Fair Value	$ 0

Noncontrolling and Redeemable_4

Noncontrolling and Redeemable Noncontrolling Interests - Changes in Noncontrolling Interests (Details) - USD ($) $ in Thousands	1 Months Ended	2 Months Ended	3 Months Ended		7 Months Ended	9 Months Ended
	Aug. 01, 2021	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Aug. 01, 2021	Sep. 30, 2021	Sep. 30, 2020
Noncontrolling Interest [Line Items]
Net loss attributable to MDC Partners Inc.	$ 3,102	$ 2,229	$ (2,071)	$ 17,808	$ 27,435	$ 20,199	$ 34,124
Purchases of NCI		(771)
Stagwell Inc. Shareholders' Equity
Noncontrolling Interest [Line Items]
Net loss attributable to MDC Partners Inc.	$ 3,032	(4,545)	(2,071)	17,808	$ 24,742	20,199	34,124
Purchases of NCI		$ 9,679	9,679	0		9,679	0
Change from net income (loss) attributable to Stagwell Inc. and transfers to noncontrolling interests			$ (7,608)	$ (17,808)		$ (29,878)	$ (34,124)

Noncontrolling and Redeemable_5

Noncontrolling and Redeemable Noncontrolling Interests - Changes in Redeemable Noncontrolling Interests (Details) - USD ($) $ in Thousands	1 Months Ended	2 Months Ended	3 Months Ended		7 Months Ended	9 Months Ended
	Aug. 01, 2021	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Aug. 01, 2021	Sep. 30, 2021	Sep. 30, 2020
Noncontrolling Interest [Abstract]
Beginning Balance			$ 604		$ 604	$ 604	$ 3,603
Redemptions			0			2,831
Noncontrolling Interest, Increase from Business Combination			0			30,830
Changes in redemption value	$ (2,559)	$ 1,608	(127)	$ (199)	$ 72	(1,680)	$ 193
Net loss attributable to redeemable noncontrolling interests			3,126			956
Other			$ 0			460
Ending Balance		$ 29,787				$ 29,787

Share Capital (Details Textual)

Share Capital (Details Textual) $ / shares in Units, $ in Thousands	Aug. 04, 2021USD ($)shares	Nov. 08, 2021shares	Oct. 07, 2021shares	Sep. 30, 2021USD ($)votetradingDay$ / sharesshares	Jun. 30, 2021USD ($)shares	Dec. 31, 2020USD ($)shares	Sep. 30, 2020USD ($)shares	Jun. 30, 2020USD ($)shares	Dec. 31, 2019USD ($)shares
Share Capital [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest | $				$ 1,041,230	$ 381,342	$ 398,543	$ 366,519	$ 348,984	$ 348,537
Preference shares, outstanding (in shares)				123,849,000		0
Preferred Stock, Premium Percentage				125.00%
Preferred Stock, Conversion Price | $ / shares				$ 5
Preferred Stock, Threshold Trading Days | tradingDay				30
Common Class A
Share Capital [Line Items]
Common Stock, Shares Authorized				1,000,000,000
Common Class A | Subsequent Event [Member]
Share Capital [Line Items]
Convertible preferred stock, common shares issuable upon conversion (shares)		20,948,746	12,086,700
Series 6 Convertible Preferred Stock
Share Capital [Line Items]
Preferred Stock, Par or Stated Value Per Share | $ / shares				$ 0.001
Preference shares, outstanding (in shares)				50,000,000
Series 6 Convertible Preferred Stock | Subsequent Event [Member]
Share Capital [Line Items]
Preference shares, outstanding (in shares)			50,000,000
Common Class B
Share Capital [Line Items]
Common Stock, Shares Authorized				5,000
Common Class C
Share Capital [Line Items]
Common Stock, Shares Authorized				250,000,000
Common Stock, Shares, Issued				179,970,051
Common Stock, Shares, Outstanding				179,970,051
Series 8 Preferred Stock
Share Capital [Line Items]
Preferred Stock, Liquidation Preference, Value | $	$ 30,000
Preferred Stock, Par or Stated Value Per Share | $ / shares				$ 0.001
Preference shares, outstanding (in shares)				73,849,000
Stock Redeemed or Called During Period, Value | $	$ 25,000
Stock Redeemed or Called During Period, Shares	21,151,000
Series 8 Preferred Stock | Subsequent Event [Member]
Share Capital [Line Items]
Preference shares, outstanding (in shares)		73,849,000
Preferred Stock
Share Capital [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest | $				$ 209,980	$ 0	$ 0	$ 0	$ 0	$ 0
Shares outstanding (shares)				123,849,000	0	0	0	0	0
Preferred Stock | Series 4 Convertible Preferred Stock
Share Capital [Line Items]
Convertible preferred stock, common shares issuable upon conversion (shares)				33,035,446
Paid-in Capital
Share Capital [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest | $				$ 169,537	$ 0	$ 0	$ 0	$ 0	$ 0
Common Shares
Share Capital [Line Items]
Shares outstanding (shares)							0
Common Shares | Common Class A
Share Capital [Line Items]
Shares outstanding (shares)				78,979,960
Common stock, voting rights, number of votes per share | vote				1
Common Stock, Par or Stated Value Per Share | $ / shares				$ 0.001
Common Shares | Common Class B
Share Capital [Line Items]
Shares outstanding (shares)				3,946
Common stock, voting rights, number of votes per share | vote				20
Preferred Stock, Par or Stated Value Per Share | $ / shares				$ 0
Common Shares | Common Class C
Share Capital [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest | $				$ 2	$ 0	$ 0	$ 0	$ 0	$ 0
Shares outstanding (shares)				179,970,051	0	0	0	0	0

Fair Value Measurements - Finan

Fair Value Measurements - Financial Instruments not measured at Fair Value on a Recurring Basis (Details) - Senior Notes - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	$ 1,100,000	$ 0
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Fair Value Disclosure	$ 1,133,891	$ 0

Fair Value Measurements - Fin_2

Fair Value Measurements - Financial Instruments Measured on a Recurring Basis (Details) - Fair Value, Inputs, Level 3 - Fair Value, Recurring - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Shares	$ 0	$ 12,033
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Shares	0	12,033
Interest Rate Swap | Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives	155	416
Interest Rate Swap | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives	155	416
Call Option | Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives	0	360
Call Option | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives	$ 0	$ 360

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) $ in Thousands	Mar. 11, 2021USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Gain on sale of business and other, net		$ 45,621	$ 263	$ 46,806	$ 948
Redeemable Preferred Stock
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Gain on sale of business and other, net	$ 1,200
Dividend rate						6.00%
Debt Securities, Available-for-sale						$ 10,000
Conversion ratio						1.00%
Amount of shares held						$ 1,000
Minimum | Measurement Input, Discount Rate | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration liability, measurement input		0.035		0.035
Maximum | Measurement Input, Discount Rate | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration liability, measurement input		0.051		0.051

Supplemental Information (Detai

Supplemental Information (Details) - USD ($) $ in Thousands	Aug. 02, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share Capital [Line Items]
Asset Impairment Charges		$ 14,926	$ 0	$ 14,926	$ 0
Income tax expense		5,183	2,618	9,205	3,211
Income before income taxes and equity in earnings of non-consolidated affiliates		$ 13,182	$ 24,075	$ 40,466	$ 41,964
Effective tax rate (percent)		39.30%	10.90%	22.70%	7.70%
Share-based Payment Arrangement, Expense		$ 53,465		$ 53,465
Targeted Victory
Share Capital [Line Items]
Sale of Stock, Percentage of Ownership after Transaction	13.30%
Code and Theory
Share Capital [Line Items]
Sale of Stock, Percentage of Ownership after Transaction	8.50%
Observatory
Share Capital [Line Items]
Sale of Stock, Percentage of Ownership after Transaction	8.10%
SMG Units
Share Capital [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	12,131
Share-based Payment Arrangement, Expense		$ 45,986
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	6,661
RSUs outstanding (shares)	5,470
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	6 months

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	Mar. 11, 2021	Aug. 01, 2021	Sep. 30, 2021	Sep. 30, 2020	Aug. 01, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Aug. 31, 2016
Related Party Transaction [Line Items]
Sublease rental income			$ 2,359,000	$ 938,000		$ 4,290,000	$ 2,818,000
Distributions		$ 165,717,000	165,700,000	4,724,000	$ 204,929,000	191,900,000	98,638,000
Stagwell Subsidiary [Member] | Development of Advertising Technology [Member]
Related Party Transaction [Line Items]
Due from Related Parties			200,000			200,000			$ 1,800,000
Revenue from Related Parties			200,000			300,000
Stagwell Subsidiary [Member] | Interagency Customer Services Agreement
Related Party Transaction [Line Items]
Revenue from Related Parties			0	100,000		0	1,200,000
Related Party Transaction, Expenses from Transactions with Related Party			0	0		0	200,000
Affiliated Entity [Member] | 2018 Arrangement to Perform Marketing Services
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party			400,000			1,200,000
Due to Related Parties			700,000			700,000
Affiliated Entity [Member] | 2020 Arrangement to Perform Marketing Services
Related Party Transaction [Line Items]
Due from Related Parties			0			0
Revenue from Related Parties			500,000			5,100,000
Affiliated Entity [Member] | June 2021 Arrangement to Perform Marketing Services
Related Party Transaction [Line Items]
Due from Related Parties			2,200,000			2,200,000
Revenue from Related Parties			1,300,000			2,700,000
Affiliated Entity [Member] | Loan Agreement, Related Party
Related Party Transaction [Line Items]
Notes Receivable, Related Parties			3,800,000			3,800,000		$ 3,400,000
Interest Income, Related Party			200,000			300,000
Immediate Family Member of Management or Principal Owner | 2018 Arrangement to Perform Marketing Services
Related Party Transaction [Line Items]
Due from Related Parties			200,000			200,000
Revenue from Related Parties			100,000			200,000
Stagwell Affiliate [Member]
Related Party Transaction [Line Items]
Noncash or Part Noncash Divestiture, Amount of Consideration Received	$ 13,000,000
Stagwell Affiliate [Member] | Noncash Investment Agreement
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction			300,000	$ 0		12,400,000	$ 83,200,000
Stagwell Affiliate [Member] | Cash Investment Agreement
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction			$ 1,600,000			$ 1,600,000

Segment Information (Details 1)

Segment Information (Details 1) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)reportable_segment	Sep. 30, 2020USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | reportable_segment			3
Revenues	$ 466,634	$ 228,097	$ 857,436	$ 574,970
Adjusted EBITDA	87,518	37,123	150,079	78,971
Depreciation, Depletion and Amortization, Nonproduction	(24,790)	(9,974)	(46,122)	(29,838)
Asset Impairment Charges	(14,926)	0	(14,926)	0
Stock-based compensation	(53,465)	0	(53,465)	0
Deferred acquisition consideration	(3,422)	(149)	(9,456)	(1,270)
Other Operating Income	(10,549)	(554)	(15,298)	(2,976)
Segment operating income (loss)	(19,634)	26,446	10,812	44,887
Interest expense, net	(11,912)	(1,778)	(15,197)	(4,665)
Foreign exchange, net	(893)	(856)	(1,955)	794
Gain on sale of business and other, net	45,621	263	46,806	948
Income before income taxes and equity in earnings of non-consolidated affiliates	13,182	24,075	40,466	41,964
Income tax expense	5,183	2,618	9,205	3,211
Income before equity in earnings of non-consolidated affiliates	7,999	21,457	31,261	38,753
Equity in losses (income) of non-consolidated affiliates	(76)	(35)	(75)	7
Net income		22,330		41,455
Net income attributable to noncontrolling and redeemable noncontrolling interests	(9,994)	(3,614)	(10,987)	(4,636)
Net income (loss) attributable to Stagwell Inc. common shareholders	(4,545)		(4,545)
Operating Segments | Integrated Agencies Network
Segment Reporting Information [Line Items]
Revenues	288,479	55,293	441,229	163,540
Adjusted EBITDA	68,356	11,270	100,960	28,913
Depreciation, Depletion and Amortization, Nonproduction	(14,396)	(2,292)	(19,816)	(6,715)
Stock-based compensation	(32,443)	0	(32,443)	0
Operating Segments | Media Network
Segment Reporting Information [Line Items]
Revenues	103,418	60,777	235,539	185,714
Adjusted EBITDA	15,371	8,131	29,789	14,993
Depreciation, Depletion and Amortization, Nonproduction	(6,597)	(4,903)	(17,041)	(14,751)
Stock-based compensation	(2,608)	0	(2,608)	0
Operating Segments | Communications Network
Segment Reporting Information [Line Items]
Revenues	67,348	106,909	157,794	210,100
Adjusted EBITDA	10,312	20,231	28,302	39,139
Depreciation, Depletion and Amortization, Nonproduction	(2,110)	(1,455)	(5,087)	(4,210)
Stock-based compensation	(15,384)	0	(15,384)	0
Operating Segments | All Other
Segment Reporting Information [Line Items]
Revenues	7,389	5,118	22,874	15,616
Adjusted EBITDA	419	(193)	(1,316)	(749)
Depreciation, Depletion and Amortization, Nonproduction	(493)	(815)	(2,013)	(2,696)
Stock-based compensation	(16)	0	(16)	0
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Adjusted EBITDA	(6,940)	(2,316)	(7,656)	(3,325)
Depreciation, Depletion and Amortization, Nonproduction	(1,194)	(509)	(2,165)	(1,466)
Stock-based compensation	$ (3,014)	$ 0	$ (3,014)	$ 0

Uncategorized Items - stgw-2021

Label	Element	Value
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	$ 49,895,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	7,561,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	11,936,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	934,000
Stockholders' Equity, Other1	stgw_StockholdersEquityOther1	300,000
Stockholders' Equity, Other1	stgw_StockholdersEquityOther1	(161,000)
Contribution from Limited Liability Company (LLC)	stgw_ContributionFromLimitedLiabilityCompanyLLC	11,834,000
Contribution from Limited Liability Company (LLC)	stgw_ContributionFromLimitedLiabilityCompanyLLC	(250,000)
Stockholders' Equity, Other	us-gaap_StockholdersEquityOther	(55,000)
Stock Issued During Period, Value, Noncontrolling Interest, Increase from Business Combination	stgw_StockIssuedDuringPeriodValueNoncontrollingInterestIncreaseFromBusinessCombination	778,658,000
Stock Repurchased and Retired During Period, Value	us-gaap_StockRepurchasedAndRetiredDuringPeriodValue	820,000
Stock Issued During Period, Value, Restricted Stock Award, Gross	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross	0
Noncontrolling Interest [Member]
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	0
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	11,936,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	934,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	7,561,000
Stockholders' Equity, Other1	stgw_StockholdersEquityOther1	(161,000)
Stockholders' Equity, Other1	stgw_StockholdersEquityOther1	300,000
Stockholders' Equity, Other	us-gaap_StockholdersEquityOther	173,000
Stock Issued During Period, Value, Noncontrolling Interest, Increase from Business Combination	stgw_StockIssuedDuringPeriodValueNoncontrollingInterestIncreaseFromBusinessCombination	636,416,000
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	2,693,000
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	6,774,000
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	70,000
Adjustments to Additional Paid in Capital, Changes due to Business Combinations	stgw_AdjustmentstoAdditionalPaidinCapitalChangesduetoBusinessCombinations	(10,450,000)
Member Units [Member]
Distribution Made to Limited Liability Company (LLC) Member, Cash Distributions Declared	us-gaap_DistributionMadeToLimitedLiabilityCompanyLLCMemberCashDistributionsDeclared	165,717,000
Distribution Made to Limited Liability Company (LLC) Member, Cash Distributions Declared	us-gaap_DistributionMadeToLimitedLiabilityCompanyLLCMemberCashDistributionsDeclared	204,929,000
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	(63,000)
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	(375,000)
Contribution from Limited Liability Company (LLC)	stgw_ContributionFromLimitedLiabilityCompanyLLC	(250,000)
Contribution from Limited Liability Company (LLC)	stgw_ContributionFromLimitedLiabilityCompanyLLC	11,834,000
Stock Issued During Period, Value, Noncontrolling Interest, Increase from Business Combination	stgw_StockIssuedDuringPeriodValueNoncontrollingInterestIncreaseFromBusinessCombination	(178,372,000)
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	3,032,000
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	24,742,000
Redeemable noncontrolling interest, changes in redemption value	stgw_Redeemablenoncontrollinginterestchangesinredemptionvalue	72,000
Redeemable noncontrolling interest, changes in redemption value	stgw_Redeemablenoncontrollinginterestchangesinredemptionvalue	(2,559,000)
Parent [Member]
Distribution Made to Limited Liability Company (LLC) Member, Cash Distributions Declared	us-gaap_DistributionMadeToLimitedLiabilityCompanyLLCMemberCashDistributionsDeclared	165,717,000
Distribution Made to Limited Liability Company (LLC) Member, Cash Distributions Declared	us-gaap_DistributionMadeToLimitedLiabilityCompanyLLCMemberCashDistributionsDeclared	204,929,000
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	49,895,000
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	(375,000)
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	12,537,000
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	(63,000)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	0
Stockholders' Equity, Other1	stgw_StockholdersEquityOther1	0
Stockholders' Equity, Other1	stgw_StockholdersEquityOther1	0
Contribution from Limited Liability Company (LLC)	stgw_ContributionFromLimitedLiabilityCompanyLLC	11,834,000
Contribution from Limited Liability Company (LLC)	stgw_ContributionFromLimitedLiabilityCompanyLLC	(250,000)
Stockholders' Equity, Other	us-gaap_StockholdersEquityOther	(228,000)
Stock Issued During Period, Value, Noncontrolling Interest, Increase from Business Combination	stgw_StockIssuedDuringPeriodValueNoncontrollingInterestIncreaseFromBusinessCombination	142,242,000
Stock Repurchased and Retired During Period, Value	us-gaap_StockRepurchasedAndRetiredDuringPeriodValue	820,000
Redeemable noncontrolling interest, changes in redemption value	stgw_Redeemablenoncontrollinginterestchangesinredemptionvalue	(2,559,000)
Redeemable noncontrolling interest, changes in redemption value	stgw_Redeemablenoncontrollinginterestchangesinredemptionvalue	(1,608,000)
Redeemable noncontrolling interest, changes in redemption value	stgw_Redeemablenoncontrollinginterestchangesinredemptionvalue	72,000
Stock Issued During Period, Value, Restricted Stock Award, Gross	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross	$ 0
Common Stock [Member]
Adjustments to Additional Paid in Capital, Changes due to Business Combinations, Shares	stgw_AdjustmentsToAdditionalPaidInCapitalChangesDueToBusinessCombinationsShares	0
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures	us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures	0
AOCI Attributable to Parent [Member]
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	$ 0
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	0
Other Comprehensive Income (Loss), Net of Tax	us-gaap_OtherComprehensiveIncomeLossNetOfTax	12,537,000
Stockholders' Equity, Other	us-gaap_StockholdersEquityOther	0
Preferred Stock [Member]
Stock Issued During Period, Value, Noncontrolling Interest, Increase from Business Combination	stgw_StockIssuedDuringPeriodValueNoncontrollingInterestIncreaseFromBusinessCombination	$ 209,980,000
Stock Issued During Period, Noncontrolling Interest, Increase from Business Combination	stgw_StockIssuedDuringPeriodNoncontrollingInterestIncreaseFromBusinessCombination	123,849,000
Additional Paid-in Capital [Member]
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	$ 49,895,000
Stockholders' Equity, Other	us-gaap_StockholdersEquityOther	(228,000)
Stock Issued During Period, Value, Noncontrolling Interest, Increase from Business Combination	stgw_StockIssuedDuringPeriodValueNoncontrollingInterestIncreaseFromBusinessCombination	110,555,000
Stock Repurchased and Retired During Period, Value	us-gaap_StockRepurchasedAndRetiredDuringPeriodValue	820,000
Adjustments to Additional Paid in Capital, Changes due to Business Combinations	stgw_AdjustmentstoAdditionalPaidinCapitalChangesduetoBusinessCombinations	9,679,000
Stock Issued During Period, Value, Restricted Stock Award, Gross	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross	0
Retained Earnings [Member]
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	(4,545,000)
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	0
Net Income (Loss) Attributable to Parent	us-gaap_NetIncomeLoss	0
Redeemable noncontrolling interest, changes in redemption value	stgw_Redeemablenoncontrollinginterestchangesinredemptionvalue	(1,608,000)
Common Class C [Member] | Common Stock [Member]
Stock Issued During Period, Value, Noncontrolling Interest, Increase from Business Combination	stgw_StockIssuedDuringPeriodValueNoncontrollingInterestIncreaseFromBusinessCombination	$ 2,000
Stock Issued During Period, Noncontrolling Interest, Increase from Business Combination	stgw_StockIssuedDuringPeriodNoncontrollingInterestIncreaseFromBusinessCombination	179,970,051
Common Class A And B [Member] | Common Stock [Member]
Stock Issued During Period, Value, Noncontrolling Interest, Increase from Business Combination	stgw_StockIssuedDuringPeriodValueNoncontrollingInterestIncreaseFromBusinessCombination	$ 77,000
Stock Issued During Period, Noncontrolling Interest, Increase from Business Combination	stgw_StockIssuedDuringPeriodNoncontrollingInterestIncreaseFromBusinessCombination	78,793,502
Stock Issued During Period, Shares, Restricted Stock Award, Gross	us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross	202,488
Stock Repurchased and Retired During Period, Shares	us-gaap_StockRepurchasedAndRetiredDuringPeriodShares	12,084