Fidelis Insurance Holdings Limited (FIHL) 6-K 12 Nov 24 Fidelis Insurance Group Reports 2024 Third Quarter Results Financial data

Cover

Cover	9 Months Ended
	Sep. 30, 2024
Cover [Abstract]
Document Type	6-K
Entity Registrant Name	FIDELIS INSURANCE HOLDINGS LIMITED
Entity Central Index Key	0001636639
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Amendment Flag	false
Document Period End Date	Sep. 30, 2024
Current Fiscal Year End Date	--12-31

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Assets
Other investments, at fair value (amortized cost: $50.1, 2023: $50.8)	$ 48.7	$ 47.5
Total investments	3,717.3	3,341.4
Cash and cash equivalents	806.8	712.4
Restricted cash and cash equivalents	212.3	251.7
Accrued investment income	27.4	27.2
Premiums and other receivables (net of allowances for credit losses of $13.4, 2023: $17.3)	2,808.1	2,209.3
Deferred reinsurance premiums	1,405.5	1,061.4
Reinsurance balances recoverable on paid losses (net of allowances for credit losses of $nil, 2023: $nil)	194.1	182.7
Reinsurance balances recoverable on reserves for losses and loss adjustment expenses (net of allowances for credit losses of $1.3, 2023: $1.3)	1,164.9	1,108.6
Deferred policy acquisition costs (includes The Fidelis Partnership deferred commissions of $220.8, 2023: $164.1)	926.3	786.6
Other assets	173.9	173.5
Total assets	11,685.1	10,028.1
Liabilities
Reserves for losses and loss adjustment expenses	2,800.8	2,448.9
Unearned premiums	3,789.3	3,149.5
Reinsurance balances payable	1,402.9	1,071.5
Long term debt	448.8	448.2
Preference securities ($0.01 par, redemption price and liquidation preference $10,000)	58.4	58.4
Other liabilities	141.9	67.3
Total liabilities	9,052.8	7,578.3
Commitments and contingencies
Shareholders' equity
Common shares ($0.01 par, issued and outstanding: 111,726,363, 2023: 117,914,754)	1.2	1.2
Additional paid-in capital	2,043.6	2,039
Accumulated other comprehensive income/(loss)	56.1	(27)
Retained earnings	636.9	436.6
Common shares held in treasury, at cost (shares held: 6,570,003, 2023: nil)	(105.5)	0
Total shareholders' equity	2,632.3	2,449.8
Total liabilities and shareholders' equity	11,685.1	10,028.1
Related Party
Assets
Amounts due from The Fidelis Partnership (net of allowances for credit losses of $nil, 2023: $nil)	248.5	173.3
Liabilities
Amounts due to The Fidelis Partnership	410.7	334.5
Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3))
Assets
Debt Securities, Available-for-Sale, Excluding Accrued Interest	3,535.3	3,244.9
Short-term investments, available-for-sale, at fair value (amortized cost: $133.1, 2023: $49.0 (net of allowances for credit losses of $nil, 2023: $nil))
Assets
Debt Securities, Available-for-Sale, Excluding Accrued Interest	$ 133.3	$ 49

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt securities, available-for-sale, allowance for credit loss, excluding accrued interest	$ 300	$ 1,300
Other long-term investments, amortized cost	50,100	50,800
Premium receivable, allowance for credit loss	13,400	17,300
Other receivables, allowance for credit loss	0	0
Reinsurance recoverables on paid losses, allowance	0	0
Reinsurance recoverables on unpaid losses, allowance	$ 1,300	$ 1,300
Preferred stock, liquidation preference per share (in dollar per share)	$ 0.01	$ 0.01
Preferred stock, liquidation preference, value	$ 10	$ 10
Common stock, par or stated value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares, issued (in shares)	111,726,363	117,914,754
Common stock, shares, outstanding (in shares)	111,726,363	117,914,754
Treasury stock, common, shares (in shares)	6,570,003	0
Related Party
Deferred policy acquisition cost, deferred commissions	$ 220,800	$ 164,100
Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3))
Amortized cost	3,471,800	3,271,400
Debt securities, available-for-sale, allowance for credit loss, excluding accrued interest	300	1,300
Short-term investments, available-for-sale, at fair value (amortized cost: $133.1, 2023: $49.0 (net of allowances for credit losses of $nil, 2023: $nil))
Amortized cost	133,100	49,000
Debt securities, available-for-sale, allowance for credit loss, excluding accrued interest	$ 0	$ 0

Consolidated Statements of Inco

Consolidated Statements of Income and Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenues
Gross premiums written	$ 741.9	$ 592.6	$ 3,449.4	$ 2,795.1
Reinsurance premiums ceded	(274)	(280)	(1,533.5)	(1,207.7)
Net premiums written	467.9	312.6	1,915.9	1,587.4
Change in net unearned premiums	166.6	197.1	(292.3)	(262.6)
Net premiums earned	634.5	509.7	1,623.6	1,324.8
Net investment income	52.1	33.1	139.1	80.8
Net realized and unrealized investment losses	(0.5)	(5.3)	(16.5)	(2.4)
Other income	0	0	0	0.2
Total revenues before net gain on distribution of The Fidelis Partnership	686.1	537.5	1,746.2	1,403.4
Net gain on distribution of The Fidelis Partnership	0	0	0	1,639.1
Total revenues	686.1	537.5	1,746.2	3,042.5
Expenses
Losses and loss adjustment expenses	237.8	191.7	642.8	509.6
Policy acquisition expenses (includes The Fidelis Partnership commissions of $97.3 and $249.0 (2023: $70.6 and $147.4))	294	221.4	724.2	525.3
General and administrative expenses	22.7	21.8	70.7	57
Corporate and other expenses	0	0.4	1.6	3.4
Net foreign exchange (gains)/losses	4.8	(2.4)	4.9	(0.8)
Financing costs	8.9	9	26.1	26.6
Total expenses	568.2	441.9	1,470.3	1,121.1
Income before income taxes	117.9	95.6	275.9	1,921.4
Income tax expense	(17.3)	(7.9)	(40.4)	(17.2)
Net income	100.6	87.7	235.5	1,904.2
Other comprehensive income
Unrealized gains/(losses) on available-for-sale investments	79	(0.1)	70.4	14.9
Reclassification of net realized losses recognized in net income	6	0.2	19.5	0.6
Income tax (expense)/benefit, all of which relates to unrealized gains/(losses) on available-for-sale investments	(6.6)	0.2	(6.8)	(1.4)
Total other comprehensive income	78.4	0.3	83.1	14.1
Comprehensive income	$ 179	$ 88	$ 318.6	$ 1,918.3
Per share data earnings per common share
Earnings per common share (in dollars per share)	$ 0.88	$ 0.75	$ 2.02	$ 16.84
Earnings per diluted common share (in dollars per share)	$ 0.88	$ 0.74	$ 2.02	$ 16.82
Weighted average basic common shares outstanding (in shares)	114,445,447	117,681,835	116,390,461	113,100,521
Weighted average diluted common shares outstanding (in shares)	114,734,526	117,975,099	116,845,991	113,232,930

Consolidated Statements of In_2

Consolidated Statements of Income and Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Related Party
Total Fidelis MGU commissions	$ 97.3	$ 70.6	$ 249	$ 147.4

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders’ Equity (Unaudited) - USD ($) $ in Millions	Total	Common shares	Additional paid-in capital	Unrealized gains/(losses) on available-for-sale securities, net of tax	Currency translation reserve	Accumulated other comprehensive income/(loss), net of tax	Retained earnings	Common shares held in treasury, at cost	Total shareholders' equity attributable to common shareholders	Non-controlling interests
Balance - beginning of year at Dec. 31, 2022		$ 1.9	$ 2,075.2	$ (99.7)	$ (1.1)		$ 0.5	$ 0		$ 10.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of common shares		0.2	89.3
Shares cancelled upon distribution of The Fidelis Partnership		(0.9)
Share compensation expense			24.8
Shares withheld for employee taxes on restricted share unit vesting			(50.6)
Cumulative dividends on warrants			(34.1)
Distribution of The Fidelis Partnership net assets to shareholders			(68.4)				(1,696.4)			(10.3)
Unrealized gains/(losses) arising during the period, net of reclassification adjustment	$ 14.1			14.1	1.1
Net income	$ 1,904.2						1,904.2
Common stock, dividends, per share, declared (in dollars per share)	$ 0
Dividends							0
Repurchase of common shares								0
Balance – end of year at Sep. 30, 2023	$ 2,160.1	1.2	2,036.2	(85.6)	0	$ (85.6)	208.3	0	$ 2,160.1	0
Balance - beginning of year at Jun. 30, 2023		1.1	1,944.8	(85.9)	0		120.6	0		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of common shares		0.1	89.3
Shares cancelled upon distribution of The Fidelis Partnership		0
Share compensation expense			2.6
Shares withheld for employee taxes on restricted share unit vesting			0
Cumulative dividends on warrants			0
Distribution of The Fidelis Partnership net assets to shareholders			(0.5)				0			0
Unrealized gains/(losses) arising during the period, net of reclassification adjustment	0.3			0.3	0
Net income	$ 87.7						87.7
Common stock, dividends, per share, declared (in dollars per share)	$ 0
Dividends							0
Repurchase of common shares								0
Balance – end of year at Sep. 30, 2023	$ 2,160.1	1.2	2,036.2	(85.6)	0	(85.6)	208.3	0	2,160.1	0
Balance - beginning of year at Dec. 31, 2023		1.2	2,039	(27)	0		436.6	0		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of common shares		0	0
Shares cancelled upon distribution of The Fidelis Partnership		0
Share compensation expense			6.8
Shares withheld for employee taxes on restricted share unit vesting			(2.2)
Cumulative dividends on warrants			0
Distribution of The Fidelis Partnership net assets to shareholders			0				0			0
Unrealized gains/(losses) arising during the period, net of reclassification adjustment	83.1			83.1	0
Net income	$ 235.5						235.5
Common stock, dividends, per share, declared (in dollars per share)	$ 0.30
Dividends							(35.2)
Repurchase of common shares								(105.5)
Balance – end of year at Sep. 30, 2024	$ 2,632.3	1.2	2,043.6	56.1	0	56.1	636.9	(105.5)	2,632.3	0
Balance - beginning of year at Jun. 30, 2024		1.2	2,041.7	(22.3)	0		548	(38.7)		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issue of common shares		0	0
Shares cancelled upon distribution of The Fidelis Partnership		0
Share compensation expense			1.9
Shares withheld for employee taxes on restricted share unit vesting			0
Cumulative dividends on warrants			0
Distribution of The Fidelis Partnership net assets to shareholders			0				0			0
Unrealized gains/(losses) arising during the period, net of reclassification adjustment	78.4			78.4	0
Net income	$ 100.6						100.6
Common stock, dividends, per share, declared (in dollars per share)	$ 0.10
Dividends							(11.7)
Repurchase of common shares								(66.8)
Balance – end of year at Sep. 30, 2024	$ 2,632.3	$ 1.2	$ 2,043.6	$ 56.1	$ 0	$ 56.1	$ 636.9	$ (105.5)	$ 2,632.3	$ 0

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Shareholders’ Equity (Unaudited) (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Statement of Stockholders' Equity [Abstract]
Common stock, dividends, per share, declared (in dollars per share)	$ 0.10	$ 0	$ 0.30	$ 0

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Operating activities
Net income	$ 235.5	$ 1,904.2
Adjustments to reconcile net income after tax to net cash provided by operating activities:
Revaluation of The Fidelis Partnership	0	(1,707.1)
Share compensation expense	6.8	24.8
Accretion, amortization and depreciation	(9)	0.1
Net realized and unrealized loss on investments	16.5	3.1
Net changes in assets and liabilities:
Accrued investment income	(0.2)	(10.4)
Premiums and other receivables	(584.4)	(262.7)
Amounts due from The Fidelis Partnership	(74.3)	(224.8)
Deferred reinsurance premiums	(344.1)	(330.3)
Reinsurance balances recoverable on paid losses	(9.6)	(9.4)
Reinsurance balances recoverable on reserves for losses and loss adjustment expenses	(54)	(94.6)
Deferred policy acquisition costs	(139.7)	(255.9)
Other assets	4.7	(49.5)
Reserves for losses and loss adjustment expenses	347.3	274.7
Unearned premiums	639.8	583.3
Reinsurance balances payable	316.5	132.3
Amounts due to The Fidelis Partnership	75.6	244.3
Other liabilities	64.7	75.7
Net cash provided by operating activities	492.1	297.8
Investing activities
Purchase of available-for-sale securities	(1,544)	(1,976.1)
Proceeds from maturities of available-for-sale securities	639.2	1,137
Proceeds from sales of available-for-sale securities	612.5	0
Proceeds from sale of other investments	0.6	75.2
Purchase of fixed assets	(3.9)	(1.8)
Net cash used in investing activities	(295.6)	(765.7)
Financing activities
Dividends on common shares	(35)	0
Repurchase of common shares	(105.5)	0
Proceeds from issuance of common stock, net of issuance costs	0	89.4
Non-controlling interest share transactions	0	(6.1)
Net cash used in disposal of subsidiary	0	(105.5)
Cumulative dividends on warrants	0	(34.1)
Tax paid on withheld shares	(2.2)	(50.6)
Net cash used in financing activities	(142.7)	(106.9)
Effect of exchange rate changes on foreign currency cash	1.2	(2.6)
Net increase/(decrease) in cash, restricted cash, and cash equivalents	55	(577.4)
Cash, restricted cash, and cash equivalents, beginning of period	964.1	1,407.9
Cash, restricted cash, and cash equivalents, end of period	1,019.1	830.5
Cash, restricted cash, and cash equivalents comprise the following:
Cash and cash equivalents	806.8	569
Restricted cash and cash equivalents	212.3	261.5
Total cash, cash equivalents and restricted cash	$ 1,019.1	$ 830.5

Nature of Operations

Nature of Operations	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	1. Nature of Operations Fidelis Insurance Holdings Limited (“Fidelis” and together with its subsidiaries, the “Group”) is a holding company which was incorporated under the laws of Bermuda on August 22, 2014. The Group provides Specialty and Bespoke Insurance and Reinsurance. Fidelis’ principal operating subsidiaries are: • Fidelis Insurance Bermuda Limited (“FIBL”) is a Class 4 Bermuda domiciled company which writes most of the Group’s Reinsurance business, as well as writing Specialty and Bespoke lines. FIBL is regulated by the Bermuda Monetary Authority. • Fidelis Underwriting Limited (“FUL”) is a U.K. domiciled company which principally writes Specialty and Bespoke insurance, as well as Reinsurance. FUL is regulated by the Prudential Regulation Authority ("PRA") and the Financial Conduct Authority (“FCA”). • Fidelis Insurance Ireland DAC (“FIID”) is a Republic of Ireland domiciled company that writes Specialty and Bespoke insurance and reinsurance within the European Economic Area. FIID is regulated by the Central Bank of Ireland (“CBI”). • FIHL (UK) Services Limited (“FSL”) is a U.K. service company that also has a branch in Ireland. On January 3, 2023, the Group completed a series of transactions pursuant to which (i) it distributed its investment in Fidelis Marketing Limited (“FML”) and Pine Walk Capital Limited (“Pine Walk”) to shareholders to form a new managing general underwriter business (“The Fidelis Partnership” or “TFP”, formerly known as “Fidelis MGU”) and (ii) The Fidelis Partnership was acquired by a consortium of investors (together known as the “Separation Transactions”). FML was previously the service company for the U.K. and Ireland operations of the Group and is now the service company for The Fidelis Partnership. Pine Walk held the Group’s investments in eight managing general agents (“MGAs”). The financial statements of Pine Walk, the eight MGAs and FML have been deconsolidated from January 3, 2023. Through various long-term contractual agreements, effective from January 1, 2023 The Fidelis Partnership manages origination, underwriting, underwriting administration and claims handling under delegated authority agreements with the Group. Other services provided by The Fidelis Partnership to the Group include sourcing and administering outwards reinsurance, support with business planning, capital management, insurance contract accounting and information technology. Further information can be found at Note 3 (Separation Transactions) and Note 13 (Related Party Transactions). On July 3, 2023, Fidelis completed an initial public offering (“IPO”) of an aggregate of 15,000,000 common shares, including 7,142,857 common shares sold by Fidelis and 7,857,143 common shares sold by certain selling shareholders, at an offering price of $14.00 per common share. The net proceeds of the offering to Fidelis were $89.4 million, after deducting underwriting discounts, commissions, and other offering expenses paid by the Group. Fidelis’ common shares are listed on the New York Stock Exchange under the symbol “FIHL”. On May 22, 2024, the Group established a Lloyds corporate member, Nameco (No 1404) Limited (the “Fidelis IG Corporate Member”), a wholly owned subsidiary of FIBL, to facilitate its 9.9% participation in Syndicate 3123’s underwriting activity commencing July 1, 2024.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Basis of presentation The unaudited consolidated financial statements include the results of FIHL and its subsidiaries and have been prepared in conformity with generally accepted accounting principles in the United States (“U.S. GAAP”) for interim financial information and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. These unaudited financial statements should be read in conjunction with the audited consolidated financial statements for the year ended December 31, 2023, in Fidelis’ Form 20-F filed with the Securities and Exchange Commission on March 15, 2024. All intercompany balances and transactions have been eliminated on consolidation. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ materially from those estimates and assumptions. In the opinion of management, the accompanying unaudited interim consolidated financial statements reflect all adjustments (consisting of normally recurring accruals) necessary for a fair statement of results on an interim basis. The results of any interim period are not necessarily indicative of the results for a full year or any future periods. The consolidated financial statements have been prepared on a going concern basis. Reporting currency The financial information is reported in United States dollars (“U.S. dollars” or “$”), expressed in millions, except for share and per share amounts. Significant Accounting Policies There were no notable changes to the Group’s significant accounting policies subsequent to December 31, 2023.

Separation Transactions

Separation Transactions	9 Months Ended
	Sep. 30, 2024
Related Party Transactions [Abstract]
Separation Transactions	3. Separation Transactions On January 3, 2023, the Group completed a transaction pursuant to which (i) Pine Walk and its investments in the MGAs, together with FML, were distributed to shareholders to form a new managing general underwriting business, The Fidelis Partnership and (ii) The Fidelis Partnership was acquired by a consortium of investors. Following the consummation of the Separation Transactions, The Fidelis Partnership acquired 9.9% of the common shares in the Group. The Separation Transactions resulted in certain shareholders receiving cash in lieu of their interest in The Fidelis Partnership. As a result, the distribution of The Fidelis Partnership was recorded at its fair value of $1,775.0 million. The fair value was determined in accordance with the requirements of Financial Accounting Standards Board Accounting Standards Codification 820 – Fair Value Measurements (“ASC 820”). We obtained the services of a third-party independent valuation expert in arriving at that determination of fair value. ASC 820 explains the concept of fair value for financial reporting. Under ASC 820, fair value is a market-based measurement, not an entity specific measurement. The objective of ASC 820 is to estimate the price at which an orderly transaction to sell the asset would take place between market participants at the measurement date under current market conditions (that is, an exit price at the measurement date from the perspective of a market participant). When a price for an identical asset is not observable, a reporting entity measures fair value using another valuation technique that maximizes the use of relevant observable inputs and minimizes the use of unobservable inputs. Fair value is measured using the assumptions that market participants would use when pricing the asset or liability, including assumptions about risk. For purposes of the valuation of The Fidelis Partnership, we used an income approach using a discounted cash flow methodology, and a market approach using comparable listed trading and precedent transaction multiples. These approaches generated a range of values for The Fidelis Partnership of $1.7 billion to $1.9 billion. The determined fair value for The Fidelis Partnership of $1,775.0 million was based on the price of the most recent transactions in The Fidelis Partnership shares, and close to the mid-point of the valuation range. On January 3, 2023, following the distribution of The Fidelis Partnership to shareholders of the Group, certain shareholders sold their shares, and certain third parties purchased shares, in The Fidelis Partnership at a price per share determined using a fair value of $1,775.0 million. Immediately prior to the consummation of the Separation Transactions, the Group accelerated the vesting of all unvested Restricted Share Units (“RSUs”). This resulted in the acceleration of compensation expense of $21.0 million and an employer payroll tax expense of $17.3 million in the nine months ended September 30, 2023. The RSUs and warrants were exercised on the date of the Separation Transactions, resulting in the issuance of 13,553,681 common shares. The RSUs were net settled, resulting in a $50.6 million reduction of additional paid-in capital for the employees’ tax obligations with respect to these awards. The exercise of the warrants triggered the payment of cumulative dividends of $34.1 million. The distribution of The Fidelis Partnership to shareholders of the Group resulted in the deconsolidation of net assets of $67.9 million, and the cancellation of 97,327,049 common shares in the Group. Following the Separation Transactions there were 110,771,897 common shares issued and outstanding. The distribution resulted in the elimination of the Group’s non-controlling interests, all of which related to the subsidiaries of Pine Walk. In connection with the successful consummation of the Separation Transactions, the Group incurred professional fee s of $28.6 million d uring the nine months ended September 30, 2023. The net gain on distribution of The Fidelis Partnership of $1,639.1 million has been calculated as the fair value of The Fidelis Partnership of $1,775.0 million, less the net assets of The Fidelis Partnership of $67.9 million and less the direct costs of the Separation Transactions of $68.0 million. Direct costs primarily related to professional fees of $28.6 million , acceleration of compensation expense of $21.0 million and an employer payroll tax expense of $17.3 million. Within operating activities on the Consolidated Statements of Cash Flows, the revaluation of The Fidelis Partnership of $1,707.1 million, being the fair value of The Fidelis Partnership of $1,775.0 million less the net assets of $67.9 million, is shown as a non-cash adjustment to reconcile net income to net cash provided by operating activities. On January 3, 2023, the financial statements of Pine Walk, the eight MGAs and FML have been deconsolidated and the non-controlling interests were disposed upon consummation of the Separation Transactions. 13. Related Party Transactions On January 3, 2023, The Fidelis Partnership acquired 9.9% of the common shares of the Group. Certain directors, executive officers and management of The Fidelis Partnership also own common shares of the Group. On December 20, 2022, the Group and The Fidelis Partnership entered into a rolling 10-year framework agreement (the “Framework Agreement”), effective January 1, 2023, that governs the ongoing relationship between the two groups. Years one to three roll automatically, whereas from year four onwards, the Framework Agreement will roll at the sole written election of the Group, with such election to be delivered at least 90 days prior to the commencement of the subsequent contract year. Any decision by FIHL to elect not to roll the Framework Agreement will mean that the remainder of the 10-year terms then in effect will continue in place. The underwriting activities of FIBL, FUL and FIID have been outsourced to the corresponding operating subsidiaries of The Fidelis Partnership on a jurisdictional basis. Each of FIBL, FUL and FIID have delegated underwriting authority to source and bind contracts to Shelf Opco Bermuda Limited, Pine Walk and Pine Walk Europe, respectively. The Fidelis Partnership manages origination, underwriting, underwriting administration and claims handling under delegated authority agreements with the Group. Other services provided by The Fidelis Partnership to the Group include sourcing and administering the outwards reinsurance program, and support with business planning, capital management, insurance contract accounting and information technology. The Framework Agreement provides for the payment of the following fees with effect from January 1, 2023: a. Ceding commissions: (i) a ceding commission of 11.5% of net premiums written of open market business procured by The Fidelis Partnership on or after January 1, 2023; (ii) a ceding commission of 3% of net premiums written of business sourced by The Fidelis Partnership via third party managing general underwriters on or after January 1, 2023; and (iii) a portfolio management fee of 3.0% of net premiums written of the business sourced by The Fidelis Partnership. b. Profit commission: a profit commission of 20.0% of the aggregate operating profit (as defined in the Framework Agreement) generated on the sourced business, subject to a hurdle rate of return of 5.0% of underwriting return on equity. For insurance contracts sourced by Pine Walk MGAs for FUL, FIBL or FIID, the fees and commissions follow separately negotiated arrangements, and will not attract additional commissions under the terms of the Framework Agreement. The following table summarizes The Fidelis Partnership commissions earned, which are included in policy acquisition expenses in the Consolidated Statements of Income: Three months ended Nine months ended September 30, 2024 September 30, 2023 September 30, 2024 September 30, 2023 Ceding commission expense $ 84.2 $ 56.3 $ 225.3 $ 107.4 Profit commission expense 13.1 14.3 23.7 40.0 Total commissions $ 97.3 $ 70.6 $ 249.0 $ 147.4 Amounts receivable from The Fidelis Partnership at September 30, 2024, of $248.5 million (December 31, 2023: $173.3 million) primarily consist of amounts collected by The Fidelis Partnership on behalf of the Group that were not remitted prior to the end of the quarter, and prepaid portfolio management fees. Amounts payable to The Fidelis Partnership at September 30, 2024, of $410.7 million (December 31, 2023: $334.5 million) primarily consist of amounts payable to The Fidelis Partnership for ceding and profit commissions, and claims paid by The Fidelis Partnership on the Group’s behalf. The Framework Agreement also provides that from January 1, 2023, in respect of commissions and profit commissions on ceded quota share business the Group shall retain 1.0% of reinsurance premiums ceded and the remainder is to be paid to The Fidelis Partnership. Commissions on ceded business for the three and nine months ended September 30, 2024, of $33.7 million and $76.8 million, respectively, (2023: $24.7 million and $37.3 million) were paid to The Fidelis Partnership. For the three and nine months ended September 30, 2024, profit commissions on ceded business of $40.9 million and $55.0 million, respectively, (2023: $12.9 million and $20.7 million) were paid to The Fidelis Partnership. Insurance contracts sourced by Pine Walk contain profit commissions based on the results of each individual contract. The expense/(income) for the three and nine months ended September 30, 2024, was $17.1 million and $33.6 million, respectively, (2023: $(4.1) million and $14.5 million) and was included within policy acquisition expenses. The Fidelis Partnership provides the Group with certain support services on a cost-plus basis, which include sourcing and administering outwards reinsurance, support with business planning, capital management, insurance contract accounting and information technology. Included within general and administrative expenses for the three and nine months ended September 30, 2024, are charges of $1.6 million and $4.6 million, respectively, (2023: $1.6 million and $4.3 million) from The Fidelis Partnership for such services. The Group provides certain services to The Fidelis Partnership for which it charged $0.7 million and $1.1 million for the three and nine months ended September 30, 2024, respectively, (2023: $0.6 million and $1.9 million). These charges to The Fidelis Partnership are included within general and administrative expenses.

Segments

Segments	9 Months Ended
	Sep. 30, 2024
Segment Reporting [Abstract]
Segments	4. Segments The chief operating decision maker (“CODM”) reviews the Group's ongoing underwriting operations across three operating segments: Specialty, Bespoke, and Reinsurance. In determining how to allocate resources and assess the performance of the Group's underwriting results, management considers many factors including the nature of the insurance product offered, the risks that are covered and the nature of the client. The Specialty segment comprises a specialized portfolio of niche risks that includes Aviation and Aerospace, Energy, Marine, Property, Property Direct & Facultative (“D&F”) business and other specialty risks. The Bespoke segment is highly specialized in nature providing customized risk solutions for clients, which includes Credit & Political Risk and other specific risk transfer opportunities. The Reinsurance segment comprises a property catastrophe book, which includes Property Reinsurance, Retrocession and Whole Account reinsurance. Assets are not allocated to segments, nor are general and administrative expenses allocated between segments as employees, including underwriters, may work across different segments. The Fidelis Partnership commissions (see Note 13, Related Party Transactions) are not allocated to segments as they are not included in the measure of segment profit reviewed by the CODM, nor is a segment analysis of such expenses provided in other information reviewed by the CODM. The following tables summarize the Group's segment disclosures: Three Months Ended September 30, 2024 Specialty Bespoke Reinsurance Other Total Gross premiums written $ 398.4 $ 185.8 $ 157.7 $ — $ 741.9 Net premiums written 285.2 109.1 73.6 — 467.9 Net premiums earned 372.0 105.0 157.5 — 634.5 Losses and loss adjustment expenses (182.3) (19.4) (36.1) — (237.8) Policy acquisition expenses (122.4) (37.4) (36.9) (97.3) (294.0) General and administrative expenses — — — (22.7) (22.7) Underwriting income 67.3 48.2 84.5 (120.0) 80.0 Net investment income 52.1 Net realized and unrealized investment losses (0.5) Corporate and other expenses — Net foreign exchange losses (4.8) Financing costs (8.9) Income before income taxes 117.9 Income tax expense (17.3) Net income $ 100.6 Losses and loss adjustment expenses incurred - current year (168.3) (30.5) (49.1) $ (247.9) Losses and loss adjustment expenses incurred - prior accident years (14.0) 11.1 13.0 10.1 Losses and loss adjustment expenses incurred - total $ (182.3) $ (19.4) $ (36.1) $ (237.8) Underwriting Ratios (1) Loss ratio - current year 45.2 % 29.1 % 31.2 % 39.1 % Loss ratio - prior accident years 3.8 % (10.6 %) (8.3 %) (1.6 %) Loss ratio - total 49.0 % 18.5 % 22.9 % 37.5 % Policy acquisition expense ratio 32.9 % 35.6 % 23.4 % 31.0 % Underwriting ratio 81.9 % 54.1 % 46.3 % 68.5 % The Fidelis Partnership commissions ratio 15.3 % General and administrative expense ratio 3.6 % Combined ratio 87.4 % _________________ (1) Underwriting ratios are calculated by dividing the related expense by net premiums earned. Three Months Ended September 30, 2023 Specialty Bespoke Reinsurance Other Total Gross premiums written $ 326.9 $ 161.7 $ 104.0 $ — $ 592.6 Net premiums written 203.6 78.1 30.9 — 312.6 Net premiums earned 294.6 98.8 116.3 — 509.7 Losses and loss adjustment expenses (138.3) (43.2) (10.2) — (191.7) Policy acquisition expenses (83.4) (34.9) (32.5) (70.6) (221.4) General and administrative expenses — — — (21.8) (21.8) Underwriting income 72.9 20.7 73.6 (92.4) 74.8 Net investment income 33.1 Net realized and unrealized investment losses (5.3) Corporate and other expenses (0.4) Net foreign exchange gains 2.4 Financing costs (9.0) Income before income taxes 95.6 Income tax expense (7.9) Net income $ 87.7 Losses and loss adjustment expenses incurred - current year (141.0) (55.5) (38.5) $ (235.0) Losses and loss adjustment expenses incurred - prior accident years 2.7 12.3 28.3 43.3 Losses and loss adjustment expenses incurred - total $ (138.3) $ (43.2) $ (10.2) $ (191.7) Underwriting Ratios (1) Loss ratio - current year 47.8 % 56.1 % 33.1 % 46.1 % Loss ratio - prior accident years (0.9 %) (12.4 %) (24.3 %) (8.5 %) Loss ratio - total 46.9 % 43.7 % 8.8 % 37.6 % Policy acquisition expense ratio 28.3 % 35.3 % 27.9 % 29.6 % Underwriting ratio 75.2 % 79.0 % 36.7 % 67.2 % The Fidelis Partnership commissions ratio 13.9 % General and administrative expense ratio 4.3 % Combined ratio 85.4 % __________________ (1) Underwriting ratios are calculated by dividing the related expense by net premiums earned. Nine Months Ended September 30, 2024 Specialty Bespoke Reinsurance Other Total Gross premiums written $ 2,188.9 $ 429.9 $ 830.6 $ — $ 3,449.4 Net premiums written 1,337.5 189.8 388.6 — 1,915.9 Net premiums earned 1,073.4 287.9 262.3 — 1,623.6 Losses and loss adjustment expenses (545.9) (75.7) (21.2) — (642.8) Policy acquisition expenses (313.4) (101.1) (60.7) (249.0) (724.2) General and administrative expenses — — — (70.7) (70.7) Underwriting income 214.1 111.1 180.4 (319.7) 185.9 Net investment income 139.1 Net realized and unrealized investment losses (16.5) Corporate and other expenses (1.6) Net foreign exchange losses (4.9) Financing costs (26.1) Income before income taxes 275.9 Income tax expense (40.4) Net income $ 235.5 Losses and loss adjustment expenses incurred - current year (580.4) (137.9) (70.2) $ (788.5) Losses and loss adjustment expenses incurred - prior accident years 34.5 62.2 49.0 145.7 Losses and loss adjustment expenses incurred - total $ (545.9) $ (75.7) $ (21.2) $ (642.8) Underwriting Ratios (1) Loss ratio - current year 54.1 % 47.9 % 26.8 % 48.6 % Loss ratio - prior accident years (3.2 %) (21.6 %) (18.7 %) (9.0 %) Loss ratio - total 50.9 % 26.3 % 8.1 % 39.6 % Policy acquisition expense ratio 29.2 % 35.1 % 23.1 % 29.3 % Underwriting ratio 80.1 % 61.4 % 31.2 % 68.9 % The Fidelis Partnership commissions ratio 15.3 % General & administrative expense ratio 4.4 % Combined ratio 88.6 % _________________ (1) Underwriting ratios are calculated by dividing the related expense by net premiums earned. Nine Months Ended September 30, 2023 Specialty Bespoke Reinsurance Other Total Gross premiums written $ 1,818.3 $ 367.2 $ 609.6 $ — $ 2,795.1 Net premiums written 1,158.4 189.9 239.1 — 1,587.4 Net premiums earned 868.0 280.4 176.4 — 1,324.8 Losses and loss adjustment expenses (416.4) (72.5) (20.7) — (509.6) Policy acquisition expenses (227.2) (105.1) (45.6) (147.4) (525.3) General and administrative expenses — — — (57.0) (57.0) Underwriting income 224.4 102.8 110.1 (204.4) 232.9 Net investment income 80.8 Net realized and unrealized investment losses (2.4) Other income 0.2 Net gain on distribution of The Fidelis Partnership 1,639.1 Corporate and other expenses (3.4) Net foreign exchange gains 0.8 Financing costs (26.6) Income before income taxes 1,921.4 Income tax expense (17.2) Net income $ 1,904.2 Losses and loss adjustment expenses incurred - current year (383.7) (101.1) (72.6) $ (557.4) Losses and loss adjustment expenses incurred - prior accident years (32.7) 28.6 51.9 47.8 Losses and loss adjustment expenses incurred - total $ (416.4) $ (72.5) $ (20.7) $ (509.6) Underwriting Ratios (1) Loss ratio - current year 44.2 % 36.1 % 41.1 % 42.1 % Loss ratio - prior accident years 3.8 % (10.2 %) (29.4 %) (3.6 %) Loss ratio - total 48.0 % 25.9 % 11.7 % 38.5 % Policy acquisition expense ratio 26.2 % 37.5 % 25.9 % 28.5 % Underwriting ratio 74.2 % 63.4 % 37.6 % 67.0 % The Fidelis Partnership commissions ratio 11.1 % General & administrative expense ratio 4.3 % Combined ratio 82.4 % __________________ (1) Underwriting ratios are calculated by dividing the related expense by net premiums earned.

Investments

Investments	9 Months Ended
	Sep. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Investments	5. Investments At September 30, 2024, the Group’s investments are substantially all managed by external investment managers through individual investment management agreements. The Group monitors activity and performance of the external managers on an ongoing basis. a. Fixed maturity securities The following table summarizes the fair value of fixed maturity investments: September 30, 2024 Amortized Cost Unrealized Unrealized Fair U.S. Treasuries $ 702.7 $ 13.9 $ (0.8) $ 715.8 Agencies 12.0 0.1 — 12.1 Non-U.S. government 51.0 0.9 (0.1) 51.8 Corporate bonds 1,965.7 46.4 (2.5) 2,009.6 Residential mortgage-backed 272.3 6.1 (3.8) 274.6 Commercial mortgage-backed 21.5 0.1 (0.2) 21.4 Other asset backed securities 446.6 3.9 (0.5) 450.0 Total fixed maturity securities $ 3,471.8 $ 71.4 $ (7.9) $ 3,535.3 December 31, 2023 Amortized Cost Unrealized Unrealized Fair U.S. Treasuries $ 692.4 $ 4.1 $ (9.8) $ 686.7 Agencies 16.2 0.1 (0.1) 16.2 Non-U.S. government 77.6 0.2 (1.8) 76.0 Corporate bonds 1,798.4 14.7 (25.8) 1,787.3 Residential mortgage-backed 192.0 2.0 (5.8) 188.2 Commercial mortgage-backed 53.1 — (2.0) 51.1 Other asset backed securities 441.7 1.3 (3.6) 439.4 Total fixed maturity securities $ 3,271.4 $ 22.4 $ (48.9) $ 3,244.9 Review of the fixed maturity securities is performed on a regular basis to consider concentration, credit quality and compliance with established guidelines. For individual fixed maturity securities, nationally recognized statistical rating organizations are used and the lower of two or middle of three ratings is taken. The composition of the fair values of fixed maturity securities by credit rating is as follows: September 30, 2024 December 31, 2023 Fair Value % Fair Value % AAA $ 455.2 13 % $ 399.5 12 % AA 1,242.8 35 % 1,119.0 35 % A 1,419.2 40 % 1,145.8 35 % BBB 416.6 12 % 573.6 18 % BB 1.5 — % 7.0 — % Total fixed maturity securities $ 3,535.3 100 % $ 3,244.9 100 % The contractual maturities for fixed maturity securities are listed in the following table: September 30, 2024 December 31, 2023 Amortized Cost Fair Value Amortized Cost Fair Value Due in one year or less $ 220.5 $ 219.9 $ 566.7 $ 555.9 Due after one year through five years 2,288.2 2,331.9 2,130.3 2,119.5 Due after five years through ten years 602.2 619.4 255.5 256.0 Due after ten years 360.9 364.1 318.9 313.5 Total fixed maturity securities $ 3,471.8 $ 3,535.3 $ 3,271.4 $ 3,244.9 Expected maturities may differ from contractual maturities as borrowers may have the right to call or repay obligations with or without call or prepayment penalties. Additionally, lenders may have the right to put the securities back to the borrower. b. Short-term investments The following investments were included in short-term investments and are classified as available-for-sale: September 30, 2024 Amortized Cost Unrealized Unrealized Fair U.S. Treasuries $ 133.1 $ 0.2 $ — $ 133.3 Total short-term investments $ 133.1 $ 0.2 $ — $ 133.3 December 31, 2023 Amortized Cost Unrealized Unrealized Fair U.S. Treasuries $ 49.0 $ — $ — $ 49.0 Total short-term investments $ 49.0 $ — $ — $ 49.0 The composition of the fair values of short-term investments by credit rating is as follows: September 30, 2024 December 31, 2023 Fair Value % Fair Value % AA $ 133.3 100 % $ 49.0 100 % Total short-term investments $ 133.3 100 % $ 49.0 100 % c. Available-for-sale - net loss position The following table summarizes, by type of security, the aggregate fair value and gross unrealized loss by length of time the security has been in an unrealized loss position for the Group’s available-for-sale portfolio: September 30, 2024 0 - 12 months > 12 months Fair Gross unrealized losses Gross unrealized losses Number of securities U.S. Treasuries $ 52.2 $ (0.1) $ (0.7) 20 Agencies 0.6 — — 1 Non-U.S. government 2.7 — (0.1) 2 Corporate bonds 164.1 (0.1) (2.4) 106 Residential mortgage-backed 29.0 (0.1) (3.7) 37 Commercial mortgage-backed 13.7 — (0.2) 6 Other asset backed securities 63.8 — (0.5) 23 Total $ 326.1 $ (0.3) $ (7.6) 195 December 31, 2023 0 - 12 months > 12 months Fair Gross unrealized losses Gross unrealized losses Number of securities U.S. Treasuries $ 362.2 $ (0.2) $ (9.6) 52 Agencies 5.9 — (0.1) 5 Non-U.S. government 51.3 — (1.8) 29 Corporate bonds 894.8 (0.9) (24.9) 527 Residential mortgage-backed 84.3 (0.2) (5.6) 54 Commercial mortgage-backed 43.2 (0.1) (1.9) 23 Other asset backed securities 208.2 (0.3) (3.3) 74 Total $ 1,649.9 $ (1.7) $ (47.2) 764 At September 30, 2024, on a security level basis, 195 securities out of a total of approximately 1,141 securities were in an unrealized loss position and the largest single unrealized loss from a single security in the Group’s fixed maturity portfolio was $0.5 million. The Group believes that such securities were temporarily impaired at September 30, 2024. At December 31, 2023, on a security level basis, approximately 764 securities out of a total of approximately 1,263 securities were in an unrealized loss position and the largest single unrealized loss from a single security in the Group’s fixed maturity portfolio was $1.7 million. d. Allowance for Expected Credit Losses - Available-for-sale The following table provides a roll forward of the allowance for expected credit losses of the Group’s securities classified as available-for-sale: Three months ended Nine months ended September 30, 2024 September 30, 2023 September 30, 2024 September 30, 2023 Balance at beginning of period $ 3.2 $ 1.9 $ 1.3 $ 1.1 Expected credit losses on securities where credit losses were not previously recognized — 2.7 1.7 4.1 Additions/(reductions) for expected credit losses on securities where credit losses were previously recognized (2.7) 1.2 (2.2) 0.6 Securities sold/redeemed/matured (0.2) — (0.5) — Balance at end of period $ 0.3 $ 5.8 $ 0.3 $ 5.8 The Group assesses each quarter whether the decline in the fair value of an available-for-sale investment below its amortized cost is the result of a credit loss. All available-for-sale securities with unrealized losses are reviewed. The Group considers many factors to determine whether a credit loss exists, including the extent to which fair value is below cost, the implied yield to maturity, rating downgrades of the security and whether or not the issuer has failed to make scheduled principal or interest payments. The Group also takes into consideration information about the financial condition of the issuer and industry factors that could negatively impact the capital markets. If the decline in fair value of an available-for-sale security below its amortized cost is considered to be the result of a credit loss, the Group compares the estimated present value of the cash flows expected to be collected to the amortized cost of the security. The extent to which the estimated present value of the cash flows expected to be collected is less than the amortized cost of the security represents the expected credit loss, which is recorded as an allowance and recognized in net income. e. Other investments, at fair value At September 30, 2024, other investments consisted primarily of an opportunistic fixed income Undertakings for the Collective Investment in Transferable Securities fund managed by Wellington Investment Management ("Wellington Funds"). September 30, 2024 December 31, 2023 Fair Value % Fair Value % Wellington Funds $ 48.6 100 % $ 46.9 99 % Other securities valued at net asset value per share 0.1 — % 0.6 1 % Total other investments at fair value $ 48.7 100 % $ 47.5 100 % In 2021, the Group invested $50.0 million in Wellington Funds. The fair value of the investment at September 30, 2024, was $48.6 million (December 31, 2023: $46.9 million). f. Net Investment Income and Net Realized and Unrealized Investment Gains The components of net investment return are as follows: Three Months Ended Nine Months Ended September 30, 2024 September 30, 2023 September 30, 2024 September 30, 2023 Net interest and dividend income $ 53.4 $ 34.0 $ 142.9 $ 83.5 Investment expenses (1.3) (0.9) (3.8) (2.7) Net investment income 52.1 33.1 139.1 80.8 Net realized losses on fixed maturity securities, available-for-sale (6.0) (0.2) (19.5) (0.6) Net realized gains on other investments 0.1 — 0.1 2.2 Change in net unrealized gains/(losses) on other investments 2.5 (1.2) 1.9 0.7 Change in provision for expected credit losses 2.9 (3.9) 1.0 (4.7) Net realized and unrealized investment losses (0.5) (5.3) (16.5) (2.4) Total realized and unrealized investments gains/(losses) and net investment income $ 51.6 $ 27.8 $ 122.6 $ 78.4

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	6. Fair Value Measurements FASB ASC 820-10, Fair Value Measurements and Disclosures, defines fair value, establishes a consistent framework for measuring fair value and requires disclosures about fair value measurements. The standard requires the Group to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Fair value hierarchy FASB ASC 820-10 specifies a hierarchy of inputs based on whether the inputs are observable or unobservable. Observable inputs are developed using market data and reflect market participant assumptions, while unobservable inputs reflect the Group’s market assumptions. The fair value hierarchy is as follows: • Level 1: Inputs to the valuation methodology are quoted prices (unadjusted) for identical assets or liabilities traded in active markets. The fair value is determined by multiplying the quoted price by the quantity held by the Group. • Level 2: Inputs to the valuation methodology include quoted prices for similar assets or liabilities in active markets, quoted prices (e.g. interest rates, yield curves, prepayment spreads, default rate, etc.) for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability or can be corroborated by observable market data. • Level 3: Inputs to the valuation methodology are unobservable for the asset or liability and are significant to the fair value measurement. Significant management assumptions can be used to establish management’s best estimate of the assumptions used by other market participants in determining the fair value of the asset or liability. As required under the fair value hierarchy, the Group considers relevant and observable market inputs in its valuations where possible. The frequency of transactions, the size of the bid-ask spread and the amount of adjustment necessary when comparing similar transactions are all factors in determining the liquidity of markets and the relevance of observable prices in those markets. The Group’s policy with respect to transfer between levels of the fair value hierarchy is to recognize transfers into and out of each level as of the end of the reporting period. Determination of fair value The following section describes the valuation methodologies used by the Group to measure assets and liabilities at fair value, including an indication of the level within the fair value hierarchy in which each asset or liability is generally classified. Fixed maturity securities Fair values for all securities in the fixed income investment portfolio are independently provided by the investment administrator, investment custodians, and investment managers, each of which utilize internationally recognized independent pricing services. For determining the fair value of securities that are not actively traded, in general, pricing services use “matrix pricing” in which the independent pricing service uses observable market inputs including, but not limited to, reported trades, benchmark yields, broker-dealer quotes, interest rates, prepayment spreads, default rates and such other inputs as are available from market sources to determine a reasonable fair value. The following describes the techniques generally used to determine the fair value of the Group’s fixed maturity securities by asset class. • U.S. Treasuries are bonds issued by the U.S. government. The significant inputs used to determine the fair value of these securities are based on quoted prices in active markets for identical assets and are therefore classified within Level 1. • Agency securities consist of securities issued by U.S. and non-U.S. government sponsored agencies such as the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, government development banks and other agencies which are not mortgage pass-through. The fair values of these securities are classified as Level 2. • Non-U.S. government securities consist of bonds issued by non-U.S. governments and supranationals. The significant inputs used to determine the fair value of these securities include the spread above the risk-free yield curve, reported trades and broker-dealer quotes. These are considered to be observable market inputs and, therefore, the fair values of these securities are classified within Level 2. • Corporate bonds consist primarily of investment-grade debt of a wide variety of corporate issuers and industries. When available, significant inputs are used to determine the fair value of these securities and are based on quoted prices in active markets for similar assets. When not available, the fair values of these securities are determined using the spread above the risk-free yield curve, reported trades, broker-dealer quotes, benchmark yields, and industry and market indicators. The fair values of these securities are classified as Level 2. • Residential mortgage-backed securities include agency mortgage-backed securities and agency collateralized mortgage obligations. These are individually evaluated using option adjusted spreads (“OAS”) and nominal spreads. The OAS valuations use a third-party prepayment model and OAS. Spreads are based upon tranche type and average life volatility. These spreads are gathered from dealer quotes, trade prices, and the new issue market. The fair values of these securities are classified as Level 2. • Commercial mortgage-backed securities consist of investment grade bonds backed by pools of loans with underlying collateral. Securities held in this sector are primarily priced by pricing services. Inputs to the valuation process include broker-dealer quotes and other available trade information, prepayment speeds, current price data, the swap curve as well as cash settlement. The fair values of these securities are classified as Level 2. • Other asset-backed securities consist of investment grade bonds backed by pools of loans with underlying collateral. The underlying collateral for asset-backed securities consists mainly of student loans, automobile loans and credit card receivables. These securities are primarily priced by index providers and pricing vendors. Inputs to the valuation process include broker-dealer quotes and other available trade information, prepayment speeds, tranche type, interest rate data and credit spreads. The Group classifies these securities within Level 2. Short-term investments The Group’s short-term investments consist of commercial paper and bonds with maturities of 90 days or greater but less than one year at the time of purchase. The significant inputs used to determine the fair value of these securities include the spread above the risk-free yield curve, reported trades and broker-dealer quotes. These are considered to be observable market inputs and, therefore, the fair values of these securities are classified within Level 1. Derivative assets and liabilities Exchange-traded derivatives, measured at fair value using quoted prices in active markets, where available, are classified as Level 1 of the fair value hierarchy. Derivatives without quoted prices in an active market and derivatives executed over the counter are valued using internal valuation techniques that consider the time value of money, volatility, the current market and contractual prices of underlying financial instruments. These derivative instruments are classified as either Level 2 or Level 3 depending upon the observability of the significant inputs to the model. The valuation techniques and key inputs depend on the type of derivative and the nature of the underlying instrument. Other investments The fair value of the Wellington Funds is based on unadjusted quoted market prices in active markets; therefore, the fair value of this security is classified as Level 1. The following table presents the financial instruments measured at fair value on a recurring basis at September 30, 2024 and December 31, 2023: September 30, 2024 Assets Level 1 Level 2 Level 3 Total Cash equivalents - money market funds $ 663.3 $ — $ — $ 663.3 Fixed maturity securities U.S. Treasuries 715.8 — — 715.8 Agencies — 12.1 — 12.1 Non-U.S. government — 51.8 — 51.8 Corporate bonds — 2,009.6 — 2,009.6 Residential mortgage-backed — 274.6 — 274.6 Commercial mortgage-backed — 21.4 — 21.4 Other asset backed securities — 450.0 — 450.0 Total fixed maturity securities 715.8 2,819.5 — 3,535.3 Short-term investments U.S. Treasuries 133.3 — — 133.3 Total short-term investments 133.3 — — 133.3 Other investments* 48.6 — — 48.6 Other assets Investments pending settlement 0.6 — — 0.6 Total other assets 0.6 — — 0.6 Total assets measured at fair value $ 1,561.6 $ 2,819.5 $ — $ 4,381.1 Liabilities Other liabilities Derivative liabilities $ — $ (6.1) $ — $ (6.1) Investments pending settlement (5.5) — — (5.5) Total other liabilities (5.5) (6.1) — (11.6) Total liabilities measured at fair value $ (5.5) $ (6.1) $ — $ (11.6) __________________ * excludes investments valued at net asset value per share. December 31, 2023 Assets Level 1 Level 2 Level 3 Total Cash equivalents - money market funds $ 557.9 $ — $ — $ 557.9 Fixed maturity securities U.S. Treasuries 686.7 — — 686.7 Agencies — 16.2 — 16.2 Non-U.S. government — 76.0 — 76.0 Corporate bonds — 1,787.3 — 1,787.3 Residential mortgage-backed — 188.2 — 188.2 Commercial mortgage-backed — 51.1 — 51.1 Other asset backed securities — 439.4 — 439.4 Total fixed maturity securities 686.7 2,558.2 — 3,244.9 Short-term investments U.S. Treasuries 49.0 — — 49.0 Total short-term investments 49.0 — — 49.0 Other investments* 46.9 — — 46.9 Other assets Investments pending settlement 2.2 — — 2.2 Total other assets 2.2 — — 2.2 Total assets measured at fair value $ 1,342.7 $ 2,558.2 $ — $ 3,900.9 Liabilities Other liabilities Derivative liabilities $ — $ (1.1) $ — $ (1.1) Total other liabilities — (1.1) — (1.1) Total liabilities measured at fair value $ — $ (1.1) $ — $ (1.1) __________________ * excludes investments valued at net asset value per share. There were no transfers into or out of Level 1 and Level 2 during the nine months ended September 30, 2024 and the year ended December 31, 2023. Fair Value of Financial Instrument Liabilities The following table includes financial instruments for which the carrying value differs from the estimated fair values at September 30, 2024 and December 31, 2023. The fair values of the below financial instruments are based on observable inputs and are considered Level 2 measurements. September 30, 2024 December 31, 2023 Fair Value Carrying Value Fair Value Carrying Value 4.875% Senior notes due 2030 $ 326.3 $ 325.6 $ 273.1 $ 325.0 6.625% Fixed Rate Reset Junior Subordinated notes due 2041 123.8 123.2 121.6 123.2 Preference securities $ 56.9 $ 58.4 $ 55.6 $ 58.4

Total Cash, Cash Equivalents, R

Total Cash, Cash Equivalents, Restricted Cash and Restricted Investments	9 Months Ended
	Sep. 30, 2024
Cash and Cash Equivalents [Abstract]
Total Cash, Cash Equivalents, Restricted Cash and Restricted Investments	7. Total Cash, Cash Equivalents, Restricted Cash and Restricted Investments The Group has cash and investments in trust funds that support the insurance contracts written on certain lines of business and in segregated portfolios primarily to provide collateral for letters of credit. The following table provides a summary of cash and cash equivalents, restricted cash and restricted investments at September 30, 2024 and December 31, 2023: September 30, December 31, 2023 Cash and cash equivalents $ 806.8 $ 712.4 Restricted cash securing letter of credit facilities 8.9 5.8 Restricted cash securing reinsurance contracts 203.4 245.9 Total cash, cash equivalents and restricted cash 1,019.1 964.1 Restricted investments securing reinsurance contracts and letter of credit facilities 1,225.7 1,347.0 Total cash, cash equivalents, restricted cash and restricted investments $ 2,244.8 $ 2,311.1

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	8. Derivative Financial Instruments The Group enters into derivative instruments such as futures and forward contracts primarily for duration, interest rate and foreign currency exposure management. The Group’s derivative instruments are generally traded under International Swaps and Derivatives Association master agreements, which establish the terms of the transactions entered into with the Group’s derivative counterparties. In the event one party becomes insolvent or otherwise defaults on its obligations, a master agreement generally permits the non-defaulting party to accelerate and terminate all outstanding transactions and net the transactions’ marked-to-market values so that a single sum in a single currency will be owed by, or owed to, the non-defaulting party. Effectively, this contractual close-out netting reduces credit exposure from gross to net exposure. The following tables identify the listing currency, fair value and notional amounts of derivative instruments included in the Consolidated Balance Sheets, categorized by primary underlying risk: September 30, 2024 December 31, 2023 Listing currency (1) Notional amounts (2) Fair value Notional amounts (2) Fair value Derivative liabilities by primary underlying risk Foreign exchange contracts Forwards (3) AUD/CAD/EUR/GBP/JPY $ 176.2 $ (6.1) $ (9.7) $ (1.1) Total derivative liabilities $ 176.2 $ (6.1) $ (9.7) $ (1.1) __________________ (1) AUD = Australian Dollar, CAD = Canadian Dollar, EUR = Euro, GBP = British Pound Sterling and JPY = Japanese Yen. (2) The absolute notional exposure represents the Group’s derivative activity, which is representative of the volume of derivatives held during the period. (3) Contracts used to manage foreign currency risks in underwriting and non-investment operations. The following table presents derivative instruments by major risk type, the Group’s net realized gains/(losses) and change in net unrealized gains/(losses) relating to derivative trading activities for the three and nine months ended September 30, 2024 and 2023. Net realized gains/(losses) and net unrealized gains/(losses) related to derivatives are included in net foreign exchange (gains)/losses in the Consolidated Statements of Income. Three Months Ended Nine Months Ended September 30, 2024 September 30, 2023 September 30, 2024 September 30, 2023 Derivatives Net realized gains/(losses) Change in net unrealized Net realized gains/(losses) Change in net unrealized gains/(losses) Net realized gains/(losses) Change in net unrealized Net realized gains/(losses) Change in net unrealized gains/(losses) Foreign exchange contracts Forwards (1) $ (3.4) $ (4.7) $ (1.8) $ 4.6 $ (4.7) $ (5.0) $ 0.5 $ (3.0) Total foreign exchange contracts (3.4) (4.7) (1.8) 4.6 (4.7) (5.0) 0.5 (3.0) Total $ (3.4) $ (4.7) $ (1.8) $ 4.6 $ (4.7) $ (5.0) $ 0.5 $ (3.0) __________________ (1) Contracts used to manage foreign currency risks in underwriting and non-investment operations. The Group obtains/provides collateral from/to counterparties for over-the-counter derivative financial instruments in accordance with bilateral credit facilities. The Group does not offset its derivative instruments and presents all amounts in the Consolidated Balance Sheets on a gross basis. Unrealized gains are included within other assets and unrealized losses are included within other liabilities. The Group has pledged cash collateral to counterparties to support the current value of amounts due to the counterparties based on the value of the underlying security.

Reserves for Losses and Loss Ad

Reserves for Losses and Loss Adjustment Expenses	9 Months Ended
	Sep. 30, 2024
Insurance [Abstract]
Reserves for Losses and Loss Adjustment Expenses	9. Reserves for Losses and Loss Adjustment Expenses The reserves for losses and loss adjustment expenses include an amount determined from reported claims, and estimates based on historical loss experience and industry statistics for losses incurred but not reported using a variety of actuarial methods. The unpaid reported reserves for losses and loss adjustment expenses are established by management based on reports from brokers, ceding companies and insureds and represent the estimated ultimate cost of events or conditions that have been reported to, or specifically identified by the Group. The reserves for IBNR losses and loss adjustment expenses are established by management based on actuarially determined estimates of ultimate losses and loss adjustment expenses. Inherent in the estimate of ultimate losses and loss adjustment expenses are expected trends in claim severity and frequency and other factors which may vary significantly as claims are settled. Accordingly, ultimate losses and loss adjustment expenses may differ materially from the amounts recorded in the consolidated financial statements. These estimates are reviewed regularly and, as experience develops and new information becomes known, the reserves are adjusted as necessary. Such adjustments, if any, will be recorded in losses and loss adjustment expenses in the period in which they become known. IBNR reserves are calculated on a best estimate basis and are estimated by management using various actuarial methods as well as the Group’s own growing loss experience, historical insurance industry loss experience, estimates of pricing adequacy trends and management’s professional judgement. Due to the limited historical data available, reliance is placed upon industry data and a review of individual policies. Estimates are calculated at the lowest level line of business, separately for gross and ceded, and for attritional, extreme and catastrophic claims. The reserve estimates contain an inherent level of uncertainty and actual results may vary, potentially significantly, from the estimates the Group has made. Reserves are reviewed on a quarterly basis and estimates are adjusted to reflect emerging claims experience. The Group estimates reserves for unallocated claims adjustment expenses (“ULAE”) based on a percentage of loss reserves as determined by management. However, this may be overridden in exceptional circumstances where this approach is not deemed appropriate. There were no material changes made to the Group’s methodology for calculating reserves for unallocated claims adjustment expenses for the nine months ended September 30, 2024. The following table presents a reconciliation of reserves for losses and loss adjustment expenses for the nine months ended September 30, 2024 and September 30, 2023: September 30, 2024 September 30, 2023 Reserves for losses and loss adjustment expenses, beginning of period $ 2,448.9 $ 2,045.2 Reinsurance recoverable on reserves for losses and loss adjustment expenses (1,108.6) (976.1) Net reserves for losses and loss adjustment expenses, beginning of period 1,340.3 1,069.1 Net losses and loss adjustment expenses incurred in respect of losses occurring in: Current year 788.5 557.4 Prior years (145.7) (47.8) Total incurred 642.8 509.6 Net losses and loss adjustment expenses paid in respect of losses occurring in: Current year (97.7) (61.9) Prior years (251.5) (267.1) Total paid (349.2) (329.0) Foreign exchange 2.0 (7.4) Net reserves for losses and loss adjustment expenses, end of period 1,635.9 1,242.3 Reinsurance recoverable on reserves for losses and loss adjustment expenses 1,164.9 1,066.3 Reserves for losses and loss adjustment expenses, end of period $ 2,800.8 $ 2,308.6 As a result of the changes in estimates of insured events in prior years, the reserves for losses and loss adjustment expenses net of reinsurance recoveries for prior accident year periods decreased by $145.7 million for the nine months ended September 30, 2024 (2023: $47.8 million). Net favorable development for the nine months ended September 30, 2024, resulted from better than expected loss development across all segments. The favorable development in the Bespoke segment of $62.2 million was driven by benign attritional experience and favorable claims settlements. The favorable development in the Reinsurance segment of $49.0 million was driven by positive development on catastrophe losses and benign prior year attritional experience. The favorable development in the Specialty segment of $34.5 million was driven primarily by better than expected loss emergence in our Property D&F and Marine lines of business, partially offset by an increase in our Aviation and Aerospace line of business. Net favorable development for the nine months ended September 30, 2023, resulted from better than expected loss development in the Reinsurance and Bespoke segments, partially offset by net adverse development in the Specialty segment. The favorable development in the Reinsurance segment of $51.9 million related primarily to loss reductions from Hurricane Ian as well as favorable attritional experience driven by a benign claim experience on prior accident years. The favorable development in the Bespoke segment of $28.6 million was primarily driven by better than expected loss emergence. The adverse development in the Specialty segment of $32.7 million related primarily to increased estimates on two contracts in the Energy line of business, Winter Storm Elliot in the Property D&F line of business, as well as updated legal expense provisions in the reserve for the Ukraine Conflict in the Aviation and Aerospace line of business.

Reinsurance and Retrocessional

Reinsurance and Retrocessional Reinsurance	9 Months Ended
	Sep. 30, 2024
Insurance [Abstract]
Reinsurance and Retrocessional Reinsurance	10. Reinsurance and Retrocessional Reinsurance The Group is exposed to the credit risk of the reinsurers, including the risk that one of its reinsurers becomes insolvent or otherwise unable or unwilling to pay policyholder claims. This credit risk is generally mitigated by either selecting well capitalized, highly rated authorized capacity providers or requiring that the capacity provider post collateral to secure the reinsured risks, which, in some instances, exceeds the related reinsurance recoverable. Allowances are established for amounts deemed uncollectible. The Group evaluates the financial condition of its reinsurers on a regular basis and monitors concentrations of credit risk with reinsurers. At September 30, 2024, the reinsurance balance recoverable on reserves for losses and loss adjustment expenses was $1,164.9 million (December 31, 2023: $1,108.6 million) and the reinsurance balance recoverable on paid losses was $194.1 million (December 31, 2023: $182.7 million). In evaluating the allowance for expected credit losses, the Group assesses the probability of default and loss given default for each reinsurer. This uses counterparty ratings from a major rating agency and an assessment of the current market conditions for the likelihood of default. Although the Group has not experienced any credit losses to date, an inability of its reinsurers or retrocessionaires to meet their obligations to it over the relevant exposure periods for any reason could have a material adverse effect on its financial condition and results of operations. The allowance for expected credit losses of the Group's reinsurance recoverables due from third parties on paid and unpaid claims was $nil and $1.3 million at September 30, 2024, respectively (December 31, 2023: $nil and $1.3 million).

Long Term Debt and Preference S

Long Term Debt and Preference Securities	9 Months Ended
	Sep. 30, 2024
Debt Disclosure [Abstract]
Long Term Debt and Preference Securities	11. Long Term Debt and Preference Securities Long-term Debt On June 18, 2020, the Group issued $300.0 million and on July 2, 2020 the Group issued a further $30.0 million of its 4.875% Senior Notes due June 30, 2030 (collectively, the “Senior Notes”), with interest payable on June 30 and December 30 of each year, commencing on December 30, 2020. The Senior Notes are redeemable at the applicable redemption price, subject to the terms described in the indenture for the Senior Notes. However, the Senior Notes may not be redeemed at any time prior to their maturity if enhanced capital requirements, as established by the Bermuda Monetary Authority (“BMA”), would be breached immediately before or after giving effect to the redemption of such notes, unless, in each case, the Group replaces the capital represented by the Senior Notes to be redeemed with capital having equal or better capital treatment as the notes under applicable BMA rules. The Senior Notes contain covenants, including limitations on liens on the stock of certain designated subsidiaries, limitations on consolidations, mergers, amalgamations and sales of substantially all assets and certain reporting obligations. On October 16, 2020, the Group issued $105.0 million, and on October 20, 2020, the Group issued a further $20.0 million of its 6.625% Fixed-Rate Reset Junior Subordinated Notes due April 1, 2041 (collectively, the “Junior Notes”) with interest payable on April 1 and October 1 of each year, commencing on April 1, 2021. The interest rate is reset on April 1, 2026 at the U.S. five-year treasury rate on the reset interest determination date plus 6.323%, and every five years thereafter. The Junior Notes are redeemable at par value for six months after each interest rate reset date. The Junior Notes contain covenants, including limitations on liens on the stock of certain designated subsidiaries, limitations on consolidations, mergers, amalgamations and sales of substantially all assets and certain reporting obligations. The following table sets forth the principal amount of the debt issued as well as the unamortized discount and debt issuance costs at September 30, 2024 and December 31, 2023: September 30, 2024 December 31, 2023 Principal Unamortized Principal Unamortized 4.875% Senior notes due 2030 $ 330.0 $ (4.4) $ 330.0 $ (5.0) 6.625% Fixed Rate Reset Junior Subordinated notes due 2041 125.0 (1.8) 125.0 (1.8) Total $ 455.0 $ (6.2) $ 455.0 $ (6.8) Preference Securities In 2015, the Group issued shares of cumulative 9% preference securities with a redemption price equal to $10,000 per share, plus all declared and unpaid dividends (the “Preference Securities”). The Preference Securities are subject to mandatory redemption on June 15, 2050. The Preference Securities are subject to redemption at the option of the Group as follows: (i) if the redemption occurs prior to December 15, 2025, at an amount equal to the present value (calculated using the Treasury Rate plus 0.5%) of the redemption price plus the remaining scheduled dividend payments up to December 15, 2025; or (ii) if the redemption occurs after December 15, 2025, at an amount equal to the redemption price plus all accrued and unpaid dividends, if any, through the date of redemption. Holders of Preference Securities are entitled to receive quarterly dividend payments on March 15, June 15, September 15, and December 15 only when, and if, declared by the Group’s Board of Directors. To the extent declared, these dividends will accumulate, with respect to each dividend period, in the amount per share equal to 9% of the $10,000 liquidation preference per annum. From December 15, 2025, the dividend rate resets to the greater of: (i) three-month LIBOR plus 9.773% and (ii) 9%, determined quarterly. Due to the discontinuation of LIBOR on June 30, 2023, an alternative reference rate will be determined in advance of the interest rate reset date. Currently the holders of all Preference Securities do not have any voting rights. During the three and nine months ended September 30, 2024, the Group paid quarterly preference dividends of $1.3 million and $3.9 million, respectively, (2023: $1.3 million and $3.9 million) to holders of the Group’s Preference Securities. The preference dividends are recorded as a component of financing costs on the Consolidated Statements of Income. At September 30, 2024, dividends payable of $0.2 million (December 31, 2023: $0.2 million) are included in other liabilities. No other outstanding amounts are payable to holders of the Preference Securities. September 30, December 31, 2023 Preference securities, par value $0.01 per share Authorized 1,000,000 1,000,000 Issued and outstanding: 9% cumulative preference shares 5,835 5,835

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	12. Commitments and Contingencies a. Letter of credit facilities At September 30, 2024, and December 31, 2023, the Group had the following letter of credit facilities: September 30, 2024 December 31, 2023 Bank Commitment In Use Date of Expiry Commitment In Use Date of Expiry Lloyds Bank plc (2) Unsecured (1) $ 25.0 $ 19.8 September 21, 2025 $ 25.0 $ 20.6 September 20, 2024 Secured (1) 100.0 34.0 September 21, 2025 100.0 38.2 September 20, 2024 Ancillary own funds n/a n/a n/a 75.0 75.0 March 13, 2027 Total Lloyds Bank Plc 125.0 53.8 200.0 133.8 Citibank N.A. London branch (1)(2) Secured 70.0 44.0 December 31, 2024 70.0 52.3 December 31, 2024 Total Citibank N.A. London branch 70.0 44.0 70.0 52.3 Barclays Bank plc (1)(2) Unsecured 60.0 51.3 September 13, 2025 60.0 53.3 September 13, 2024 Secured 80.0 31.0 September 13, 2025 80.0 31.0 September 13, 2024 Total Barclays Bank plc 140.0 82.3 140.0 84.3 Bank of Montreal (1)(2) Unsecured 40.0 32.0 September 18, 2025 40.0 36.1 September 17, 2024 Secured 100.0 26.0 September 18, 2025 100.0 32.1 September 17, 2024 Total Bank of Montreal 140.0 58.0 140.0 68.2 Total letters of credit facilities $ 475.0 $ 238.1 $ 550.0 $ 338.6 __________________ (1) Letters of credit can be issued under the Standby Letter of Credit Facility for the purposes of supporting insurance and reinsurance obligations. (2) The Facility agreements allow for additional capacity in the form of accordions and uncommitted amounts. The maximum additional capacity from the lenders as of September 30, 2024, was: Lloyds Bank plc $50.0 million; Citibank N.A. London Branch $200.0 million; Barclays Bank plc $80.0 million; and Bank of Montreal $60.0 million. The following table shows the collateral underlying the secured letter of credit facilities: Bank September 30, 2024 December 31, 2023 Lloyds Bank plc $ 43.1 $ 44.2 Citibank N.A. London branch 46.4 55.2 Barclays Bank plc 41.4 37.7 Bank of Montreal 31.4 35.9 Total $ 162.3 $ 173.0 The Group's letter of credit facilities are generally bilateral agreements with a one two The Group also entered into a Standby Letter of Credit Facility Agreement with Lloyds to provide regulated capital in respect of Ancillary Own Funds (“AOF”). On August 6, 2024, the Prudential Regulation Authority granted approval such that the AOF expiry date could be amended to August 30, 2024. Following receipt of this approval, the AOF facility was cancelled effective August 30, 2024. b. Legal proceedings From time to time in the normal course of business, the Group may be involved in formal and informal dispute resolution procedures, which may include arbitration or litigation, the outcomes of which determine the rights and obligations of the Group under the Group’s (re)insurance contracts, and other contractual agreements, or other matters as the case may be. In some disputes, the Group may seek to enforce its rights under an agreement or to collect funds owing to it. In other matters, the Group may resist attempts by others to collect funds or enforce alleged rights. While the final outcome of legal disputes that may arise cannot be predicted with certainty, the Group does not believe that the eventual outcome of any specific litigation, arbitration or alternative dispute resolution proceedings to which the Group is currently a party will have a material adverse effect on the financial condition of the Group’s business as a whole after consideration of any applicable reserves. c. Concentration of credit risk Credit risk arises out of the failure of a counterparty to perform according to the terms of the contract. The Group underwrites a significant portion of its (re)insurance business through brokers and as a result credit risk exists should any of these brokers be unable to fulfil their contractual obligations with respect to the payments of premium or failure to pass on claims, if there is risk transfer, to the Group. The Group has policies and standards in place to manage and monitor the credit risk of intermediaries with a focus on day-to-day monitoring of the largest positions. Note 10 (Reinsurance and Retrocessional Reinsurance) describes the credit risk related to the Group’s reinsurance recoverables.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2024
Related Party Transactions [Abstract]
Related Party Transactions	3. Separation Transactions On January 3, 2023, the Group completed a transaction pursuant to which (i) Pine Walk and its investments in the MGAs, together with FML, were distributed to shareholders to form a new managing general underwriting business, The Fidelis Partnership and (ii) The Fidelis Partnership was acquired by a consortium of investors. Following the consummation of the Separation Transactions, The Fidelis Partnership acquired 9.9% of the common shares in the Group. The Separation Transactions resulted in certain shareholders receiving cash in lieu of their interest in The Fidelis Partnership. As a result, the distribution of The Fidelis Partnership was recorded at its fair value of $1,775.0 million. The fair value was determined in accordance with the requirements of Financial Accounting Standards Board Accounting Standards Codification 820 – Fair Value Measurements (“ASC 820”). We obtained the services of a third-party independent valuation expert in arriving at that determination of fair value. ASC 820 explains the concept of fair value for financial reporting. Under ASC 820, fair value is a market-based measurement, not an entity specific measurement. The objective of ASC 820 is to estimate the price at which an orderly transaction to sell the asset would take place between market participants at the measurement date under current market conditions (that is, an exit price at the measurement date from the perspective of a market participant). When a price for an identical asset is not observable, a reporting entity measures fair value using another valuation technique that maximizes the use of relevant observable inputs and minimizes the use of unobservable inputs. Fair value is measured using the assumptions that market participants would use when pricing the asset or liability, including assumptions about risk. For purposes of the valuation of The Fidelis Partnership, we used an income approach using a discounted cash flow methodology, and a market approach using comparable listed trading and precedent transaction multiples. These approaches generated a range of values for The Fidelis Partnership of $1.7 billion to $1.9 billion. The determined fair value for The Fidelis Partnership of $1,775.0 million was based on the price of the most recent transactions in The Fidelis Partnership shares, and close to the mid-point of the valuation range. On January 3, 2023, following the distribution of The Fidelis Partnership to shareholders of the Group, certain shareholders sold their shares, and certain third parties purchased shares, in The Fidelis Partnership at a price per share determined using a fair value of $1,775.0 million. Immediately prior to the consummation of the Separation Transactions, the Group accelerated the vesting of all unvested Restricted Share Units (“RSUs”). This resulted in the acceleration of compensation expense of $21.0 million and an employer payroll tax expense of $17.3 million in the nine months ended September 30, 2023. The RSUs and warrants were exercised on the date of the Separation Transactions, resulting in the issuance of 13,553,681 common shares. The RSUs were net settled, resulting in a $50.6 million reduction of additional paid-in capital for the employees’ tax obligations with respect to these awards. The exercise of the warrants triggered the payment of cumulative dividends of $34.1 million. The distribution of The Fidelis Partnership to shareholders of the Group resulted in the deconsolidation of net assets of $67.9 million, and the cancellation of 97,327,049 common shares in the Group. Following the Separation Transactions there were 110,771,897 common shares issued and outstanding. The distribution resulted in the elimination of the Group’s non-controlling interests, all of which related to the subsidiaries of Pine Walk. In connection with the successful consummation of the Separation Transactions, the Group incurred professional fee s of $28.6 million d uring the nine months ended September 30, 2023. The net gain on distribution of The Fidelis Partnership of $1,639.1 million has been calculated as the fair value of The Fidelis Partnership of $1,775.0 million, less the net assets of The Fidelis Partnership of $67.9 million and less the direct costs of the Separation Transactions of $68.0 million. Direct costs primarily related to professional fees of $28.6 million , acceleration of compensation expense of $21.0 million and an employer payroll tax expense of $17.3 million. Within operating activities on the Consolidated Statements of Cash Flows, the revaluation of The Fidelis Partnership of $1,707.1 million, being the fair value of The Fidelis Partnership of $1,775.0 million less the net assets of $67.9 million, is shown as a non-cash adjustment to reconcile net income to net cash provided by operating activities. On January 3, 2023, the financial statements of Pine Walk, the eight MGAs and FML have been deconsolidated and the non-controlling interests were disposed upon consummation of the Separation Transactions. 13. Related Party Transactions On January 3, 2023, The Fidelis Partnership acquired 9.9% of the common shares of the Group. Certain directors, executive officers and management of The Fidelis Partnership also own common shares of the Group. On December 20, 2022, the Group and The Fidelis Partnership entered into a rolling 10-year framework agreement (the “Framework Agreement”), effective January 1, 2023, that governs the ongoing relationship between the two groups. Years one to three roll automatically, whereas from year four onwards, the Framework Agreement will roll at the sole written election of the Group, with such election to be delivered at least 90 days prior to the commencement of the subsequent contract year. Any decision by FIHL to elect not to roll the Framework Agreement will mean that the remainder of the 10-year terms then in effect will continue in place. The underwriting activities of FIBL, FUL and FIID have been outsourced to the corresponding operating subsidiaries of The Fidelis Partnership on a jurisdictional basis. Each of FIBL, FUL and FIID have delegated underwriting authority to source and bind contracts to Shelf Opco Bermuda Limited, Pine Walk and Pine Walk Europe, respectively. The Fidelis Partnership manages origination, underwriting, underwriting administration and claims handling under delegated authority agreements with the Group. Other services provided by The Fidelis Partnership to the Group include sourcing and administering the outwards reinsurance program, and support with business planning, capital management, insurance contract accounting and information technology. The Framework Agreement provides for the payment of the following fees with effect from January 1, 2023: a. Ceding commissions: (i) a ceding commission of 11.5% of net premiums written of open market business procured by The Fidelis Partnership on or after January 1, 2023; (ii) a ceding commission of 3% of net premiums written of business sourced by The Fidelis Partnership via third party managing general underwriters on or after January 1, 2023; and (iii) a portfolio management fee of 3.0% of net premiums written of the business sourced by The Fidelis Partnership. b. Profit commission: a profit commission of 20.0% of the aggregate operating profit (as defined in the Framework Agreement) generated on the sourced business, subject to a hurdle rate of return of 5.0% of underwriting return on equity. For insurance contracts sourced by Pine Walk MGAs for FUL, FIBL or FIID, the fees and commissions follow separately negotiated arrangements, and will not attract additional commissions under the terms of the Framework Agreement. The following table summarizes The Fidelis Partnership commissions earned, which are included in policy acquisition expenses in the Consolidated Statements of Income: Three months ended Nine months ended September 30, 2024 September 30, 2023 September 30, 2024 September 30, 2023 Ceding commission expense $ 84.2 $ 56.3 $ 225.3 $ 107.4 Profit commission expense 13.1 14.3 23.7 40.0 Total commissions $ 97.3 $ 70.6 $ 249.0 $ 147.4 Amounts receivable from The Fidelis Partnership at September 30, 2024, of $248.5 million (December 31, 2023: $173.3 million) primarily consist of amounts collected by The Fidelis Partnership on behalf of the Group that were not remitted prior to the end of the quarter, and prepaid portfolio management fees. Amounts payable to The Fidelis Partnership at September 30, 2024, of $410.7 million (December 31, 2023: $334.5 million) primarily consist of amounts payable to The Fidelis Partnership for ceding and profit commissions, and claims paid by The Fidelis Partnership on the Group’s behalf. The Framework Agreement also provides that from January 1, 2023, in respect of commissions and profit commissions on ceded quota share business the Group shall retain 1.0% of reinsurance premiums ceded and the remainder is to be paid to The Fidelis Partnership. Commissions on ceded business for the three and nine months ended September 30, 2024, of $33.7 million and $76.8 million, respectively, (2023: $24.7 million and $37.3 million) were paid to The Fidelis Partnership. For the three and nine months ended September 30, 2024, profit commissions on ceded business of $40.9 million and $55.0 million, respectively, (2023: $12.9 million and $20.7 million) were paid to The Fidelis Partnership. Insurance contracts sourced by Pine Walk contain profit commissions based on the results of each individual contract. The expense/(income) for the three and nine months ended September 30, 2024, was $17.1 million and $33.6 million, respectively, (2023: $(4.1) million and $14.5 million) and was included within policy acquisition expenses. The Fidelis Partnership provides the Group with certain support services on a cost-plus basis, which include sourcing and administering outwards reinsurance, support with business planning, capital management, insurance contract accounting and information technology. Included within general and administrative expenses for the three and nine months ended September 30, 2024, are charges of $1.6 million and $4.6 million, respectively, (2023: $1.6 million and $4.3 million) from The Fidelis Partnership for such services. The Group provides certain services to The Fidelis Partnership for which it charged $0.7 million and $1.1 million for the three and nine months ended September 30, 2024, respectively, (2023: $0.6 million and $1.9 million). These charges to The Fidelis Partnership are included within general and administrative expenses.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Earnings Per Share	14. Earnings Per Share Three months ended Nine months ended September 30, 2024 September 30, 2023 September 30, 2024 September 30, 2023 Earnings per common share Net income $ 100.6 $ 87.7 $ 235.5 $ 1,904.2 Weighted average common shares outstanding 114,445,447 117,681,835 116,390,461 113,100,521 Earnings per common share $ 0.88 $ 0.75 $ 2.02 $ 16.84 Earnings per diluted common share Net income $ 100.6 $ 87.7 $ 235.5 $ 1,904.2 Weighted average common shares outstanding 114,445,447 117,681,835 116,390,461 113,100,521 Share-based compensation plans 289,079 293,264 455,530 132,409 Weighted average diluted common shares outstanding 114,734,526 117,975,099 116,845,991 113,232,930 Earnings per diluted common share $ 0.88 $ 0.74 $ 2.02 $ 16.82

Share Capital Authorized and Is

Share Capital Authorized and Issued	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Share Capital Authorized and Issued	15. Share Capital Authorized and Issued The following sets out the number and par value of shares authorized, issued and outstanding: September 30, 2024 December 31, 2023 Common shares, par value $0.01 per share Authorized 600,000,000 600,000,000 Issued and outstanding Common shares 111,726,363 117,914,754 Common shares On January 3, 2023, consummation of the Separation Transactions resulted in the issuance of 13,553,681 common shares upon exercise of outstanding warrants and accelerated vesting of restricted stock units. The distribution of The Fidelis Partnership to shareholders on January 3, 2023 resulted in the cancellation of 97,327,049 common shares in the Group. The consummation of the Separation Transactions triggered the payment of cumulative dividends on warrants of $34.1 million. These dividends related to declarations made in 2019 and prior years. The warrant dividends, together with the net assets distributed to shareholders discussed in Note 3 (Separation Transactions), were recorded in additional paid-in capital as the Group’s retained earnings on January 3, 2023 was $0.5 million. On January 3, 2023 the excess fair value of the net assets distributed to shareholders of $1,696.4 million was recorded in retained earnings as the gain on revaluation of The Fidelis Partnership was recorded in the Consolidated Statements of Income as a component of the net gain on distribution of The Fidelis Partnership. The excess fair value is calculated as the fair value of The Fidelis Partnership of $1,775 million less the book value of The Fidelis Partnership net assets and less the non-controlling interest share of Pine Walk. On July 3, 2023, Fidelis completed an IPO of an aggregate of 15,000,000 common shares, including 7,142,857 common shares sold by Fidelis and 7,857,143 common shares sold by certain selling shareholders, at an offering price of $14.00 per common share. The net proceeds of the offering to Fidelis were $89.4 million, after deducting underwriting discounts, commissions, and other offering expenses paid by the Group. Fidelis’ common shares are listed on the New York Stock Exchange under the symbol “FIHL”. Cash dividends of $0.10 and $0.30 per share were declared and paid in the three and nine months ended September 30, 2024, respectively (2023: $nil and $nil). Common share repurchases On December 21, 2023 and on August 14, 2024, the Board of Directors approved the adoption of common share repurchase programs of up to $50.0 million and up to $200.0 million, respectively, of Fidelis’ outstanding common shares, utilizing a variety of methods, including open market purchases, accelerated share repurchases and privately negotiated transactions. During the three and nine months ended September 30, 2024, the Group repurchased 4,279,983 and 6,570,003 common shares, respectively, (2023: $nil and $nil), for $66.8 million and $105.5 million, respectively, (2023: $nil and $nil) at a weighted average cost per share of $15.61 and $16.06, respectively, (2023: $nil and $nil). Of these shares repurchased in the three and nine months ended September 30, 2024, 422,658 and 577,383 common shares, respectively, were repurchased from The Fidelis Partnership for $6.6 million and $9.3 million, respectively. These transactions were effected at a price equal to the average price paid by the Group on such day for share repurchases from all other shareholders. Common shares repurchased by the Group are held as treasury shares.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2024
Income Tax Disclosure [Abstract]
Income Taxes	16. Income Taxes The Group’s income tax expense for the three and nine months ended September 30, 2024, resulted in an effective tax rate of 14.7% and 14.6%, respectively, (2023: 8.3% and 0.9%). The income tax expense for the three and nine months ended September 30, 2024, of $17.3 million and $40.4 million, respectively, (2023: $7.9 million and $17.2 million) was net of discrete income tax benefits of $nil and $nil, respectively (2023: $nil and $6.2 million). The discrete tax items in the nine months ended September 30, 2023 primarily related to the tax allowable costs of the Separation Transactions of $38.3 million. Additionally, the gross gain on distribution of The Fidelis Partnership (before deduction of the direct transaction costs) is exempt from taxation under the substantial shareholding exemption in Schedule 7AC to the U.K. Taxation of Chargeable Gains Act 1992. Due to FIHL being a U.K. tax resident company, in 2024 a U.K. top-up tax of 15% is payable on the taxable net income of FIBL. This results from the Pillar II requirements that became effective from January 1, 2024 in the U.K. In 2025, FIBL will instead be subject to the Bermuda Corporate Income Tax regime that was enacted in 2023 and will become effective from January 1, 2025. The Group’s income tax expense may fluctuate from period to period based on the relative mix of income or loss reported by jurisdiction and the varying tax rates in each jurisdiction.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation

Segments (Tables)

Segments (Tables)	9 Months Ended
	Sep. 30, 2024
Segment Reporting [Abstract]
Schedule of Reconciliation of Operating Profit (Loss) from Segments to Consolidated	The following tables summarize the Group's segment disclosures: Three Months Ended September 30, 2024 Specialty Bespoke Reinsurance Other Total Gross premiums written $ 398.4 $ 185.8 $ 157.7 $ — $ 741.9 Net premiums written 285.2 109.1 73.6 — 467.9 Net premiums earned 372.0 105.0 157.5 — 634.5 Losses and loss adjustment expenses (182.3) (19.4) (36.1) — (237.8) Policy acquisition expenses (122.4) (37.4) (36.9) (97.3) (294.0) General and administrative expenses — — — (22.7) (22.7) Underwriting income 67.3 48.2 84.5 (120.0) 80.0 Net investment income 52.1 Net realized and unrealized investment losses (0.5) Corporate and other expenses — Net foreign exchange losses (4.8) Financing costs (8.9) Income before income taxes 117.9 Income tax expense (17.3) Net income $ 100.6 Losses and loss adjustment expenses incurred - current year (168.3) (30.5) (49.1) $ (247.9) Losses and loss adjustment expenses incurred - prior accident years (14.0) 11.1 13.0 10.1 Losses and loss adjustment expenses incurred - total $ (182.3) $ (19.4) $ (36.1) $ (237.8) Underwriting Ratios (1) Loss ratio - current year 45.2 % 29.1 % 31.2 % 39.1 % Loss ratio - prior accident years 3.8 % (10.6 %) (8.3 %) (1.6 %) Loss ratio - total 49.0 % 18.5 % 22.9 % 37.5 % Policy acquisition expense ratio 32.9 % 35.6 % 23.4 % 31.0 % Underwriting ratio 81.9 % 54.1 % 46.3 % 68.5 % The Fidelis Partnership commissions ratio 15.3 % General and administrative expense ratio 3.6 % Combined ratio 87.4 % _________________ (1) Underwriting ratios are calculated by dividing the related expense by net premiums earned. Three Months Ended September 30, 2023 Specialty Bespoke Reinsurance Other Total Gross premiums written $ 326.9 $ 161.7 $ 104.0 $ — $ 592.6 Net premiums written 203.6 78.1 30.9 — 312.6 Net premiums earned 294.6 98.8 116.3 — 509.7 Losses and loss adjustment expenses (138.3) (43.2) (10.2) — (191.7) Policy acquisition expenses (83.4) (34.9) (32.5) (70.6) (221.4) General and administrative expenses — — — (21.8) (21.8) Underwriting income 72.9 20.7 73.6 (92.4) 74.8 Net investment income 33.1 Net realized and unrealized investment losses (5.3) Corporate and other expenses (0.4) Net foreign exchange gains 2.4 Financing costs (9.0) Income before income taxes 95.6 Income tax expense (7.9) Net income $ 87.7 Losses and loss adjustment expenses incurred - current year (141.0) (55.5) (38.5) $ (235.0) Losses and loss adjustment expenses incurred - prior accident years 2.7 12.3 28.3 43.3 Losses and loss adjustment expenses incurred - total $ (138.3) $ (43.2) $ (10.2) $ (191.7) Underwriting Ratios (1) Loss ratio - current year 47.8 % 56.1 % 33.1 % 46.1 % Loss ratio - prior accident years (0.9 %) (12.4 %) (24.3 %) (8.5 %) Loss ratio - total 46.9 % 43.7 % 8.8 % 37.6 % Policy acquisition expense ratio 28.3 % 35.3 % 27.9 % 29.6 % Underwriting ratio 75.2 % 79.0 % 36.7 % 67.2 % The Fidelis Partnership commissions ratio 13.9 % General and administrative expense ratio 4.3 % Combined ratio 85.4 % __________________ (1) Underwriting ratios are calculated by dividing the related expense by net premiums earned. Nine Months Ended September 30, 2024 Specialty Bespoke Reinsurance Other Total Gross premiums written $ 2,188.9 $ 429.9 $ 830.6 $ — $ 3,449.4 Net premiums written 1,337.5 189.8 388.6 — 1,915.9 Net premiums earned 1,073.4 287.9 262.3 — 1,623.6 Losses and loss adjustment expenses (545.9) (75.7) (21.2) — (642.8) Policy acquisition expenses (313.4) (101.1) (60.7) (249.0) (724.2) General and administrative expenses — — — (70.7) (70.7) Underwriting income 214.1 111.1 180.4 (319.7) 185.9 Net investment income 139.1 Net realized and unrealized investment losses (16.5) Corporate and other expenses (1.6) Net foreign exchange losses (4.9) Financing costs (26.1) Income before income taxes 275.9 Income tax expense (40.4) Net income $ 235.5 Losses and loss adjustment expenses incurred - current year (580.4) (137.9) (70.2) $ (788.5) Losses and loss adjustment expenses incurred - prior accident years 34.5 62.2 49.0 145.7 Losses and loss adjustment expenses incurred - total $ (545.9) $ (75.7) $ (21.2) $ (642.8) Underwriting Ratios (1) Loss ratio - current year 54.1 % 47.9 % 26.8 % 48.6 % Loss ratio - prior accident years (3.2 %) (21.6 %) (18.7 %) (9.0 %) Loss ratio - total 50.9 % 26.3 % 8.1 % 39.6 % Policy acquisition expense ratio 29.2 % 35.1 % 23.1 % 29.3 % Underwriting ratio 80.1 % 61.4 % 31.2 % 68.9 % The Fidelis Partnership commissions ratio 15.3 % General & administrative expense ratio 4.4 % Combined ratio 88.6 % _________________ (1) Underwriting ratios are calculated by dividing the related expense by net premiums earned. Nine Months Ended September 30, 2023 Specialty Bespoke Reinsurance Other Total Gross premiums written $ 1,818.3 $ 367.2 $ 609.6 $ — $ 2,795.1 Net premiums written 1,158.4 189.9 239.1 — 1,587.4 Net premiums earned 868.0 280.4 176.4 — 1,324.8 Losses and loss adjustment expenses (416.4) (72.5) (20.7) — (509.6) Policy acquisition expenses (227.2) (105.1) (45.6) (147.4) (525.3) General and administrative expenses — — — (57.0) (57.0) Underwriting income 224.4 102.8 110.1 (204.4) 232.9 Net investment income 80.8 Net realized and unrealized investment losses (2.4) Other income 0.2 Net gain on distribution of The Fidelis Partnership 1,639.1 Corporate and other expenses (3.4) Net foreign exchange gains 0.8 Financing costs (26.6) Income before income taxes 1,921.4 Income tax expense (17.2) Net income $ 1,904.2 Losses and loss adjustment expenses incurred - current year (383.7) (101.1) (72.6) $ (557.4) Losses and loss adjustment expenses incurred - prior accident years (32.7) 28.6 51.9 47.8 Losses and loss adjustment expenses incurred - total $ (416.4) $ (72.5) $ (20.7) $ (509.6) Underwriting Ratios (1) Loss ratio - current year 44.2 % 36.1 % 41.1 % 42.1 % Loss ratio - prior accident years 3.8 % (10.2 %) (29.4 %) (3.6 %) Loss ratio - total 48.0 % 25.9 % 11.7 % 38.5 % Policy acquisition expense ratio 26.2 % 37.5 % 25.9 % 28.5 % Underwriting ratio 74.2 % 63.4 % 37.6 % 67.0 % The Fidelis Partnership commissions ratio 11.1 % General & administrative expense ratio 4.3 % Combined ratio 82.4 % __________________ (1) Underwriting ratios are calculated by dividing the related expense by net premiums earned.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Schedule of Debt Securities, Available-for-Sale	The following table summarizes the fair value of fixed maturity investments: September 30, 2024 Amortized Cost Unrealized Unrealized Fair U.S. Treasuries $ 702.7 $ 13.9 $ (0.8) $ 715.8 Agencies 12.0 0.1 — 12.1 Non-U.S. government 51.0 0.9 (0.1) 51.8 Corporate bonds 1,965.7 46.4 (2.5) 2,009.6 Residential mortgage-backed 272.3 6.1 (3.8) 274.6 Commercial mortgage-backed 21.5 0.1 (0.2) 21.4 Other asset backed securities 446.6 3.9 (0.5) 450.0 Total fixed maturity securities $ 3,471.8 $ 71.4 $ (7.9) $ 3,535.3 December 31, 2023 Amortized Cost Unrealized Unrealized Fair U.S. Treasuries $ 692.4 $ 4.1 $ (9.8) $ 686.7 Agencies 16.2 0.1 (0.1) 16.2 Non-U.S. government 77.6 0.2 (1.8) 76.0 Corporate bonds 1,798.4 14.7 (25.8) 1,787.3 Residential mortgage-backed 192.0 2.0 (5.8) 188.2 Commercial mortgage-backed 53.1 — (2.0) 51.1 Other asset backed securities 441.7 1.3 (3.6) 439.4 Total fixed maturity securities $ 3,271.4 $ 22.4 $ (48.9) $ 3,244.9 September 30, 2024 December 31, 2023 Fair Value % Fair Value % AAA $ 455.2 13 % $ 399.5 12 % AA 1,242.8 35 % 1,119.0 35 % A 1,419.2 40 % 1,145.8 35 % BBB 416.6 12 % 573.6 18 % BB 1.5 — % 7.0 — % Total fixed maturity securities $ 3,535.3 100 % $ 3,244.9 100 % The contractual maturities for fixed maturity securities are listed in the following table: September 30, 2024 December 31, 2023 Amortized Cost Fair Value Amortized Cost Fair Value Due in one year or less $ 220.5 $ 219.9 $ 566.7 $ 555.9 Due after one year through five years 2,288.2 2,331.9 2,130.3 2,119.5 Due after five years through ten years 602.2 619.4 255.5 256.0 Due after ten years 360.9 364.1 318.9 313.5 Total fixed maturity securities $ 3,471.8 $ 3,535.3 $ 3,271.4 $ 3,244.9 The following investments were included in short-term investments and are classified as available-for-sale: September 30, 2024 Amortized Cost Unrealized Unrealized Fair U.S. Treasuries $ 133.1 $ 0.2 $ — $ 133.3 Total short-term investments $ 133.1 $ 0.2 $ — $ 133.3 December 31, 2023 Amortized Cost Unrealized Unrealized Fair U.S. Treasuries $ 49.0 $ — $ — $ 49.0 Total short-term investments $ 49.0 $ — $ — $ 49.0 The composition of the fair values of short-term investments by credit rating is as follows: September 30, 2024 December 31, 2023 Fair Value % Fair Value % AA $ 133.3 100 % $ 49.0 100 % Total short-term investments $ 133.3 100 % $ 49.0 100 %
Schedule of Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value	The following table summarizes, by type of security, the aggregate fair value and gross unrealized loss by length of time the security has been in an unrealized loss position for the Group’s available-for-sale portfolio: September 30, 2024 0 - 12 months > 12 months Fair Gross unrealized losses Gross unrealized losses Number of securities U.S. Treasuries $ 52.2 $ (0.1) $ (0.7) 20 Agencies 0.6 — — 1 Non-U.S. government 2.7 — (0.1) 2 Corporate bonds 164.1 (0.1) (2.4) 106 Residential mortgage-backed 29.0 (0.1) (3.7) 37 Commercial mortgage-backed 13.7 — (0.2) 6 Other asset backed securities 63.8 — (0.5) 23 Total $ 326.1 $ (0.3) $ (7.6) 195 December 31, 2023 0 - 12 months > 12 months Fair Gross unrealized losses Gross unrealized losses Number of securities U.S. Treasuries $ 362.2 $ (0.2) $ (9.6) 52 Agencies 5.9 — (0.1) 5 Non-U.S. government 51.3 — (1.8) 29 Corporate bonds 894.8 (0.9) (24.9) 527 Residential mortgage-backed 84.3 (0.2) (5.6) 54 Commercial mortgage-backed 43.2 (0.1) (1.9) 23 Other asset backed securities 208.2 (0.3) (3.3) 74 Total $ 1,649.9 $ (1.7) $ (47.2) 764
Schedule of Debt Securities, Available-for-Sale, Allowance for Credit Loss	The following table provides a roll forward of the allowance for expected credit losses of the Group’s securities classified as available-for-sale: Three months ended Nine months ended September 30, 2024 September 30, 2023 September 30, 2024 September 30, 2023 Balance at beginning of period $ 3.2 $ 1.9 $ 1.3 $ 1.1 Expected credit losses on securities where credit losses were not previously recognized — 2.7 1.7 4.1 Additions/(reductions) for expected credit losses on securities where credit losses were previously recognized (2.7) 1.2 (2.2) 0.6 Securities sold/redeemed/matured (0.2) — (0.5) — Balance at end of period $ 0.3 $ 5.8 $ 0.3 $ 5.8
Schedule of Other Investments Not Readily Marketable	September 30, 2024 December 31, 2023 Fair Value % Fair Value % Wellington Funds $ 48.6 100 % $ 46.9 99 % Other securities valued at net asset value per share 0.1 — % 0.6 1 % Total other investments at fair value $ 48.7 100 % $ 47.5 100 %
Schedule of Investment Income	The components of net investment return are as follows: Three Months Ended Nine Months Ended September 30, 2024 September 30, 2023 September 30, 2024 September 30, 2023 Net interest and dividend income $ 53.4 $ 34.0 $ 142.9 $ 83.5 Investment expenses (1.3) (0.9) (3.8) (2.7) Net investment income 52.1 33.1 139.1 80.8 Net realized losses on fixed maturity securities, available-for-sale (6.0) (0.2) (19.5) (0.6) Net realized gains on other investments 0.1 — 0.1 2.2 Change in net unrealized gains/(losses) on other investments 2.5 (1.2) 1.9 0.7 Change in provision for expected credit losses 2.9 (3.9) 1.0 (4.7) Net realized and unrealized investment losses (0.5) (5.3) (16.5) (2.4) Total realized and unrealized investments gains/(losses) and net investment income $ 51.6 $ 27.8 $ 122.6 $ 78.4

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following table presents the financial instruments measured at fair value on a recurring basis at September 30, 2024 and December 31, 2023: September 30, 2024 Assets Level 1 Level 2 Level 3 Total Cash equivalents - money market funds $ 663.3 $ — $ — $ 663.3 Fixed maturity securities U.S. Treasuries 715.8 — — 715.8 Agencies — 12.1 — 12.1 Non-U.S. government — 51.8 — 51.8 Corporate bonds — 2,009.6 — 2,009.6 Residential mortgage-backed — 274.6 — 274.6 Commercial mortgage-backed — 21.4 — 21.4 Other asset backed securities — 450.0 — 450.0 Total fixed maturity securities 715.8 2,819.5 — 3,535.3 Short-term investments U.S. Treasuries 133.3 — — 133.3 Total short-term investments 133.3 — — 133.3 Other investments* 48.6 — — 48.6 Other assets Investments pending settlement 0.6 — — 0.6 Total other assets 0.6 — — 0.6 Total assets measured at fair value $ 1,561.6 $ 2,819.5 $ — $ 4,381.1 Liabilities Other liabilities Derivative liabilities $ — $ (6.1) $ — $ (6.1) Investments pending settlement (5.5) — — (5.5) Total other liabilities (5.5) (6.1) — (11.6) Total liabilities measured at fair value $ (5.5) $ (6.1) $ — $ (11.6) __________________ * excludes investments valued at net asset value per share. December 31, 2023 Assets Level 1 Level 2 Level 3 Total Cash equivalents - money market funds $ 557.9 $ — $ — $ 557.9 Fixed maturity securities U.S. Treasuries 686.7 — — 686.7 Agencies — 16.2 — 16.2 Non-U.S. government — 76.0 — 76.0 Corporate bonds — 1,787.3 — 1,787.3 Residential mortgage-backed — 188.2 — 188.2 Commercial mortgage-backed — 51.1 — 51.1 Other asset backed securities — 439.4 — 439.4 Total fixed maturity securities 686.7 2,558.2 — 3,244.9 Short-term investments U.S. Treasuries 49.0 — — 49.0 Total short-term investments 49.0 — — 49.0 Other investments* 46.9 — — 46.9 Other assets Investments pending settlement 2.2 — — 2.2 Total other assets 2.2 — — 2.2 Total assets measured at fair value $ 1,342.7 $ 2,558.2 $ — $ 3,900.9 Liabilities Other liabilities Derivative liabilities $ — $ (1.1) $ — $ (1.1) Total other liabilities — (1.1) — (1.1) Total liabilities measured at fair value $ — $ (1.1) $ — $ (1.1) __________________ * excludes investments valued at net asset value per share.
Schedule of Fair Value, by Balance Sheet Grouping	The following table includes financial instruments for which the carrying value differs from the estimated fair values at September 30, 2024 and December 31, 2023. The fair values of the below financial instruments are based on observable inputs and are considered Level 2 measurements. September 30, 2024 December 31, 2023 Fair Value Carrying Value Fair Value Carrying Value 4.875% Senior notes due 2030 $ 326.3 $ 325.6 $ 273.1 $ 325.0 6.625% Fixed Rate Reset Junior Subordinated notes due 2041 123.8 123.2 121.6 123.2 Preference securities $ 56.9 $ 58.4 $ 55.6 $ 58.4

Total Cash, Cash Equivalents,_2

Total Cash, Cash Equivalents, Restricted Cash and Restricted Investments (Tables)	9 Months Ended
	Sep. 30, 2024
Cash and Cash Equivalents [Abstract]
Schedule of Cash and Cash Equivalents	The following table provides a summary of cash and cash equivalents, restricted cash and restricted investments at September 30, 2024 and December 31, 2023: September 30, December 31, 2023 Cash and cash equivalents $ 806.8 $ 712.4 Restricted cash securing letter of credit facilities 8.9 5.8 Restricted cash securing reinsurance contracts 203.4 245.9 Total cash, cash equivalents and restricted cash 1,019.1 964.1 Restricted investments securing reinsurance contracts and letter of credit facilities 1,225.7 1,347.0 Total cash, cash equivalents, restricted cash and restricted investments $ 2,244.8 $ 2,311.1
Schedule of Restrictions on Cash and Cash Equivalents	The following table provides a summary of cash and cash equivalents, restricted cash and restricted investments at September 30, 2024 and December 31, 2023: September 30, December 31, 2023 Cash and cash equivalents $ 806.8 $ 712.4 Restricted cash securing letter of credit facilities 8.9 5.8 Restricted cash securing reinsurance contracts 203.4 245.9 Total cash, cash equivalents and restricted cash 1,019.1 964.1 Restricted investments securing reinsurance contracts and letter of credit facilities 1,225.7 1,347.0 Total cash, cash equivalents, restricted cash and restricted investments $ 2,244.8 $ 2,311.1

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments	The following tables identify the listing currency, fair value and notional amounts of derivative instruments included in the Consolidated Balance Sheets, categorized by primary underlying risk: September 30, 2024 December 31, 2023 Listing currency (1) Notional amounts (2) Fair value Notional amounts (2) Fair value Derivative liabilities by primary underlying risk Foreign exchange contracts Forwards (3) AUD/CAD/EUR/GBP/JPY $ 176.2 $ (6.1) $ (9.7) $ (1.1) Total derivative liabilities $ 176.2 $ (6.1) $ (9.7) $ (1.1) __________________ (1) AUD = Australian Dollar, CAD = Canadian Dollar, EUR = Euro, GBP = British Pound Sterling and JPY = Japanese Yen. (2) The absolute notional exposure represents the Group’s derivative activity, which is representative of the volume of derivatives held during the period. (3) Contracts used to manage foreign currency risks in underwriting and non-investment operations.
Schedule of Derivative Instruments, Gain (Loss)	The following table presents derivative instruments by major risk type, the Group’s net realized gains/(losses) and change in net unrealized gains/(losses) relating to derivative trading activities for the three and nine months ended September 30, 2024 and 2023. Net realized gains/(losses) and net unrealized gains/(losses) related to derivatives are included in net foreign exchange (gains)/losses in the Consolidated Statements of Income. Three Months Ended Nine Months Ended September 30, 2024 September 30, 2023 September 30, 2024 September 30, 2023 Derivatives Net realized gains/(losses) Change in net unrealized Net realized gains/(losses) Change in net unrealized gains/(losses) Net realized gains/(losses) Change in net unrealized Net realized gains/(losses) Change in net unrealized gains/(losses) Foreign exchange contracts Forwards (1) $ (3.4) $ (4.7) $ (1.8) $ 4.6 $ (4.7) $ (5.0) $ 0.5 $ (3.0) Total foreign exchange contracts (3.4) (4.7) (1.8) 4.6 (4.7) (5.0) 0.5 (3.0) Total $ (3.4) $ (4.7) $ (1.8) $ 4.6 $ (4.7) $ (5.0) $ 0.5 $ (3.0) __________________ (1) Contracts used to manage foreign currency risks in underwriting and non-investment operations.

Reserves for Losses and Loss _2

Reserves for Losses and Loss Adjustment Expenses (Tables)	9 Months Ended
	Sep. 30, 2024
Insurance [Abstract]
Schedule of Liability for Unpaid Claims and Claims Adjustment Expense	The following table presents a reconciliation of reserves for losses and loss adjustment expenses for the nine months ended September 30, 2024 and September 30, 2023: September 30, 2024 September 30, 2023 Reserves for losses and loss adjustment expenses, beginning of period $ 2,448.9 $ 2,045.2 Reinsurance recoverable on reserves for losses and loss adjustment expenses (1,108.6) (976.1) Net reserves for losses and loss adjustment expenses, beginning of period 1,340.3 1,069.1 Net losses and loss adjustment expenses incurred in respect of losses occurring in: Current year 788.5 557.4 Prior years (145.7) (47.8) Total incurred 642.8 509.6 Net losses and loss adjustment expenses paid in respect of losses occurring in: Current year (97.7) (61.9) Prior years (251.5) (267.1) Total paid (349.2) (329.0) Foreign exchange 2.0 (7.4) Net reserves for losses and loss adjustment expenses, end of period 1,635.9 1,242.3 Reinsurance recoverable on reserves for losses and loss adjustment expenses 1,164.9 1,066.3 Reserves for losses and loss adjustment expenses, end of period $ 2,800.8 $ 2,308.6

Long Term Debt and Preference_2

Long Term Debt and Preference Securities (Tables)	9 Months Ended
	Sep. 30, 2024
Debt Disclosure [Abstract]
Schedule of Debt	The following table sets forth the principal amount of the debt issued as well as the unamortized discount and debt issuance costs at September 30, 2024 and December 31, 2023: September 30, 2024 December 31, 2023 Principal Unamortized Principal Unamortized 4.875% Senior notes due 2030 $ 330.0 $ (4.4) $ 330.0 $ (5.0) 6.625% Fixed Rate Reset Junior Subordinated notes due 2041 125.0 (1.8) 125.0 (1.8) Total $ 455.0 $ (6.2) $ 455.0 $ (6.8)
Schedule of Stock by Class	September 30, December 31, 2023 Preference securities, par value $0.01 per share Authorized 1,000,000 1,000,000 Issued and outstanding: 9% cumulative preference shares 5,835 5,835 The following sets out the number and par value of shares authorized, issued and outstanding: September 30, 2024 December 31, 2023 Common shares, par value $0.01 per share Authorized 600,000,000 600,000,000 Issued and outstanding Common shares 111,726,363 117,914,754

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Schedule of Line of Credit Facilities	At September 30, 2024, and December 31, 2023, the Group had the following letter of credit facilities: September 30, 2024 December 31, 2023 Bank Commitment In Use Date of Expiry Commitment In Use Date of Expiry Lloyds Bank plc (2) Unsecured (1) $ 25.0 $ 19.8 September 21, 2025 $ 25.0 $ 20.6 September 20, 2024 Secured (1) 100.0 34.0 September 21, 2025 100.0 38.2 September 20, 2024 Ancillary own funds n/a n/a n/a 75.0 75.0 March 13, 2027 Total Lloyds Bank Plc 125.0 53.8 200.0 133.8 Citibank N.A. London branch (1)(2) Secured 70.0 44.0 December 31, 2024 70.0 52.3 December 31, 2024 Total Citibank N.A. London branch 70.0 44.0 70.0 52.3 Barclays Bank plc (1)(2) Unsecured 60.0 51.3 September 13, 2025 60.0 53.3 September 13, 2024 Secured 80.0 31.0 September 13, 2025 80.0 31.0 September 13, 2024 Total Barclays Bank plc 140.0 82.3 140.0 84.3 Bank of Montreal (1)(2) Unsecured 40.0 32.0 September 18, 2025 40.0 36.1 September 17, 2024 Secured 100.0 26.0 September 18, 2025 100.0 32.1 September 17, 2024 Total Bank of Montreal 140.0 58.0 140.0 68.2 Total letters of credit facilities $ 475.0 $ 238.1 $ 550.0 $ 338.6 __________________ (1) Letters of credit can be issued under the Standby Letter of Credit Facility for the purposes of supporting insurance and reinsurance obligations. (2) The Facility agreements allow for additional capacity in the form of accordions and uncommitted amounts. The maximum additional capacity from the lenders as of September 30, 2024, was: Lloyds Bank plc $50.0 million; Citibank N.A. London Branch $200.0 million; Barclays Bank plc $80.0 million; and Bank of Montreal $60.0 million. The following table shows the collateral underlying the secured letter of credit facilities: Bank September 30, 2024 December 31, 2023 Lloyds Bank plc $ 43.1 $ 44.2 Citibank N.A. London branch 46.4 55.2 Barclays Bank plc 41.4 37.7 Bank of Montreal 31.4 35.9 Total $ 162.3 $ 173.0

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2024
Related Party Transactions [Abstract]
Schedule of Other Nonoperating Income (Expense)	The following table summarizes The Fidelis Partnership commissions earned, which are included in policy acquisition expenses in the Consolidated Statements of Income: Three months ended Nine months ended September 30, 2024 September 30, 2023 September 30, 2024 September 30, 2023 Ceding commission expense $ 84.2 $ 56.3 $ 225.3 $ 107.4 Profit commission expense 13.1 14.3 23.7 40.0 Total commissions $ 97.3 $ 70.6 $ 249.0 $ 147.4

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic, by Common Class, Including Two Class Method	Three months ended Nine months ended September 30, 2024 September 30, 2023 September 30, 2024 September 30, 2023 Earnings per common share Net income $ 100.6 $ 87.7 $ 235.5 $ 1,904.2 Weighted average common shares outstanding 114,445,447 117,681,835 116,390,461 113,100,521 Earnings per common share $ 0.88 $ 0.75 $ 2.02 $ 16.84 Earnings per diluted common share Net income $ 100.6 $ 87.7 $ 235.5 $ 1,904.2 Weighted average common shares outstanding 114,445,447 117,681,835 116,390,461 113,100,521 Share-based compensation plans 289,079 293,264 455,530 132,409 Weighted average diluted common shares outstanding 114,734,526 117,975,099 116,845,991 113,232,930 Earnings per diluted common share $ 0.88 $ 0.74 $ 2.02 $ 16.82

Share Capital Authorized and _2

Share Capital Authorized and Issued (Tables)	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Schedule of Stock by Class	September 30, December 31, 2023 Preference securities, par value $0.01 per share Authorized 1,000,000 1,000,000 Issued and outstanding: 9% cumulative preference shares 5,835 5,835 The following sets out the number and par value of shares authorized, issued and outstanding: September 30, 2024 December 31, 2023 Common shares, par value $0.01 per share Authorized 600,000,000 600,000,000 Issued and outstanding Common shares 111,726,363 117,914,754

Nature of Operations (Details)

Nature of Operations (Details) - USD ($) $ / shares in Units, $ in Millions	Jul. 03, 2023	May 22, 2024
Syndicate 3123
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Non-Controlling interest %		9.90%
IPO
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of stock, number of shares issued in transaction (in shares)	15,000,000
Sale of stock, price per share (in dollars per share)	$ 14
Sale of stock, consideration received on transaction	$ 89.4
IPO, Shares Sold By Fidelis
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of stock, number of shares issued in transaction (in shares)	7,142,857
IPO, Shares Sold By Selling Shareholders
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of stock, number of shares issued in transaction (in shares)	7,857,143

Separation Transactions (Detail

Separation Transactions (Details) - USD ($) $ in Millions		9 Months Ended
	Jan. 03, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Related Party Transaction [Line Items]
Share-based payment arrangement, accelerated cost			$ 21
Accrued payroll taxes			17.3
Stock issued during period, shares, new issues (in shares)	13,553,681
Share-based payment arrangement, decrease for tax withholding obligation	$ 50.6
Cumulative dividends	$ 34.1
Stock repurchased and retired during period (in shares)	97,327,049
Common stock, shares, issued (in shares)		111,726,363		117,914,754
Common stock, shares, outstanding (in shares)		111,726,363		117,914,754
Accrued professional fees			28.6
Revaluation of Fidelis MGU	$ 1,707.1	$ 0	$ 1,707.1
Group | Fidelis MGU
Related Party Transaction [Line Items]
Subsidiary, ownership percentage, noncontrolling owner	9.90%
Consolidation, less than wholly owned subsidiary, parent ownership interest, changes, sale of interest by parent	$ 1,775
Accrued payroll taxes	17.3
Noncontrolling interest, decrease from redemptions or purchase of interests	$ 67.9
Stock repurchased and retired during period (in shares)	97,327,049
Common stock, shares, issued (in shares)	110,771,897
Common stock, shares, outstanding (in shares)	110,771,897
Accrued professional fees	$ 28.6
Consolidation, less than wholly owned subsidiary, parent ownership interest, changes, net	1,639.1
Consolidation, less than wholly owned subsidiary, parent ownership interest, changes, additional interest issued to parent	68
Deferred compensation arrangement with individual, compensation expense	21
Group | Fidelis MGU | Minimum
Related Party Transaction [Line Items]
Consolidation, less than wholly owned subsidiary, parent ownership interest, changes, sale of interest by parent	1,700
Group | Fidelis MGU | Maximum
Related Party Transaction [Line Items]
Consolidation, less than wholly owned subsidiary, parent ownership interest, changes, sale of interest by parent	$ 1,900

Segments - Narrative (Details)

Segments - Narrative (Details)	9 Months Ended
	Sep. 30, 2024 segment
Segment Reporting [Abstract]
Number of Operating Segments	3

Segments - Summary of Group Seg

Segments - Summary of Group Segment Disclosures (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Gross premiums written	$ 741.9	$ 592.6	$ 3,449.4	$ 2,795.1
Net premiums written	467.9	312.6	1,915.9	1,587.4
Net premiums earned	634.5	509.7	1,623.6	1,324.8
Losses and loss adjustment expenses	(237.8)	(191.7)	(642.8)	(509.6)
Policy acquisition expenses	(294)	(221.4)	(724.2)	(525.3)
General and administrative expenses	(22.7)	(21.8)	(70.7)	(57)
Underwriting income	80	74.8	185.9	232.9
Net investment (loss) income	52.1	33.1	139.1	80.8
Net realized and unrealized investment losses	(0.5)	(5.3)	(16.5)	(2.4)
Other income (loss)	0	0	0	0.2
Net gain on distribution of The Fidelis Partnership	0	0	0	1,639.1
Corporate and other expenses	0	(0.4)	(1.6)	(3.4)
Net foreign exchange (gains)/losses	(4.8)	2.4	(4.9)	0.8
Financing costs	(8.9)	(9)	(26.1)	(26.6)
Income before income taxes	117.9	95.6	275.9	1,921.4
Income tax expense	(17.3)	(7.9)	(40.4)	(17.2)
Net income	100.6	87.7	235.5	1,904.2
Losses and loss adjustment expenses incurred - current year	(247.9)	(235)	(788.5)	(557.4)
Losses and loss adjustment expenses incurred - prior accident years	10.1	43.3	145.7	47.8
Losses and loss adjustment expenses incurred - total	$ (237.8)	$ (191.7)	$ (642.8)	$ (509.6)
Underwriting Ratios
Loss ratio - current year	39.10%	46.10%	48.60%	42.10%
Loss ratio - prior accident years	(1.60%)	(8.50%)	(9.00%)	(3.60%)
Loss ratio - total	37.50%	37.60%	39.60%	38.50%
Policy acquisition expense ratio	31%	29.60%	29.30%	28.50%
Underwriting ratio	68.50%	67.20%	68.90%	67%
The Fidelis Partnership commissions ratio	15.30%	13.90%	15.30%	11.10%
General and administrative expense ratio	3.60%	4.30%	4.40%	4.30%
Combined ratio	87.40%	85.40%	88.60%	82.40%
Other
Segment Reporting Information [Line Items]
Gross premiums written	$ 0	$ 0	$ 0	$ 0
Net premiums written	0	0	0	0
Net premiums earned	0	0	0	0
Losses and loss adjustment expenses	0	0	0	0
Policy acquisition expenses	(97.3)	(70.6)	(249)	(147.4)
General and administrative expenses	(22.7)	(21.8)	(70.7)	(57)
Underwriting income	(120)	(92.4)	(319.7)	(204.4)
Losses and loss adjustment expenses incurred - total	0	0	0	0
Specialty
Segment Reporting Information [Line Items]
Losses and loss adjustment expenses incurred - prior accident years			34.5	(32.7)
Specialty | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	398.4	326.9	2,188.9	1,818.3
Net premiums written	285.2	203.6	1,337.5	1,158.4
Net premiums earned	372	294.6	1,073.4	868
Losses and loss adjustment expenses	(182.3)	(138.3)	(545.9)	(416.4)
Policy acquisition expenses	(122.4)	(83.4)	(313.4)	(227.2)
General and administrative expenses	0	0	0	0
Underwriting income	67.3	72.9	214.1	224.4
Losses and loss adjustment expenses incurred - current year	(168.3)	(141)	(580.4)	(383.7)
Losses and loss adjustment expenses incurred - prior accident years	(14)	2.7	34.5	(32.7)
Losses and loss adjustment expenses incurred - total	$ (182.3)	$ (138.3)	$ (545.9)	$ (416.4)
Underwriting Ratios
Loss ratio - current year	45.20%	47.80%	54.10%	44.20%
Loss ratio - prior accident years	3.80%	(0.90%)	(3.20%)	3.80%
Loss ratio - total	49%	46.90%	50.90%	48%
Policy acquisition expense ratio	32.90%	28.30%	29.20%	26.20%
Underwriting ratio	81.90%	75.20%	80.10%	74.20%
Bespoke
Segment Reporting Information [Line Items]
Losses and loss adjustment expenses incurred - prior accident years			$ 62.2	$ (28.6)
Bespoke | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	$ 185.8	$ 161.7	429.9	367.2
Net premiums written	109.1	78.1	189.8	189.9
Net premiums earned	105	98.8	287.9	280.4
Losses and loss adjustment expenses	(19.4)	(43.2)	(75.7)	(72.5)
Policy acquisition expenses	(37.4)	(34.9)	(101.1)	(105.1)
General and administrative expenses	0	0	0	0
Underwriting income	48.2	20.7	111.1	102.8
Losses and loss adjustment expenses incurred - current year	(30.5)	(55.5)	(137.9)	(101.1)
Losses and loss adjustment expenses incurred - prior accident years	11.1	12.3	62.2	28.6
Losses and loss adjustment expenses incurred - total	$ (19.4)	$ (43.2)	$ (75.7)	$ (72.5)
Underwriting Ratios
Loss ratio - current year	29.10%	56.10%	47.90%	36.10%
Loss ratio - prior accident years	(10.60%)	(12.40%)	(21.60%)	(10.20%)
Loss ratio - total	18.50%	43.70%	26.30%	25.90%
Policy acquisition expense ratio	35.60%	35.30%	35.10%	37.50%
Underwriting ratio	54.10%	79%	61.40%	63.40%
Reinsurance
Segment Reporting Information [Line Items]
Losses and loss adjustment expenses incurred - prior accident years			$ 49	$ (51.9)
Reinsurance | Operating Segments
Segment Reporting Information [Line Items]
Gross premiums written	$ 157.7	$ 104	830.6	609.6
Net premiums written	73.6	30.9	388.6	239.1
Net premiums earned	157.5	116.3	262.3	176.4
Losses and loss adjustment expenses	(36.1)	(10.2)	(21.2)	(20.7)
Policy acquisition expenses	(36.9)	(32.5)	(60.7)	(45.6)
General and administrative expenses	0	0	0	0
Underwriting income	84.5	73.6	180.4	110.1
Losses and loss adjustment expenses incurred - current year	(49.1)	(38.5)	(70.2)	(72.6)
Losses and loss adjustment expenses incurred - prior accident years	13	28.3	49	51.9
Losses and loss adjustment expenses incurred - total	$ (36.1)	$ (10.2)	$ (21.2)	$ (20.7)
Underwriting Ratios
Loss ratio - current year	31.20%	33.10%	26.80%	41.10%
Loss ratio - prior accident years	(8.30%)	(24.30%)	(18.70%)	(29.40%)
Loss ratio - total	22.90%	8.80%	8.10%	11.70%
Policy acquisition expense ratio	23.40%	27.90%	23.10%	25.90%
Underwriting ratio	46.30%	36.70%	31.20%	37.60%

Investments - Fair Value of Inv

Investments - Fair Value of Investments (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3))
Debt Securities, Available-for-Sale [Line Items]
Total fixed maturity securities	$ 3,471.8	$ 3,271.4
Unrealized gains	71.4	22.4
Unrealized losses	(7.9)	(48.9)
Fair value	3,535.3	3,244.9
Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3)) | U.S. Treasuries
Debt Securities, Available-for-Sale [Line Items]
Total fixed maturity securities	702.7	692.4
Unrealized gains	13.9	4.1
Unrealized losses	(0.8)	(9.8)
Fair value	715.8	686.7
Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3)) | Agencies
Debt Securities, Available-for-Sale [Line Items]
Total fixed maturity securities	12	16.2
Unrealized gains	0.1	0.1
Unrealized losses	0	(0.1)
Fair value	12.1	16.2
Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3)) | Non-U.S. government
Debt Securities, Available-for-Sale [Line Items]
Total fixed maturity securities	51	77.6
Unrealized gains	0.9	0.2
Unrealized losses	(0.1)	(1.8)
Fair value	51.8	76
Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3)) | Corporate bonds
Debt Securities, Available-for-Sale [Line Items]
Total fixed maturity securities	1,965.7	1,798.4
Unrealized gains	46.4	14.7
Unrealized losses	(2.5)	(25.8)
Fair value	2,009.6	1,787.3
Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3)) | Residential mortgage-backed
Debt Securities, Available-for-Sale [Line Items]
Total fixed maturity securities	272.3	192
Unrealized gains	6.1	2
Unrealized losses	(3.8)	(5.8)
Fair value	274.6	188.2
Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3)) | Commercial mortgage-backed
Debt Securities, Available-for-Sale [Line Items]
Total fixed maturity securities	21.5	53.1
Unrealized gains	0.1	0
Unrealized losses	(0.2)	(2)
Fair value	21.4	51.1
Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3)) | Other asset backed securities
Debt Securities, Available-for-Sale [Line Items]
Total fixed maturity securities	446.6	441.7
Unrealized gains	3.9	1.3
Unrealized losses	(0.5)	(3.6)
Fair value	450	439.4
Short-term investments, available-for-sale, at fair value (amortized cost: $133.1, 2023: $49.0 (net of allowances for credit losses of $nil, 2023: $nil))
Debt Securities, Available-for-Sale [Line Items]
Total fixed maturity securities	133.1	49
Unrealized gains	0.2	0
Unrealized losses	0	0
Fair value	133.3	49
Short-term investments, available-for-sale, at fair value (amortized cost: $133.1, 2023: $49.0 (net of allowances for credit losses of $nil, 2023: $nil)) | U.S. Treasuries
Debt Securities, Available-for-Sale [Line Items]
Total fixed maturity securities	133.1	49
Unrealized gains	0.2	0
Unrealized losses	0	0
Fair value	$ 133.3	$ 49

Investments - Composition of th

Investments - Composition of the Fair Values of Investments by Credit Rating (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Credit Rating | Credit Concentration Risk
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Concentration risk, percentage	100%	100%
Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3))
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Fair value	$ 3,535.3	$ 3,244.9
Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3)) | Credit Rating | Credit Concentration Risk
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Concentration risk, percentage	100%	100%
Short-term investments, available-for-sale, at fair value (amortized cost: $133.1, 2023: $49.0 (net of allowances for credit losses of $nil, 2023: $nil))
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Fair value	$ 133.3	$ 49
Short-term investments, available-for-sale, at fair value (amortized cost: $133.1, 2023: $49.0 (net of allowances for credit losses of $nil, 2023: $nil)) | Credit Rating | Credit Concentration Risk
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Concentration risk, percentage	100%	100%
AAA | Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3))
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Fair value	$ 455.2	$ 399.5
AAA | Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3)) | Credit Rating | Credit Concentration Risk
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Concentration risk, percentage	13%	12%
AA | Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3))
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Fair value	$ 1,242.8	$ 1,119
AA | Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3)) | Credit Rating | Credit Concentration Risk
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Concentration risk, percentage	35%	35%
AA | Short-term investments, available-for-sale, at fair value (amortized cost: $133.1, 2023: $49.0 (net of allowances for credit losses of $nil, 2023: $nil))
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Fair value	$ 133.3	$ 49
AA | Short-term investments, available-for-sale, at fair value (amortized cost: $133.1, 2023: $49.0 (net of allowances for credit losses of $nil, 2023: $nil)) | Credit Rating | Credit Concentration Risk
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Concentration risk, percentage	100%	100%
A | Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3))
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Fair value	$ 1,419.2	$ 1,145.8
A | Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3)) | Credit Rating | Credit Concentration Risk
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Concentration risk, percentage	40%	35%
BBB | Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3))
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Fair value	$ 416.6	$ 573.6
BBB | Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3)) | Credit Rating | Credit Concentration Risk
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Concentration risk, percentage	12%	18%
BB | Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3))
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Fair value	$ 1.5	$ 7
BB | Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3)) | Credit Rating | Credit Concentration Risk
Debt Securities, Held-to-Maturity, Credit Quality Indicator [Line Items]
Concentration risk, percentage	0%	0%

Investments - Contractual Matur

Investments - Contractual Maturities for Investments (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Fixed maturity securities, available-for-sale, at fair value (amortized cost: $3,471.8, 2023: $3,271.4 (net of allowances for credit losses of $0.3, 2023: $1.3))
Amortized Cost
Due in one year or less	$ 220.5	$ 566.7
Due after one year through five years	2,288.2	2,130.3
Due after five years through ten years	602.2	255.5
Due after ten years	360.9	318.9
Total fixed maturity securities	3,471.8	3,271.4
Fair Value
Due in one year or less	219.9	555.9
Due after one year through five years	2,331.9	2,119.5
Due after five years through ten years	619.4	256
Due after ten years	364.1	313.5
Total fixed maturity securities	3,535.3	3,244.9
Short-term investments, available-for-sale, at fair value (amortized cost: $133.1, 2023: $49.0 (net of allowances for credit losses of $nil, 2023: $nil))
Amortized Cost
Total fixed maturity securities	133.1	49
Fair Value
Total fixed maturity securities	$ 133.3	$ 49

Investments - Continuous Loss P

Investments - Continuous Loss Position (Details) $ in Millions	Sep. 30, 2024 USD ($) security	Dec. 31, 2023 USD ($) security
Debt Securities, Available-for-Sale [Line Items]
Fair value	$ 326.1	$ 1,649.9
Gross unrealized losses	(0.3)	(1.7)
Gross unrealized losses	$ (7.6)	$ (47.2)
Number of securities | security	195	764
U.S. Treasuries
Debt Securities, Available-for-Sale [Line Items]
Fair value	$ 52.2	$ 362.2
Gross unrealized losses	(0.1)	(0.2)
Gross unrealized losses	$ (0.7)	$ (9.6)
Number of securities | security	20	52
Agencies
Debt Securities, Available-for-Sale [Line Items]
Fair value	$ 0.6	$ 5.9
Gross unrealized losses	0	0
Gross unrealized losses	$ 0	$ (0.1)
Number of securities | security	1	5
Non-U.S. government
Debt Securities, Available-for-Sale [Line Items]
Fair value	$ 2.7	$ 51.3
Gross unrealized losses	0	0
Gross unrealized losses	$ (0.1)	$ (1.8)
Number of securities | security	2	29
Corporate bonds
Debt Securities, Available-for-Sale [Line Items]
Fair value	$ 164.1	$ 894.8
Gross unrealized losses	(0.1)	(0.9)
Gross unrealized losses	$ (2.4)	$ (24.9)
Number of securities | security	106	527
Residential mortgage-backed
Debt Securities, Available-for-Sale [Line Items]
Fair value	$ 29	$ 84.3
Gross unrealized losses	(0.1)	(0.2)
Gross unrealized losses	$ (3.7)	$ (5.6)
Number of securities | security	37	54
Commercial mortgage-backed
Debt Securities, Available-for-Sale [Line Items]
Fair value	$ 13.7	$ 43.2
Gross unrealized losses	0	(0.1)
Gross unrealized losses	$ (0.2)	$ (1.9)
Number of securities | security	6	23
Other asset backed securities
Debt Securities, Available-for-Sale [Line Items]
Fair value	$ 63.8	$ 208.2
Gross unrealized losses	0	(0.3)
Gross unrealized losses	$ (0.5)	$ (3.3)
Number of securities | security	23	74

Investments - Narrative (Detail

Investments - Narrative (Details) $ in Millions	Sep. 30, 2024 USD ($) security	Dec. 31, 2023 USD ($) security	Dec. 31, 2021 USD ($)
Debt Securities, Available-for-Sale [Line Items]
Number of securities | security	195	764
Number of positions | security	1,141	1,263
Debt securities, available-for-sale, continuous unrealized loss position, largest single amount	$ 0.5	$ 1.7
Fair Value	48.7	47.5
Wellington Funds
Debt Securities, Available-for-Sale [Line Items]
Fair Value	$ 48.6	$ 46.9	$ 50

Investments - Allowance for Exp

Investments - Allowance for Expected Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 3.2	$ 1.9	$ 1.3	$ 1.1
Expected credit losses on securities where credit losses were not previously recognized	0	2.7	1.7	4.1
Additions/(reductions) for expected credit losses on securities where credit losses were previously recognized	(2.7)	1.2	(2.2)	0.6
Securities sold/redeemed/matured	(0.2)	0	(0.5)	0
Balance at end of period	$ 0.3	$ 5.8	$ 0.3	$ 5.8

Investments - Other Investments

Investments - Other Investments at Fair Value (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023	Dec. 31, 2021
Debt Securities, Available-for-Sale [Line Items]
Fair Value	$ 48.7	$ 47.5
Credit Rating | Credit Concentration Risk
Debt Securities, Available-for-Sale [Line Items]
Concentration risk, percentage	100%	100%
Wellington Funds
Debt Securities, Available-for-Sale [Line Items]
Fair Value	$ 48.6	$ 46.9	$ 50
Wellington Funds | Credit Rating | Credit Concentration Risk
Debt Securities, Available-for-Sale [Line Items]
Concentration risk, percentage	100%	99%
Other Securities Valued At Net Asset Value Per Share
Debt Securities, Available-for-Sale [Line Items]
Fair Value	$ 0.1	$ 0.6
Other Securities Valued At Net Asset Value Per Share | Credit Rating | Credit Concentration Risk
Debt Securities, Available-for-Sale [Line Items]
Concentration risk, percentage	0%	1%

Investments - Components of Net

Investments - Components of Net Investment Return (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Net interest and dividend income	$ 53.4	$ 34	$ 142.9	$ 83.5
Investment expenses	(1.3)	(0.9)	(3.8)	(2.7)
Net investment income	52.1	33.1	139.1	80.8
Net realized losses on fixed maturity securities, available-for-sale	(6)	(0.2)	(19.5)	(0.6)
Net realized gains on other investments	0.1	0	0.1	2.2
Change in net unrealized gains/(losses) on other investments	2.5	(1.2)	1.9	0.7
Change in provision for expected credit losses	2.9	(3.9)	1	(4.7)
Net realized and unrealized investment losses	(0.5)	(5.3)	(16.5)	(2.4)
Total realized and unrealized investments gains/(losses) and net investment income	$ 51.6	$ 27.8	$ 122.6	$ 78.4

Fair Value Measurements - Finan

Fair Value Measurements - Financial Instruments Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Assets
Cash equivalents - money market funds	$ 663.3	$ 557.9
Other Investments	48.6	46.9
Investments pending settlement	0.6	2.2
Total other assets	0.6	2.2
Total assets measured at fair value	4,381.1	3,900.9
Liabilities
Derivative liabilities	(6.1)	(1.1)
Investments pending settlement	(5.5)
Total other liabilities	(11.6)	(1.1)
Total liabilities measured at fair value	(11.6)	(1.1)
Fixed maturity securities
Assets
Fair value	3,535.3	3,244.9
Fixed maturity securities | U.S. Treasuries
Assets
Fair value	715.8	686.7
Fixed maturity securities | Agencies
Assets
Fair value	12.1	16.2
Fixed maturity securities | Non-U.S. government
Assets
Fair value	51.8	76
Fixed maturity securities | Corporate bonds
Assets
Fair value	2,009.6	1,787.3
Fixed maturity securities | Residential mortgage-backed
Assets
Fair value	274.6	188.2
Fixed maturity securities | Commercial mortgage-backed
Assets
Fair value	21.4	51.1
Fixed maturity securities | Other asset backed securities
Assets
Fair value	450	439.4
Short-term investments
Assets
Fair value	133.3	49
Short-term investments | U.S. Treasuries
Assets
Fair value	133.3	49
Level 1
Assets
Cash equivalents - money market funds	663.3	557.9
Other Investments	48.6	46.9
Investments pending settlement	0.6	2.2
Total other assets	0.6	2.2
Total assets measured at fair value	1,561.6	1,342.7
Liabilities
Derivative liabilities	0	0
Investments pending settlement	(5.5)
Total other liabilities	(5.5)	0
Total liabilities measured at fair value	(5.5)	0
Level 1 | Fixed maturity securities
Assets
Fair value	715.8	686.7
Level 1 | Fixed maturity securities | U.S. Treasuries
Assets
Fair value	715.8	686.7
Level 1 | Fixed maturity securities | Agencies
Assets
Fair value	0	0
Level 1 | Fixed maturity securities | Non-U.S. government
Assets
Fair value	0	0
Level 1 | Fixed maturity securities | Corporate bonds
Assets
Fair value	0	0
Level 1 | Fixed maturity securities | Residential mortgage-backed
Assets
Fair value	0	0
Level 1 | Fixed maturity securities | Commercial mortgage-backed
Assets
Fair value	0	0
Level 1 | Fixed maturity securities | Other asset backed securities
Assets
Fair value	0	0
Level 1 | Short-term investments
Assets
Fair value	133.3	49
Level 1 | Short-term investments | U.S. Treasuries
Assets
Fair value	133.3	49
Level 2
Assets
Cash equivalents - money market funds	0	0
Other Investments	0	0
Investments pending settlement	0	0
Total other assets	0	0
Total assets measured at fair value	2,819.5	2,558.2
Liabilities
Derivative liabilities	(6.1)	(1.1)
Investments pending settlement	0
Total other liabilities	(6.1)	(1.1)
Total liabilities measured at fair value	(6.1)	(1.1)
Level 2 | Fixed maturity securities
Assets
Fair value	2,819.5	2,558.2
Level 2 | Fixed maturity securities | U.S. Treasuries
Assets
Fair value	0	0
Level 2 | Fixed maturity securities | Agencies
Assets
Fair value	12.1	16.2
Level 2 | Fixed maturity securities | Non-U.S. government
Assets
Fair value	51.8	76
Level 2 | Fixed maturity securities | Corporate bonds
Assets
Fair value	2,009.6	1,787.3
Level 2 | Fixed maturity securities | Residential mortgage-backed
Assets
Fair value	274.6	188.2
Level 2 | Fixed maturity securities | Commercial mortgage-backed
Assets
Fair value	21.4	51.1
Level 2 | Fixed maturity securities | Other asset backed securities
Assets
Fair value	450	439.4
Level 2 | Short-term investments
Assets
Fair value	0	0
Level 2 | Short-term investments | U.S. Treasuries
Assets
Fair value	0	0
Level 3
Assets
Cash equivalents - money market funds	0	0
Other Investments	0	0
Investments pending settlement	0	0
Total other assets	0	0
Total assets measured at fair value	0	0
Liabilities
Derivative liabilities	0	0
Investments pending settlement	0
Total other liabilities	0	0
Total liabilities measured at fair value	0	0
Level 3 | Fixed maturity securities
Assets
Fair value	0	0
Level 3 | Fixed maturity securities | U.S. Treasuries
Assets
Fair value	0	0
Level 3 | Fixed maturity securities | Agencies
Assets
Fair value	0	0
Level 3 | Fixed maturity securities | Non-U.S. government
Assets
Fair value	0	0
Level 3 | Fixed maturity securities | Corporate bonds
Assets
Fair value	0	0
Level 3 | Fixed maturity securities | Residential mortgage-backed
Assets
Fair value	0	0
Level 3 | Fixed maturity securities | Commercial mortgage-backed
Assets
Fair value	0	0
Level 3 | Fixed maturity securities | Other asset backed securities
Assets
Fair value	0	0
Level 3 | Short-term investments
Assets
Fair value	0	0
Level 3 | Short-term investments | U.S. Treasuries
Assets
Fair value	$ 0	$ 0

Fair Value Measurements - Fin_2

Fair Value Measurements - Financial Instruments Based on Observable Inputs (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023	Oct. 20, 2020	Jul. 02, 2020
Senior Notes | Senior Notes Due 2030
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Interest rate, stated percentage	4.875%	4.875%		4.875%
Junior Subordinated Debt | Fixed Rate Reset Junior Subordinated notes due 2041
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Interest rate, stated percentage	6.625%	6.625%	6.625%
Fair Value | Preference securities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Debt instrument, fair value disclosure	$ 56.9	$ 55.6
Fair Value | Level 2 | Senior Notes | 4.875% Senior notes due 2030
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Debt instrument, fair value disclosure	326.3	273.1
Fair Value | Level 2 | Senior Subordinated Notes | 6.625% Fixed Rate Reset Junior Subordinated notes due 2041
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Debt instrument, fair value disclosure	123.8	121.6
Carrying Value | Preference securities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Debt instrument, fair value disclosure	58.4	58.4
Carrying Value | Level 2 | Senior Notes | 4.875% Senior notes due 2030
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Debt instrument, fair value disclosure	325.6	325
Carrying Value | Level 2 | Senior Subordinated Notes | 6.625% Fixed Rate Reset Junior Subordinated notes due 2041
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Debt instrument, fair value disclosure	$ 123.2	$ 123.2

Total Cash, Cash Equivalents,_3

Total Cash, Cash Equivalents, Restricted Cash and Restricted Investments - Summary of Cash and Cash Equivalents, Restricted Cash and Restricted Investments (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 806.8	$ 712.4	$ 569
Restricted cash and cash equivalents	212.3	251.7	261.5
Total cash, cash equivalents and restricted cash	1,019.1	964.1	$ 830.5	$ 1,407.9
Restricted investments securing reinsurance contracts and letter of credit facilities	1,225.7	1,347
Total cash, cash equivalents, restricted cash and restricted investments	2,244.8	2,311.1
Financial Standby Letter of Credit
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and cash equivalents	8.9	5.8
Reinsurance Contracts
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and cash equivalents	$ 203.4	$ 245.9

Derivative Financial Instrume_3

Derivative Financial Instruments - Fair Value and Notional Amounts of Derivative Instruments (Details) - Not Designated as Hedging Instrument - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Notional amounts
Total derivative liabilities	$ (176.2)	$ (9.7)
Fair value
Fair value	(6.1)	(1.1)
Forwards
Notional amounts
Total derivative liabilities	(176.2)	(9.7)
Fair value
Fair value	$ (6.1)	$ (1.1)

Derivative Financial Instrume_4

Derivative Financial Instruments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Derivative [Line Items]
Net realized gains/(losses)	$ (3.4)	$ (1.8)	$ (4.7)	$ 0.5
Change in net unrealized gains/(losses)	(4.7)	4.6	$ (5)	$ (3)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]			Gain (Loss) on Investments	Gain (Loss) on Investments
Forwards
Derivative [Line Items]
Net realized gains/(losses)	(3.4)	(1.8)	$ (4.7)	$ 0.5
Change in net unrealized gains/(losses)	(4.7)	4.6	(5)	(3)
Total foreign exchange contracts
Derivative [Line Items]
Net realized gains/(losses)	(3.4)	(1.8)	(4.7)	0.5
Change in net unrealized gains/(losses)	$ (4.7)	$ 4.6	$ (5)	$ (3)

Reserves for Losses and Loss _3

Reserves for Losses and Loss Adjustment Expenses - Reconciliation of Unpaid Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Reserves for losses and loss adjustment expenses, beginning of period			$ 2,448.9	$ 2,045.2
Reinsurance recoverable on reserves for losses and loss adjustment expenses	$ (1,164.9)	$ (1,066.3)	(1,164.9)	(1,066.3)	$ (1,108.6)	$ (976.1)
Net reserves for losses and loss adjustment expenses, beginning of period			1,340.3	1,069.1
Current year	247.9	235	788.5	557.4
Prior years	(10.1)	(43.3)	(145.7)	(47.8)
Total incurred	237.8	191.7	642.8	509.6
Current year			(97.7)	(61.9)
Prior years			(251.5)	(267.1)
Total paid			(349.2)	(329)
Foreign exchange			2	(7.4)
Net reserves for losses and loss adjustment expenses, end of period	1,635.9	1,242.3	1,635.9	1,242.3
Reserves for losses and loss adjustment expenses, end of period	$ 2,800.8	$ 2,308.6	$ 2,800.8	$ 2,308.6

Reserves for Losses and Loss _4

Reserves for Losses and Loss Adjustment Expenses - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Short-Duration Insurance Contracts, Historical Claims Duration [Line Items]
Prior years	$ (10.1)	$ (43.3)	$ (145.7)	$ (47.8)
Bespoke
Short-Duration Insurance Contracts, Historical Claims Duration [Line Items]
Prior years			(62.2)	28.6
Specialty
Short-Duration Insurance Contracts, Historical Claims Duration [Line Items]
Prior years			(34.5)	32.7
Reinsurance
Short-Duration Insurance Contracts, Historical Claims Duration [Line Items]
Prior years			$ (49)	$ 51.9

Reinsurance and Retrocessiona_2

Reinsurance and Retrocessional Reinsurance (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Insurance [Abstract]
Reinsurance recoverable on reserves for losses and loss adjustment expenses	$ 1,164.9	$ 1,108.6	$ 1,066.3	$ 976.1
Reinsurance recoverable for paid claims and claims adjustments	194.1	182.7
Reinsurance recoverables on paid losses, allowance	0	0
Reinsurance recoverables on unpaid losses, allowance	$ 1.3	$ 1.3

Long Term Debt and Preference_3

Long Term Debt and Preference Securities - Narrative (Details) - USD ($) $ / shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2015	Dec. 31, 2023	Oct. 20, 2020	Oct. 16, 2020	Jul. 02, 2020	Jun. 18, 2020
Debt Instrument [Line Items]
Preferred stock, liquidation preference, value	$ 10		$ 10			$ 10
Preference Securities
Debt Instrument [Line Items]
Preference securities, issued (in shares)	5,835		5,835			5,835
Preferred stock, dividend rate, percentage					9%
Preferred stock, dividend rate, per-dollar-amount (in dollars per share)					$ 10
Preferred stock, liquidation preference, value					$ 10
Preference Securities | Minimum
Debt Instrument [Line Items]
Preferred stock, dividend rate, percentage					9%
Preference Securities | Redemption Price
Debt Instrument [Line Items]
Preferred stock, dividend rate, percentage					0.50%
Preference Securities | Treasury Rate Determination
Debt Instrument [Line Items]
Preferred stock, dividend rate, percentage					9.773%
Preference Securities | Other Liabilities
Debt Instrument [Line Items]
Dividends payable	$ 200		$ 200			$ 200
Preference Securities | Financing Costs
Debt Instrument [Line Items]
Dividends, preferred stock	$ 1,300	$ 1,300	$ 3,900	$ 3,900
Senior Notes Due 2030 | Senior Notes
Debt Instrument [Line Items]
Debt instrument, face amount									$ 30,000	$ 300,000
Interest rate, stated percentage	4.875%		4.875%			4.875%			4.875%
Fixed Rate Reset Junior Subordinated notes due 2041 | Junior Subordinated Debt
Debt Instrument [Line Items]
Debt instrument, face amount							$ 20,000	$ 105,000
Interest rate, stated percentage	6.625%		6.625%			6.625%	6.625%
Fixed Rate Reset Junior Subordinated notes due 2041 | Junior Subordinated Debt | Treasury Rate Determination
Debt Instrument [Line Items]
Derivative, basis spread on variable rate							6.323%

Long Term Debt and Preference_4

Long Term Debt and Preference Securities - Debt Issued (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023	Oct. 20, 2020	Jul. 02, 2020
Debt Instrument [Line Items]
Principal	$ 455	$ 455
Unamortized discount and debt issuance costs	(6.2)	(6.8)
Senior Notes Due 2030 | Senior Notes
Debt Instrument [Line Items]
Principal	330	330
Unamortized discount and debt issuance costs	$ (4.4)	$ (5)
Interest rate, stated percentage	4.875%	4.875%		4.875%
Fixed Rate Reset Junior Subordinated notes due 2041 | Junior Subordinated Debt
Debt Instrument [Line Items]
Principal	$ 125	$ 125
Unamortized discount and debt issuance costs	$ (1.8)	$ (1.8)
Interest rate, stated percentage	6.625%	6.625%	6.625%

Long Term Debt and Preference_5

Long Term Debt and Preference Securities - Preference Securities Authorized Issued and Outstanding (Details) - $ / shares	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Preferred stock, liquidation preference per share (in dollar per share)		$ 0.01	$ 0.01
Preference Securities
Debt Instrument [Line Items]
Preference securities, authorized (in shares)		1,000,000	1,000,000
Preference securities, issued (in shares)		5,835	5,835
Preference securities, outstanding (in shares)		5,835	5,835
Preferred stock, dividend rate, percentage	9%

Commitments and Contingencies -

Commitments and Contingencies - Letters of Credit (Details) - Standby Letters of Credit - Line of Credit - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Line of Credit Facility [Line Items]
Commitment	$ 475	$ 550
In Use	238.1	338.6
Letters of credit outstanding, amount	$ 162.3	173
Minimum
Line of Credit Facility [Line Items]
Debt instrument, term	1 year
Maximum
Line of Credit Facility [Line Items]
Debt instrument, term	2 years
Lloyds Bank plc
Line of Credit Facility [Line Items]
Commitment	$ 125	200
In Use	53.8	133.8
Letters of credit outstanding, amount	43.1	44.2
Citibank N.A. London branch
Line of Credit Facility [Line Items]
Commitment	70	70
In Use	44	52.3
Letters of credit outstanding, amount	46.4	55.2
Barclays Bank plc
Line of Credit Facility [Line Items]
Commitment	140	140
In Use	82.3	84.3
Letters of credit outstanding, amount	41.4	37.7
Bank of Montreal
Line of Credit Facility [Line Items]
Commitment	140	140
In Use	58	68.2
Letters of credit outstanding, amount	31.4	35.9
Unsecured | Lloyds Bank plc
Line of Credit Facility [Line Items]
Commitment	25	25
In Use	19.8	20.6
Unsecured | Barclays Bank plc
Line of Credit Facility [Line Items]
Commitment	60	60
In Use	51.3	53.3
Unsecured | Bank of Montreal
Line of Credit Facility [Line Items]
Commitment	40	40
In Use	32	36.1
Secured | Lloyds Bank plc
Line of Credit Facility [Line Items]
Commitment	100	100
In Use	34	38.2
Secured | Citibank N.A. London branch
Line of Credit Facility [Line Items]
Commitment	70	70
In Use	44	52.3
Secured | Barclays Bank plc
Line of Credit Facility [Line Items]
Commitment	80	80
In Use	31	31
Secured | Bank of Montreal
Line of Credit Facility [Line Items]
Commitment	100	100
In Use	26	32.1
Ancillary own funds | Lloyds Bank plc
Line of Credit Facility [Line Items]
Commitment		75
In Use		$ 75
Ancillary own funds | Barclays Bank plc
Line of Credit Facility [Line Items]
Commitment	80
Ancillary own funds | Bank of Montreal
Line of Credit Facility [Line Items]
Commitment	60
Uncommitted Tranche | Lloyds Bank plc
Line of Credit Facility [Line Items]
Commitment	50
Uncommitted Tranche | Citibank N.A. London branch
Line of Credit Facility [Line Items]
Commitment	$ 200

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
	Dec. 20, 2022	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2023 USD ($)	Jan. 03, 2023
Related Party Transaction [Line Items]
Reinsurance, profit commission, percentage				0.200
Reinsurance, profit commission, hurdle rate of return, percentage				0.050
Related Party
Related Party Transaction [Line Items]
Other receivables		$ 248.5		$ 248.5			$ 173.3
Amounts due to The Fidelis Partnership		410.7		$ 410.7			$ 334.5
Framework Agreement | Related Party
Related Party Transaction [Line Items]
Related party transaction, agreement duration	10 years
Reinsurance, ceded commission, percentage				0.115
Property management fee, percent fee				3%
Insurance commissions		33.7	$ 24.7	$ 76.8	$ 37.3
Payments for commissions		40.9	12.9	55	20.7
Origination of notes receivable from related parties						$ 4.5
Framework Agreement | Related Party | Policy Acquisition Expenses
Related Party Transaction [Line Items]
Insurance commissions		17.1	4.1	33.6	14.5
Framework Agreement | Related Party | General and Administrative Expense
Related Party Transaction [Line Items]
Costs and expenses, related party		1.6	1.6	4.6	4.3
Related party transaction, purchases from related party		$ 0.7	$ 0.6	$ 1.1	$ 1.9
Framework Agreement | Related Party | Third Party Managing General Underwriters
Related Party Transaction [Line Items]
Reinsurance, ceded commission, percentage				0.03
Group | Fidelis MGU
Related Party Transaction [Line Items]
Subsidiary, ownership percentage, noncontrolling owner								9.90%
Group | Framework Agreement | Related Party | Fidelis MGU
Related Party Transaction [Line Items]
Subsidiary, ownership percentage, noncontrolling owner								9.90%

Related Party Transactions - Su

Related Party Transactions - Summary of Commissions (Details) - Related Party - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Related Party Transaction [Line Items]
Ceding commission expense	$ 84.2	$ 56.3	$ 225.3	$ 107.4
Profit commission expense	13.1	14.3	23.7	40
Total commissions	$ 97.3	$ 70.6	$ 249	$ 147.4

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Earnings per common share
Net income available to common shareholders (in shares)	$ 100.6	$ 87.7	$ 235.5	$ 1,904.2
Weighted average basic common shares outstanding (in shares)	114,445,447	117,681,835	116,390,461	113,100,521
Earnings per common share (in dollars per share)	$ 0.88	$ 0.75	$ 2.02	$ 16.84
Earnings per diluted common share
Share-based compensation plans (in shares)	289,079	293,264	455,530	132,409
Weighted average diluted common shares outstanding (in shares)	114,734,526	117,975,099	116,845,991	113,232,930
Earnings per diluted common share (in dollars per share)	$ 0.88	$ 0.74	$ 2.02	$ 16.82

Share Capital Authorized and _3

Share Capital Authorized and Issued - Common Shares Information (Details) - $ / shares	Sep. 30, 2024	Dec. 31, 2023
Equity [Abstract]
Common stock, shares authorized (in shares)	600,000,000	600,000,000
Common stock, shares, outstanding (in shares)	111,726,363	117,914,754
Common stock, shares, issued (in shares)	111,726,363	117,914,754
Common stock, par or stated value per share (in dollars per share)	$ 0.01	$ 0.01

Share Capital Authorized and _4

Share Capital Authorized and Issued - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended		9 Months Ended
	Jul. 03, 2023	Jan. 03, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Aug. 14, 2024	Dec. 21, 2023
Capital Unit [Line Items]
Stock issued during period, shares, new issues (in shares)		13,553,681
Stock repurchased and retired during period (in shares)		97,327,049
Dividends, common stock, cash		$ 34.1
Adjustments to additional paid in capital, dividends in excess of retained earnings		0.5
Accumulated distributions in excess of net income		$ 1,696.4
Common stock, dividends, per share, declared (in dollars per share)			$ 0.10	$ 0	$ 0.30	$ 0
Stock repurchase program, authorized amount							$ 200	$ 50
Treasury stock, shares, acquired (in shares)			4,279,983	0	6,570,003	0
Treasury stock, value, acquired, cost method			$ 66.8	$ 0	$ 105.5	$ 0
Shares acquired, average cost per share (in dollars per share)			$ 15.61	$ 0	$ 16.06	$ 0
Fidelis Partnership
Capital Unit [Line Items]
Treasury stock, shares, acquired (in shares)			422,658		577,383
Treasury stock, value, acquired, cost method			$ 6.6		$ 9.3
IPO
Capital Unit [Line Items]
Stock issued during period, shares, new issues (in shares)	15,000,000
Sale of stock, number of shares issued in transaction (in shares)	15,000,000
Sale of stock, price per share (in dollars per share)	$ 14
Sale of stock, consideration received on transaction	$ 89.4
IPO, Shares Sold By Fidelis
Capital Unit [Line Items]
Sale of stock, number of shares issued in transaction (in shares)	7,142,857
IPO, Shares Sold By Selling Shareholders
Capital Unit [Line Items]
Sale of stock, number of shares issued in transaction (in shares)	7,857,143
Group | Fidelis MGU
Capital Unit [Line Items]
Stock repurchased and retired during period (in shares)		97,327,049
Consolidation, less than wholly owned subsidiary, parent ownership interest, changes, sale of interest by parent		$ 1,775

Income Taxes (Details)

Income Taxes (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Effective income tax rate reconciliation, percent	14.70%	8.30%	14.60%	0.90%
Income tax expense	$ 17,300,000	$ 7,900,000	$ 40,400,000	$ 17,200,000
Effective income Tax rate reconciliation, nondeductible expense, share-based payment arrangement, amount	$ 0	$ 0	$ 0	6,200,000
Effective income tax rate reconciliation, discrete items, non-cash income tax benefit amount				$ 38,300,000