StoneX (SNEX) 10-Q 5 Feb 25 2025 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Dec. 31, 2024	Feb. 03, 2025
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Dec. 31, 2024
Document Transition Report	false
Entity File Number	000-23554
Entity Registrant Name	StoneX Group Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	59-2921318
Entity Address, Address Line One	230 Park Ave
Entity Address, Address Line Two	10th Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10169
City Area Code	(212)
Local Phone Number	485-3500
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	SNEX
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		32,084,624
Entity Central Index Key	0000913760
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q1
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024
ASSETS
Cash and cash equivalents	$ 1,398.2	$ 1,269
Cash, securities and other assets segregated under federal and other regulations (including $309.0 million and $51.8 million at fair value at December 31, 2024 and September 30, 2024, respectively)	3,156.6	2,841.2
Collateralized transactions:
Securities purchased under agreements to resell	5,479.2	5,201.5
Securities borrowed	2,120.7	1,662.3
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net (including $4,781.3 million and $3,287.5 million at fair value at December 31, 2024 and September 30, 2024, respectively)	7,783.9	7,283.2
Receivable from clients, net (including $(2.8) million and $(8.4) million at fair value at December 31, 2024 and September 30, 2024, respectively)	1,096.3	1,013.1
Income taxes receivable	20.9	19.3
Financial instruments owned, at fair value (includes securities pledged as collateral that can be sold or repledged of $1,500.0 million and $2,172.0 million at December 31, 2024 and September 30, 2024, respectively)	6,918.1	6,767.1
Physical commodities inventory, net (including $476.7 million and $376.6 million at fair value at December 31, 2024 and September 30, 2024, respectively)	861.4	681.1
Deferred tax asset	53.6	46.3
Property and equipment, net	145.1	143.1
Operating right of use assets	159.7	157
Goodwill and intangible assets, net	87	80.6
Other assets	304.6	301.5
Total assets	29,585.3	27,466.3
Liabilities:
Accounts payable and other accrued liabilities (including $2.9 million and $2.3 million at fair value at December 31, 2024 and September 30, 2024, respectively)	441.8	522.1
Operating lease liabilities	198.6	195.9
Payables to:
Clients (including $371.1 million and $265.9 million at fair value at December 31, 2024 and September 30, 2024, respectively)	11,338.2	10,345.9
Broker-dealers, clearing organizations and counterparties (including $37.5 million and $(1.4) million at fair value at December 31, 2024 and September 30, 2024, respectively)	445.5	734.2
Lenders under loans	550	338.8
Senior secured borrowings, net	543.3	543.1
Income taxes payable	33.7	18.1
Deferred tax liability	15.8	8.6
Collateralized transactions:
Securities sold under agreements to repurchase	8,872.9	8,581.3
Securities loaned	1,826.5	1,615.9
Financial instruments sold, not yet purchased, at fair value	3,541.6	2,853.3
Total liabilities	27,807.9	25,757.2
Commitments and contingencies (Note 11)
Stockholders' equity:
Preferred stock, $0.01 par value. Authorized 1,000,000 shares; no shares issued or outstanding	0	0
Common stock, $0.01 par value. Authorized 200,000,000 shares; 35,945,614 issued and 32,034,629 outstanding at December 31, 2024 and 35,785,432 issued and 31,874,447 outstanding at September 30, 2024	0.4	0.4
Common stock in treasury, at cost. 3,910,985 shares at December 31, 2024 and September 30, 2024	(69.3)	(69.3)
Additional paid-in-capital	422.7	414.3
Retained earnings	1,474	1,388.9
Accumulated other comprehensive loss, net	(50.4)	(25.2)
Total equity	1,777.4	1,709.1
Total liabilities and stockholders' equity	$ 29,585.3	$ 27,466.3

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024
Statement of Financial Position [Abstract]
Cash, securities and other assets segregated under federal and other regulations at fair value	$ 309	$ 51.8
Deposits with and receivables from broker-dealers, clearing organizations and counterparties at fair value	4,781.3	3,287.5
Receivables from clients at fair value	(2.8)	(8.4)
Financial instruments owned at fair value, securities pledged as collateral that can be sold or repledged	1,500	2,172
Physical commodities inventory at fair value	476.7	376.6
Accounts payable and other accrued liabilities at fair value	2.9	2.3
Payables to client at fair value	371.1	265.9
Payables to broker-dealers, clearing organizations and counterparties at fair value	$ 37.5	$ (1.4)
Preferred stock - par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock - authorized (in shares)	1,000,000	1,000,000
Preferred stock - issued (in shares)	0	0
Preferred stock - outstanding (in shares)	0	0
Common stock - par value (in dollars per share)	$ 0.01	$ 0.01
Common stock - authorized (in shares)	200,000,000	200,000,000
Common stock - issued (in shares)	35,945,614	35,785,432
Common stock - outstanding (in shares)	32,034,629	31,874,447
Common stock in treasury, cost (in shares)	3,910,985	3,910,985

Condensed Consolidated Income S

Condensed Consolidated Income Statements (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Revenues:
Total revenues	$ 27,935.3	$ 19,573
Cost of sales of physical commodities	26,991	18,788.8
Operating revenues	944.3	784.2
Transaction-based clearing expenses	86.5	74.3
Introducing broker commissions	44.3	39.1
Interest expense	306.2	236
Interest expense on corporate funding	15.2	13.2
Net operating revenues	492.1	421.6
Compensation and other expenses:
Compensation and benefits	252.5	218.1
Trading systems and market information	20	18.7
Professional fees	19	15.7
Non-trading technology and support	19.7	16.9
Occupancy and equipment rental	13	7.7
Selling and marketing	12	11.7
Travel and business development	8.4	7.1
Communications	2.1	2.2
Depreciation and amortization	15.7	11.2
Bad debts (recoveries), net	1.8	(0.3)
Other	16.7	16.9
Total compensation and other expenses	380.9	325.9
Other gains	5.7	0
Income before tax	116.9	95.7
Income tax expense	31.8	26.6
Net income	$ 85.1	$ 69.1
Earnings per share:
Basic (in dollars per share)	$ 2.66	$ 2.20
Diluted (in dollars per share)	$ 2.54	$ 2.13
Weighted-average number of common shares outstanding:
Basic (in shares)	30,976,042	30,233,107
Diluted (in shares)	32,444,772	31,274,307
Sales of physical commodities
Revenues:
Total revenues	$ 27,051.1	$ 18,820.9
Principal gains, net
Revenues:
Total revenues	308.9	293.8
Commission and clearing fees
Revenues:
Total revenues	149.3	129.7
Consulting, management, and account fees
Revenues:
Total revenues	47.8	38.5
Interest income
Revenues:
Total revenues	$ 378.2	$ 290.1

Condensed Consolidated Statemen

Condensed Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Statement of Comprehensive Income [Abstract]
Net income	$ 85.1	$ 69.1
Other comprehensive (loss)/gain, net of tax:
Foreign currency translation adjustment	(18.3)	6.9
Cash flow hedges	(6.9)	20.7
Total other comprehensive (loss)/gain, net of tax	(25.2)	27.6
Comprehensive income	$ 59.9	$ 96.7

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions		3 Months Ended
		Dec. 31, 2024	Dec. 31, 2023
Cash flows from operating activities:
Net income		$ 85.1	$ 69.1
Adjustments to reconcile net income to net cash (used in)/provided by operating activities:
Depreciation and amortization		15.7	11.2
Amortization of right of use assets		7.7	3.2
Bad debts (recoveries), net		1.8	(0.3)
Deferred income taxes		5.4	1.5
Amortization of debt issuance costs		0.9	1.5
Amortization of share-based compensation		11.3	7.6
Changes in operating assets and liabilities, net:
Securities and other assets segregated under federal and other regulations		42.7	2.3
Securities purchased under agreements to resell		(277.7)	(820.3)
Securities borrowed		(458.4)	134.6
Deposits with and receivables from broker-dealers, clearing organizations, and counterparties, net		(1,317.6)	(206.8)
Receivables from clients, net		(85)	(142.2)
Notes receivable, net		0	(0.1)
Income taxes receivable		(12.1)	4.2
Financial instruments owned, at fair value		(158.9)	(11.1)
Physical commodities inventory, net		(178.6)	18.9
Other assets		(3.7)	(44.8)
Accounts payable and other accrued liabilities		(64.3)	(87)
Operating lease liabilities		(7.7)	1
Payables to clients		992.3	72.6
Payables to broker-dealers, clearing organizations, and counterparties		(288.7)	99.1
Income taxes payable		21.7	3.7
Securities sold under agreements to repurchase		291.6	1,527.6
Securities loaned		210.6	(174.6)
Financial instruments sold, not yet purchased, at fair value		688.1	(318.5)
Net cash (used in)/provided by operating activities		(477.8)	152.4
Cash flows from investing activities:
Acquisition of businesses and assets, net of cash received		(8)	0
Purchases of property and equipment		(13.6)	(12.7)
Net cash used in investing activities		(21.6)	(12.7)
Cash flows from financing activities:
Net change in payables to lenders under loans with maturities 90 days or less		211.2	77.5
Deferred payments on acquisitions		(20.1)	0
Shares withheld to cover taxes on vesting of equity awards		(3.7)	(1.1)
Exercise of stock options		0.8	0.5
Net cash provided by financing activities		188.2	76.9
Effect of exchange rates on cash, segregated cash, cash equivalents, and segregated cash equivalents		(18.4)	6.8
Net (decrease)/increase in cash, segregated cash, cash equivalents, and segregated cash equivalents		(329.6)	223.4
Cash, segregated cash, cash equivalents, and segregated cash equivalents at beginning of period		6,672.6	6,041.7
Cash, segregated cash, cash equivalents, and segregated cash equivalents at end of period		6,343	6,265.1
Supplemental disclosure of cash flow information:
Cash paid for interest		304.7	281.5
Income taxes paid, net of cash refunds		17.4	18.4
Supplemental disclosure of non-cash investing and financing activities:
Identified intangible assets and goodwill on acquisitions		7.3	0
Additional consideration payable related to acquisitions, net		3.1	0
Acquisition consideration paid in silver bullion		12.6	0
Acquisition of business:
Assets acquired		18.6	0
Liabilities assumed		2.2	0
Total net assets acquired		16.4	0
Cash and cash equivalents		1,398.2	1,157.6
Cash segregated under federal and other regulations	[1]	2,847.5	2,771.1
Securities segregated under federal and other regulations	[1]	299.9	0
Cash segregated and deposited with or pledged to exchange-clearing organizations and other futures commission merchants (“FCMs”)	[2]	860.5	1,455.3
Securities segregated and pledged to exchange-clearing organizations	[2]	936.9	881.1
Total cash, segregated cash, cash equivalents, and segregated cash equivalents shown in the condensed consolidated statements of cash flows		6,343	6,265.1
Non-cash equivalent segregated assets		9.2	3.5
Non-segregated cash and other non-cash equivalent assets included within deposits and receivables from broker-dealers, clearing organizations, and counterparties		$ 5,986.5	$ 5,137.7
[1]Represents segregated client cash held at third-party banks. Excludes segregated commodity warehouse receipts, segregated U.S. Treasury obligations with original or acquired maturities of greater than 90 days, and other assets of $9.2 million and $3.5 million as of December 31, 2024 and 2023, respectively, included within Cash, securities and other assets segregated under federal and other regulations on the Condensed Consolidated Balance Sheets. Represents segregated client cash and U.S. Treasury obligations on deposit with, or pledged to, exchange clearing organizations and other FCMs. Excludes non-segregated cash, segregated U.S. Treasury obligations pledged to exchange-clearing organizations with original or acquired maturities greater than 90 days, and other assets of $5,986.5 million and $5,137.7 million as of December 31, 2024 and 2023, respectively, included within Deposits with and receivables from broker-dealers, clearing organizations, and counterparties, net on the Condensed Consolidated Balance Sheets.

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss, net
Beginning balance at Sep. 30, 2023	$ 1,379.1	$ 0.4	$ (69.3)	$ 371.7	$ 1,128.1	$ (51.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	69.1				69.1
Other comprehensive gain (loss), net of tax	27.6					27.6
Exercise of stock options	0.5			0.5
Shares withheld to cover taxes on vesting of equity awards	(1.1)			(1.1)
Share-based compensation	7.6			7.6
Ending balance at Dec. 31, 2023	1,482.8	0.4	(69.3)	378.7	1,197.2	(24.2)
Beginning balance at Sep. 30, 2024	1,709.1	0.4	(69.3)	414.3	1,388.9	(25.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	85.1				85.1
Other comprehensive gain (loss), net of tax	(25.2)					(25.2)
Exercise of stock options	0.8			0.8
Shares withheld to cover taxes on vesting of equity awards	(3.7)			(3.7)
Share-based compensation	11.3			11.3
Ending balance at Dec. 31, 2024	$ 1,777.4	$ 0.4	$ (69.3)	$ 422.7	$ 1,474	$ (50.4)

Basis of Presentation and Conso

Basis of Presentation and Consolidation and Accounting Standards Adopted	3 Months Ended
	Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Consolidation and Accounting Standards Adopted	Basis of Presentation and Consolidation and Accounting Standards Adopted StoneX Group Inc., a Delaware corporation, and its consolidated subsidiaries (collectively “StoneX” or “the Company”), is a global financial services network that connects companies, organizations, traders and investors to the global market ecosystem through a unique blend of digital platforms, end-to-end clearing and execution services, high touch service, and deep expertise. The Company’s common stock trades on The NASDAQ Global Select Market under the symbol “SNEX”. Basis of Presentation The accompanying unaudited Condensed Consolidated Balance Sheet as of September 30, 2024, which has been derived from the audited consolidated balance sheet of September 30, 2024, and the unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and disclosures normally included in annual consolidated financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) have been condensed or omitted pursuant to those rules and regulations. The Company believes that the included disclosures clearly and fairly present the information within. In management’s opinion, all adjustments, generally consisting of normal accruals, considered necessary to fairly present the condensed consolidated financial statements for the interim periods presented have been reflected as required by Rule 10-01 of Regulation S-X. Operating results for interim periods are not necessarily indicative of the results that may be expected for the full year. These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and related notes contained in the Company’s Annual Report on Form 10-K for the fiscal year ended September 30, 2024, as filed with the SEC. These condensed consolidated financial statements include the accounts of StoneX Group Inc. and all entities in which the Company has a controlling financial interest. All material intercompany transactions and balances have been eliminated in consolidation. Preparing condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent liabilities as of the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. The most significant of these estimates and assumptions in the current year relate to fair value measurements for financial instruments, revenue recognition, valuation of inventories, and income taxes. The Company reviews all significant estimates affecting the financial statements on a recurring basis and makes necessary adjustments in the financial statements presented within this Form 10-Q. Although these and other estimates and assumptions are based on the best available information, actual results could be materially different from estimates. Estimates and assumptions are based on management’s best knowledge of current events and actions the Company may undertake in the future, using information reasonably available to the Company as of December 31, 2024 and through the date of this Form 10-Q. Physical Commodities Inventory The JBR Recovery Limited assets and business acquisition, discussed and defined in Note 17, introduced stages of refining, such as raw materials, work in process, and completed goods. These are reported as components of Physical commodities inventory, net on the Condensed Consolidated Balance Sheets. The Company’s valuation policy includes estimating the cost to complete refining the various stages into finished product, the type of materials being refined, along with the market prices of the finished product to arrive at the lower of cost or net realizable value. Subsequent Common Stock Split On February 5, 2025, the Company announced a 3-for-2 split of its common stock, which will be effected as a stock dividend entitling each shareholder of record to receive one additional share of common stock for every two shares owned. Additional shares issued as a result of the stock dividend will be distributed after close of trading on March 21, 2025, to stockholders of record at the close of business on March 11, 2025. Cash will be distributed in lieu of fractional shares based on the opening price of a share of common stock on March 12, 2025. All share and per share amounts contained herein have not been retroactively adjusted for this subsequent stock split. Accounting Standards

Earnings per Share

Earnings per Share	3 Months Ended
	Dec. 31, 2024
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share The Company presents basic and diluted earnings per share (“EPS”) using the two-class method, which requires all outstanding unvested share-based payment awards that contain rights to non-forfeitable dividends and therefore participate in undistributed earnings with common stockholders be included in computing earnings per share. Under the two-class method, net income is reduced by the amount of dividends declared in the period for each class of common stock and participating security. The remaining undistributed earnings are then allocated to common stock and participating securities, based on their respective rights to receive dividends. Restricted stock awards granted to certain employees and directors contain non-forfeitable rights to dividends at the same rate as common stock and are considered participating securities. Basic EPS has been computed by dividing net income by the weighted-average number of common shares outstanding. The following is a reconciliation of the numerator and denominator of the diluted earnings per share computations for the periods presented below. Three Months Ended December 31, (in millions, except share amounts) 2024 2023 Numerator: Net income $ 85.1 $ 69.1 Less: Allocation to participating securities (2.7) (2.4) Net income allocated to common stockholders $ 82.4 $ 66.7 Denominator: Weighted average number of: Common shares outstanding 30,976,042 30,233,107 Dilutive potential common shares outstanding: Share-based awards 1,468,730 1,041,200 Diluted weighted-average common shares 32,444,772 31,274,307 The dilutive effect of share-based awards is reflected in diluted net income per share by applying the treasury stock method, which includes consideration of unamortized share-based compensation expense.

Assets and Liabilities, at Fair

Assets and Liabilities, at Fair Value	3 Months Ended
	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Assets and Liabilities, at Fair Value	Assets and Liabilities, at Fair Value Fair value is defined by U.S. GAAP as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between willing market participants on the measurement date. Fair value is a market-based measure considered from the perspective of a market participant rather than an entity-specific measure. Even when market assumptions are not readily available, the Company is required to develop a set of assumptions that reflect those that market participants would use in pricing an asset or liability at the measurement date. The Company uses prices and inputs that are current as of the measurement date, including periods of market dislocation. In periods of market dislocation, the observability of prices and inputs may be reduced for many securities. This condition could cause a security to be reclassified to a lower level within the fair value hierarchy. The Company has designed independent price verification controls to validate relevant prices. Financial and nonfinancial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). A market is active if there are sufficient transactions on an ongoing basis to provide current pricing information for the asset or liability, pricing information is released publicly, and price quotations do not vary substantially either over time or among market participants. Observable inputs reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from sources independent of the reporting entity. Relevant guidance requires the Company to consider counterparty credit risk of all parties to outstanding derivative instruments that would be considered by a market participant in the transfer or settlement of such contracts (exit price). The Company’s exposure to credit risk on derivative financial instruments principally relates to the portfolio of Over-the-counter (“OTC”) derivative contracts as all exchange-traded contracts held can be settled on an active market with a credit guarantee from the respective exchange. The Company requires each counterparty to deposit margin collateral for all OTC instruments and is also required to deposit margin collateral with counterparties. The Company has assessed the nature of these deposits and used its discretion to adjust each based on the underlying credit considerations for the counterparty and determined that the collateral deposits minimize the exposure to counterparty credit risk in the evaluation of the fair value of OTC instruments as determined by a market participant. In accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 820, Fair Value Measurement, the Company groups its assets and liabilities measured at fair value in three levels based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are: Level 1 - Valuation is based upon unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. Level 1 consists of financial assets and liabilities whose fair values are estimated using quoted market prices. Level 2 - Valuation is based upon quoted prices for identical or similar assets or liabilities in markets that are less active, that is, markets in which there are few transactions for the asset or liability that are observable for substantially the full term. Included in Level 2 are those financial assets and liabilities for which fair values are estimated using models or other valuation methodologies. These models are primarily industry-standard models that consider various observable inputs, including time value, yield curve, volatility factors, observable current market and contractual prices for the underlying financial instruments, as well as other relevant economic measures. Level 3 - Valuation is based on prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). Level 3 comprises financial assets and liabilities whose fair value is estimated based on internally developed models or methodologies utilizing significant inputs that are not readily observable from objective sources. Level 3 includes contingent liabilities that have been valued using an income approach based upon management developed discounted cash flow projections, which are an unobservable input. Fair value of financial and nonfinancial assets and liabilities that are carried on the Condensed Consolidated Balance Sheets at fair value on a recurring basis Cash and cash equivalents reported at fair value on a recurring basis includes certificates of deposit and money market mutual funds, which are stated at cost plus accrued interest, which approximates fair value. Cash, securities and other assets segregated under federal and other regulations reported at fair value on a recurring basis include the value of pledged investments, primarily U.S. Treasury obligations and commodities warehouse receipts. Deposits with and receivables from broker-dealers, clearing organizations and counterparties and payable to clients and broker-dealers, clearing organizations and counterparties includes the fair value of pledged investments, primarily U.S. Treasury obligations and foreign government obligations. These balances also include the fair value of exchange-traded options on futures and OTC forwards, swaps and options. Financial instruments owned and sold, not yet purchased include the fair value of equity securities, which includes common, preferred, and foreign ordinary shares, American Depository Receipts (“ADRs”), Global Depository Receipts (“GDRs”), and exchange-traded funds (“ETFs”), corporate and municipal bonds, U.S. Treasury obligations, U.S. government agency obligations, foreign government obligations, agency mortgage-backed obligations, asset-backed obligations, derivative financial instruments, commodities warehouse receipts, exchange firm common stock, and investments in managed funds. The fair value of exchange firm common stock is determined by quoted market prices. Cash equivalents, debt and equity securities, commodities warehouse receipts, physical commodities inventory, derivative financial instruments and contingent liabilities are carried at fair value, on a recurring basis, and are classified and disclosed into three levels in the fair value hierarchy. The following section describes the valuation methodologies used by the Company to measure classes of financial instruments at fair value and specifies the level within the fair value hierarchy where various financial instruments are classified. The Company uses quoted prices in active markets, where available, and classifies instruments with such quotes within Level 1 of the fair value hierarchy. Examples include U.S. Treasury obligations, foreign government obligations, commodities warehouse receipts, certain equity securities traded in active markets, physical precious metals inventory held by a regulated broker-dealer subsidiary, exchange firm common stock, investments in managed funds, as well as options on futures contracts traded on national exchanges. The fair value of exchange firm common stock is determined by recent sale transactions and is included within Level 1. When instruments are traded in secondary markets and observable prices are not available for substantially the full term, the Company generally relies on internal valuation techniques based upon observable inputs for comparable financial instruments, or prices obtained from third-party pricing services or brokers or a combination thereof, and accordingly, classifies these instruments as Level 2. Examples include corporate and municipal bonds, U.S. government agency obligations, agency-mortgage backed obligations, asset-backed obligations, certain equity securities traded in less active markets, and OTC derivative contracts, which include purchase and sale commitments related to the Company’s foreign exchange, agricultural, and energy commodities. Certain derivatives without a quoted price in an active market and derivatives executed OTC are valued using internal valuation techniques, including pricing models which utilize significant inputs observable to market participants. The valuation techniques and inputs depend on the type of derivative and the nature of the underlying instrument. The key inputs depend upon the type of derivative and the nature of the underlying instrument and include interest yield curves, foreign exchange rates, commodity prices, volatilities and correlation. These derivative instruments are included within Level 2 of the fair value hierarchy. Physical commodities inventory includes precious metals that are a part of the trading activities of a regulated broker-dealer subsidiary. The physical commodities held by the broker dealer are recorded at fair value using exchange-quoted prices. Physical commodities inventory also includes agricultural commodities that are a part of the trading activities of a non-broker dealer subsidiary and are recorded at net realizable value using exchange-quoted prices. The fair value of precious metals physical commodities inventory is based upon unadjusted exchange-quoted prices and is, therefore, classified within Level 1 of the fair value hierarchy. The fair value of agricultural physical commodities inventory and related the OTC firm sale and purchase commitments are generally based upon exchange-quoted prices, adjusted for basis or differences in local markets, broker or dealer quotations or market transactions in either listed or OTC markets. Exchange-quoted prices are adjusted for location and quality because the exchange-quoted prices for agricultural and energy related products represent contracts that have standardized terms for commodity, quantity, future delivery period, delivery location, and commodity quality or grade. The basis or local market adjustments are observable inputs or have an insignificant impact on the measurement of fair value and, therefore, the agricultural physical commodities inventory, as well as the related OTC forward firm sale and purchase commitments have been included within Level 2 of the fair value hierarchy. With the exception of certain derivative instruments where the valuation approach is disclosed above, financial instruments owned and sold are primarily valued using third-party pricing sources. Third-party pricing vendors compile prices from various sources and often apply matrix pricing for similar securities when market-observable transactions for the instruments are not observable for substantially the full term. The Company reviews the pricing methodologies used by third-party pricing vendors in order to evaluate the fair value hierarchy classification of vendor-priced financial instruments and the accuracy of vendor pricing, which typically involves comparing of primary vendor prices to internal trader prices or secondary vendor prices. When evaluating the propriety of vendor-priced financial instruments using secondary prices, considerations include the range and quality of vendor prices, level of observable transactions for identical and similar instruments, and judgments based upon knowledge of a particular market and asset class. If the primary vendor price does not represent fair value, justification for using a secondary price, including source data used to make the determination, is subject to review and approval by authorized personnel prior to using a secondary price. Financial instruments owned and sold that are valued using third party pricing sources are included within either Level 1 or Level 2 of the fair value hierarchy based upon the observability of the inputs used and the level of activity in the market. The fair value estimates presented herein are based on pertinent information available to management as of December 31, 2024 and September 30, 2024 and through the dates of the respective reports. Although management is not aware of any factors that would significantly affect the estimated fair value amounts, such amounts have not been comprehensively revalued for purposes of these condensed consolidated financial statements since that date and current estimates of fair value may differ significantly from the amounts presented herein. The following tables set forth the Company’s financial and nonfinancial assets and liabilities accounted for at fair value, on a recurring basis, as of December 31, 2024 and September 30, 2024 by level in the fair value hierarchy. All fair value measurements were performed on a recurring basis as of December 31, 2024 and September 30, 2024. December 31, 2024 (in millions) Level 1 Level 2 Level 3 Netting (1) Total Assets: Certificates of deposit $ 10.2 $ — $ — $ — $ 10.2 Money market mutual funds 35.6 — — — 35.6 Cash and cash equivalents 45.8 — — — 45.8 Commodities warehouse receipts 9.1 — — — 9.1 U.S. Treasury obligations 299.9 — — — 299.9 Securities and other assets segregated under federal and other regulations 309.0 — — — 309.0 U.S. Treasury obligations 4,241.5 — — — 4,241.5 To be announced and forward settling securities — 74.0 — (24.7) 49.3 Foreign government obligations 16.7 — — — 16.7 Derivatives 3,706.9 2,789.7 — (6,022.8) 473.8 Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net 7,965.1 2,863.7 — (6,047.5) 4,781.3 Receivables from clients, net - Derivatives (7.0) 499.5 — (495.3) (2.8) Equity securities 515.9 24.4 — — 540.3 Corporate and municipal bonds — 475.6 — — 475.6 U.S. Treasury obligations 623.7 — — — 623.7 U.S. government agency obligations — 488.7 — — 488.7 Foreign government obligations 0.8 — — — 0.8 Agency mortgage-backed obligations — 4,197.1 — — 4,197.1 Asset-backed obligations — 265.5 — — 265.5 Derivatives — 819.2 — (593.2) 226.0 Commodities warehouse receipts 61.0 — — — 61.0 Exchange firm common stock 13.9 — — — 13.9 Cash flow hedges — 1.2 — — 1.2 Mutual funds and other 22.2 — 2.1 — 24.3 Financial instruments owned 1,237.5 6,271.7 2.1 (593.2) 6,918.1 Physical commodities inventory 201.0 275.7 — — 476.7 Total assets at fair value $ 9,751.4 $ 9,910.6 $ 2.1 $ (7,136.0) $ 12,528.1 Liabilities: Accounts payable and other accrued liabilities $ — $ — $ 2.9 $ — $ 2.9 Payables to clients - Derivatives 3,401.7 240.5 — (3,271.1) 371.1 To be announced and forward settling securities — 30.9 — (15.0) 15.9 Derivatives 279.3 2,969.4 — (3,227.1) 21.6 Payable to broker-dealers, clearing organizations and counterparties 279.3 3,000.3 — (3,242.1) 37.5 Equity securities 420.3 9.5 — — 429.8 Foreign government obligations 0.8 — — — 0.8 Corporate and municipal bonds — 230.3 — — 230.3 U.S. Treasury obligations 2,583.2 — — — 2,583.2 U.S. government agency obligations — 0.2 — — 0.2 Agency mortgage-backed obligations — 1.7 — — 1.7 Asset-backed obligations — 5.0 — — 5.0 Derivatives 3.3 798.8 — (513.2) 288.9 Cash flow hedges — 0.9 — — 0.9 Other — — 0.8 — 0.8 Financial instruments sold, not yet purchased 3,007.6 1,046.4 0.8 (513.2) 3,541.6 Total liabilities at fair value $ 6,688.6 $ 4,287.2 $ 3.7 $ (7,026.4) $ 3,953.1 (1) Represents cash collateral and the impact of netting across at each level of the fair value hierarchy. September 30, 2024 (in millions) Level 1 Level 2 Level 3 Netting (1) Total Assets: Certificates of deposit $ 13.9 $ — $ — $ — $ 13.9 Money market mutual funds 35.3 — — — 35.3 Cash and cash equivalents 49.2 — — — 49.2 Commodities warehouse receipts 51.8 — — — 51.8 Securities and other assets segregated under federal and other regulations 51.8 — — — 51.8 U.S. Treasury obligations 2,933.2 — — — 2,933.2 To be announced and forward settling securities — 26.1 — (18.3) 7.8 Foreign government obligations 18.3 — — — 18.3 Derivatives 3,900.1 2,168.2 — (5,740.1) 328.2 Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net 6,851.6 2,194.3 — (5,758.4) 3,287.5 Receivables from clients, net - Derivatives 22.4 506.2 — (537.0) (8.4) Equity securities 363.9 15.0 — — 378.9 Corporate and municipal bonds — 322.1 — — 322.1 U.S. Treasury obligations 1,088.6 — — — 1,088.6 U.S. government agency obligations — 531.0 — — 531.0 Foreign government obligations 41.4 — — — 41.4 Agency mortgage-backed obligations — 3,837.2 — — 3,837.2 Asset-backed obligations — 223.5 — — 223.5 Derivatives 0.1 603.2 — (375.2) 228.1 Commodities warehouse receipts 67.8 — — — 67.8 Exchange firm common stock 13.2 — — — 13.2 Cash flow hedges — 9.6 — — 9.6 Mutual funds and other 23.6 — 2.1 — 25.7 Financial instruments owned 1,598.6 5,541.6 2.1 (375.2) 6,767.1 Physical commodities inventory 207.6 169.0 — — 376.6 Total assets at fair value $ 8,781.2 $ 8,411.1 $ 2.1 $ (6,670.6) $ 10,523.8 Liabilities: Accounts payable and other accrued liabilities - contingent liabilities $ — $ — $ 2.3 $ — $ 2.3 Payables to clients - Derivatives 3,577.1 228.9 — (3,540.1) 265.9 To be announced and forward settling securities — 24.4 — (22.9) 1.5 Derivatives 378.0 2,356.4 — (2,737.3) (2.9) Payable to broker-dealers, clearing organizations and counterparties 378.0 2,380.8 — (2,760.2) (1.4) Equity securities 219.8 5.0 — — 224.8 Foreign government obligations 41.0 — — — 41.0 Corporate and municipal bonds — 154.6 — — 154.6 U.S. Treasury obligations 2,139.3 — — — 2,139.3 U.S. government agency obligations — 0.2 — — 0.2 Agency mortgage-backed obligations — 23.6 — — 23.6 Asset-backed obligations — 3.9 — — 3.9 Derivatives 8.1 571.0 — (314.3) 264.8 Cash flow hedges — 0.2 — — 0.2 Other — — 0.9 — 0.9 Financial instruments sold, not yet purchased 2,408.2 758.5 0.9 (314.3) 2,853.3 Total liabilities at fair value $ 6,363.3 $ 3,368.2 $ 3.2 $ (6,614.6) $ 3,120.1 (1) Represents cash collateral and the impact of netting across at each level of the fair value hierarchy. Realized and unrealized gains and losses are included in Principal gains, net , Interest income , and Cost of sales of physical commodities in the Condensed Consolidated Income Statements. Additional disclosures about the fair value of financial instruments that are not carried on the Condensed Consolidated Balance Sheets at fair value Many, but not all, of the financial instruments that the Company holds are recorded at fair value in the Condensed Consolidated Balance Sheets. The following represents financial instruments for which the ending balance at December 31, 2024 and September 30, 2024 was not carried at fair value on the Condensed Consolidated Balance Sheets in accordance with U.S. GAAP: Short-term financial instruments : The carrying value of short-term financial instruments, including cash and cash equivalents, cash segregated under federal and other regulations, securities purchased under agreements to resell and securities sold under agreements to repurchase, and securities borrowed and loaned are recorded at amounts that approximate the fair value of these instruments due to their short-term nature and level of collateralization. These financial instruments generally expose the Company to limited credit risk and have no stated maturities or have short-term maturities and carry interest rates that approximate market rates. Under the fair value hierarchy, cash and cash equivalents and cash segregated under federal and other regulations are classified as Level 1. Securities purchased under agreements to resell and securities sold under agreements to repurchase, and securities borrowed and loaned are classified as Level 2 under the fair value hierarchy as they are generally overnight, or short-term in nature, and are collateralized by equity securities, U.S. Treasury obligations, U.S. government agency obligations, agency mortgage-backed obligations, and asset-backed obligations. Receivables and other assets : Receivables from broker-dealers, clearing organizations, and counterparties, receivables from clients, net, notes receivables and certain other assets are recorded at amounts that approximate fair value due to their short-term nature and are classified as Level 2 under the fair value hierarchy. Payables : Payables to clients and payables to broker-dealers, clearing organizations, and counterparties are recorded at amounts that approximate fair value due to their short-term nature and are classified as Level 2 under the fair value hierarchy. Lenders under loans : Payables to lenders under loans carry variable rates of interest and thus approximate fair value and are classified as Level 2 under the fair value hierarchy. Senior secured borrowings, net : Senior secured borrowings, net includes the Company's 7.875% Senior Secured Notes due 2031 (the “Notes due 2031”), as further described in Note 9, with a carrying value of $543.3 million as of December 31, 2024. The carrying value of the Notes due 2031 represents their principal amount net of unamortized deferred financing costs. As of December 31, 2024, the Notes due 2031 had a fair value of $575.0 million. They

Financial Instruments with Off-

Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk	3 Months Ended
	Dec. 31, 2024
Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk [Abstract]
Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk	Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk The Company is party to certain financial instruments with off-balance sheet risk in the normal course of its business. The Company has sold financial instruments that it does not currently own and will therefore be obliged to purchase such financial instruments at a future date. The Company has recorded these obligations in the condensed consolidated financial statements as of December 31, 2024 and September 30, 2024 at the fair values of the related financial instruments. The Company will incur losses if the fair value of the underlying financial instruments increases subsequent to December 31, 2024. The total Financial instruments sold, not yet purchased of $3,541.6 million and $2,853.3 million as of December 31, 2024 and September 30, 2024, respectively, includes $288.9 million and $264.8 million for derivative contracts not designated as hedges, respectively, which represented a liability to the Company based on their fair values as of December 31, 2024 and September 30, 2024. Derivatives The Company utilizes derivative products in its trading capacity as a dealer in order to satisfy client needs and mitigate risk. The Company manages risks from both derivatives and non-derivative cash instruments on a consolidated basis. The risks of derivatives should not be viewed in isolation, but in aggregate with the Company’s other trading activities. The Company’s derivative positions are included in the Condensed Consolidated Balance Sheets in Deposits with and receivables from broker-dealers, clearing organizations and counterparties, Receivables from clients, net; Financial instruments owned and sold, not yet purchased, at fair value, Payable to clients, and Payables to broker-dealers, clearing organizations and counterparties . Listed below are the fair values of the Company’s derivative assets and liabilities as of December 31, 2024 and September 30, 2024. Assets represent net unrealized gains and liabilities represent net unrealized losses. December 31, 2024 September 30, 2024 (in millions) Assets (1) Liabilities (1) Assets (1) Liabilities (1) Derivative contracts not accounted for as hedges: Exchange-traded commodity derivatives $ 1,303.8 $ 1,281.3 $ 1,383.1 $ 1,415.7 OTC commodity derivatives 2,919.4 2,817.1 1,967.9 1,924.3 Exchange-traded foreign exchange derivatives (1.7) 2.1 2.0 2.0 OTC foreign exchange derivatives 815.1 858.2 975.2 938.2 Exchange-traded interest rate derivatives 587.8 590.9 720.1 728.1 OTC interest rate derivatives 220.4 220.4 207.1 207.1 Exchange-traded equity index derivatives 1,810.0 1,810.0 1,817.4 1,817.4 OTC equity and indices derivatives 153.5 113.0 127.4 86.7 TBA and forward settling securities 74.0 30.9 26.1 24.4 Subtotal 7,882.3 7,723.9 7,226.3 7,143.9 Derivative contracts designated as hedging instruments: Interest rate contracts — — — 0.2 Foreign currency forward contracts 1.2 0.9 9.6 — Subtotal 1.2 0.9 9.6 0.2 Gross fair value of derivative contracts $ 7,883.5 $ 7,724.8 $ 7,235.9 $ 7,144.1 Impact of netting and collateral (7,136.0) (7,026.4) (6,670.6) (6,614.6) Total fair value included in Deposits with and receivables from broker-dealers, clearing organizations, and counterparties, net $ 523.1 $ 336.0 Total fair value included in Receivable from clients, net $ (2.8) $ (8.4) Total fair value included in Financial instruments owned, at fair value $ 227.2 $ 237.7 Total fair value included in Payables to clients $ 371.1 $ 265.9 Total fair value included in Payables to broker-dealers, clearing organizations and counterparties $ 37.5 $ (1.4) Total fair value included in Financial instruments sold, not yet purchased, at fair value $ 289.8 $ 265.0 (1) As of December 31, 2024 and September 30, 2024, the Company’s derivative contract volume for open positions was approximately 11.3 million and 12.2 million contracts, respectively. The Company’s derivative contracts are principally held in its Institutional, Commercial, and Self-Directed/Retail segments. The Company provides its Institutional segment clients access to exchanges at which they can carry out their trading strategies. The Company assists its Commercial segment clients in protecting the value of their future production by entering into option or forward agreements with them on an OTC basis. The Company also provides its Commercial segment clients with exchange products, including combinations of buying and selling puts and calls. In its Self-Directed/Retail segment, the Company provides its retail clients with access to spot foreign exchange, precious metals trading, as well as contracts for difference (“CFD”) and spread bets, where permitted. The Company mitigates its risk by generally offsetting the client’s transaction simultaneously with one of the Company’s trading counterparties or will offset that transaction with a similar but not identical position on the exchange. The risk mitigation of these offsetting trades is not within the documented hedging designation requirements of the Derivatives and Hedging Topic of the ASC. These derivative contracts are traded along with cash transactions because of the integrated nature of the markets for these products. The Company manages the risks associated with derivatives on an aggregate basis along with the risks associated with its proprietary trading and market-making activities in cash instruments as part of its firm-wide risk management policies. In particular, the risks related to derivative positions may be partially offset by inventory, other derivatives, or cash collateral paid or received. Hedging Activities The Company uses foreign currency derivatives, in the form of forward contracts, to hedge risk related to the variability in exchange rates relative to certain of the Company’s non-USD expenditures. These hedges are designated cash flow hedges, through which the Company mitigates variability in exchange rates by exchanging foreign currency for USD at fixed exchange rates at a pre-determined future date, or several cash flows at several pre-determined future dates. While the forward contracts mitigate exchange rate variability risk, they do introduce credit risk, which is the possibility that the Company’s trading counterparty fails to meet its obligation. The Company minimizes this risk by entering into its forward contracts with highly-rated, multi-national institutions. These hedges will all mature within 2 years from the end of the current period. The Company used interest rate derivatives, in the form of swaps, to hedge risk related to variability in overnight rates. These hedges were designated cash flow hedges, through which the Company mitigated uncertainty in its interest income by converting floating-rate interest income to fixed-rate interest income. The swaps introduced credit risk, which the Company minimized by entering into its swaps with highly-rated, multi-national institutions. In addition to credit risk, there was limited market risk associated with the swap position, because any amounts the Company paid from having exchanged variable interest was funded by the variable interest the Company received on its deposits. During the period ended December 31, 2024, the Company’s interest rate hedges all matured. The Company assesses the effectiveness of its hedges at each reporting period to identify any required reclassifications into current earnings. During the three months ended December 31, 2024 and 2023, the Company did not designate any portion of its hedges as ineffective and thus did not have any values in current earnings related to ineffective hedges. The fair values of derivative instruments designated for hedging held as of December 31, 2024 and September 30, 2024 are as follow: December 31, 2024 September 30, 2024 (in millions) Balance Sheet Location Fair Value Fair Value Asset Derivatives Derivatives designated as hedging instruments: Foreign currency forward contracts Financial instruments owned, net $ 1.2 $ 9.6 Total derivatives designated as hedging instruments $ 1.2 $ 9.6 Derivative assets expected to be released from Other comprehensive income into current earnings: Foreign currency forward contracts $ 0.8 $ 9.2 Total expected to be released from Other comprehensive income into earnings $ 0.8 $ 9.2 Liability Derivatives Derivatives designated as hedging instruments: Interest rate contracts Financial instruments sold, not yet purchased $ — $ 0.2 Foreign currency forward contracts Financial instruments sold, not yet purchased 0.9 — Total derivatives designated as hedging instruments $ 0.9 $ 0.2 Derivative liabilities expected to be released from Other comprehensive income into current earnings: Interest rate contracts $ — $ 0.2 Total expected to be released from Other comprehensive income into earnings $ — $ 0.2 The notional values of derivative instruments designated for hedging held as of December 31, 2024 and September 30, 2024 are as follows: December 31, 2024 September 30, 2024 (in millions) Notional Value Notional Value Derivatives designated as hedging instruments: Interest rate contracts $ — $ 500.0 Foreign currency forward contracts: Foreign currency forward contracts to purchase Polish Zloty: Local currency zł 133.8 zł 156.1 USD $ 32.6 $ 37.5 Foreign currency forward contracts to purchase British Pound Sterling: Local currency £ 48.0 £ 72.0 USD $ 59.2 $ 88.8 The Condensed Consolidated Income Statement effects of derivative instruments designated for hedging held for the three months ended December 31, 2024 and 2023 are as follows: (in millions) Income Statement Location Three Months Ended December 31, 2024 Three Months Ended December 31, 2023 Total amounts of gain/(loss) reclassified from Accumulated Other Comprehensive Income into Income: Interest rate contracts Interest income $ (0.2) $ (15.9) Foreign currency forward contracts Compensation and benefits 0.8 1.9 Total derivatives designated as hedging instruments $ 0.6 $ (14.0) Amount of gain reclassified from accumulated other comprehensive income into income as a result of a forecasted transaction that is no longer probable of occurring $ — $ — The accumulated other comprehensive income effects of derivative instruments designated for hedging held for three months ended December 31, 2024 and 2023 are as follows: Amount of (Loss)/Gain Recognized in Other Comprehensive Income on Derivatives, net of tax (in millions) Three Months Ended December 31, 2024 Three Months Ended December 31, 2023 Derivatives in Cash Flow Hedging Relationships: Interest rate contracts $ 0.1 $ 12.6 Foreign currency forward contracts (7.0) 8.1 Total $ (6.9) $ 20.7 The following table sets forth the Company’s net gains/(losses) related to derivative financial instruments for the three months ended December 31, 2024 and 2023 in accordance with the Derivatives and Hedging Topic of the ASC. The net gains/(losses) set forth below are included in Principal gains, net and Cost of sales of physical commodities in the Condensed Consolidated Income Statements. Three Months Ended December 31, (in millions) 2024 2023 Commodities $ 54.8 $ 87.1 Foreign exchange 45.4 25.2 Interest rate, equities, and indices 42.3 27.4 To be announced (“TBA”) and forward settling securities 92.0 (93.2) Net gains from derivative contracts $ 234.5 $ 46.5 Credit Risk In the normal course of business, the Company purchases and sells financial instruments, commodities and foreign currencies as either a principal or agent on behalf of its clients. If either the client or counterparty fails to perform, the Company may be required to discharge the obligations of the nonperforming party. In such circumstances, the Company may sustain a loss if the fair value of the financial instrument, commodity, or foreign currency is different from the contract value of the transaction. The majority of the Company’s transactions and, consequently, the concentration of its credit exposure are with commodity exchanges, clients, broker-dealers and other financial institutions. These activities primarily involve collateralized and uncollateralized arrangements and may result in credit exposure in the event that a counterparty fails to meet its contractual obligations. The Company’s exposure to credit risk can be directly impacted by volatile financial markets, which may impair counterparties’ ability to satisfy contractual obligations. The Company seeks to control its credit risk through a variety of reporting and control procedures, including establishing credit and/or position limits based upon a review of the counterparties’ financial condition and credit ratings. The Company monitors collateral levels on a daily basis for compliance with regulatory and internal guidelines and requests changes in collateral levels as appropriate. The Company is a party to financial instruments in the normal course of its business through client and proprietary trading accounts in exchange-traded and OTC derivative instruments. These instruments are primarily the result of the execution of orders for commodity futures, options on futures, OTC swaps and options and spot and forward foreign currency contracts on behalf of its clients, substantially all of which are transacted on a margin basis. Such transactions may expose the Company to significant credit risk in the event that margin requirements are not sufficient to fully cover losses which clients may incur. The Company controls the risks associated with these transactions by requiring clients to maintain margin deposits in compliance with individual exchange regulations and internal guidelines. The Company monitors required margin levels daily, and therefore, may require clients to deposit additional collateral or reduce positions when necessary. The Company also establishes credit limits for clients, which are monitored daily. The Company evaluates each client’s creditworthiness on a case by case basis. Clearing, financing, and settlement activities may require the Company to maintain funds with or pledge securities as collateral with other financial institutions. Generally, these exposures to both clients and exchanges are subject to master netting, or client agreements, which reduce the exposure to the Company by permitting receivables and payables with such clients to be offset in the event of a client default. Management believes that the margin deposits held as of December 31, 2024 and September 30, 2024 were adequate to minimize the risk of material loss that could be created by positions held at that time. Additionally, the Company monitors collateral fair value on a daily basis and adjusts collateral levels in the event of excess market exposure. Derivative financial instruments involve varying degrees of off-balance sheet market risk whereby changes in the fair values of underlying financial instruments may result in changes in the fair value of the financial instruments in excess of the amounts reflected in the Condensed Consolidated Balance Sheets. Exposure to market risk is influenced by a number of factors, including the relationships between the financial instruments and the Company’s positions, as well as the volatility and liquidity in the markets in which the financial instruments are traded. The principal risk components of financial instruments include, among other things, interest rate volatility, the duration of the underlying instruments and changes in commodity pricing and foreign exchange rates. The Company attempts to manage its exposure to market risk through various techniques. Aggregate market limits have been established and market risk measures are routinely monitored against these limits.

Allowance for Doubtful Accounts

Allowance for Doubtful Accounts	3 Months Ended
	Dec. 31, 2024
Receivables [Abstract]
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts The allowance for doubtful accounts related to deposits with and receivables from broker-dealers, clearing organizations, and counterparties was $0.1 million as of December 31, 2024 and $0.0 million as of September 30, 2024. The allowance for doubtful accounts related to receivables from clients was $52.8 million and $51.9 million as of December 31, 2024 and September 30, 2024, respectively. Activity in the allowance for doubtful accounts for the three months ended December 31, 2024 was as follows: (in millions) Balance as of September 30, 2024 $ 51.9 Provision for bad debts (1) 1.1 Allowance charge-offs 0.1 Other (0.2) Balance as of December 31, 2024 $ 52.9 (1) An additional $0.7 million is included in bad debt expense for the quarter ended December 31, 2024 on the Condensed Consolidated Income Statements, which is not included in the allowance.

Physical Commodities Inventory

Physical Commodities Inventory	3 Months Ended
	Dec. 31, 2024
Inventory Disclosure [Abstract]
Physical Commodities Inventory	Physical Commodities Inventory The Company’s inventories consist of physical commodities as shown below: (in millions) December 31, September 30, Physical ag and energy $ 275.7 $ 169.0 Precious metals - held by broker-dealer subsidiary 201.0 207.6 Precious metals - held by non-broker-dealer subsidiaries (1) 384.7 304.5 Physical commodities inventory, net $ 861.4 $ 681.1 (1) Includes raw materials of $5.4 million and work in process of $9.6 million as of December 31, 2024 Physical ag and energy consists of agricultural commodity inventories, including corn, soybeans, wheat, dried distillers grain, canola, sorghum, coffee, cocoa, cotton, and various energy commodity inventories. Agricultural inventories have reliable, readily determinable and realizable market prices, have relatively insignificant costs of disposal and are available for immediate delivery. The Company records changes to these values in Cost of sales of physical commodities on the Condensed Consolidated Income Statements.

Goodwill

Goodwill	3 Months Ended
	Dec. 31, 2024
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill Goodwill allocated to the Company’s operating segments is as follows: (in millions) December 31, September 30, Commercial $ 38.1 $ 33.3 Institutional 9.8 9.8 Self-Directed/Retail 7.9 7.9 Payments 10.0 10.0 Total Goodwill $ 65.8 $ 61.0

Intangible Assets

Intangible Assets	3 Months Ended
	Dec. 31, 2024
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets	Intangible Assets The gross and net carrying values of intangible assets as of the balance sheet dates, by major intangible asset class are as follows (in millions): December 31, 2024 September 30, 2024 Gross Amount Accumulated Net Amount Gross Amount Accumulated Net Amount Intangible assets subject to amortization Trade/domain names and other licenses $ 6.7 $ (3.4) $ 3.3 $ 4.1 $ (3.2) $ 0.9 Software programs/platforms 2.3 (1.5) 0.8 4.9 (4.1) 0.8 Client and supplier base 24.0 (12.6) 11.4 37.7 (25.6) 12.1 Total intangible assets subject to amortization 33.0 (17.5) 15.5 46.7 (32.9) 13.8 Intangible assets not subject to amortization Website domains 2.0 — 2.0 2.1 — 2.1 Business licenses 3.7 — 3.7 3.7 — 3.7 Total intangible assets not subject to amortization 5.7 — 5.7 5.8 — 5.8 Total intangible assets $ 38.7 $ (17.5) $ 21.2 $ 52.5 $ (32.9) $ 19.6 Amortization expense related to intangible assets was $1.1 million and $2.0 million for the three months ended December 31, 2024 and 2023, respectively. The Company wrote off $16.2 million of fully amortized intangible assets during the three months ended December 31, 2024. As of December 31, 2024, estimated future amortization expense was as follows: (in millions) Fiscal 2025 (remaining months) $ 3.3 Fiscal 2026 3.7 Fiscal 2027 3.0 Fiscal 2028 2.1 Fiscal 2029 and thereafter 3.4 Total intangible assets subject to amortization $ 15.5

Credit Facilities

Credit Facilities	3 Months Ended
	Dec. 31, 2024
Debt Disclosure [Abstract]
Credit Facilities	Credit Facilities Committed Credit Facilities The Company and its subsidiaries have committed credit facilities under which they may borrow up to $1,205.0 million, subject to the terms and conditions of these facilities. The amounts outstanding under these credit facilities carry variable rates of interest, thus approximating fair value. The committed credit facilities generally have covenant requirements that relate to various leverage, debt to net worth, fixed charge, tangible net worth, excess net capital, or profitability measures. The Company and its subsidiaries were in compliance with all relevant covenants as of December 31, 2024. Uncommitted Credit Facilities The Company has access to certain uncommitted financing agreements that support its ordinary course securities and commodities inventories. The agreements are subject to certain borrowing terms and conditions. Note Payable to Bank The Company has a note payable to a commercial bank related to the financing of certain equipment which secures the note. Senior Secured Notes On March 1, 2024, the Company issued $550 million in aggregate principal amount of its 7.875% Notes due 2031 at the offering price of 100% of the aggregate principal amount. The Notes due 2031 are fully and unconditionally guaranteed, jointly and severally, on a senior secured second lien basis by each of the Company’s existing and future subsidiaries that guarantee indebtedness under the Company’s senior secured revolving credit facility and certain other senior indebtedness. Interest related to these notes is payable twice annually, in arrears. The Company incurred debt issuance costs of $7.7 million, which are being amortized over the term of the Notes due 2031 under the effective interest method. The following table sets forth a listing of credit facilities, the current committed amounts as of the report date on the facilities, and outstanding (in millions, except for percentages): (in millions) Amounts Outstanding Borrower Security Renewal/Expiration Date Total Commitment December 31, 2024 September 30, Committed Credit Facilities Senior StoneX Group Inc. Committed Credit Facility - Revolving Line of Credit (1) April 21, 2026 $ 500.0 $ 274.0 (5) $ 161.0 StoneX Financial Inc. None October 28, 2025 250.0 — (5) — StoneX Commodity Solutions LLC Certain assets July 29, 2025 325.0 113.0 (5) 66.0 StoneX Financial Ltd. None October 9, 2025 115.0 25.0 (5) — StoneX Financial Pte. Ltd. None September 5, 2025 15.0 — (5) — $ 1,205.0 $ 412.0 $ 227.0 Uncommitted Credit Facilities Various 131.2 (5) 104.9 Note Payable to Bank Certain equipment 6.8 (5) 6.9 Senior Secured Notes due 2031 (2) 543.3 (3),(4) 543.1 Total outstanding borrowings $ 1,093.3 $ 881.9 (1) The StoneX Group Inc. senior committed credit facility is a revolving facility secured by substantially all of the assets of StoneX Group Inc. and certain subsidiaries identified in the credit facility agreement as obligors, and pledged equity of certain subsidiaries identified in the credit facility as limited guarantors. (2) The Notes due 2031 and the related guarantees are secured by liens on substantially all of the Company’s and the guarantors’ assets, subject to certain customary and other exceptions and permitted liens. The liens on the assets that secure the Notes and the related guarantees are contractually subordinated to the liens on the assets that secure the Company’s and the guarantors’ existing and future first lien secured indebtedness, including indebtedness under the Company’s senior committed credit facility. (3) Amounts outstanding under the Notes due 2031 are reported net of unamortized deferred financing costs of $6.7 million and $6.9 million, in the respective periods presented. (4) Included in Senior secured borrowings, net on the Condensed Consolidated Balance Sheets . (5) Included in Payables to Lenders under loans on the Condensed Consolidated Balance Sheets . As reflected above, certain of the Company’s committed credit facilities are scheduled to expire during the next twelve months following the quarterly period ended December 31, 2024. The Company intends to renew or replace these facilities as they expire, and based on the Company’s liquidity position and capital structure, the Company believes it will be able to do so.

Securities and Commodity Financ

Securities and Commodity Financing Transactions	3 Months Ended
	Dec. 31, 2024
Broker-Dealer [Abstract]
Securities and Commodity Financing Transactions	Securities and Commodity Financing Transactions The Company’s repurchase agreements and securities borrowing and lending arrangements are generally recorded at cost in the Condensed Consolidated Balance Sheets, which is a reasonable approximation of their fair values due to their short-term nature. Secured borrowing and lending arrangements are entered into to obtain collateral necessary to effect settlement, finance inventory positions, meet customer needs or re-lend as part of our dealer operations. The fair value of securities loaned and borrowed is monitored daily compared with the related payable or receivable, and additional collateral or returning excess collateral is requested, as appropriate. These arrangements may serve to limit credit risk resulting from transactions with counterparties. Financial instruments are pledged as collateral under repurchase agreements, securities lending agreements and other secured arrangements, including clearing arrangements. Agreements with counterparties generally contain contractual provisions allowing counterparties the right to sell or repledge collateral. Either the Company or its counterparties may require additional collateral. All collateral is held by the Company or a custodian. The following tables set forth the carrying value of repurchase agreements, and securities lending agreements by remaining contractual maturity (in millions): December 31, 2024 Overnight and Open Less than 30 Days 30-90 Days Over 90 Days Total Securities sold under agreements to repurchase $ 14,954.4 $ 1,762.7 $ 218.3 $ 81.3 $ 17,016.7 Securities loaned 1,826.5 — — — 1,826.5 Gross amount of secured financing $ 16,780.9 $ 1,762.7 $ 218.3 $ 81.3 $ 18,843.2 September 30, 2024 Overnight and Open Less than 30 Days 30-90 Days Over 90 Days Total Securities sold under agreements to repurchase $ 15,260.8 $ 585.4 $ 631.0 $ 50.7 $ 16,527.9 Securities loaned 1,615.9 — — — 1,615.9 Gross amount of secured financing $ 16,876.7 $ 585.4 $ 631.0 $ 50.7 $ 18,143.8 Offsetting of Collateralized Transactions The following table sets forth the carrying value of repurchase agreements and securities lending agreements by class of collateral pledged (in millions): Securities sold under agreements to repurchase December 31, 2024 September 30, 2024 U.S. Treasury obligations $ 9,287.3 $ 9,673.7 U.S. government agency obligations and municipal bonds 459.3 652.0 Asset-backed obligations 220.8 136.1 Agency mortgage-backed obligations 5,479.2 5,079.6 Foreign government obligations 969.0 649.6 Corporate bonds 601.1 336.9 Total securities sold under agreement to repurchase $ 17,016.7 $ 16,527.9 Securities loaned Equity securities $ 1,826.5 $ 1,615.9 Total securities loaned 1,826.5 1,615.9 Gross amount of secured financing $ 18,843.2 $ 18,143.8 The following tables provide the netting of securities purchased under agreements to resell, securities sold under agreements to repurchase, securities borrowed and securities loaned as of the periods indicated (in millions): December 31, 2024 Offsetting of collateralized transactions: Gross Amounts Recognized Amounts Offset in the Condensed Consolidated Balance Sheet Net Amounts Presented in the Condensed Consolidated Balance Sheet Securities purchased under agreements to resell $ 13,623.0 $ (8,143.8) $ 5,479.2 Securities borrowed $ 2,120.7 $ — $ 2,120.7 Securities sold under agreements to repurchase $ 17,016.7 $ (8,143.8) $ 8,872.9 Securities loaned $ 1,826.5 $ — $ 1,826.5 September 30, 2024 Offsetting of collateralized transactions: Gross Amounts Recognized Amounts Offset in the Condensed Consolidated Balance Sheet Net Amounts Presented in the Condensed Consolidated Balance Sheet Securities purchased under agreements to resell $ 13,148.1 $ (7,946.6) $ 5,201.5 Securities borrowed $ 1,662.3 $ — $ 1,662.3 Securities sold under agreements to repurchase $ 16,527.9 $ (7,946.6) $ 8,581.3 Securities loaned $ 1,615.9 $ — $ 1,615.9 The Company pledges securities owned as collateral in both tri-party and bilateral arrangements. Pledged securities under tri-party arrangements may not be repledged or sold by the Company’s counterparties, whereas bilaterally pledged securities may be. The approximate fair value of pledged securities that can be sold or repledged by the Company’s counterparties has been parenthetically disclosed on the Condensed Consolidated Balance Sheets. The Company receives securities as collateral under reverse repurchase agreements, securities borrowed agreements, and margin securities held on behalf of counterparties. This collateral is used by the Company to cover financial instruments sold, not yet purchased; to obtain financing in the form of repurchase agreements; and to meet counterparties’ needs under lending arrangement and matched-booked trading strategies. Additional securities collateral is obtained as necessary to ensure such transactions are adequately collateralized. In many instances, the Company is permitted by contract to repledge the securities received as collateral, which may include pledges to cover collateral requirements for tri-party repurchase agreements. The following table sets forth the fair values, which approximates carrying value because of the short term nature of collateral pledged, received and repledged (in millions): December 31, 2024 September 30, 2024 Securities pledged or repledged to cover collateral requirements for tri-party arrangements $ 7,020.0 $ 6,777.9 Securities received as collateral that may be repledged $ 26,154.0 $ 20,126.8 Securities received as collateral that may be repledged covering securities sold short $ 2,552.0 $ 2,408.3 Repledged securities borrowed and client securities held under custodial clearing arrangements to collateralize securities loaned agreements $ 1,544.4 $ 1,533.3

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Dec. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings From time to time and in the ordinary course of business, the Company is involved in various legal actions and proceedings, including tort claims, contractual disputes, employment matters, workers’ compensation claims and collections. The Company carries insurance that provides protection against certain types of claims, up to the relevant policy’s limits. In November 2023, BTIG filed a civil complaint (the “BTIG complaint”) against the Company and StoneX Financial Inc. in San Francisco Superior Court (CGC-23-610525) seeking monetary damages and injunctive relief for, among other things, alleged theft of purported trade secrets by former BTIG employees later employed at StoneX. The proceedings have moved to FINRA Arbitration and the court action is stayed. The Company intends to vigorously defend itself. The Company subsequently received from the U.S. Department of Justice (the “DOJ”) and the SEC subpoenas that the Company believes are related to conduct alleged in the BTIG complaint, and the Company is cooperating with these agencies. The ultimate outcomes of the BTIG complaint and the DOJ and SEC subpoenas cannot presently be determined. As of December 31, 2024 and September 30, 2024, the Condensed Consolidated Balance Sheets include loss contingency accruals which are not material, individually or in the aggregate, to the Company’s financial position or liquidity. In the opinion of management, possible exposure from loss contingencies in excess of the amounts accrued, is not likely to be material to the Company’s earnings, financial position or liquidity. Contractual Commitments Post-Acquisition Commitment Subsequent to the Gain Capital Holdings, Inc (“Gain”) acquisition, which closed on July 30, 2020 (“the Gain acquisition date”), certain holders of Gain common stock outstanding at the Gain acquisition date who did not vote to approve the merger (“Dissenting Holders”, and the shares held by such Dissenting Holders, the “Dissenting Shares”) purportedly demanded appraisal rights pursuant to Section 262 of the Delaware General Corporation Law in the Court of Chancery of the State of Delaware. In December 2024, the Company’s settlement with the Dissenting Holders was approved by the Court, and funds that were placed in escrow and included in Other Assets in the Consolidated Balance Shee ts as of September 30, 2024 were released, extinguishing $31.1 million due to the Dissenting Holders, which had been recorded in Accounts Payable and Other Accrued Liabilities , in the Consolidated Balance Shee ts as of September 30, 2024.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss, Net	3 Months Ended
	Dec. 31, 2024
Equity [Abstract]
Accumulated Other Comprehensive Loss, Net	Accumulated Other Comprehensive Loss, Net Accumulated other comprehensive loss , net consists of net income and other gains and losses affecting stockholders’ equity that, under U.S. GAAP, are excluded from net income. Other comprehensive income includes net actuarial losses from defined benefit pension plans, foreign currency translation adjustments, and cash flow hedge gains or losses. See note 4 for additional information on cash flow hedges. The following table summarizes the changes in accumulated other comprehensive loss, net for the three months ended December 31, 2024. (in millions) Foreign Currency Translation Adjustment Pension Benefits Adjustment Cash Flow Hedge Accumulated Other Comprehensive Loss, net Balances as of September 30, 2024 $ (31.3) $ (1.2) $ 7.3 $ (25.2) Other comprehensive loss, net of tax (18.3) — (6.9) (25.2) Balances as of December 31, 2024 $ (49.6) $ (1.2) $ 0.4 $ (50.4)

Revenue from Contracts with Cli

Revenue from Contracts with Clients	3 Months Ended
	Dec. 31, 2024
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Clients	Revenue from Contracts with Clients The Company accounts for revenue earned from contracts with clients for services such as the execution, clearing, brokering, and custody of futures and options on futures contracts, OTC derivatives, and securities, investment management, and underwriting services in accordance FASB ASC 606, Revenues from Contracts with Customers (“Topic 606”). Revenues for these services are recognized when the performance obligations related to the underlying transaction are completed. Revenues are recognized when control of the promised goods or services are transferred to clients, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. Revenues are analyzed to determine whether the Company is the principal (i.e. reports revenue on a gross basis) or agent (i.e., reports revenues on a net basis) in the contract. Principal or agent designations depend primarily on the control an entity has over the good or service before control is transferred to a client. The indicators of which party exercises control include primary responsibility over performance obligations, inventory risk before the good or service is transferred, and discretion in establishing the price. Topic 606 does not apply to revenues associated with dealing, or market-making, activities in financial instruments or contracts in the capacity of a principal, including derivative sales contracts which result in physical settlement and interest income. Revenues within the scope of Topic 606 are presented within Commission and clearing fees , Consulting, management, and account fees; and Sales of physical commodities on the Condensed Consolidated Income Statements. Revenues that are not within the scope of Topic 606 are presented within Sales of physical commodities , Principal gains, net , and Interest income on the Condensed Consolidated Income Statements. Three Months Ended December 31, (in millions) 2024 2023 Revenues from contracts with clients as a percentage of total revenues 2.4 % 3.2 % The following table represents a disaggregation of the Company’s total revenues separated between revenues from contracts with clients and other sources of revenue for the periods indicated. Three Months Ended December 31, (in millions) 2024 2023 Revenues from contracts with clients: Commission and clearing fees: Sales-based: Exchange-traded futures and options $ 63.2 $ 51.4 OTC derivative brokerage 2.8 2.8 Equities and fixed income 15.1 16.5 Mutual funds 0.8 0.7 Insurance and annuity products 3.2 2.0 Other 0.4 (0.1) Total sales-based commission 85.5 73.3 Trailing: Mutual funds 3.4 3.0 Insurance and annuity products 4.0 3.7 Total trailing commission 7.4 6.7 Clearing fees 44.1 43.3 Trade conversion fees 2.2 4.0 Other 10.1 2.4 Total commission and clearing fees 149.3 129.7 Consulting, management, and account fees: Underwriting fees 0.3 — Asset management fees 14.8 11.4 Advisory and consulting fees 8.6 8.2 Sweep program fees 11.6 11.4 Client account fees 6.2 4.2 Other 6.3 3.3 Total consulting, management, and account fees 47.8 38.5 Sales of physical commodities: Precious metals sales under ASC Topic 606 466.0 459.2 Total revenues from contracts with clients $ 663.1 $ 627.4 Method of revenue recognition: Point-in-time $ 620.7 $ 589.7 Time elapsed 42.4 37.7 Total revenues from contracts with clients 663.1 627.4 Other sources of revenues Physical precious metals under ASC Topic 815 25,522.4 17,162.5 Physical agricultural and energy products 1,062.7 1,199.2 Principal gains, net 308.9 293.8 Interest income 378.2 290.1 Total revenues $ 27,935.3 $ 19,573.0 Total revenues by primary geographic region: United States $ 1,695.6 $ 1,603.5 Europe 782.5 658.4 South America 168.0 128.0 Middle East and Asia 25,285.4 17,175.6 Other 3.8 7.5 Total revenues $ 27,935.3 $ 19,573.0 Operating revenues by primary geographic region: United States $ 659.1 $ 568.0 Europe 189.6 135.6 South America 35.9 41.2 Middle East and Asia 55.9 32.0 Other 3.8 7.4 Total operating revenues $ 944.3 $ 784.2 The substantial majority of the Company’s performance obligations for revenues from contracts with clients are satisfied at a point in time and are typically collected from clients by debiting their accounts with the Company. Commission and clearing fees revenue and Consulting, management, and account fees revenue are primarily related to the Commercial, Institutional and Self-Directed/Retail reportable segments. Sales of physical commodities under topic 606 are primarily related to the Company’s Commercial and Self-Directed/Retail segments. Principal gains, net are contributed by all of the Company’s reportable segments. Interest income is primarily related to the Commercial and Institutional reportable segments. Precious metals trading and agricultural and energy product trading revenues are primarily related to the Commercial reportable segment. Precious metals sales that are recognized on a point-in-time basis are included in the Self-Directed/Retail and the Commercial reportable segments. Principal gains, net also includes dividend income on long equity positions and dividend expense on short equity positions, which are recognized on the ex-dividend date. The following table indicates the relevant income and expense: Three Months Ended December 31, (in millions) 2024 2023 Dividend income on long equity positions $ 35.6 $ 20.2 Dividend expense on short equity positions 36.4 18.8 Dividend (expense) income, net reported within Principal Gains, net $ (0.8) $ 1.4 Remaining Performance Obligations Remaining performance obligations are services that the firm has committed to perform in the future in connection with its contracts with clients. The Company’s remaining performance obligations are generally related to its risk management consulting and asset management contracts with clients. Revenues associated with remaining performance obligations related to these contracts with clients are not material to the overall consolidated results of the Company. For the Company’s asset management activities, where fees are calculated based on a percentage of the fair value of eligible assets in clients’ accounts, future revenue associated with remaining performance obligations cannot be determined as such fees are subject to fluctuations in the fair value of eligible assets in clients’ accounts.

Other Expenses

Other Expenses	3 Months Ended
	Dec. 31, 2024
Other Expenses [Abstract]
Other Expenses	Other Expenses Other expenses consisted of the following, for the periods indicated. Three Months Ended December 31, (in millions) 2024 2023 Non-income taxes $ 2.8 $ 2.5 Insurance 3.6 2.9 Employee related expenses 1.9 1.9 Other direct business expenses 4.0 4.4 Membership fees 0.9 0.9 Director and public company expenses 0.5 0.5 Office expenses 0.7 0.6 Other expenses 2.3 3.2 Total other expenses $ 16.7 $ 16.9

Income Taxes

Income Taxes	3 Months Ended
	Dec. 31, 2024
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The income tax provision for interim periods comprises income tax on ordinary income/(loss) at the most recent estimated annual effective income tax rate, adjusted for the income tax effect of discrete items. Management uses an estimated annual effective income tax rate based on the forecasted pretax income/(loss) and statutory tax rates in the various jurisdictions in which the Company operates. The Organization for Economic Co-operation and Development (“OECD”) and the G20 Inclusive Framework on Base Erosion and Profit Shifting (the "Inclusive Framework") have put forth Pillar Two proposals that ensure a minimal level of taxation. Several countries in which the Company operates, including several European Union member states, have adopted domestic legislation to implement the Inclusive Framework's global corporate minimum tax rate of fifteen percent. This legislation became effective for the Company beginning October 1, 2024. Based on the Company's current analysis of Pillar Two provisions, these tax law changes did not have a material impact on the Company's financial statements for the three months ended December 31, 2024, and are not expected to have a material impact for fiscal 2025. Current and Prior Period Tax Expense Income tax expense of $31.8 million and $26.6 million for the three months ended December 31, 2024 and 2023, respectively, reflects estimated federal, foreign, state and local income taxes. The Company’s effective tax rate was 27% and 28% for the three months ended December 31, 2024 and 2023, respectively. The effective tax rate was higher than the U.S. federal statutory rate of 21% for the three months ended December 31, 2023 due to U.S. state and local taxes, Global Intangible Low-Taxed Income (“GILTI”), U.S. and foreign permanent differences, and the amount of foreign earnings taxed at higher rates.

Regulatory Capital Requirements

Regulatory Capital Requirements	3 Months Ended
	Dec. 31, 2024
Capital and Other Regulatory Requirements [Abstract]
Regulatory Capital Requirements	Regulatory Capital Requirements The Company’s activities are subject to significant governmental regulation, both in the U.S. and in the international jurisdictions in which it operates. Subsidiaries of the Company were in compliance with all of their regulatory requirements as of December 31, 2024. The following table details those subsidiaries with minimum regulatory requirements in excess of $10.0 million along with the actual balance maintained as of that date. (in millions) As of December 31, 2024 Subsidiary Regulatory Authority Actual Minimum StoneX Financial Inc. SEC and CFTC $ 439.7 $ 277.2 StoneX Financial Ltd. FCA $ 522.9 $ 358.0 Gain Capital Group, LLC CFTC and NFA $ 47.0 $ 29.4 StoneX Financial Pte. Ltd. MAS $ 107.8 $ 24.1 StoneX Markets LLC CFTC and NFA $ 244.4 $ 133.1 Certain other subsidiaries of the Company, typically with a minimum requirement less than $10.0 million, are also subject to net capital requirements promulgated by authorities in the countries in which they operate. As of December 31, 2024, all of the Company’s subsidiaries were in compliance with their local regulatory requirements.

Acquisitions

Acquisitions	3 Months Ended
	Dec. 31, 2024
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Acquisitions	Acquisitions The Company’s consolidated financial statements include the operating results and cash flows of the acquired businesses from the dates of acquisition. Assets of JBR Recovery Limited On October 1, 2024, the Company’s subsidiary, StoneX Metals Limited, executed a sale and purchase agreement to acquire the recycling and refining business, along with certain assets, including licenses, silver inventory and refining/recycling equipment, from JBR Recovery Limited (“JBR”) a company incorporated in England and Wales. This transaction was effective on the closing date of October 1, 2024. The asset purchase was accounted for as a business acquisition in accordance with ASC 805. JBR is one of only two UK companies accredited for the supply of “Good Delivery” silver to the London Bullion Market and is expected to enhance the Company’s supply chain integration. The purchase price consists of $8.0 million of cash consideration paid at closing, approximately $12.6 million in silver bullion paid at closing, approximately $0.7 million of silver bullion payable upon determination of final silver inventory valuation, and deferred consideration totaling $2.4 million due in two equal annual payments beginning on October 1, 2025. The business activities of JBR have been assigned to the Company’s Commercial reportable segment. The acquisition generated $4.8 million of Goodwill and $2.5 million of intangible assets. Subsequent Acquisition - Octo Finances SA

Segment Analysis

Segment Analysis	3 Months Ended
	Dec. 31, 2024
Segment Reporting [Abstract]
Segment Analysis	Segment Analysis The Company’s operating segments are principally based on the nature of the clients it serves (commercial, institutional, and self-directed/retail), and a fourth operating segment, its payments business. The Company manages its business in this manner due to its large global footprint, in which it has approximately 4,600 employees allowing it to serve clients in more than 180 countries. The Company’s business activities are managed as operating segments, which are our reportable segments for financial statement purposes as shown below. • Commercial • Institutional • Self-Directed/Retail • Payments Commercial The Company offers commercial clients a comprehensive array of products and services, including risk management and hedging services, execution and clearing of exchange-traded and OTC products, voice brokerage, market intelligence and physical trading, as well as commodity trading, marketing, procurement, logistics and price management services. The ability to provide these high-value-added products and services, differentiates the Company from its competitors and maximizes the opportunity to retain clients. Institutional The Company provides institutional clients with a complete suite of equity trading services to help them find liquidity with best execution, consistent liquidity across a robust array of fixed income products, competitive and efficient clearing and execution in all major futures and securities exchanges globally as well as prime brokerage in equities and major foreign currency pairs and swap transactions. In addition, the Company originates, structures and places debt instruments in the international and domestic capital markets. These instruments include asset-backed securities (primarily in Argentina) and domestic municipal securities. Self-Directed/Retail The Company provides self-directed/retail clients around the world access to over 18,000 global financial markets, including spot foreign exchange ("forex"), both financial trading and physical investment in precious metals, as well as CFDs, which are investment products with returns linked to the performance of underlying assets. In addition, its independent wealth management business offers a comprehensive product suite to self-directed/retail investors in the U.S. Payments The Company provides customized foreign exchange and treasury services to banks and commercial businesses as well as charities and non-governmental organizations and government organizations. The Company provides transparent pricing and offers payments services in more than 180 countries and 140 currencies, which it believes is more than any other payments solution provider. ******** The total revenues reported combine gross revenues from physical contracts for subsidiaries that are not broker-dealers and net revenues for all other businesses. In order to reflect the way that the Company’s management views the results, the table below also reflects the segment contribution to Operating revenues , which is shown on the face of the Condensed Consolidated Income Statements and which is calculated by deducting physical commodities cost of sales from total revenues. Segment data includes the profitability measure of net contribution by segment. Net contribution is one of the key measures used by management to assess the performance of each segment and for decisions regarding the allocation of the Company’s resources. Net contribution is calculated as revenue less direct cost of sales, transaction-based clearing expenses, variable compensation, introducing broker commissions, and interest expense. Variable compensation paid to risk management consultants/traders generally represents a fixed percentage of revenues generated, and in some cases, revenues generated less transaction-based clearing expenses, base salaries and an overhead allocation. Segment data also includes segment income which is calculated as net contribution less non-variable direct expenses of the segment. These non-variable direct expenses include trader base compensation and benefits, operational employee compensation and benefits, communication and data services, business development, professional fees, bad debt expense and other direct expenses. Inter-segment revenues, expenses, receivables and payables are eliminated upon consolidation. Total revenues, operating revenues and net operating revenues shown in the table below as “Corporate” primarily consist of interest income from the Company’s centralized corporate treasury function. In the normal course of operations, the Company operates a centralized corporate treasury function in which it may sweep excess cash from certain subsidiaries, where permitted within regulatory limitations, in exchange for a short-term interest bearing intercompany payable, or provide excess cash to subsidiaries in exchange for a short-term interest bearing intercompany receivable in lieu of the subsidiary borrowing on external credit facilities. The intercompany receivables and payables are eliminated during consolidation. “Overhead costs and expenses” include costs and expenses of certain shared services such as information technology, accounting and treasury, credit and risk, legal and compliance, and human resources and other activities. These amounts represent the gross overhead costs and expenses, before any allocation of overhead costs to operating segments. Information for the reportable segments is shown in accordance with the Segment Reporting Topic of the ASC as follows: Three Months Ended December 31, (in millions) 2024 2023 Total revenues: Commercial $ 27,209.0 $ 18,978.0 Institutional 539.6 435.7 Self-Directed/Retail 138.4 101.7 Payments 58.1 60.6 Corporate 11.1 9.2 Eliminations (20.9) (12.2) Total $ 27,935.3 $ 19,573.0 Operating revenues: Commercial $ 232.3 $ 198.4 Institutional 539.6 435.7 Self-Directed/Retail 124.1 92.5 Payments 58.1 60.6 Corporate 11.1 9.2 Eliminations (20.9) (12.2) Total $ 944.3 $ 784.2 Net operating revenues (loss): Commercial $ 189.2 $ 163.4 Institutional 174.0 148.6 Self-Directed/Retail 94.6 67.0 Payments 55.4 58.2 Corporate (21.1) (15.6) Total $ 492.1 $ 421.6 Net contribution: (Revenues less cost of sales of physical commodities, transaction-based clearing expenses, variable compensation, introducing broker commissions and interest expense) Commercial $ 145.7 $ 126.4 Institutional 117.8 100.2 Self-Directed/Retail 91.6 62.6 Payments 46.3 47.6 Total $ 401.4 $ 336.8 Segment income: (Net contribution less non-variable direct segment costs) Commercial $ 102.2 $ 87.2 Institutional 78.1 65.2 Self-Directed/Retail 56.9 28.7 Payments 34.1 35.0 Total $ 271.3 $ 216.1 Reconciliation of segment income to income before tax: Segment income $ 271.3 $ 216.1 Net operating loss within Corporate (21.1) (15.6) Overhead costs and expenses (133.3) (104.8) Income before tax $ 116.9 $ 95.7 (in millions) As of December 31, 2024 As of September 30, 2024 Total assets: Commercial $ 5,690.7 $ 5,387.0 Institutional 21,571.4 19,492.9 Self-Directed/Retail 930.8 1,024.1 Payments 418.3 438.8 Corporate 974.1 1,123.5 Total $ 29,585.3 $ 27,466.3

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Pay vs Performance Disclosure
Net income	$ 85.1	$ 69.1

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2024 shares
Trading Arrangements, by Individual
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
John Fowler [Member]
Trading Arrangements, by Individual
Name	John Fowler
Title	Director
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	11/22/2024
Arrangement Duration	462 days
Aggregate Available	7,042
Sean O’Connor [Member]
Trading Arrangements, by Individual
Name	Sean O’Connor
Title	Chief Executive Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	12/12/2024
Arrangement Duration	384 days
Aggregate Available	95,000
Philip Smith [Member]
Trading Arrangements, by Individual
Name	Philip Smith
Title	Chief Executive Officer - EMEA
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	12/13/2024
Arrangement Duration	383 days
Director Trading Arrangement [Member] | Eric Parthemore [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	Name and Title Type of Plan Adoption Date Duration or End Date Aggregate Number of Securities to be Sold Description of Trading Arrangement John Fowler - Director Rule 10b5-1 trading arrangement 11/22/2024 2/27/2026 7,042 Sales of shares Sean O’Connor - Chief Executive Officer Rule 10b5-1 trading arrangement 12/12/2024 12/31/2025 95,000 Sales of shares Philip Smith - Chief Executive Officer - EMEA Rule 10b5-1 trading arrangement 12/13/2024 12/31/2025 15,971 Sales of shares Philip Smith - Chief Executive Officer - EMEA Rule 10b5-1 trading arrangement 12/13/2024 12/31/2025 60,000 Exercise of stock options and sale of the underlying shares
Philip Smith Trading Arrangement, Sales Of Shares [Member] | Philip Smith [Member]
Trading Arrangements, by Individual
Aggregate Available	15,971
Philip Smith Trading Arrangement, Exercise Of Stock Options And Sale Of The Underlying Shares [Member] | Philip Smith [Member]
Trading Arrangements, by Individual
Aggregate Available	60,000

Basis of Presentation and Con_2

Basis of Presentation and Consolidation and Accounting Standards Adopted (Policies)	3 Months Ended
	Dec. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying unaudited Condensed Consolidated Balance Sheet as of September 30, 2024, which has been derived from the audited consolidated balance sheet of September 30, 2024, and the unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and disclosures normally included in annual consolidated financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) have been condensed or omitted pursuant to those rules and regulations. The Company believes that the included disclosures clearly and fairly present the information within. In management’s opinion, all adjustments, generally consisting of normal accruals, considered necessary to fairly present the condensed consolidated financial statements for the interim periods presented have been reflected as required by Rule 10-01 of Regulation S-X. Operating results for interim periods are not necessarily indicative of the results that may be expected for the full year. These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and related notes contained in the Company’s Annual Report on Form 10-K for the fiscal year ended September 30, 2024, as filed with the SEC.
Consolidation	These condensed consolidated financial statements include the accounts of StoneX Group Inc. and all entities in which the Company has a controlling financial interest. All material intercompany transactions and balances have been eliminated in consolidation.
Use of Estimates	Preparing condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent liabilities as of the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. The most significant of these estimates and assumptions in the current year relate to fair value measurements for financial instruments, revenue recognition, valuation of inventories, and income taxes. The Company reviews all significant estimates affecting the financial statements on a recurring basis and makes necessary adjustments in the financial statements presented within this Form 10-Q. Although these and other estimates and assumptions are based on the best available information, actual results could be materially different from estimates. Estimates and assumptions are based on management’s best knowledge of current events and actions the Company may undertake in the future, using information reasonably available to the Company as of December 31, 2024 and through the date of this Form 10-Q.
Physical Commodities Inventory	The JBR Recovery Limited assets and business acquisition, discussed and defined in Note 17, introduced stages of refining, such as raw materials, work in process, and completed goods. These are reported as components of Physical commodities inventory, net on the Condensed Consolidated Balance Sheets. The Company’s valuation policy includes estimating the cost to complete refining the various stages into finished product, the type of materials being refined, along with the market prices of the finished product to arrive at the lower of cost or net realizable value.
Accounting Standards	The Company did not adopt any new accounting standards during the three months ended December 31, 2024.
Earnings per Share	The Company presents basic and diluted earnings per share (“EPS”) using the two-class method, which requires all outstanding unvested share-based payment awards that contain rights to non-forfeitable dividends and therefore participate in undistributed earnings with common stockholders be included in computing earnings per share. Under the two-class method, net income is reduced by the amount of dividends declared in the period for each class of common stock and participating security. The remaining undistributed earnings are then allocated to common stock and participating securities, based on their respective rights to receive dividends. Restricted stock awards granted to certain employees and directors contain non-forfeitable rights to dividends at the same rate as common stock and are considered participating securities. Basic EPS has been computed by dividing net income by the weighted-average number of common shares outstanding.
Income Taxes	The income tax provision for interim periods comprises income tax on ordinary income/(loss) at the most recent estimated annual effective income tax rate, adjusted for the income tax effect of discrete items. Management uses an estimated annual effective income tax rate based on the forecasted pretax income/(loss) and statutory tax rates in the various jurisdictions in which the Company operates. The Organization for Economic Co-operation and Development (“OECD”) and the G20 Inclusive Framework on Base Erosion and Profit Shifting (the "Inclusive Framework") have put forth Pillar Two proposals that ensure a minimal level of taxation. Several countries in which the Company operates, including several European Union member states, have adopted domestic legislation to implement the Inclusive Framework's global corporate minimum tax rate of fifteen percent. This legislation became effective for the Company beginning October 1, 2024. Based on the Company's current analysis of Pillar Two provisions, these tax law changes did not have a material impact on the Company's financial statements for the three months ended December 31, 2024, and are not expected to have a material impact for fiscal 2025.

Earnings per Share (Tables)

Earnings per Share (Tables)	3 Months Ended
	Dec. 31, 2024
Earnings Per Share [Abstract]
Schedule of Calculation of Numerator and Denominator in Earnings Per Share	The following is a reconciliation of the numerator and denominator of the diluted earnings per share computations for the periods presented below. Three Months Ended December 31, (in millions, except share amounts) 2024 2023 Numerator: Net income $ 85.1 $ 69.1 Less: Allocation to participating securities (2.7) (2.4) Net income allocated to common stockholders $ 82.4 $ 66.7 Denominator: Weighted average number of: Common shares outstanding 30,976,042 30,233,107 Dilutive potential common shares outstanding: Share-based awards 1,468,730 1,041,200 Diluted weighted-average common shares 32,444,772 31,274,307

Assets and Liabilities, at Fa_2

Assets and Liabilities, at Fair Value (Tables)	3 Months Ended
	Dec. 31, 2024
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets Measured on Recurring Basis	The following tables set forth the Company’s financial and nonfinancial assets and liabilities accounted for at fair value, on a recurring basis, as of December 31, 2024 and September 30, 2024 by level in the fair value hierarchy. All fair value measurements were performed on a recurring basis as of December 31, 2024 and September 30, 2024. December 31, 2024 (in millions) Level 1 Level 2 Level 3 Netting (1) Total Assets: Certificates of deposit $ 10.2 $ — $ — $ — $ 10.2 Money market mutual funds 35.6 — — — 35.6 Cash and cash equivalents 45.8 — — — 45.8 Commodities warehouse receipts 9.1 — — — 9.1 U.S. Treasury obligations 299.9 — — — 299.9 Securities and other assets segregated under federal and other regulations 309.0 — — — 309.0 U.S. Treasury obligations 4,241.5 — — — 4,241.5 To be announced and forward settling securities — 74.0 — (24.7) 49.3 Foreign government obligations 16.7 — — — 16.7 Derivatives 3,706.9 2,789.7 — (6,022.8) 473.8 Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net 7,965.1 2,863.7 — (6,047.5) 4,781.3 Receivables from clients, net - Derivatives (7.0) 499.5 — (495.3) (2.8) Equity securities 515.9 24.4 — — 540.3 Corporate and municipal bonds — 475.6 — — 475.6 U.S. Treasury obligations 623.7 — — — 623.7 U.S. government agency obligations — 488.7 — — 488.7 Foreign government obligations 0.8 — — — 0.8 Agency mortgage-backed obligations — 4,197.1 — — 4,197.1 Asset-backed obligations — 265.5 — — 265.5 Derivatives — 819.2 — (593.2) 226.0 Commodities warehouse receipts 61.0 — — — 61.0 Exchange firm common stock 13.9 — — — 13.9 Cash flow hedges — 1.2 — — 1.2 Mutual funds and other 22.2 — 2.1 — 24.3 Financial instruments owned 1,237.5 6,271.7 2.1 (593.2) 6,918.1 Physical commodities inventory 201.0 275.7 — — 476.7 Total assets at fair value $ 9,751.4 $ 9,910.6 $ 2.1 $ (7,136.0) $ 12,528.1 Liabilities: Accounts payable and other accrued liabilities $ — $ — $ 2.9 $ — $ 2.9 Payables to clients - Derivatives 3,401.7 240.5 — (3,271.1) 371.1 To be announced and forward settling securities — 30.9 — (15.0) 15.9 Derivatives 279.3 2,969.4 — (3,227.1) 21.6 Payable to broker-dealers, clearing organizations and counterparties 279.3 3,000.3 — (3,242.1) 37.5 Equity securities 420.3 9.5 — — 429.8 Foreign government obligations 0.8 — — — 0.8 Corporate and municipal bonds — 230.3 — — 230.3 U.S. Treasury obligations 2,583.2 — — — 2,583.2 U.S. government agency obligations — 0.2 — — 0.2 Agency mortgage-backed obligations — 1.7 — — 1.7 Asset-backed obligations — 5.0 — — 5.0 Derivatives 3.3 798.8 — (513.2) 288.9 Cash flow hedges — 0.9 — — 0.9 Other — — 0.8 — 0.8 Financial instruments sold, not yet purchased 3,007.6 1,046.4 0.8 (513.2) 3,541.6 Total liabilities at fair value $ 6,688.6 $ 4,287.2 $ 3.7 $ (7,026.4) $ 3,953.1 (1) Represents cash collateral and the impact of netting across at each level of the fair value hierarchy. September 30, 2024 (in millions) Level 1 Level 2 Level 3 Netting (1) Total Assets: Certificates of deposit $ 13.9 $ — $ — $ — $ 13.9 Money market mutual funds 35.3 — — — 35.3 Cash and cash equivalents 49.2 — — — 49.2 Commodities warehouse receipts 51.8 — — — 51.8 Securities and other assets segregated under federal and other regulations 51.8 — — — 51.8 U.S. Treasury obligations 2,933.2 — — — 2,933.2 To be announced and forward settling securities — 26.1 — (18.3) 7.8 Foreign government obligations 18.3 — — — 18.3 Derivatives 3,900.1 2,168.2 — (5,740.1) 328.2 Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net 6,851.6 2,194.3 — (5,758.4) 3,287.5 Receivables from clients, net - Derivatives 22.4 506.2 — (537.0) (8.4) Equity securities 363.9 15.0 — — 378.9 Corporate and municipal bonds — 322.1 — — 322.1 U.S. Treasury obligations 1,088.6 — — — 1,088.6 U.S. government agency obligations — 531.0 — — 531.0 Foreign government obligations 41.4 — — — 41.4 Agency mortgage-backed obligations — 3,837.2 — — 3,837.2 Asset-backed obligations — 223.5 — — 223.5 Derivatives 0.1 603.2 — (375.2) 228.1 Commodities warehouse receipts 67.8 — — — 67.8 Exchange firm common stock 13.2 — — — 13.2 Cash flow hedges — 9.6 — — 9.6 Mutual funds and other 23.6 — 2.1 — 25.7 Financial instruments owned 1,598.6 5,541.6 2.1 (375.2) 6,767.1 Physical commodities inventory 207.6 169.0 — — 376.6 Total assets at fair value $ 8,781.2 $ 8,411.1 $ 2.1 $ (6,670.6) $ 10,523.8 Liabilities: Accounts payable and other accrued liabilities - contingent liabilities $ — $ — $ 2.3 $ — $ 2.3 Payables to clients - Derivatives 3,577.1 228.9 — (3,540.1) 265.9 To be announced and forward settling securities — 24.4 — (22.9) 1.5 Derivatives 378.0 2,356.4 — (2,737.3) (2.9) Payable to broker-dealers, clearing organizations and counterparties 378.0 2,380.8 — (2,760.2) (1.4) Equity securities 219.8 5.0 — — 224.8 Foreign government obligations 41.0 — — — 41.0 Corporate and municipal bonds — 154.6 — — 154.6 U.S. Treasury obligations 2,139.3 — — — 2,139.3 U.S. government agency obligations — 0.2 — — 0.2 Agency mortgage-backed obligations — 23.6 — — 23.6 Asset-backed obligations — 3.9 — — 3.9 Derivatives 8.1 571.0 — (314.3) 264.8 Cash flow hedges — 0.2 — — 0.2 Other — — 0.9 — 0.9 Financial instruments sold, not yet purchased 2,408.2 758.5 0.9 (314.3) 2,853.3 Total liabilities at fair value $ 6,363.3 $ 3,368.2 $ 3.2 $ (6,614.6) $ 3,120.1 (1)

Financial Instruments with Of_2

Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk (Tables)	3 Months Ended
	Dec. 31, 2024
Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk [Abstract]
Schedule of Derivative Instruments	Listed below are the fair values of the Company’s derivative assets and liabilities as of December 31, 2024 and September 30, 2024. Assets represent net unrealized gains and liabilities represent net unrealized losses. December 31, 2024 September 30, 2024 (in millions) Assets (1) Liabilities (1) Assets (1) Liabilities (1) Derivative contracts not accounted for as hedges: Exchange-traded commodity derivatives $ 1,303.8 $ 1,281.3 $ 1,383.1 $ 1,415.7 OTC commodity derivatives 2,919.4 2,817.1 1,967.9 1,924.3 Exchange-traded foreign exchange derivatives (1.7) 2.1 2.0 2.0 OTC foreign exchange derivatives 815.1 858.2 975.2 938.2 Exchange-traded interest rate derivatives 587.8 590.9 720.1 728.1 OTC interest rate derivatives 220.4 220.4 207.1 207.1 Exchange-traded equity index derivatives 1,810.0 1,810.0 1,817.4 1,817.4 OTC equity and indices derivatives 153.5 113.0 127.4 86.7 TBA and forward settling securities 74.0 30.9 26.1 24.4 Subtotal 7,882.3 7,723.9 7,226.3 7,143.9 Derivative contracts designated as hedging instruments: Interest rate contracts — — — 0.2 Foreign currency forward contracts 1.2 0.9 9.6 — Subtotal 1.2 0.9 9.6 0.2 Gross fair value of derivative contracts $ 7,883.5 $ 7,724.8 $ 7,235.9 $ 7,144.1 Impact of netting and collateral (7,136.0) (7,026.4) (6,670.6) (6,614.6) Total fair value included in Deposits with and receivables from broker-dealers, clearing organizations, and counterparties, net $ 523.1 $ 336.0 Total fair value included in Receivable from clients, net $ (2.8) $ (8.4) Total fair value included in Financial instruments owned, at fair value $ 227.2 $ 237.7 Total fair value included in Payables to clients $ 371.1 $ 265.9 Total fair value included in Payables to broker-dealers, clearing organizations and counterparties $ 37.5 $ (1.4) Total fair value included in Financial instruments sold, not yet purchased, at fair value $ 289.8 $ 265.0 (1) As of December 31, 2024 and September 30, 2024, the Company’s derivative contract volume for open positions was approximately 11.3 million and 12.2 million contracts, respectively.
Schedule of Fair Value of Derivative Instruments Designated for Hedging	The fair values of derivative instruments designated for hedging held as of December 31, 2024 and September 30, 2024 are as follow: December 31, 2024 September 30, 2024 (in millions) Balance Sheet Location Fair Value Fair Value Asset Derivatives Derivatives designated as hedging instruments: Foreign currency forward contracts Financial instruments owned, net $ 1.2 $ 9.6 Total derivatives designated as hedging instruments $ 1.2 $ 9.6 Derivative assets expected to be released from Other comprehensive income into current earnings: Foreign currency forward contracts $ 0.8 $ 9.2 Total expected to be released from Other comprehensive income into earnings $ 0.8 $ 9.2 Liability Derivatives Derivatives designated as hedging instruments: Interest rate contracts Financial instruments sold, not yet purchased $ — $ 0.2 Foreign currency forward contracts Financial instruments sold, not yet purchased 0.9 — Total derivatives designated as hedging instruments $ 0.9 $ 0.2 Derivative liabilities expected to be released from Other comprehensive income into current earnings: Interest rate contracts $ — $ 0.2 Total expected to be released from Other comprehensive income into earnings $ — $ 0.2
Schedule of Notional Amounts of Outstanding Derivative Positions	The notional values of derivative instruments designated for hedging held as of December 31, 2024 and September 30, 2024 are as follows: December 31, 2024 September 30, 2024 (in millions) Notional Value Notional Value Derivatives designated as hedging instruments: Interest rate contracts $ — $ 500.0 Foreign currency forward contracts: Foreign currency forward contracts to purchase Polish Zloty: Local currency zł 133.8 zł 156.1 USD $ 32.6 $ 37.5 Foreign currency forward contracts to purchase British Pound Sterling: Local currency £ 48.0 £ 72.0 USD $ 59.2 $ 88.8
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	The Condensed Consolidated Income Statement effects of derivative instruments designated for hedging held for the three months ended December 31, 2024 and 2023 are as follows: (in millions) Income Statement Location Three Months Ended December 31, 2024 Three Months Ended December 31, 2023 Total amounts of gain/(loss) reclassified from Accumulated Other Comprehensive Income into Income: Interest rate contracts Interest income $ (0.2) $ (15.9) Foreign currency forward contracts Compensation and benefits 0.8 1.9 Total derivatives designated as hedging instruments $ 0.6 $ (14.0) Amount of gain reclassified from accumulated other comprehensive income into income as a result of a forecasted transaction that is no longer probable of occurring $ — $ — The following table sets forth the Company’s net gains/(losses) related to derivative financial instruments for the three months ended December 31, 2024 and 2023 in accordance with the Derivatives and Hedging Topic of the ASC. The net gains/(losses) set forth below are included in Principal gains, net and Cost of sales of physical commodities in the Condensed Consolidated Income Statements. Three Months Ended December 31, (in millions) 2024 2023 Commodities $ 54.8 $ 87.1 Foreign exchange 45.4 25.2 Interest rate, equities, and indices 42.3 27.4 To be announced (“TBA”) and forward settling securities 92.0 (93.2) Net gains from derivative contracts $ 234.5 $ 46.5
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income	The accumulated other comprehensive income effects of derivative instruments designated for hedging held for three months ended December 31, 2024 and 2023 are as follows: Amount of (Loss)/Gain Recognized in Other Comprehensive Income on Derivatives, net of tax (in millions) Three Months Ended December 31, 2024 Three Months Ended December 31, 2023 Derivatives in Cash Flow Hedging Relationships: Interest rate contracts $ 0.1 $ 12.6 Foreign currency forward contracts (7.0) 8.1 Total $ (6.9) $ 20.7

Allowance for Doubtful Accoun_2

Allowance for Doubtful Accounts (Tables)	3 Months Ended
	Dec. 31, 2024
Receivables [Abstract]
Schedule of Financing Receivable, Allowance for Doubtful Accounts	Activity in the allowance for doubtful accounts for the three months ended December 31, 2024 was as follows: (in millions) Balance as of September 30, 2024 $ 51.9 Provision for bad debts (1) 1.1 Allowance charge-offs 0.1 Other (0.2) Balance as of December 31, 2024 $ 52.9 (1) An additional $0.7 million is included in bad debt expense for the quarter ended December 31, 2024 on the Condensed Consolidated Income Statements, which is not included in the allowance.

Physical Commodities Inventory

Physical Commodities Inventory (Tables)	3 Months Ended
	Dec. 31, 2024
Inventory Disclosure [Abstract]
Schedule of Inventory	The Company’s inventories consist of physical commodities as shown below: (in millions) December 31, September 30, Physical ag and energy $ 275.7 $ 169.0 Precious metals - held by broker-dealer subsidiary 201.0 207.6 Precious metals - held by non-broker-dealer subsidiaries (1) 384.7 304.5 Physical commodities inventory, net $ 861.4 $ 681.1 (1) Includes raw materials of $5.4 million and work in process of $9.6 million as of December 31, 2024

Goodwill (Tables)

Goodwill (Tables)	3 Months Ended
	Dec. 31, 2024
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	Goodwill allocated to the Company’s operating segments is as follows: (in millions) December 31, September 30, Commercial $ 38.1 $ 33.3 Institutional 9.8 9.8 Self-Directed/Retail 7.9 7.9 Payments 10.0 10.0 Total Goodwill $ 65.8 $ 61.0

Intangible Assets (Tables)

Intangible Assets (Tables)	3 Months Ended
	Dec. 31, 2024
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite and Indefinite-Lived Intangible Assets	The gross and net carrying values of intangible assets as of the balance sheet dates, by major intangible asset class are as follows (in millions): December 31, 2024 September 30, 2024 Gross Amount Accumulated Net Amount Gross Amount Accumulated Net Amount Intangible assets subject to amortization Trade/domain names and other licenses $ 6.7 $ (3.4) $ 3.3 $ 4.1 $ (3.2) $ 0.9 Software programs/platforms 2.3 (1.5) 0.8 4.9 (4.1) 0.8 Client and supplier base 24.0 (12.6) 11.4 37.7 (25.6) 12.1 Total intangible assets subject to amortization 33.0 (17.5) 15.5 46.7 (32.9) 13.8 Intangible assets not subject to amortization Website domains 2.0 — 2.0 2.1 — 2.1 Business licenses 3.7 — 3.7 3.7 — 3.7 Total intangible assets not subject to amortization 5.7 — 5.7 5.8 — 5.8 Total intangible assets $ 38.7 $ (17.5) $ 21.2 $ 52.5 $ (32.9) $ 19.6
Schedule of Expected Amortization Expense	As of December 31, 2024, estimated future amortization expense was as follows: (in millions) Fiscal 2025 (remaining months) $ 3.3 Fiscal 2026 3.7 Fiscal 2027 3.0 Fiscal 2028 2.1 Fiscal 2029 and thereafter 3.4 Total intangible assets subject to amortization $ 15.5

Credit Facilities (Tables)

Credit Facilities (Tables)	3 Months Ended
	Dec. 31, 2024
Debt Disclosure [Abstract]
Schedule of Debt	The following table sets forth a listing of credit facilities, the current committed amounts as of the report date on the facilities, and outstanding (in millions, except for percentages): (in millions) Amounts Outstanding Borrower Security Renewal/Expiration Date Total Commitment December 31, 2024 September 30, Committed Credit Facilities Senior StoneX Group Inc. Committed Credit Facility - Revolving Line of Credit (1) April 21, 2026 $ 500.0 $ 274.0 (5) $ 161.0 StoneX Financial Inc. None October 28, 2025 250.0 — (5) — StoneX Commodity Solutions LLC Certain assets July 29, 2025 325.0 113.0 (5) 66.0 StoneX Financial Ltd. None October 9, 2025 115.0 25.0 (5) — StoneX Financial Pte. Ltd. None September 5, 2025 15.0 — (5) — $ 1,205.0 $ 412.0 $ 227.0 Uncommitted Credit Facilities Various 131.2 (5) 104.9 Note Payable to Bank Certain equipment 6.8 (5) 6.9 Senior Secured Notes due 2031 (2) 543.3 (3),(4) 543.1 Total outstanding borrowings $ 1,093.3 $ 881.9 (1) The StoneX Group Inc. senior committed credit facility is a revolving facility secured by substantially all of the assets of StoneX Group Inc. and certain subsidiaries identified in the credit facility agreement as obligors, and pledged equity of certain subsidiaries identified in the credit facility as limited guarantors. (2) The Notes due 2031 and the related guarantees are secured by liens on substantially all of the Company’s and the guarantors’ assets, subject to certain customary and other exceptions and permitted liens. The liens on the assets that secure the Notes and the related guarantees are contractually subordinated to the liens on the assets that secure the Company’s and the guarantors’ existing and future first lien secured indebtedness, including indebtedness under the Company’s senior committed credit facility. (3) Amounts outstanding under the Notes due 2031 are reported net of unamortized deferred financing costs of $6.7 million and $6.9 million, in the respective periods presented. (4) Included in Senior secured borrowings, net on the Condensed Consolidated Balance Sheets . (5) Included in Payables to Lenders under loans on the Condensed Consolidated Balance Sheets .

Securities and Commodity Fina_2

Securities and Commodity Financing Transactions (Tables)	3 Months Ended
	Dec. 31, 2024
Broker-Dealer [Abstract]
Schedule of Underlying Assets of Repurchase Agreements when Amount of Repurchase Agreements Exceeds 10 Percent of Assets	The following tables set forth the carrying value of repurchase agreements, and securities lending agreements by remaining contractual maturity (in millions): December 31, 2024 Overnight and Open Less than 30 Days 30-90 Days Over 90 Days Total Securities sold under agreements to repurchase $ 14,954.4 $ 1,762.7 $ 218.3 $ 81.3 $ 17,016.7 Securities loaned 1,826.5 — — — 1,826.5 Gross amount of secured financing $ 16,780.9 $ 1,762.7 $ 218.3 $ 81.3 $ 18,843.2 September 30, 2024 Overnight and Open Less than 30 Days 30-90 Days Over 90 Days Total Securities sold under agreements to repurchase $ 15,260.8 $ 585.4 $ 631.0 $ 50.7 $ 16,527.9 Securities loaned 1,615.9 — — — 1,615.9 Gross amount of secured financing $ 16,876.7 $ 585.4 $ 631.0 $ 50.7 $ 18,143.8
Schedule of Financial Instruments Owned and Pledged as Collateral	The following table sets forth the carrying value of repurchase agreements and securities lending agreements by class of collateral pledged (in millions): Securities sold under agreements to repurchase December 31, 2024 September 30, 2024 U.S. Treasury obligations $ 9,287.3 $ 9,673.7 U.S. government agency obligations and municipal bonds 459.3 652.0 Asset-backed obligations 220.8 136.1 Agency mortgage-backed obligations 5,479.2 5,079.6 Foreign government obligations 969.0 649.6 Corporate bonds 601.1 336.9 Total securities sold under agreement to repurchase $ 17,016.7 $ 16,527.9 Securities loaned Equity securities $ 1,826.5 $ 1,615.9 Total securities loaned 1,826.5 1,615.9 Gross amount of secured financing $ 18,843.2 $ 18,143.8 The following tables provide the netting of securities purchased under agreements to resell, securities sold under agreements to repurchase, securities borrowed and securities loaned as of the periods indicated (in millions): December 31, 2024 Offsetting of collateralized transactions: Gross Amounts Recognized Amounts Offset in the Condensed Consolidated Balance Sheet Net Amounts Presented in the Condensed Consolidated Balance Sheet Securities purchased under agreements to resell $ 13,623.0 $ (8,143.8) $ 5,479.2 Securities borrowed $ 2,120.7 $ — $ 2,120.7 Securities sold under agreements to repurchase $ 17,016.7 $ (8,143.8) $ 8,872.9 Securities loaned $ 1,826.5 $ — $ 1,826.5 September 30, 2024 Offsetting of collateralized transactions: Gross Amounts Recognized Amounts Offset in the Condensed Consolidated Balance Sheet Net Amounts Presented in the Condensed Consolidated Balance Sheet Securities purchased under agreements to resell $ 13,148.1 $ (7,946.6) $ 5,201.5 Securities borrowed $ 1,662.3 $ — $ 1,662.3 Securities sold under agreements to repurchase $ 16,527.9 $ (7,946.6) $ 8,581.3 Securities loaned $ 1,615.9 $ — $ 1,615.9
Schedule of Carrying Value of Collateral Pledged, Received and Repledged	The following table sets forth the fair values, which approximates carrying value because of the short term nature of collateral pledged, received and repledged (in millions): December 31, 2024 September 30, 2024 Securities pledged or repledged to cover collateral requirements for tri-party arrangements $ 7,020.0 $ 6,777.9 Securities received as collateral that may be repledged $ 26,154.0 $ 20,126.8 Securities received as collateral that may be repledged covering securities sold short $ 2,552.0 $ 2,408.3 Repledged securities borrowed and client securities held under custodial clearing arrangements to collateralize securities loaned agreements $ 1,544.4 $ 1,533.3

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss, Net (Tables)	3 Months Ended
	Dec. 31, 2024
Equity [Abstract]
Schedule of Changes in Accumulated Other Comprehensive Loss	The following table summarizes the changes in accumulated other comprehensive loss, net for the three months ended December 31, 2024. (in millions) Foreign Currency Translation Adjustment Pension Benefits Adjustment Cash Flow Hedge Accumulated Other Comprehensive Loss, net Balances as of September 30, 2024 $ (31.3) $ (1.2) $ 7.3 $ (25.2) Other comprehensive loss, net of tax (18.3) — (6.9) (25.2) Balances as of December 31, 2024 $ (49.6) $ (1.2) $ 0.4 $ (50.4)

Revenue from Contracts with C_2

Revenue from Contracts with Clients (Tables)	3 Months Ended
	Dec. 31, 2024
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	Three Months Ended December 31, (in millions) 2024 2023 Revenues from contracts with clients as a percentage of total revenues 2.4 % 3.2 % The following table represents a disaggregation of the Company’s total revenues separated between revenues from contracts with clients and other sources of revenue for the periods indicated. Three Months Ended December 31, (in millions) 2024 2023 Revenues from contracts with clients: Commission and clearing fees: Sales-based: Exchange-traded futures and options $ 63.2 $ 51.4 OTC derivative brokerage 2.8 2.8 Equities and fixed income 15.1 16.5 Mutual funds 0.8 0.7 Insurance and annuity products 3.2 2.0 Other 0.4 (0.1) Total sales-based commission 85.5 73.3 Trailing: Mutual funds 3.4 3.0 Insurance and annuity products 4.0 3.7 Total trailing commission 7.4 6.7 Clearing fees 44.1 43.3 Trade conversion fees 2.2 4.0 Other 10.1 2.4 Total commission and clearing fees 149.3 129.7 Consulting, management, and account fees: Underwriting fees 0.3 — Asset management fees 14.8 11.4 Advisory and consulting fees 8.6 8.2 Sweep program fees 11.6 11.4 Client account fees 6.2 4.2 Other 6.3 3.3 Total consulting, management, and account fees 47.8 38.5 Sales of physical commodities: Precious metals sales under ASC Topic 606 466.0 459.2 Total revenues from contracts with clients $ 663.1 $ 627.4 Method of revenue recognition: Point-in-time $ 620.7 $ 589.7 Time elapsed 42.4 37.7 Total revenues from contracts with clients 663.1 627.4 Other sources of revenues Physical precious metals under ASC Topic 815 25,522.4 17,162.5 Physical agricultural and energy products 1,062.7 1,199.2 Principal gains, net 308.9 293.8 Interest income 378.2 290.1 Total revenues $ 27,935.3 $ 19,573.0 Total revenues by primary geographic region: United States $ 1,695.6 $ 1,603.5 Europe 782.5 658.4 South America 168.0 128.0 Middle East and Asia 25,285.4 17,175.6 Other 3.8 7.5 Total revenues $ 27,935.3 $ 19,573.0 Operating revenues by primary geographic region: United States $ 659.1 $ 568.0 Europe 189.6 135.6 South America 35.9 41.2 Middle East and Asia 55.9 32.0 Other 3.8 7.4 Total operating revenues $ 944.3 $ 784.2
Schedule of Income and Expense	The following table indicates the relevant income and expense: Three Months Ended December 31, (in millions) 2024 2023 Dividend income on long equity positions $ 35.6 $ 20.2 Dividend expense on short equity positions 36.4 18.8 Dividend (expense) income, net reported within Principal Gains, net $ (0.8) $ 1.4

Other Expenses (Tables)

Other Expenses (Tables)	3 Months Ended
	Dec. 31, 2024
Other Expenses [Abstract]
Schedule of Other Operating Cost and Expense, by Component	Other expenses consisted of the following, for the periods indicated. Three Months Ended December 31, (in millions) 2024 2023 Non-income taxes $ 2.8 $ 2.5 Insurance 3.6 2.9 Employee related expenses 1.9 1.9 Other direct business expenses 4.0 4.4 Membership fees 0.9 0.9 Director and public company expenses 0.5 0.5 Office expenses 0.7 0.6 Other expenses 2.3 3.2 Total other expenses $ 16.7 $ 16.9

Regulatory Capital Requiremen_2

Regulatory Capital Requirements (Tables)	3 Months Ended
	Dec. 31, 2024
Capital and Other Regulatory Requirements [Abstract]
Schedule of Subsidiaries with Minimum Regulatory Requirements	The following table details those subsidiaries with minimum regulatory requirements in excess of $10.0 million along with the actual balance maintained as of that date. (in millions) As of December 31, 2024 Subsidiary Regulatory Authority Actual Minimum StoneX Financial Inc. SEC and CFTC $ 439.7 $ 277.2 StoneX Financial Ltd. FCA $ 522.9 $ 358.0 Gain Capital Group, LLC CFTC and NFA $ 47.0 $ 29.4 StoneX Financial Pte. Ltd. MAS $ 107.8 $ 24.1 StoneX Markets LLC CFTC and NFA $ 244.4 $ 133.1

Segment Analysis (Tables)

Segment Analysis (Tables)	3 Months Ended
	Dec. 31, 2024
Segment Reporting [Abstract]
Schedule of Segment Reporting Information	Information for the reportable segments is shown in accordance with the Segment Reporting Topic of the ASC as follows: Three Months Ended December 31, (in millions) 2024 2023 Total revenues: Commercial $ 27,209.0 $ 18,978.0 Institutional 539.6 435.7 Self-Directed/Retail 138.4 101.7 Payments 58.1 60.6 Corporate 11.1 9.2 Eliminations (20.9) (12.2) Total $ 27,935.3 $ 19,573.0 Operating revenues: Commercial $ 232.3 $ 198.4 Institutional 539.6 435.7 Self-Directed/Retail 124.1 92.5 Payments 58.1 60.6 Corporate 11.1 9.2 Eliminations (20.9) (12.2) Total $ 944.3 $ 784.2 Net operating revenues (loss): Commercial $ 189.2 $ 163.4 Institutional 174.0 148.6 Self-Directed/Retail 94.6 67.0 Payments 55.4 58.2 Corporate (21.1) (15.6) Total $ 492.1 $ 421.6 Net contribution: (Revenues less cost of sales of physical commodities, transaction-based clearing expenses, variable compensation, introducing broker commissions and interest expense) Commercial $ 145.7 $ 126.4 Institutional 117.8 100.2 Self-Directed/Retail 91.6 62.6 Payments 46.3 47.6 Total $ 401.4 $ 336.8 Segment income: (Net contribution less non-variable direct segment costs) Commercial $ 102.2 $ 87.2 Institutional 78.1 65.2 Self-Directed/Retail 56.9 28.7 Payments 34.1 35.0 Total $ 271.3 $ 216.1 Reconciliation of segment income to income before tax: Segment income $ 271.3 $ 216.1 Net operating loss within Corporate (21.1) (15.6) Overhead costs and expenses (133.3) (104.8) Income before tax $ 116.9 $ 95.7 (in millions) As of December 31, 2024 As of September 30, 2024 Total assets: Commercial $ 5,690.7 $ 5,387.0 Institutional 21,571.4 19,492.9 Self-Directed/Retail 930.8 1,024.1 Payments 418.3 438.8 Corporate 974.1 1,123.5 Total $ 29,585.3 $ 27,466.3

Basis of Presentation and Con_3

Basis of Presentation and Consolidation and Accounting Standards Adopted (Details)	Feb. 05, 2025
Subsequent Event
Subsequent Event [Line Items]
Stock split, conversion ratio	1.5

Earnings per Share - Schedule o

Earnings per Share - Schedule of Calculation of Numerator and Denominator in Earnings Per Share (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Numerator:
Net income	$ 85.1	$ 69.1
Less: Allocation to participating securities	(2.7)	(2.4)
Net income allocated to common stockholders, basic	82.4	66.7
Net income allocated to common stockholders, diluted	$ 82.4	$ 66.7
Denominator:
Common shares outstanding (in shares)	30,976,042	30,233,107
Dilutive potential common shares outstanding:
Share-based awards (in shares)	1,468,730	1,041,200
Diluted weighted-average common shares (in shares)	32,444,772	31,274,307

Earnings per Share - Narrative

Earnings per Share - Narrative (Details) - shares	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Earnings Per Share [Abstract]
Antidilutive securities (in shares)	478,555	272,888

Assets and Liabilities, at Fa_3

Assets and Liabilities, at Fair Value - Schedule of Financial Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 309	$ 51.8
Securities and other assets segregated under federal and other regulations	3,156.6	2,841.2
Financial instruments owned	6,918.1	6,767.1
Physical commodities inventory	861.4	681.1
Accounts payable and other accrued liabilities	441.8	522.1
Financial instruments sold, not yet purchased	3,541.6	2,853.3
Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	45.8	49.2
Securities and other assets segregated under federal and other regulations	309	51.8
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	4,781.3	3,287.5
Receivables from clients, net - Derivatives	(2.8)	(8.4)
Financial instruments owned	6,918.1	6,767.1
Total assets at fair value	12,528.1	10,523.8
Accounts payable and other accrued liabilities	2.9
Payables to clients - Derivatives	371.1	265.9
Total liabilities at fair value	3,953.1	3,120.1
Fair Value, Recurring | To be announced and forward settling securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	15.9	1.5
Fair Value, Recurring | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	21.6	(2.9)
Fair Value, Recurring | Payable to broker-dealers, clearing organizations and counterparties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	37.5	(1.4)
Fair Value, Recurring | Accounts payable and other accrued liabilities - contingent liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts payable and other accrued liabilities		2.3
Fair Value, Recurring | Physical commodities inventory
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Physical commodities inventory	476.7	376.6
Fair Value, Recurring | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	623.7	1,088.6
Financial instruments sold, not yet purchased	2,583.2	2,139.3
Fair Value, Recurring | Foreign government obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0.8	41.4
Financial instruments sold, not yet purchased	0.8	41
Fair Value, Recurring | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	226	228.1
Financial instruments sold, not yet purchased	288.9	264.8
Fair Value, Recurring | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	540.3	378.9
Financial instruments sold, not yet purchased	429.8	224.8
Fair Value, Recurring | Corporate and municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	475.6	322.1
Financial instruments sold, not yet purchased	230.3	154.6
Fair Value, Recurring | U.S. government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	488.7	531
Financial instruments sold, not yet purchased	0.2	0.2
Fair Value, Recurring | Agency mortgage-backed obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	4,197.1	3,837.2
Financial instruments sold, not yet purchased	1.7	23.6
Fair Value, Recurring | Asset-backed obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	265.5	223.5
Financial instruments sold, not yet purchased	5	3.9
Fair Value, Recurring | Commodities warehouse receipts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	61	67.8
Fair Value, Recurring | Exchange firm common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	13.9	13.2
Fair Value, Recurring | Cash flow hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	1.2	9.6
Financial instruments sold, not yet purchased	0.9	0.2
Fair Value, Recurring | Mutual funds and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	24.3	25.7
Fair Value, Recurring | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments sold, not yet purchased	0.8	0.9
Fair Value, Recurring | To be announced and forward settling securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	49.3	7.8
Fair Value, Recurring | Foreign government obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	16.7	18.3
Fair Value, Recurring | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	4,241.5	2,933.2
Fair Value, Recurring | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	473.8	328.2
Fair Value, Recurring | Commodities warehouse receipts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and other assets segregated under federal and other regulations	9.1	51.8
Fair Value, Recurring | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and other assets segregated under federal and other regulations	299.9
Fair Value, Recurring | Netting
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Securities and other assets segregated under federal and other regulations	0	0
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	(6,047.5)	(5,758.4)
Receivables from clients, net - Derivatives	(495.3)	(537)
Financial instruments owned	(593.2)	(375.2)
Total assets at fair value	(7,136)	(6,670.6)
Accounts payable and other accrued liabilities	0
Payables to clients - Derivatives	(3,271.1)	(3,540.1)
Financial instruments sold, not yet purchased	(513.2)	(314.3)
Total liabilities at fair value	(7,026.4)	(6,614.6)
Fair Value, Recurring | Netting | To be announced and forward settling securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	(15)	(22.9)
Fair Value, Recurring | Netting | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	(3,227.1)	(2,737.3)
Fair Value, Recurring | Netting | Payable to broker-dealers, clearing organizations and counterparties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	(3,242.1)	(2,760.2)
Fair Value, Recurring | Netting | Accounts payable and other accrued liabilities - contingent liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts payable and other accrued liabilities		0
Fair Value, Recurring | Netting | Physical commodities inventory
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Physical commodities inventory	0	0
Fair Value, Recurring | Netting | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Fair Value, Recurring | Netting | Foreign government obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Fair Value, Recurring | Netting | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	(593.2)	(375.2)
Financial instruments sold, not yet purchased	(513.2)	(314.3)
Fair Value, Recurring | Netting | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Fair Value, Recurring | Netting | Corporate and municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Fair Value, Recurring | Netting | U.S. government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Fair Value, Recurring | Netting | Agency mortgage-backed obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Fair Value, Recurring | Netting | Asset-backed obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Fair Value, Recurring | Netting | Commodities warehouse receipts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Fair Value, Recurring | Netting | Exchange firm common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Fair Value, Recurring | Netting | Cash flow hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Fair Value, Recurring | Netting | Mutual funds and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Fair Value, Recurring | Netting | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments sold, not yet purchased	0	0
Fair Value, Recurring | Netting | To be announced and forward settling securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	(24.7)	(18.3)
Fair Value, Recurring | Netting | Foreign government obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	0	0
Fair Value, Recurring | Netting | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	0	0
Fair Value, Recurring | Netting | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	(6,022.8)	(5,740.1)
Fair Value, Recurring | Netting | Commodities warehouse receipts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and other assets segregated under federal and other regulations	0	0
Fair Value, Recurring | Netting | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and other assets segregated under federal and other regulations	0
Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	45.8	49.2
Securities and other assets segregated under federal and other regulations	309	51.8
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	7,965.1	6,851.6
Receivables from clients, net - Derivatives	(7)	22.4
Financial instruments owned	1,237.5	1,598.6
Total assets at fair value	9,751.4	8,781.2
Accounts payable and other accrued liabilities	0
Payables to clients - Derivatives	3,401.7	3,577.1
Financial instruments sold, not yet purchased	3,007.6	2,408.2
Total liabilities at fair value	6,688.6	6,363.3
Level 1 | Fair Value, Recurring | To be announced and forward settling securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	0	0
Level 1 | Fair Value, Recurring | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	279.3	378
Level 1 | Fair Value, Recurring | Payable to broker-dealers, clearing organizations and counterparties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	279.3	378
Level 1 | Fair Value, Recurring | Accounts payable and other accrued liabilities - contingent liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts payable and other accrued liabilities		0
Level 1 | Fair Value, Recurring | Physical commodities inventory
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Physical commodities inventory	201	207.6
Level 1 | Fair Value, Recurring | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	623.7	1,088.6
Financial instruments sold, not yet purchased	2,583.2	2,139.3
Level 1 | Fair Value, Recurring | Foreign government obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0.8	41.4
Financial instruments sold, not yet purchased	0.8	41
Level 1 | Fair Value, Recurring | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0.1
Financial instruments sold, not yet purchased	3.3	8.1
Level 1 | Fair Value, Recurring | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	515.9	363.9
Financial instruments sold, not yet purchased	420.3	219.8
Level 1 | Fair Value, Recurring | Corporate and municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 1 | Fair Value, Recurring | U.S. government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 1 | Fair Value, Recurring | Agency mortgage-backed obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 1 | Fair Value, Recurring | Asset-backed obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 1 | Fair Value, Recurring | Commodities warehouse receipts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	61	67.8
Level 1 | Fair Value, Recurring | Exchange firm common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	13.9	13.2
Level 1 | Fair Value, Recurring | Cash flow hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 1 | Fair Value, Recurring | Mutual funds and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	22.2	23.6
Level 1 | Fair Value, Recurring | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments sold, not yet purchased	0	0
Level 1 | Fair Value, Recurring | To be announced and forward settling securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	0	0
Level 1 | Fair Value, Recurring | Foreign government obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	16.7	18.3
Level 1 | Fair Value, Recurring | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	4,241.5	2,933.2
Level 1 | Fair Value, Recurring | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	3,706.9	3,900.1
Level 1 | Fair Value, Recurring | Commodities warehouse receipts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and other assets segregated under federal and other regulations	9.1	51.8
Level 1 | Fair Value, Recurring | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and other assets segregated under federal and other regulations	299.9
Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Securities and other assets segregated under federal and other regulations	0	0
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	2,863.7	2,194.3
Receivables from clients, net - Derivatives	499.5	506.2
Financial instruments owned	6,271.7	5,541.6
Total assets at fair value	9,910.6	8,411.1
Accounts payable and other accrued liabilities	0
Payables to clients - Derivatives	240.5	228.9
Financial instruments sold, not yet purchased	1,046.4	758.5
Total liabilities at fair value	4,287.2	3,368.2
Level 2 | Fair Value, Recurring | To be announced and forward settling securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	30.9	24.4
Level 2 | Fair Value, Recurring | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	2,969.4	2,356.4
Level 2 | Fair Value, Recurring | Payable to broker-dealers, clearing organizations and counterparties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	3,000.3	2,380.8
Level 2 | Fair Value, Recurring | Accounts payable and other accrued liabilities - contingent liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts payable and other accrued liabilities		0
Level 2 | Fair Value, Recurring | Physical commodities inventory
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Physical commodities inventory	275.7	169
Level 2 | Fair Value, Recurring | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 2 | Fair Value, Recurring | Foreign government obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 2 | Fair Value, Recurring | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	819.2	603.2
Financial instruments sold, not yet purchased	798.8	571
Level 2 | Fair Value, Recurring | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	24.4	15
Financial instruments sold, not yet purchased	9.5	5
Level 2 | Fair Value, Recurring | Corporate and municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	475.6	322.1
Financial instruments sold, not yet purchased	230.3	154.6
Level 2 | Fair Value, Recurring | U.S. government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	488.7	531
Financial instruments sold, not yet purchased	0.2	0.2
Level 2 | Fair Value, Recurring | Agency mortgage-backed obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	4,197.1	3,837.2
Financial instruments sold, not yet purchased	1.7	23.6
Level 2 | Fair Value, Recurring | Asset-backed obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	265.5	223.5
Financial instruments sold, not yet purchased	5	3.9
Level 2 | Fair Value, Recurring | Commodities warehouse receipts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Level 2 | Fair Value, Recurring | Exchange firm common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Level 2 | Fair Value, Recurring | Cash flow hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	1.2	9.6
Financial instruments sold, not yet purchased	0.9	0.2
Level 2 | Fair Value, Recurring | Mutual funds and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Level 2 | Fair Value, Recurring | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments sold, not yet purchased	0	0
Level 2 | Fair Value, Recurring | To be announced and forward settling securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	74	26.1
Level 2 | Fair Value, Recurring | Foreign government obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	0	0
Level 2 | Fair Value, Recurring | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	0	0
Level 2 | Fair Value, Recurring | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	2,789.7	2,168.2
Level 2 | Fair Value, Recurring | Commodities warehouse receipts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and other assets segregated under federal and other regulations	0	0
Level 2 | Fair Value, Recurring | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and other assets segregated under federal and other regulations	0
Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Securities and other assets segregated under federal and other regulations	0	0
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	0	0
Receivables from clients, net - Derivatives	0	0
Financial instruments owned	2.1	2.1
Total assets at fair value	2.1	2.1
Accounts payable and other accrued liabilities	2.9
Payables to clients - Derivatives	0	0
Financial instruments sold, not yet purchased	0.8	0.9
Total liabilities at fair value	3.7	3.2
Level 3 | Fair Value, Recurring | To be announced and forward settling securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	0	0
Level 3 | Fair Value, Recurring | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	0	0
Level 3 | Fair Value, Recurring | Payable to broker-dealers, clearing organizations and counterparties
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Payable to broker-dealers, clearing organizations and counterparties	0	0
Level 3 | Fair Value, Recurring | Accounts payable and other accrued liabilities - contingent liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts payable and other accrued liabilities		2.3
Level 3 | Fair Value, Recurring | Physical commodities inventory
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Physical commodities inventory	0	0
Level 3 | Fair Value, Recurring | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 3 | Fair Value, Recurring | Foreign government obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 3 | Fair Value, Recurring | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 3 | Fair Value, Recurring | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 3 | Fair Value, Recurring | Corporate and municipal bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 3 | Fair Value, Recurring | U.S. government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 3 | Fair Value, Recurring | Agency mortgage-backed obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 3 | Fair Value, Recurring | Asset-backed obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 3 | Fair Value, Recurring | Commodities warehouse receipts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Level 3 | Fair Value, Recurring | Exchange firm common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Level 3 | Fair Value, Recurring | Cash flow hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	0	0
Financial instruments sold, not yet purchased	0	0
Level 3 | Fair Value, Recurring | Mutual funds and other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments owned	2.1	2.1
Level 3 | Fair Value, Recurring | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments sold, not yet purchased	0.8	0.9
Level 3 | Fair Value, Recurring | To be announced and forward settling securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	0	0
Level 3 | Fair Value, Recurring | Foreign government obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	0	0
Level 3 | Fair Value, Recurring | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	0	0
Level 3 | Fair Value, Recurring | Derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deposits with and receivables from broker-dealers, clearing organizations and counterparties, net	0	0
Level 3 | Fair Value, Recurring | Commodities warehouse receipts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and other assets segregated under federal and other regulations	0	0
Level 3 | Fair Value, Recurring | U.S. Treasury obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities and other assets segregated under federal and other regulations	0
Certificates of deposit | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	10.2	13.9
Certificates of deposit | Fair Value, Recurring | Netting
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Certificates of deposit | Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	10.2	13.9
Certificates of deposit | Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Certificates of deposit | Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Money market mutual funds | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	35.6	35.3
Money market mutual funds | Fair Value, Recurring | Netting
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Money market mutual funds | Level 1 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	35.6	35.3
Money market mutual funds | Level 2 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Money market mutual funds | Level 3 | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 0	$ 0

Assets and Liabilities, at Fa_4

Assets and Liabilities, at Fair Value - Narrative (Details) - Senior Secured Notes due 2031 - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024	Mar. 01, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior secured notes	$ 543.3	$ 543.1
Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stated interest rate (as a percent)	7.875%		7.875%
Level 2 | Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 575

Financial Instruments with Of_3

Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Sep. 30, 2024
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]
Financial instruments sold, not yet purchased	$ 3,541.6	$ 2,853.3
Foreign currency forward contracts
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]
Maximum length of time hedged in cash flow hedge	2 years
Fair Value, Recurring | Derivatives
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]
Financial instruments sold, not yet purchased	$ 288.9	264.8
Fair Value, Recurring | Derivatives | Not Designated as Hedging Instrument
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]
Financial instruments sold, not yet purchased	$ 288.9	$ 264.8

Financial Instruments with Of_4

Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk - Schedule of Derivative Assets and Liabilities (Details) contract in Millions, $ in Millions	Dec. 31, 2024 USD ($) contract	Sep. 30, 2024 USD ($) contract
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	$ 7,883.5	$ 7,235.9
Derivative liability, fair value, gross liability	7,724.8	7,144.1
Impact of netting and collateral asset	(7,136)	(6,670.6)
Impact of netting and collateral liability	$ (7,026.4)	$ (6,614.6)
Derivative, number of instruments held | contract	11.3	12.2
Total fair value included in Deposits with and receivables from broker-dealers, clearing organizations, and counterparties, net
Derivatives, Fair Value [Line Items]
Derivative, fair value, net	$ 523.1	$ 336
Total fair value included in Receivable from clients, net
Derivatives, Fair Value [Line Items]
Derivative, fair value, net	(2.8)	(8.4)
Total fair value included in Financial instruments owned, at fair value
Derivatives, Fair Value [Line Items]
Derivative, fair value, net	227.2	237.7
Total fair value included in Payables to clients
Derivatives, Fair Value [Line Items]
Derivative, fair value, net	371.1	265.9
Total fair value included in Payables to broker-dealers, clearing organizations and counterparties
Derivatives, Fair Value [Line Items]
Derivative, fair value, net	37.5	(1.4)
Total fair value included in Financial instruments sold, not yet purchased, at fair value
Derivatives, Fair Value [Line Items]
Derivative, fair value, net	289.8	265
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	7,882.3	7,226.3
Derivative liability, fair value, gross liability	7,723.9	7,143.9
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	1.2	9.6
Derivative liability, fair value, gross liability	0.9	0.2
Exchange-traded commodity derivatives | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	1,303.8	1,383.1
Derivative liability, fair value, gross liability	1,281.3	1,415.7
OTC commodity derivatives | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	2,919.4	1,967.9
Derivative liability, fair value, gross liability	2,817.1	1,924.3
Exchange-traded foreign exchange derivatives | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	(1.7)	2
Derivative liability, fair value, gross liability	2.1	2
OTC foreign exchange derivatives | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	815.1	975.2
Derivative liability, fair value, gross liability	858.2	938.2
Exchange-traded interest rate derivatives | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	587.8	720.1
Derivative liability, fair value, gross liability	590.9	728.1
OTC interest rate derivatives | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	220.4	207.1
Derivative liability, fair value, gross liability	220.4	207.1
OTC interest rate derivatives | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	0	0
Derivative liability, fair value, gross liability	0	0.2
Exchange-traded equity index derivatives | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	1,810	1,817.4
Derivative liability, fair value, gross liability	1,810	1,817.4
OTC equity and indices derivatives | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	153.5	127.4
Derivative liability, fair value, gross liability	113	86.7
TBA and forward settling securities | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	74	26.1
Derivative liability, fair value, gross liability	30.9	24.4
Foreign currency forward contracts | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value, gross asset	1.2	9.6
Derivative liability, fair value, gross liability	$ 0.9	$ 0

Financial Instruments with Of_5

Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk - Schedule of Fair Value of Derivative Instruments Designated for Hedging (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2024	Sep. 30, 2024
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 7,883.5	$ 7,235.9
Liability Derivatives	7,724.8	7,144.1
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Asset Derivatives	1.2	9.6
Derivative assets expected to be released from Other comprehensive income into current earnings:	0.8	9.2
Liability Derivatives	0.9	0.2
Derivative liabilities expected to be released from Other comprehensive income into current earnings:	0	0.2
Designated as Hedging Instrument | Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Asset Derivatives	1.2	9.6
Derivative assets expected to be released from Other comprehensive income into current earnings:	0.8	9.2
Liability Derivatives	0.9	0
Designated as Hedging Instrument | Interest rate contracts
Derivatives, Fair Value [Line Items]
Asset Derivatives	0	0
Liability Derivatives	0	0.2
Derivative liabilities expected to be released from Other comprehensive income into current earnings:	$ 0	$ 0.2

Financial Instruments with Of_6

Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk - Schedule of Notional Values of Derivative Instruments Designated for Hedging Held (Details) - Designated as Hedging Instrument £ in Millions, zł in Millions, $ in Millions	Dec. 31, 2024 USD ($)	Dec. 31, 2024 PLN (zł)	Dec. 31, 2024 GBP (£)	Sep. 30, 2024 USD ($)	Sep. 30, 2024 PLN (zł)	Sep. 30, 2024 GBP (£)
Interest rate contracts
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]
Derivative, notional amount	$ 0			$ 500
Foreign currency forward contracts | Polish Zloty
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]
Derivative, notional amount	32.6	zł 133.8		37.5	zł 156.1
Foreign currency forward contracts | British Pound Sterling
Security Owned and Sold, Not yet Purchased, at Fair Value [Line Items]
Derivative, notional amount	$ 59.2		£ 48	$ 88.8		£ 72

Financial Instruments with Of_7

Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk - Schedule of Effects of Derivative Instruments Designated for Hedging Held (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Designated as Hedging Instrument
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Total derivatives designated as hedging instruments	$ 0.6	$ (14)
Amount of gain reclassified from accumulated other comprehensive income into income as a result of a forecasted transaction that is no longer probable of occurring	0	0
Interest rate contracts
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Total derivatives designated as hedging instruments	42.3	27.4
Interest rate contracts | Designated as Hedging Instrument
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Total derivatives designated as hedging instruments	(0.2)	(15.9)
Foreign currency forward contracts | Designated as Hedging Instrument
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Total derivatives designated as hedging instruments	$ 0.8	$ 1.9

Financial Instruments with Of_8

Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk - Schedule of Accumulated Other Comprehensive Income Effects of Derivative Instruments Designated for Hedging Held (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Amount of (Loss)/Gain Recognized in Other Comprehensive Income on Derivatives, net of tax	$ (6.9)	$ 20.7
Interest rate contracts
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Amount of (Loss)/Gain Recognized in Other Comprehensive Income on Derivatives, net of tax	0.1	12.6
Foreign currency forward contracts
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Amount of (Loss)/Gain Recognized in Other Comprehensive Income on Derivatives, net of tax	$ (7)	$ 8.1

Financial Instruments with Of_9

Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk - Schedule of Net Gains/(Losses) from Derivative Contracts (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Commodities
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) recognized in income, net	$ 54.8	$ 87.1
Foreign exchange
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) recognized in income, net	45.4	25.2
Interest rate, equities, and indices
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) recognized in income, net	42.3	27.4
TBA and forward settling securities
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) recognized in income, net	92	(93.2)
Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments, gain (loss) recognized in income, net	$ 234.5	$ 46.5

Allowance for Doubtful Accoun_3

Allowance for Doubtful Accounts - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024
Receivables [Abstract]
Allowance for doubtful accounts - deposits with and receivables from broker-dealers, clearings organizations, and counterparties	$ 0.1	$ 0
Allowance for doubtful accounts receivable	$ 52.8	$ 51.9

Allowance for Doubtful Accoun_4

Allowance for Doubtful Accounts - Schedule of Allowance for Doubtful Accounts (Details) $ in Millions	3 Months Ended
	Dec. 31, 2024 USD ($)
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance as of September 30, 2024	$ 51.9
Provision for bad debts	1.1
Allowance charge-offs	(0.1)
Other	(0.2)
Balance as of December 31, 2024	52.9
Bad debt expense	$ 0.7

Physical Commodities Inventor_2

Physical Commodities Inventory (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024
Inventory [Line Items]
Physical ag and energy	$ 275.7	$ 169
Precious metals - held by broker-dealer subsidiary	476.7	376.6
Physical commodities inventory, net	861.4	681.1
Physical Commodities Inventory - Precious Metals
Inventory [Line Items]
Precious metals - held by broker-dealer subsidiary	201	207.6
Precious metals - held by non-broker-dealer subsidiaries	384.7	$ 304.5
Raw materials	5.4
Work in process	$ 9.6

Goodwill (Details)

Goodwill (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024
Goodwill [Line Items]
Total Goodwill	$ 65.8	$ 61
Commercial
Goodwill [Line Items]
Total Goodwill	38.1	33.3
Institutional
Goodwill [Line Items]
Total Goodwill	9.8	9.8
Self-Directed/Retail
Goodwill [Line Items]
Total Goodwill	7.9	7.9
Payments
Goodwill [Line Items]
Total Goodwill	$ 10	$ 10

Intangible Assets - Schedule of

Intangible Assets - Schedule of Gross and Net Carrying Values of Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross amount	$ 33	$ 46.7
Finite-lived intangible assets, accumulated amortization	(17.5)	(32.9)
Finite-lived intangible assets, net amount	15.5	13.8
Indefinite-lived intangible assets	5.7	5.8
Intangible assets, gross amount	38.7	52.5
Total intangible assets, net amount	21.2	19.6
Website domains
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	2	2.1
Business licenses
Acquired Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	3.7	3.7
Trade/domain names and other licenses
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived trade/domain names and other licenses, gross amount	6.7	4.1
Finite-lived intangible assets, accumulated amortization	(3.4)	(3.2)
Finite-lived intangible assets, net amount	3.3	0.9
Software programs/platforms
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived software programs/platforms, gross amount	2.3	4.9
Finite-lived intangible assets, accumulated amortization	(1.5)	(4.1)
Finite-lived intangible assets, net amount	0.8	0.8
Client and supplier base
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived customer base, gross amount	24	37.7
Finite-lived intangible assets, accumulated amortization	(12.6)	(25.6)
Finite-lived intangible assets, net amount	$ 11.4	$ 12.1

Intangible Assets - Narrative (

Intangible Assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 1.1	$ 2
Write off amortized intangible assets	$ 16.2

Intangible Assets - Schedule _2

Intangible Assets - Schedule of Expected Amortization Expense (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Fiscal 2025 (remaining months)	$ 3.3
Fiscal 2026	3.7
Fiscal 2027	3
Fiscal 2028	2.1
Fiscal 2029 and thereafter	3.4
Finite-lived intangible assets, net amount	$ 15.5	$ 13.8

Credit Facilities - Narrative (

Credit Facilities - Narrative (Details) - USD ($)	Dec. 31, 2024	Mar. 01, 2024
Senior Notes | Senior Secured Notes due 2031
Line of Credit Facility [Line Items]
Debt instrument, face amount		$ 550,000,000
Stated interest rate (as a percent)	7.875%	7.875%
Discount rate at issuance of face value (as a percent)		100%
Debt issuance costs, gross		$ 7,700,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility borrowing	$ 1,205,000,000

Credit Facilities - Schedule of

Credit Facilities - Schedule of Debt (Details) - USD ($)	Dec. 31, 2024	Sep. 30, 2024
Line of Credit Facility [Line Items]
Lenders under loans	$ 550,000,000	$ 338,800,000
Uncommitted Credit Facilities	131,200,000	104,900,000
Note Payable to Bank	6,800,000	6,900,000
Total outstanding borrowings	1,093,300,000	881,900,000
Senior Secured Notes due 2031
Line of Credit Facility [Line Items]
Senior Secured Notes due 2031	543,300,000	543,100,000
Senior Secured Notes due 2031 | Senior Notes
Line of Credit Facility [Line Items]
Debt instrument, unamortized discount (premium) and debt issuance costs, net	6,700,000	6,900,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility borrowing	1,205,000,000
Lenders under loans	412,000,000	227,000,000
Revolving Credit Facility | Senior StoneX Group Inc. Committed Credit Facility - Revolving Line of Credit
Line of Credit Facility [Line Items]
Line of credit facility borrowing	500,000,000
Lenders under loans	274,000,000	161,000,000
Revolving Credit Facility | StoneX Financial Inc.
Line of Credit Facility [Line Items]
Line of credit facility borrowing	250,000,000
Lenders under loans	0	0
Revolving Credit Facility | StoneX Commodity Solutions LLC
Line of Credit Facility [Line Items]
Line of credit facility borrowing	325,000,000
Lenders under loans	113,000,000	66,000,000
Revolving Credit Facility | StoneX Financial Ltd.
Line of Credit Facility [Line Items]
Line of credit facility borrowing	115,000,000
Lenders under loans	25,000,000	0
Revolving Credit Facility | StoneX Financial Pte. Ltd.
Line of Credit Facility [Line Items]
Line of credit facility borrowing	15,000,000
Lenders under loans	$ 0	$ 0

Securities and Commodity Fina_3

Securities and Commodity Financing Transactions - Collateral Maturities of Gross Obligations (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	$ 17,016.7	$ 16,527.9
Securities loaned	1,826.5	1,615.9
Gross amount of secured financing	18,843.2	18,143.8
Overnight and Open
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	14,954.4	15,260.8
Securities loaned	1,826.5	1,615.9
Gross amount of secured financing	16,780.9	16,876.7
Less than 30 Days
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	1,762.7	585.4
Securities loaned	0	0
Gross amount of secured financing	1,762.7	585.4
30-90 Days
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	218.3	631
Securities loaned	0	0
Gross amount of secured financing	218.3	631
Over 90 Days
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	81.3	50.7
Securities loaned	0	0
Gross amount of secured financing	$ 81.3	$ 50.7

Securities and Commodity Fina_4

Securities and Commodity Financing Transactions - Underlying Collateral Types of Gross Obligations (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	$ 17,016.7	$ 16,527.9
Securities loaned	1,826.5	1,615.9
Gross amount of secured financing	18,843.2	18,143.8
U.S. Treasury obligations
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	9,287.3	9,673.7
U.S. government agency obligations and municipal bonds
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	459.3	652
Asset-backed obligations
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	220.8	136.1
Agency mortgage-backed obligations
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	5,479.2	5,079.6
Foreign government obligations
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	969	649.6
Corporate bonds
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase	601.1	336.9
Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned	$ 1,826.5	$ 1,615.9

Securities and Commodity Fina_5

Securities and Commodity Financing Transactions - Schedule of Netting of Securities Purchased Under Agreements (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024
Broker-Dealer [Abstract]
Securities purchased under agreements to resell, gross	$ 13,623	$ 13,148.1
Securities purchased under agreements to resell, offset	(8,143.8)	(7,946.6)
Securities purchased under agreements to resell, net	5,479.2	5,201.5
Securities borrowed, gross	2,120.7	1,662.3
Securities borrowed, net	2,120.7	1,662.3
Securities sold under agreements to repurchase, gross	17,016.7	16,527.9
Securities sold under agreements to repurchase, offset	(8,143.8)	(7,946.6)
Securities sold under agreements to repurchase, net	8,872.9	8,581.3
Securities loaned, gross	1,826.5	1,615.9
Securities loaned, net	$ 1,826.5	$ 1,615.9

Securities and Commodity Fina_6

Securities and Commodity Financing Transactions - Schedule of Fair Value of Collateral Pledged, Received and Repledged (Details) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024
Assets Sold under Agreements to Repurchase [Line Items]
Securities pledged or repledged to cover collateral requirements for tri-party arrangements	$ 6,918.1	$ 6,767.1
Securities received as collateral that may be repledged	26,154	20,126.8
Securities received as collateral that may be repledged covering securities sold short	2,552	2,408.3
Asset Pledged as Collateral with Right
Assets Sold under Agreements to Repurchase [Line Items]
Repledged securities borrowed and client securities held under custodial clearing arrangements to collateralize securities loaned agreements	1,544.4	1,533.3
Tri-party Repurchase Agreements
Assets Sold under Agreements to Repurchase [Line Items]
Securities pledged or repledged to cover collateral requirements for tri-party arrangements	$ 7,020	$ 6,777.9

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	Sep. 30, 2024 USD ($)
Gain Capital Holdings Inc
Loss Contingencies [Line Items]
Loss contingency accrual, current	$ 31.1

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss, Net (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,709.1	$ 1,379.1
Other comprehensive loss, net of tax	(25.2)	27.6
Ending balance	1,777.4	1,482.8
Foreign Currency Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(31.3)
Other comprehensive loss, net of tax	(18.3)
Ending balance	(49.6)
Pension Benefits Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(1.2)
Other comprehensive loss, net of tax	0
Ending balance	(1.2)
Cash Flow Hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	7.3
Other comprehensive loss, net of tax	(6.9)
Ending balance	0.4
Accumulated Other Comprehensive Loss, net
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(25.2)	(51.8)
Other comprehensive loss, net of tax	(25.2)	27.6
Ending balance	$ (50.4)	$ (24.2)

Revenue from Contracts with C_3

Revenue from Contracts with Clients - Schedule of Revenue from Contracts with Clients (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 663.1	$ 627.4
Principal gains, net	308.9	293.8
Interest income	378.2	290.1
Total revenues	27,935.3	19,573
Total operating revenues	944.3	784.2
United States
Disaggregation of Revenue [Line Items]
Total revenues	1,695.6	1,603.5
Total operating revenues	659.1	568
Europe
Disaggregation of Revenue [Line Items]
Total revenues	782.5	658.4
Total operating revenues	189.6	135.6
South America
Disaggregation of Revenue [Line Items]
Total revenues	168	128
Total operating revenues	35.9	41.2
Middle East and Asia
Disaggregation of Revenue [Line Items]
Total revenues	25,285.4	17,175.6
Total operating revenues	55.9	32
Other
Disaggregation of Revenue [Line Items]
Total revenues	3.8	7.5
Total operating revenues	3.8	7.4
Point-in-time
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	620.7	589.7
Time elapsed
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	42.4	37.7
Exchange-traded futures and options
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	63.2	51.4
OTC derivative brokerage
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2.8	2.8
Equities and fixed income
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	15.1	16.5
Mutual funds
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.8	0.7
Insurance and annuity products
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	3.2	2
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.4	(0.1)
Total sales-based commission
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	85.5	73.3
Mutual funds
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	3.4	3
Insurance and annuity products
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	4	3.7
Total trailing commission
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7.4	6.7
Clearing fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	44.1	43.3
Trade conversion fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2.2	4
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	10.1	2.4
Total commission and clearing fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	149.3	129.7
Total revenues	149.3	129.7
Underwriting fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0.3	0
Asset management fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	14.8	11.4
Advisory and consulting fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	8.6	8.2
Sweep program fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	11.6	11.4
Client account fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	6.2	4.2
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	6.3	3.3
Total consulting, management, and account fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	47.8	38.5
Total revenues	47.8	38.5
Precious metals sales under ASC Topic 606
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	466	459.2
Physical precious metals under ASC Topic 815
Disaggregation of Revenue [Line Items]
Sales of physical commodities	25,522.4	17,162.5
Physical agricultural and energy products
Disaggregation of Revenue [Line Items]
Sales of physical commodities	$ 1,062.7	$ 1,199.2
Revenue from Contract with Customer Benchmark | Customer Concentration Risk | Clients
Disaggregation of Revenue [Line Items]
Revenues from contracts with clients as a percentage of total revenues	2.40%	3.20%

Revenue from Contracts with C_4

Revenue from Contracts with Clients - Schedule of Principal Gains, Net Related To Income and Expense of Dividends (Details) - Equity securities - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Dividend (expense) income, net reported within Principal Gains, net	$ (0.8)	$ 1.4
Dividend income on long equity positions
Disaggregation of Revenue [Line Items]
Dividend (expense) income, net reported within Principal Gains, net	35.6	20.2
Dividend expense on short equity positions
Disaggregation of Revenue [Line Items]
Dividend (expense) income, net reported within Principal Gains, net	$ (36.4)	$ (18.8)

Other Expenses (Details)

Other Expenses (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Other Expenses [Abstract]
Non-income taxes	$ 2.8	$ 2.5
Insurance	3.6	2.9
Employee related expenses	1.9	1.9
Other direct business expenses	4	4.4
Membership fees	0.9	0.9
Director and public company expenses	0.5	0.5
Office expenses	0.7	0.6
Other expenses	2.3	3.2
Total other expenses	$ 16.7	$ 16.9

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income tax expense	$ 31.8	$ 26.6
Effective income tax rate	27%	28%

Regulatory Capital Requiremen_3

Regulatory Capital Requirements - Narrative (Details) $ in Millions	Dec. 31, 2024 USD ($)
Capital and Other Regulatory Requirements [Abstract]
Adjusted net capital	$ 10

Regulatory Capital Requiremen_4

Regulatory Capital Requirements - Schedule of Subsidiaries with Minimum Regulatory Requirements (Details) $ in Millions	Dec. 31, 2024 USD ($)
Capital and Other Regulatory Requirements [Abstract]
Adjusted net capital	$ 10
StoneX Financial Inc.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual	439.7
Minimum Requirement	277.2
StoneX Financial Ltd.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual	522.9
Minimum Requirement	358
Gain Capital Group, LLC
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual	47
Minimum Requirement	29.4
StoneX Financial Pte. Ltd.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual	107.8
Minimum Requirement	24.1
StoneX Markets LLC
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual	244.4
Minimum Requirement	$ 133.1

Acquisitions - JBR Recovery Lim

Acquisitions - JBR Recovery Limited (Details) $ in Millions	Oct. 01, 2024 USD ($) payment	Dec. 31, 2024 USD ($)	Sep. 30, 2024 USD ($)
Business Acquisition [Line Items]
Goodwill		$ 65.8	$ 61
JBR Recovery Limited
Business Acquisition [Line Items]
Cash consideration paid	$ 8
Silver bullion paid	12.6
Silver bullion payable	0.7
Deferred consideration	$ 2.4
Deferred consideration, number of payments | payment	2
Goodwill	$ 4.8
Intangible assets	$ 2.5

Acquisitions - Octo Finances SA

Acquisitions - Octo Finances SA (Details) $ in Millions	Jan. 31, 2025 USD ($)
Octo Finances SA | Subsequent Event
Business Acquisition [Line Items]
Purchase price	$ 10

Segment Analysis - Narrative (D

Segment Analysis - Narrative (Details) market in Thousands	3 Months Ended
	Dec. 31, 2024 employee currency market country
Segment Reporting Information [Line Items]
Number of employees (more than) | employee	4,600
Number of countries over entity operates (more than)	180
Self-Directed/Retail
Segment Reporting Information [Line Items]
Number of global financial markets (more than) | market	18
Payments
Segment Reporting Information [Line Items]
Number of countries over entity operates (more than)	180
Number of different types of foreign currencies (more then) | currency	140

Segment Analysis - Schedule of

Segment Analysis - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Sep. 30, 2024
Segment Reporting Information [Line Items]
Total revenues	$ 27,935.3	$ 19,573
Operating revenues	944.3	784.2
Net operating revenues (loss)	492.1	421.6
Net contribution	401.4	336.8
Segment income	271.3	216.1
Net operating loss within Corporate	(21.1)	(15.6)
Overhead costs and expenses	(133.3)	(104.8)
Income before tax	116.9	95.7
Assets	29,585.3		$ 27,466.3
Corporate
Segment Reporting Information [Line Items]
Total revenues	11.1	9.2
Operating revenues	11.1	9.2
Net operating revenues (loss)	(21.1)	(15.6)
Assets	974.1		1,123.5
Eliminations
Segment Reporting Information [Line Items]
Total revenues	(20.9)	(12.2)
Operating revenues	(20.9)	(12.2)
Commercial
Segment Reporting Information [Line Items]
Net contribution	145.7	126.4
Segment income	102.2	87.2
Commercial | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	27,209	18,978
Operating revenues	232.3	198.4
Net operating revenues (loss)	189.2	163.4
Assets	5,690.7		5,387
Institutional
Segment Reporting Information [Line Items]
Net contribution	117.8	100.2
Segment income	78.1	65.2
Institutional | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	539.6	435.7
Operating revenues	539.6	435.7
Net operating revenues (loss)	174	148.6
Assets	21,571.4		19,492.9
Self-Directed/Retail
Segment Reporting Information [Line Items]
Net contribution	91.6	62.6
Segment income	56.9	28.7
Self-Directed/Retail | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	138.4	101.7
Operating revenues	124.1	92.5
Net operating revenues (loss)	94.6	67
Assets	930.8		1,024.1
Payments
Segment Reporting Information [Line Items]
Net contribution	46.3	47.6
Segment income	34.1	35
Payments | Operating Segments
Segment Reporting Information [Line Items]
Total revenues	58.1	60.6
Operating revenues	58.1	60.6
Net operating revenues (loss)	55.4	$ 58.2
Assets	$ 418.3		$ 438.8