Cboe Global Markets (CBOE) 10-Q 1 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Oct. 25, 2019
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2019
Entity File Number	001-34774
Entity Registrant Name	Cboe Global Markets, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-5446972
Entity Address, Address Line One	400 South LaSalle Street
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60605
City Area Code	312
Local Phone Number	786-5600
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	CBOE
Security Exchange Name	CboeBZX
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		110,861,270
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001374310
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 150	$ 275.1
Financial investments	21.4	35.7
Accounts receivables, net	235.5	287.3
Income taxes receivable	65	70.4
Other current assets	17.6	15.2
Total Current Assets	489.5	683.7
Investments	69.7	86.2
Land		4.9
Property and equipment, net	49	71.7
Property held for sale	21
Operating lease right of use assets	53.4
Fair value of goodwill	2,663.4	2,691.4
Intangible assets, net	1,598.6	1,720.2
Other assets, net	74.7	62.9
Total Assets	5,019.3	5,321
Current Liabilities:
Accounts payable and accrued liabilities	159.2	198.5
Section 31 fees payable	25.4	81.1
Deferred revenue	8.1	8.5
Income taxes payable		4.1
Current portion of long-term debt		299.8
Contingent consideration liability	6.3	3.9
Total Current Liabilities	199	595.9
Long-term debt	867.1	915.6
Income tax liability	134.8	114.9
Deferred income taxes	418.2	436.8
Non-current operating lease liabilities	47.4
Other non-current liabilities	24.1	7.4
Total Liabilities	1,690.6	2,070.6
Commitments and Contingencies
Redeemable Noncontrolling Interest		9.4
Stockholders' Equity:
Preferred stock, $0.01 par value: 20,000,000 shares authorized, no shares issued and outstanding at June 30, 2019 and December 31, 2018
Common stock, $0.01 par value: 325,000,000 shares authorized, 125,638,347 and 111,666,897 shares issued and outstanding, respectively at June 30, 2019 and 125,080,496 and 111,601,976 shares issued and outstanding, respectively at December 31, 2018	1.2	1.2
Common stock in treasury, at cost, 13,971,450 shares at June 30, 2019 and 13,478,520 shares at December 31, 2018	(817.3)	(720.1)
Additional paid-in capital	2,686.5	2,660.2
Retained earnings	1,467.4	1,288.2
Accumulated other comprehensive income, net	(9.1)	11.5
Total stockholders' equity	3,328.7	3,241
Total Liabilities, Redeemable Noncontrolling Interest and Stockholders' Equity	$ 5,019.3	$ 5,321

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Condensed Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	325,000,000	325,000,000
Common stock, shares issued (in shares)	125,683,151	125,080,496
Common stock, shares outstanding (in shares)	111,255,022	111,601,976
Treasury stock (in shares)	14,428,129	13,478,520

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Total revenues	$ 675.4	$ 575.9	$ 1,897.5	$ 2,021.1
Cost of revenues:
Total cost of revenues	381.4	305.4	1,040.9	1,138.6
Revenues less cost of revenues	294	270.5	856.6	882.5
Operating expenses:
Compensation and benefits	49.7	51.8	150	168.1
Depreciation and amortization	42.9	50.3	133.8	154.9
Technology support services	10.6	10.6	34.3	34.5
Professional fees and outside services	17.5	16.6	52.9	51.9
Travel and promotional expenses	2.7	2.6	8.3	9.8
Facilities costs	2.7	3.3	7.8	8.6
Acquisition-related costs	16.7	5.9	39.8	23.3
Other expenses	3.8	3.3	11.7	8.5
Total operating expenses	146.6	144.4	438.6	459.6
Operating income	147.4	126.1	418	422.9
Non-operating (expenses) income:
Interest expense, net	(8.2)	(9.6)	(28.1)	(28.5)
Other (expense) income	1.7	(0.2)	(2.7)	1.1
Income before income tax provision	140.9	116.3	387.2	395.5
Income tax provision	35	30.6	102.7	108.7
Net income	105.9	85.7	284.5	286.8
Net loss attributable to redeemable noncontrolling interest	0.1	0.3	4.1	0.9
Net income excluding redeemable noncontrolling interest	106	86	288.6	287.7
Change in redemption value of redeemable noncontrolling interest	(0.1)	(0.3)	(0.5)	(0.9)
Net income allocated to participating securities	(0.4)	(0.7)	(1.5)	(2.1)
Net income allocated to common stockholders	$ 105.5	$ 85	$ 286.6	$ 284.7
Basic earnings per share (in dollars per share)	$ 0.95	$ 0.76	$ 2.57	$ 2.54
Diluted earnings per share (in dollars per share)	$ 0.94	$ 0.76	$ 2.56	$ 2.53
Basic weighted average shares outstanding (in shares)	111.6	111.4	111.6	112
Diluted weighted average shares outstanding (in shares)	111.9	111.8	112	112.4
Transaction fees
Revenues:
Total revenues	$ 465.8	$ 411.8	$ 1,322	$ 1,423.7
Access and capacity fees
Revenues:
Total revenues	55.7	53.6	164.6	156.4
Market data fees
Revenues:
Total revenues	56.3	47.6	159.7	154.3
Regulatory fees
Revenues:
Total revenues	88.1	55.2	226.5	260.8
Other revenue
Revenues:
Total revenues	9.5	7.7	24.7	25.9
Liquidity payments
Cost of revenues:
Total cost of revenues	269.7	229.2	749.2	803.2
Routing and clearing
Cost of revenues:
Total cost of revenues	9.3	8.7	27.7	28.8
Section 31 fees
Cost of revenues:
Total cost of revenues	79.4	46.8	197.9	236.7
Royalty fees
Cost of revenues:
Total cost of revenues	22.9	$ 20.7	65.8	$ 69.9
Other
Cost of revenues:
Total cost of revenues	$ 0.1		$ 0.3

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Consolidated Statements of Comprehensive Income
Net income	$ 105.9	$ 85.7	$ 284.5	$ 286.8
Other comprehensive income, net of tax:
Foreign currency translation adjustments	(17.2)	(9.1)	(20.6)	(23.9)
Post-retirement benefit obligations				(1)
Comprehensive income	88.7	76.6	263.9	261.9
Comprehensive loss attributable to redeemable noncontrolling interest	0.1	0.3	4.1	0.9
Comprehensive income excluding redeemable noncontrolling interest	88.8	76.9	268	262.8
Change in redemption value of redeemable noncontrolling interest	(0.1)	(0.3)	(0.5)	(0.9)
Comprehensive income allocated to participating securities	(0.4)	(0.7)	(1.5)	(2.1)
Comprehensive income allocated to common stockholders, net of tax	$ 88.3	$ 75.9	$ 266	$ 259.8

Condensed Consolidated Statem_3

Condensed Consolidated Statement of Changes in Stockholder's Equity - USD ($) $ in Millions	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income, net	Redeemable Noncontrolling Interests	Total
Beginning balance at Dec. 31, 2017	$ 1.2	$ (558.3)	$ 2,623.7	$ 993.3	$ 50.7	$ 9.4	$ 3,110.6
Increase (Decrease) in Stockholders' Equity
Cash dividends on common stock				(30.6)			(30.6)
Stock-based compensation			11				11
Common stock repurchased from employee stock plans		(59.3)	0.6				(58.7)
Net income excluding noncontrolling interest				118.4			118.4
Other comprehensive income					24.8		24.8
Net loss attributable to redeemable noncontrolling interest						(0.3)
Redemption value adjustment of redeemable noncontrolling interest				(0.3)		0.3	(0.3)
Ending balance at Mar. 31, 2018	1.2	(617.6)	2,635.3	1,080.8	75.5	9.4	3,175.2
Beginning balance at Dec. 31, 2017	1.2	(558.3)	2,623.7	993.3	50.7	9.4	3,110.6
Increase (Decrease) in Stockholders' Equity
Net income excluding noncontrolling interest							287.7
Ending balance at Sep. 30, 2018	1.2	(715)	2,654.5	1,185.4	25.8	9.4	3,151.9
Beginning balance at Mar. 31, 2018	1.2	(617.6)	2,635.3	1,080.8	75.5	9.4	3,175.2
Increase (Decrease) in Stockholders' Equity
Cash dividends on common stock				(30.4)			(30.4)
Stock-based compensation			10				10
Common stock repurchased from employee stock plans		43.5	0.8				44.3
Purchase of common stock		(91.8)					(91.8)
Net income excluding noncontrolling interest				83.3			83.3
Other comprehensive income					(41.3)		(41.3)
Net loss attributable to redeemable noncontrolling interest				0.6		(0.3)	0.6
Redemption value adjustment of redeemable noncontrolling interest				(0.3)		0.3	(0.3)
Ending balance at Jun. 30, 2018	1.2	(665.9)	2,646.1	1,134	34.2	9.4	3,149.6
Increase (Decrease) in Stockholders' Equity
Cash dividends on common stock				(34.6)			(34.6)
Stock-based compensation			8.4				8.4
Purchase of common stock		(49.1)					(49.1)
Net income excluding noncontrolling interest				86			86
Other comprehensive income					(8.4)		(8.4)
Net loss attributable to redeemable noncontrolling interest				0.3		(0.3)	0.3
Redemption value adjustment of redeemable noncontrolling interest				(0.3)		0.3	(0.3)
Ending balance at Sep. 30, 2018	1.2	(715)	2,654.5	1,185.4	25.8	9.4	3,151.9
Beginning balance at Dec. 31, 2018	1.2	(720.1)	2,660.2	1,288.2	11.5	9.4	3,241
Increase (Decrease) in Stockholders' Equity
Cash dividends on common stock				(34.8)			(34.8)
Stock-based compensation			5.4				5.4
Exercise of common stock options			8.1				8.1
Common stock repurchased from employee stock plans		(10)					(10)
Purchase of common stock		(35)					(35)
Shares issued under employee stock purchase plan		0.8					0.8
Net income excluding noncontrolling interest				95.4			95.4
Other comprehensive income					14.7		14.7
Net loss attributable to redeemable noncontrolling interest						(0.2)
Redemption value adjustment of redeemable noncontrolling interest				(0.2)		0.2	(0.2)
Ending balance at Mar. 31, 2019	1.2	(764.3)	2,673.7	1,348.6	26.2	9.4	3,285.4
Beginning balance at Dec. 31, 2018	1.2	(720.1)	2,660.2	1,288.2	11.5	9.4	3,241
Increase (Decrease) in Stockholders' Equity
Net income excluding noncontrolling interest							288.6
Other comprehensive income					(20.6)
Net loss attributable to redeemable noncontrolling interest						(4.1)
Ending balance at Sep. 30, 2019	1.2	(817.3)	2,686.5	1,467.4	(9.1)		3,328.7
Beginning balance at Mar. 31, 2019	1.2	(764.3)	2,673.7	1,348.6	26.2	9.4	3,285.4
Increase (Decrease) in Stockholders' Equity
Cash dividends on common stock				(34.8)			(34.8)
Stock-based compensation			6.3				6.3
Exercise of common stock options			0.4				0.4
Common stock repurchased from employee stock plans		(0.4)					(0.4)
Shares issued under employee stock purchase plan		0.1					0.1
Net income excluding noncontrolling interest				88.3			88.3
Other comprehensive income					(18.1)		(18.1)
Net loss attributable to redeemable noncontrolling interest						(3.8)
Redemption value adjustment of redeemable noncontrolling interest				(0.2)		0.2	(0.2)
Ending balance at Jun. 30, 2019	1.2	(764.6)	2,680.4	1,401.9	8.1	5.8	3,327
Increase (Decrease) in Stockholders' Equity
Cash dividends on common stock				(40.4)			(40.4)
Stock-based compensation			5.3				5.3
Exercise of common stock options			0.8				0.8
Common stock repurchased from employee stock plans		(0.3)					(0.3)
Purchase of common stock		(52.4)					(52.4)
Net income excluding noncontrolling interest				106			106
Other comprehensive income					(17.2)		(17.2)
Net loss attributable to redeemable noncontrolling interest						(0.1)
Redemption value adjustment of redeemable noncontrolling interest				(0.1)		0.1	(0.1)
Deconsolidation of former subsidiary with noncontrolling interest						$ (5.8)
Ending balance at Sep. 30, 2019	$ 1.2	$ (817.3)	$ 2,686.5	$ 1,467.4	$ (9.1)		$ 3,328.7

Condensed Consolidated Statem_4

Condensed Consolidated Statement of Changes in Stockholder's Equity (Parenthetical) - $ / shares	3 Months Ended				9 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Consolidated Statements of Changes in Stockholders' Equity
Dividends (in dollars per share)	$ 0.31	$ 0.31	$ 0.27	$ 0.27	$ 0.36	$ 0.31

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash Flows from Operating Activities:
Net income	$ 284.5	$ 286.8
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	133.8	154.9
Amortization of debt issuance cost and debt discount	1.7	1.8
Change in fair value of contingent consideration	2.4	3
Realized gain on available-for-sale securities	(1.2)	(1.2)
Provision for uncollectable accounts receivable	0.8
Provision for deferred income taxes	(18.4)	(10.3)
Stock-based compensation expense	17	29.4
Loss on disposition of property		1
Impairment of assets held for sale	6.1
Loss reelated to deconsolidation of former subsidiary	2
Impairment of goodwill	10.5
Equity in investments	(1.7)	(1.2)
Changes in assets and liabilities:
Accounts receivable	49.8	(3.8)
Income taxes receivable	5.4	(42.6)
Other prepaid expenses	(14.8)
Other current assets		(13.1)
Accounts payable and accrued liabilities	(39.4)	(3.8)
Section 31 fees payable	(55.7)	(90.5)
Deferred revenue	(0.3)	(2)
Income taxes payable	(3.1)	(3.7)
Income tax liability	20	2.9
Other liabilities	(4.3)	0.5
Net Cash Flows provided by Operating Activities	395.1	308.1
Cash Flows from Investing Activities:
Purchases of available-for-sale financial investments	(61.8)	(131.2)
Proceeds from maturities of available-for-sale financial investments	98	178.7
Return of capital from investments	22
Purchases of investments		(1.8)
Purchases of property and equipment	(26.9)	(27.8)
Net Cash Flows provided by (used in) Investing Activities	31.3	17.9
Cash Flows from Financing Activities:
Proceeds from long-term debt		300
Principal payments of long term debt	(350)	(325)
Proceeds from credit facility		39
Payments of credit facility		(39)
Dividends paid	(110)	(95.6)
Purchase of unrestricted stock from employees	(10.7)	(15.8)
Proceeds from exercise of stock-based compensation	9.1	1.6
Payment of contingent consideration with acquisition of a business		(56.6)
Purchase of common stock under announced program	(87.4)	(140.9)
Net Cash Flows used in Financing Activities	(549)	(332.3)
Effect of Foreign Currency Exchange Rate Changes on Cash and Cash equivalents	(2.5)	(0.4)
Increase in Cash and Cash Equivalents	(125.1)	(6.7)
Cash and Cash Equivalents: Beginning of Period	275.1	143.5
Cash and Cash Equivalents: End of Period	150	136.8
Supplemental disclosure of cash transactions:
Cash paid for income taxes	98.9	161.7
Interest paid	31	$ 33.2
Supplemental disclosure of noncash investing activities:
Note receivable issued in connection with deconsolidation of former subsidiary	3.7
Investment recognized in connection with deconsolidation of former subsidiary	2.9
Net assets of former subsidiary deconsolidated	$ 14.5

ORGANIZATION AND BASIS OF PRESE

ORGANIZATION AND BASIS OF PRESENTATION	9 Months Ended
	Sep. 30, 2019
ORGANIZATION AND BASIS OF PRESENTATION
ORGANIZATION AND BASIS OF PRESENTATION	1. ORGANIZATION AND BASIS OF PRESENTATION Cboe Global Markets, Inc. is one of the world’s largest exchange holding companies, offering cutting-edge trading and investment solutions to investors around the world. The Company is committed to relentless innovation, connecting global markets with world-class technology, and providing seamless solutions that enhance the customer experience. Cboe offers trading across a diverse range of products in multiple asset classes and geographies, including options, futures, U.S. and European equities, exchange-traded products (“ETPs”), global foreign exchange (“FX”) and multi-asset volatility products based on the VIX Index, the world’s barometer for equity market volatility. Cboe’s trading venues include the largest options exchange in the U.S. by volume. In addition, the Company is one of the largest stock exchange operators by volume in the U.S. and a leading market globally for ETP trading. The Company is headquartered in Chicago with offices in Kansas City, New York, London, San Francisco, Amsterdam, Singapore, Hong Kong, and Ecuador. Basis of Presentation These interim unaudited condensed consolidated financial statements have been prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018. The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities, valuation of redeemable noncontrolling interest and reported amounts of revenues and expenses. On an ongoing basis, management evaluates its estimates based upon historical experience, observance of trends, information available from outside sources and various other assumptions that management believes to be reasonable under the circumstances. Actual results may differ from these estimates under different conditions or assumptions. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation of financial position, results of operations and cash flows at the dates and for the periods presented have been included. The results of operations for interim periods are not necessarily indicative of the results of operations for the full year. For those consolidated subsidiaries in which the Company’s ownership is less than 100% and for which the Company has control over the assets and liabilities and the management of the entity, the outside stockholders’ interest is shown as noncontrolling interest. Segment information The Company reports five business segments: Options, U.S. Equities, Futures, European Equities, and Global FX, which is reflective of how the Company’s chief operating decision-maker reviews and operates the business. See Note 15 (“Segment Reporting”) for more information. Significant Accounting Policies With the exception of the change for the accounting of leases as a result of the adoption of Topic 842 (as discussed below in “Recent Accounting Pronouncements Adopted”), there have been no new or material changes to the significant accounting policies discussed in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018, that are of significance, or potential significance, to the Company. Leases The Company determines if an arrangement contains a lease at inception. For arrangements where the Company is the lessee, operating leases are included in operating lease right of use (“ROU”) assets, accrued liabilities, and non-current operating lease liabilities on the condensed consolidated balance sheet as of September 30, 2019. The Company currently does not have any finance leases. ROU assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. ROU assets also include any initial direct costs incurred and any lease payments made at or before the lease commencement date, less lease incentives received. The Company uses its incremental borrowing rate based on the information available at the lease commencement date in determining the lease liabilities, as the Company’s leases generally do not provide an implicit rate. Lease terms may include options to extend or terminate when the Company is reasonably certain that the option will be exercised. Lease expense is recognized on a straight-line basis over the lease term. The Company also has lease arrangements with lease and non-lease components. The Company elected the practical expedient not to separate non-lease components from lease components for the Company’s leases. The Company elected to apply the short-term lease measurement and recognition exemption in which ROU assets and lease liabilities are not recognized for short-term leases. Recent Accounting Pronouncements - Adopted Recent Accounting Pronouncements - Issued, not yet Adopted In June 2016, the FASB issued ASU 2016-13, Credit Losses. This update replaces the incurred loss impairment methodology in current GAAP with a methodology that requires management to estimate an expected lifetime credit loss on financial assets. For public entities, the update is effective for fiscal years and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. The Company is in the process of evaluating this guidance and assessing the impact the ASU could have on the consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, interim periods within those fiscal years, beginning after December 15, 2019. Certain disclosures in the new guidance will need to be applied on a retrospective basis and others on a prospective basis. The Company is in the process of evaluating this guidance and assessing the impact the ASU could have on the consolidated financial statements.

REVENUE RECOGNITION

REVENUE RECOGNITION	9 Months Ended
	Sep. 30, 2019
REVENUE RECOGNITION
REVENUE RECOGNITION	2. REVENUE RECOGNITION The Company’s main types of revenue contracts are: ● Transaction fees - Transaction fees represent fees charged by the Company for the performance obligation of executing a trade on its markets. These fees can be variable based on trade volume tiered discounts, however, as all tiered discounts are calculated monthly, the actual discount is recorded on a monthly basis. Transaction fees, as well as any tiered volume discounts, are calculated and billed monthly in accordance with the Company’s published fee schedules. Transaction fees are recognized across all segments. The Company also pays liquidity payments to customers based on its published fee schedules. The Company uses these payments to improve the liquidity on its markets and therefore recognizes those payments as a cost of revenue. ● Access and capacity fees - Access and capacity fees represent fees assessed for the opportunity to trade, including fees for trading-related functionality across all segments, terminal and other equipment rights, maintenance services, trading floor space and telecommunications services. These fees are billed monthly in accordance with the Company’s published fee schedules and recognized on a monthly basis when the performance obligation is met. Facilities, systems services and other fees are generally monthly fee-based, although certain services are influenced by trading volume or other defined metrics, while others are based solely on demand. All fees associated with the trading floor are recognized in the Options segment. There is no remaining performance obligation after revenue is recognized. This caption is a combination of the previous captions “access fees” and “exchange services and other fees” as the Company migrates all Exchanges to the Bats technology. The prior period presented has been updated to conform to the current period presentation. ● Market data fees - Market data fees represent the fees received by the Company from the U.S. tape plans and fees charged to customers for proprietary market data. Fees from the U.S. tape plans are collected monthly based on published fee schedules and distributed quarterly to the U.S. Exchanges based on a known formula. A contract for proprietary market data is entered into and charged on a monthly basis in accordance with the Company’s published fee schedules as the service is provided. Both types of market data are satisfied over time, and revenue is recognized on a monthly basis as the customer receives and consumes the benefit as the Company provides the data. U.S. tape plan market data is recognized in the U.S. Equities and Options segments. Proprietary market data fees are recognized across all segments. ● Regulatory fees - There are two types of regulatory fees that the Company recognizes. The first type represents fees collected by the Company to cover the Section 31 fees charged to the Exchanges by the SEC. The fees charged to customers are based on the fee set by the SEC per notional value of the transaction executed on the Company’s U.S. securities markets. These fees are calculated and billed monthly and are recognized in the U.S. Equities and Options segments. As the Exchanges are responsible for the ultimate payment to the SEC, the Exchanges are considered the principal in these transactions. Regulatory fees also include the options regulatory fee (“ORF”) which supports the Company’s regulatory oversight function in the Options segment and other miscellaneous regulatory fees and cannot be used for non-regulatory purposes. ● Other revenue - Other revenue primarily includes revenue from various licensing agreements, all fees related to the trade reporting facility operated in the European Equities segment, and revenue associated with advertisements through the Company’s website. ​ All revenue recognized in the income statement is considered to be revenue from contracts with customers. The following table depicts the disaggregation of revenue according to product line and segment (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate ​ ​ ​ ​ ​ ​ ​ ​ U.S. ​ ​ ​ ​ European ​ Global ​ Items and ​ ​ ​ ​ Options Equities Futures Equities FX Eliminations Total Three Months Ended September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Transaction fees ​ $ 207.1 ​ $ 199.4 ​ $ 31.2 ​ $ 16.9 ​ $ 11.2 ​ $ — ​ $ 465.8 Access and capacity fees ​ ​ 26.0 ​ ​ 20.1 ​ ​ 4.0 ​ ​ 3.9 ​ ​ 1.7 ​ ​ — ​ ​ 55.7 Market data fees ​ ​ 13.8 ​ ​ 37.7 ​ ​ 1.6 ​ ​ 3.0 ​ ​ 0.2 ​ ​ — ​ ​ 56.3 Regulatory fees ​ ​ 15.9 ​ ​ 72.2 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 88.1 Other revenue ​ ​ 3.3 ​ ​ 1.3 ​ ​ 2.8 ​ ​ 2.1 ​ ​ — ​ ​ — ​ ​ 9.5 ​ ​ $ 266.1 ​ $ 330.7 ​ $ 39.6 ​ $ 25.9 ​ $ 13.1 ​ $ — ​ $ 675.4 Timing of revenue recognition ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Services transferred at a point in time ​ $ 226.3 ​ $ 272.9 ​ $ 34.0 ​ $ 19.0 ​ $ 11.2 ​ $ — ​ $ 563.4 Services transferred over time ​ ​ 39.8 ​ ​ 57.8 ​ ​ 5.6 ​ ​ 6.9 ​ ​ 1.9 ​ ​ — ​ ​ 112.0 ​ ​ $ 266.1 ​ $ 330.7 ​ $ 39.6 ​ $ 25.9 ​ $ 13.1 ​ $ — ​ $ 675.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Transaction fees ​ $ 175.2 ​ $ 176.7 ​ $ 25.7 ​ $ 22.4 ​ $ 11.8 ​ $ — ​ $ 411.8 Access and capacity fees ​ ​ 25.1 ​ ​ 19.5 ​ ​ 3.8 ​ ​ 3.6 ​ ​ 1.6 ​ ​ — ​ ​ 53.6 Market data fees ​ ​ 10.6 ​ ​ 32.0 ​ ​ 1.7 ​ ​ 3.1 ​ ​ 0.2 ​ ​ — ​ ​ 47.6 Regulatory fees ​ ​ 12.6 ​ ​ 42.6 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 55.2 Other revenue ​ ​ 5.1 ​ ​ 1.1 ​ ​ — ​ ​ 1.5 ​ ​ — ​ ​ — ​ ​ 7.7 ​ ​ $ 228.6 ​ $ 271.9 ​ $ 31.2 ​ $ 30.6 ​ $ 13.6 ​ $ — ​ $ 575.9 Timing of revenue recognition ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Services transferred at a point in time ​ $ 192.9 ​ $ 220.4 ​ $ 25.7 ​ $ 23.9 ​ $ 11.8 ​ $ — ​ $ 474.7 Services transferred over time ​ ​ 35.7 ​ ​ 51.5 ​ ​ 5.5 ​ ​ 6.7 ​ ​ 1.8 ​ ​ — ​ ​ 101.2 ​ ​ $ 228.6 ​ $ 271.9 ​ $ 31.2 ​ $ 30.6 ​ $ 13.6 ​ $ — ​ $ 575.9 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate ​ ​ ​ ​ ​ ​ ​ U.S. ​ ​ ​ ​ European ​ Global ​ Items and ​ ​ ​ ​ ​ Options ​ Equities ​ Futures ​ Equities ​ FX ​ Eliminations ​ Total Nine Months Ended September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Transaction fees ​ $ 565.7 ​ $ 580.3 ​ $ 84.1 ​ $ 57.5 ​ $ 34.4 ​ $ — ​ $ 1,322.0 Access and capacity fees ​ ​ 77.6 ​ ​ 58.7 ​ ​ 11.5 ​ ​ 11.8 ​ ​ 5.0 ​ ​ — ​ ​ 164.6 Market data fees ​ ​ 41.5 ​ ​ 103.4 ​ ​ 4.9 ​ ​ 9.4 ​ ​ 0.5 ​ ​ — ​ ​ 159.7 Regulatory fees ​ ​ 47.1 ​ ​ 178.9 ​ ​ 0.5 ​ ​ — ​ ​ — ​ ​ — ​ ​ 226.5 Other revenue ​ ​ 11.3 ​ ​ 3.9 ​ ​ 2.9 ​ ​ 6.2 ​ ​ 0.2 ​ ​ 0.2 ​ ​ 24.7 ​ ​ $ 743.2 ​ $ 925.2 ​ $ 103.9 ​ $ 84.9 ​ $ 40.1 ​ $ 0.2 ​ $ 1,897.5 Timing of revenue recognition ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Services transferred at a point in time ​ $ 624.1 ​ $ 763.1 ​ $ 87.5 ​ $ 63.7 ​ $ 34.6 ​ $ 0.2 ​ $ 1,573.2 Services transferred over time ​ ​ 119.1 ​ ​ 162.1 ​ ​ 16.4 ​ ​ 21.2 ​ ​ 5.5 ​ ​ — ​ ​ 324.3 ​ ​ $ 743.2 ​ $ 925.2 ​ $ 103.9 ​ $ 84.9 ​ $ 40.1 ​ $ 0.2 ​ $ 1,897.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Transaction fees ​ $ 600.0 ​ $ 622.4 ​ $ 91.4 ​ $ 72.3 ​ $ 37.6 ​ $ — ​ $ 1,423.7 Access and capacity fees ​ ​ 73.1 ​ ​ 56.3 ​ ​ 11.3 ​ ​ 11.0 ​ ​ 4.7 ​ ​ — ​ ​ 156.4 Market data fees ​ ​ 32.0 ​ ​ 107.1 ​ ​ 4.9 ​ ​ 9.9 ​ ​ 0.4 ​ ​ — ​ ​ 154.3 Regulatory fees ​ ​ 45.9 ​ ​ 214.8 ​ ​ 0.1 ​ ​ — ​ ​ — ​ ​ — ​ ​ 260.8 Other revenue ​ ​ 15.8 ​ ​ 5.0 ​ ​ — ​ ​ 4.7 ​ ​ — ​ ​ 0.4 ​ ​ 25.9 ​ ​ $ 766.8 ​ $ 1,005.6 ​ $ 107.7 ​ $ 97.9 ​ $ 42.7 ​ $ 0.4 ​ $ 2,021.1 Timing of revenue recognition ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Services transferred at a point in time ​ $ 661.7 ​ $ 842.2 ​ $ 91.5 ​ $ 77.0 ​ $ 37.6 ​ $ 0.4 ​ $ 1,710.4 Services transferred over time ​ ​ 105.1 ​ ​ 163.4 ​ ​ 16.2 ​ ​ 20.9 ​ ​ 5.1 ​ ​ — ​ ​ 310.7 ​ ​ $ 766.8 ​ $ 1,005.6 ​ $ 107.7 ​ $ 97.9 ​ $ 42.7 ​ $ 0.4 ​ $ 2,021.1 Contract liabilities as of September 30, 2019 primarily represent prepayments of transaction fees and certain access and capacity and market data fees to the Exchanges. The revenue recognized from contract liabilities and the remaining balance is shown below (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at January 1, 2019 Cash Revenue Balance at September 30, 2019 Liquidity provider sliding scale (1) ​ $ — ​ $ 9.6 ​ $ (7.2) ​ $ 2.4 Other, net ​ ​ 8.5 ​ ​ 24.2 ​ ​ (26.9) ​ ​ 5.8 Total deferred revenue ​ $ 8.5 ​ $ 33.8 ​ $ (34.1) ​ $ 8.2 (1) Liquidity providers are eligible to participate in the sliding scale program, which involves prepayment of transaction fees, and to receive reduced fees based on the achievement of certain volume thresholds within a calendar month. These transaction fees are amortized and recorded ratably as the transactions occur over the period .

ACQUISITIONS

ACQUISITIONS	9 Months Ended
	Sep. 30, 2019
ACQUISITIONS
ACQUISITIONS	3. ACQUISITIONS Bats Global Markets, Inc. On February 28, 2017, pursuant to the Agreement and Plan of Merger, dated as of September 25, 2016 (the “Merger Agreement”), by and among Cboe, Bats, CBOE Corporation, a Delaware corporation and a wholly-owned subsidiary of Cboe (“Merger Sub”), and Cboe Bats, LLC (formerly CBOE V, LLC), a Delaware limited liability company and a wholly-owned subsidiary of Cboe (“Merger LLC”), Cboe completed the merger of Merger Sub with and into Bats and the subsequent merger of Bats with and into Merger LLC. As a result of the Merger, Bats became a wholly-owned subsidiary of Cboe. Other Acquisitions In January 2016, the Company, through its subsidiary Cboe Vest, LLC (“Cboe Vest”), acquired a majority of the outstanding equity of Cboe Vest Financial Group Inc. (“Vest”), an asset investment manager focused on Target Outcome Investment strategies. The purchase price consisted of $18.9 million in cash, reflecting payments of $14.9 million to former stockholders and $4.0 million to Vest for newly issued shares, and represented an ownership interest of 60% resulting in the consolidation of Vest operations. The remaining 40% noncontrolling interest was held by the remaining Vest stockholders. The remaining Vest stockholders had a put option that could have been exercised to Vest and Vest had a call option that could have been exercised to the remaining stockholders. The put and call options could have been exercised after five years though they could have been accelerated by certain employment-related actions. The combination of the noncontrolling interest and a redemption feature resulted in a redeemable noncontrolling interest, which was classified outside of permanent equity on the condensed consolidated balance sheet. The Company’s ownership interest decreased in August 2019 which resulted in the deconsolidation of Vest operations and the elimination of the redeemable noncontrolling interest. See Note 5 (“Investments”) for further information on the deconsolidation and Note 14 (“Redeemable Noncontrolling Interest”) for further information on the redeemable noncontrolling interest. The Company expensed $16.7 million of acquisition-related costs during the three months ended September 30, 2019 that included $12.7 million of compensation-related costs, $2.0 million of general and administrative expenses, $1.7 million of professional fees, and $0.3 million of termination fees related to an assigned lease agreement. These expenses relate to Bats and other acquisitions, and are included in acquisition-related costs in the condensed consolidated statements of income. The Company expensed $39.8 million of acquisition-related costs during the nine months ended September 30, 2019 that included $10.5 million of impairment of goodwill charges, $6.1 million of impairment of facilities charges, $16.1 million of compensation-related costs, $2.0 million of general and administrative expenses, $3.7 million of professional fees and $1.4 million of termination fees related to an assigned lease agreement. These expenses relate to Bats and other acquisitions, and are included in acquisition-related costs in the condensed consolidated statements of income. The Company expensed $5.9 million of acquisition-related costs during the three months ended September 30, 2018 that included $4.8 million of compensation-related costs and $0.9 million of professional fees. These expenses relate to Bats and other acquisitions, and are included in acquisition-related costs in the condensed consolidated statements of income. ​ The Company expensed $23.3 million of acquisition-related costs during the nine months ended September 30, 2018 that included $17.6 million of compensation-related costs, $2.7 million of stock-based compensation, $2.2 million of professional fees, and $0.6 million of general and administrative expenses. These expenses relate to Bats and other acquisitions, and are included in acquisition-related costs in the condensed consolidated statements of income. ​

SEVERANCE

SEVERANCE	9 Months Ended
	Sep. 30, 2019
SEVERANCE
SEVERANCE	4. SEVERANCE Subsequent to the Bats acquisition, the Company determined that certain employees’ positions were redundant. As such, the Company communicated employee termination benefits to these employees. The following is a summary of the employee termination benefits recognized within acquisition costs in the condensed consolidated statements of income (in millions): ​ ​ ​ ​ ​ Employee Termination Benefits Balance at December 31, 2018 ​ $ 6.1 Termination benefits accrual adjustment ​ 7.0 Termination payments made ​ (2.9) Balance at September 30, 2019 ​ $ 10.2 ​

INVESTMENTS

INVESTMENTS	9 Months Ended
	Sep. 30, 2019
INVESTMENTS
INVESTMENTS	5. INVESTMENTS As of September 30, 2019 and December 31, 2018, the Company’s investments were comprised of the following (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2019 2018 Equity Method Investments: ​ ​ ​ ​ ​ ​ Investment in Signal Trading Systems, LLC ​ $ 13.3 ​ $ 12.4 Investment in EuroCCP ​ 9.4 ​ 9.3 Total equity method investments ​ ​ 22.7 ​ ​ 21.7 ​ ​ ​ ​ ​ ​ ​ Cost Method Investments: ​ ​ ​ ​ ​ ​ Investment in OCC ​ ​ 8.3 ​ ​ 30.3 Investment in Eris Exchange Holdings, LLC ​ ​ 20.8 ​ ​ 20.0 Investment in American Financial Exchange, LLC ​ ​ 8.6 ​ ​ 5.9 Investment in Cboe Vest Financial Group, Inc. ​ ​ 2.9 ​ ​ — Other cost method investments ​ 6.4 ​ 8.3 Total cost method investments ​ ​ 47.0 ​ ​ 64.5 ​ ​ ​ ​ ​ ​ ​ Total investments ​ $ 69.7 ​ $ 86.2 ​ Equity Method Investments Equity method investments include investments in Signal Trading Systems, LLC, a 50% joint venture with FlexTrade System, Inc. to develop and market a multi-asset front-end order entry system, and EuroCCP, a Dutch domiciled clearing house. EuroCCP is one of three interoperable central counterparties, or CCPs, used to clear trades conducted on Cboe Europe Limited’s and Cboe Europe B.V.’s markets. Cboe Europe Limited owns 20% of EuroCCP and can exercise significant influence over the entity as an equal shareholder with four other investors. Cost Method Investments The carrying amount of cost method investments totaled $47.0 million as of September 30, 2019 and $64.5 million as of December 31, 2018, and is included in investments in the condensed consolidated balance sheets. The Company accounts for these investments using the measurement alternative primarily as a result of the Company’s inability to exercise significant influence as the Company is a smaller shareholder of these investments and the lack of readily determinable fair values. As of September 30, 2019, cost method investments primarily reflect a 20% investment in OCC and minority investments in American Financial Exchange, LLC, CurveGlobal, Vest, and Eris Exchange Holdings, LLC. In December 2014, OCC announced a newly-formed capital plan. The OCC capital plan was designed to strengthen OCC’s capital base and facilitate its compliance with proposed SEC regulations for Systemically Important Financial Market Utilities ("SIFMUs") as well as international standards applicable to financial market infrastructures. On February 26, 2015, the SEC issued a notice of no objection to OCC’s advance notice filing regarding the capital plan, and OCC and OCC’s existing exchange stockholders, which include Cboe Options, subsequently executed agreements effecting the capital plan. Under the plan, each of OCC’s existing exchange stockholders agreed to contribute its pro-rata share, based on ownership percentage, of $150 million in equity capital, which would increase OCC’s shareholders’ equity, and to provide its pro rata share in replenishment capital, up to a maximum of $40 million per exchange stockholder, if certain capital thresholds were to be breached. OCC also adopted policies under the plan with respect to fees, customer refunds, and stockholder dividends, which envisioned an annual dividend payment to the exchange stockholders equal to the portion of OCC’s after-tax income that exceeded OCC’s capital requirements after payment of refunds to OCC’s clearing members (with such customer refunds generally to constitute 50% of the portion of OCC’s pre-tax income that exceeded OCC’s capital requirements). On March 3, 2015, in accordance with the plan, Cboe Options contributed $30.3 million to OCC. That contribution was recorded under investments in the consolidated balance sheets as of December 31, 2018. On March 6, 2015, OCC informed Cboe Options that the SEC, acting through delegated authority, had approved OCC's proposed rule filing for the capital plan. Following petitions to review the approval based on delegated authority, the SEC conducted its own review and then approved the proposed rule change implementing OCC's capital plan. Certain petitioners subsequently appealed the SEC approval order for the OCC capital plan to the U.S. Court of Appeals for the D.C. Circuit and moved to stay the SEC approval order. On February 23, 2016, the Court denied the petitioners' motion to stay. On August 8, 2017, the Court held that the SEC’s approval order lacked reasoned decision-making sufficient to support the SEC’s conclusion that the OCC capital plan complied with applicable statutory requirements. The Court declined to vacate the SEC’s approval order or to require the unwinding of actions taken under the OCC capital plan, but instead remanded the matter to the SEC for further proceedings concerning whether that capital plan complied with those statutory requirements. Petitioners requested a stay of dividend payments to the exchange stockholders until the SEC made a final decision about the OCC capital plan, but the SEC denied that request on September 14, 2017. The SEC allowed for and received information from interested parties for the SEC’s consideration in connection with its review of the OCC capital plan on remand from the Court. On February 13, 2019, the SEC issued an order disapproving the proposed rule change implementing OCC’s capital plan following the SEC’s review of the OCC capital plan on remand from the Court. The SEC concluded, upon further review, that the information before the SEC was insufficient to support a finding that the OCC capital plan was consistent with the Exchange Act and Exchange Act rules and regulations. Among other items, the SEC noted in its order that while OCC represented to the Court that it is possible to unwind the OCC capital plan, the petitioners argued and the Court recognized that unwinding and replacing the OCC capital plan may pose considerable logistical challenges for OCC. The SEC also stated in its order, among other items, that the SEC would consider any requests for exemptive relief that OCC might seek while OCC establishes a new capital plan and seeks to come into compliance with the SEC requirement that OCC maintain a capital plan to cover potential general business losses. In an effort to achieve compliance with its target capital requirements in the absence of an approved capital plan, OCC has (i) retained funds that otherwise would have been paid to stockholders as dividends and to clearing members as refunds with respect to 2018, and (ii) raised its clearing fees. In addition, OCC’s shareholders, including Cboe Options, agreed to permit OCC to retain a portion of their previously contributed capital (equal to $8.3 million for Cboe Options) until such time as OCC has accumulated sufficient capital to satisfy certain target capital thresholds. OCC returned the rest of the shareholders’ previously contributed capital (equal to $22.0 million for Cboe Options) to the respective shareholders on February 28, 2019. With that return of capital, the Company also incurred a tax expense. OCC agreed to reimburse the Company for part of that tax liability and paid the Company $1.1 million in the third quarter of 2019. OCC will not pay its shareholders any dividend or other return on the retained portion of their capital contributions. As such, the Company reversed the $8.8 million OCC dividend declared in 2018, which was to be paid in 2019, in other income in the condensed consolidated statement of income for the nine months ended September 30, 2019. The remaining contribution has been recorded under investments in the condensed consolidated balance sheet as of September 30, 2019. In August 2019, the Company’s ownership in Vest was restructured, including a partial sale of its interest to a third-party. As a result of the restructuring, the Company’s ownership and voting interests decreased to less than 20% and less than 5%, respectively, and the Company deconsolidated Vest and changed the accounting methodology of the investment to the cost method. The deconsolidation resulted in a reduction of net assets of $14.5 million and noncontrolling interest of $5.8 million, as well as recognition of $2.9 million investment for the Company’s remaining ownership. The Company recorded an interest-bearing note receivable of $3.7 million for the consideration received from the third-party, which was recognized in other assets, net in the condensed consolidated balance sheet as of September 30, 2019. Additionally, a loss on the sale of $2.0 million was recognized in acquisition-related costs in the condensed consolidated statements of income for the three and nine months ended September 30, 2019. In the third quarter of 2019, the Company fulfilled a contractual obligation to American Financial Exchange, LLC to launch AMERIBOR futures. As a result of the fulfillment, an additional 5% ownership of American Financial Exchange, LLC was earned by the Company for an additional investment of $2.7 million. The additional revenue was recorded in the Futures segment and increased the Company’s investment in American Financial Exchange, LLC.

FINANCIAL INVESTMENTS

FINANCIAL INVESTMENTS	9 Months Ended
	Sep. 30, 2019
INVESTMENTS
FINANCIAL INVESTMENTS	6. FINANCIAL INVESTMENTS The Company’s financial investments with original or acquired maturities longer than three months, but that mature in less than one year from the condensed consolidated balance sheet date and any money market funds that are considered cash and cash equivalents are classified as current assets. The Company’s marketable securities are also considered current assets. The Company’s financial investments are summarized as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ Cost basis Unrealized gains Unrealized losses Fair value Available-for-sale securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury securities ​ $ 0.5 ​ $ — ​ $ — ​ $ 0.5 Trading securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Marketable securities (1) ​ ​ 20.9 ​ ​ — ​ ​ — ​ ​ 20.9 Total financial investments ​ $ 21.4 ​ $ — ​ $ — ​ $ 21.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ Cost basis Unrealized gains Unrealized losses Fair value Available-for-sale securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury securities ​ $ 35.7 ​ $ — ​ $ — ​ $ 35.7 Total financial investments ​ $ 35.7 ​ $ — ​ $ — ​ $ 35.7 (1) The marketable securities are primarily mutual funds maintained for non-qualified retirement and benefit plans, also referred to as deferred compensation plan assets. See Note 16 (“Employee Benefits”) for more information.

PROPERTY AND EQUIPMENT, NET

PROPERTY AND EQUIPMENT, NET	9 Months Ended
	Sep. 30, 2019
PROPERTY AND EQUIPMENT, NET
PROPERTY AND EQUIPMENT, NET	7. PROPERTY AND EQUIPMENT Property and equipment, net consisted of the following as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2019 2018 Construction in progress ​ $ — ​ $ 0.1 Building ​ ​ — ​ ​ 81.7 Furniture and equipment ​ 172.6 ​ 161.6 Total property and equipment ​ 172.6 ​ 243.4 Less accumulated depreciation ​ (123.6) ​ (171.7) Property and equipment, net ​ $ 49.0 ​ $ 71.7 ​ Depreciation expense using the straight-line method was $5.9 million and $6.2 million for the three months ended September 30, 2019 and 2018, respectively, and $18.2 million and $19.2 million for the nine months ended September 30, 2019 and 2018, respectively. As a result of the Merger, there is a reduction in employee workspace needed in Chicago, which led to the decision to market for sale the headquarters location. The Company classified the associated land, building, and certain furniture and equipment of the headquarters location as held for sale, performed an impairment assessment, and ceased depreciation effective May 1, 2019, as the Company anticipates selling the property held for sale in less than twelve months. As of September 30, 2019, the total value of the property classified as property held for sale on the condensed consolidated balance sheet was $21.0 million. The impact of ceasing depreciation of the property held for sale did not result in a material impact to the condensed consolidated financial statements. As a result of the impairment assessment, an impairment charge of $6.1 million was recorded in acquisition-related costs within the Options segment in the accompanying condensed consolidated statements of income.

OTHER ASSETS, NET

OTHER ASSETS, NET	9 Months Ended
	Sep. 30, 2019
OTHER ASSETS, NET
OTHER ASSETS, NET	8. OTHER ASSETS, NET Other assets, net consisted of the following as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2019 2018 Software development work in progress ​ $ 1.2 ​ $ 8.7 Data processing software ​ ​ 235.8 ​ ​ 219.0 Less accumulated depreciation and amortization ​ (203.8) ​ (193.2) Data processing software, net ​ 33.2 ​ 34.5 Other assets (1) ​ ​ 41.5 ​ ​ 28.4 Data processing software and other assets, net ​ $ 74.7 ​ $ 62.9 (1) At September 30, 2019 and December 31, 2018, the majority of the balance included long-term prepaid assets and notes receivable. The notes receivable included within other assets, net on the condensed consolidated balance sheets relate to the consolidated audit trail NMS plan (“CAT”), which involves the creation of a comprehensive audit trail of orders that enhances the ability to efficiently and accurately track all activity in Regulation NMS securities in the U.S. markets. While the funding of the CAT is ultimately expected to be provided by both the execution venues (which includes the Exchanges) and industry members, until the SEC approves a final funding model, the funding to date has solely been provided by the execution venues. The funding by the execution venues has been done in exchange for promissory notes, which are expected to be repaid once such industry member fees are collected. Until the SEC approves a funding model that shares the cost of the CAT between the execution venues and industry members, the execution venues may continue to incur additional significant costs. Due to circumstances associated with the development of the CAT, the Company believes a loss associated with the uncollectibility of the notes is probable, but is unable to estimate the amount of the loss as of September 30, 2019. As of September 30, 2019 and December 31, 2018, the notes receivable balance was $28.7 million and $20.3 million, respectively. ​ Amortization expense related to data processing software was $3.6 million and $5.3 million for the three months ended September 30, 2019 and 2018, respectively, and $10.5 million and $15.1 million for the nine months ended September 30, 2019 and 2018, respectively.

GOODWILL AND INTANGIBLE ASSETS,

GOODWILL AND INTANGIBLE ASSETS, NET	9 Months Ended
	Sep. 30, 2019
GOODWILL AND INTANGIBLE ASSETS, NET
GOODWILL AND INTANGIBLE ASSETS, NET	9. GOODWILL AND INTANGIBLE ASSETS, NET The following table presents the details of goodwill by segment (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. ​ European ​ ​ ​ ​ Corporate ​ ​ ​ ​ Options Equities Equities Global FX and Other Total Balance as of December 31, 2018 ​ $ 239.4 ​ $ 1,740.4 ​ $ 425.6 ​ $ 267.2 ​ $ 18.8 ​ $ 2,691.4 Additions ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ — Dispositions ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (8.3) ​ ​ (8.3) Impairment ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (10.5) ​ ​ (10.5) Changes in foreign currency exchange rates ​ — ​ — ​ (9.2) ​ — ​ — ​ (9.2) Balance as of September 30, 2019 ​ $ 239.4 ​ $ 1,740.4 ​ $ 416.4 ​ $ 267.2 ​ $ — ​ $ 2,663.4 ​ Goodwill has been allocated to specific reporting units for purposes of impairment testing - Options, U.S. Equities, European Equities and Global FX. No goodwill has been allocated to Futures. Goodwill impairment testing is performed annually in the fiscal fourth quarter or more frequently if conditions exist that indicate that the asset may be impaired. Based on the restructuring of the ownership of Vest, an impairment test was performed over the carrying value of the goodwill related to the entity as there was an indication that the carrying value after the restructuring would be less than the fair value. The impairment test indicated that the fair value of the Company’s ownership of the acquired entity was less than the carrying value, which resulted in an impairment charge of $10.5 million within the Corporate and Other segment related to Vest in the nine months ended September 30, 2019. As a result of the deconsolidation of Vest during the three months ended September 30, 2019, the remaining goodwill was disposed of, resulting in a zero balance within the Corporate and Other segment at September 30, 2019. The following table presents the details of the intangible assets (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. ​ European ​ ​ ​ ​ Corporate ​ ​ ​ ​ Options Equities Equities Global FX and Other Total Balance as of December 31, 2018 ​ $ 181.9 ​ $ 990.3 ​ $ 376.9 ​ $ 166.9 ​ $ 4.2 ​ $ 1,720.2 Additions ​ ​ — ​ — ​ — ​ — ​ — ​ ​ — Dispositions ​ — ​ — ​ — ​ — ​ (3.3) ​ (3.3) Amortization ​ (11.6) ​ (52.2) ​ (18.7) ​ ​ (21.7) ​ (0.9) ​ (105.1) Changes in foreign currency exchange rates ​ — ​ — ​ (13.2) ​ — ​ — ​ (13.2) Balance as of September 30, 2019 ​ $ 170.3 ​ $ 938.1 ​ $ 345.0 ​ $ 145.2 ​ $ — ​ $ 1,598.6 ​ For the three months ended September 30, 2019 and 2018, amortization expense was $33.4 million and $38.8 million, respectively. For the nine months ended September 30, 2019 and 2018, amortization expense was $105.1 million and $120.6 million, respectively. The estimated future amortization expense is $33.2 million for the remainder of 2019, $119.9 million for 2020, $105.4 million for 2021, $93.0 million for 2022, $82.3 million for 2023 and $62.1 million for 2024. The following tables present the categories of intangible assets as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ September 30, 2019 ​ Average ​ ​ ​ ​ U.S. ​ European ​ ​ ​ ​ Corporate ​ Amortization ​ Options Equities Equities Global FX and Other Period (in years) Trading registrations and licenses ​ $ 95.5 ​ $ 572.7 ​ $ 169.9 ​ $ — ​ $ — ​ Indefinite Customer relationships ​ 38.8 ​ 222.9 ​ 158.2 ​ 140.0 ​ — ​ 17 Market data customer relationships ​ 53.6 ​ 322.0 ​ 59.4 ​ 64.4 ​ — ​ 12 Technology ​ 24.8 ​ 22.5 ​ 22.3 ​ 22.5 ​ — ​ 4 Trademarks and tradenames ​ 1.7 ​ 6.0 ​ 1.8 ​ 1.2 ​ — ​ 6 Accumulated amortization ​ (44.1) ​ (208.0) ​ (66.6) ​ (82.9) ​ — ​ ​ ​ ​ $ 170.3 ​ $ 938.1 ​ $ 345.0 ​ $ 145.2 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ December 31, 2018 ​ Average ​ ​ ​ ​ U.S. ​ European ​ ​ ​ ​ Corporate ​ Amortization ​ Options Equities Equities Global FX and Other Period (in years) Trading registrations and licenses ​ $ 95.5 ​ $ 572.7 ​ $ 176.0 ​ $ — ​ $ — ​ Indefinite Customer relationships ​ 38.8 ​ 222.9 ​ 163.9 ​ 140.0 ​ 3.0 ​ 18 Market data customer relationships ​ 53.6 ​ 322.0 ​ 61.5 ​ 64.4 ​ — ​ 13 Technology ​ 24.8 ​ 22.5 ​ 23.1 ​ 22.5 ​ 4.0 ​ 5 Trademarks and tradenames ​ 1.7 ​ 6.0 ​ 1.8 ​ 1.2 ​ 1.0 ​ 2 Accumulated amortization ​ (32.5) ​ (155.8) ​ (49.4) ​ (61.2) ​ (3.8) ​ ​ ​ ​ $ 181.9 ​ $ 990.3 ​ $ 376.9 ​ $ 166.9 ​ $ 4.2 ​ ​ ​

ACCOUNTS PAYABLE AND ACCRUED LI

ACCOUNTS PAYABLE AND ACCRUED LIABILITIES	9 Months Ended
	Sep. 30, 2019
ACCOUNTS PAYABLE AND ACCRUED LIABILITIES
ACCOUNTS PAYABLE AND ACCRUED LIABILITIES	10. ACCOUNTS PAYABLE AND ACCRUED LIABILITIES Accounts payable and accrued liabilities consisted of the following as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 December 31, 2018 Compensation and benefit-related liabilities ​ $ 26.0 ​ $ 52.4 Termination benefits ​ ​ 10.2 ​ ​ 6.1 Royalties ​ ​ 20.4 ​ ​ 25.0 Accrued liabilities ​ 82.8 ​ ​ 91.8 Marketing fee payable ​ 9.5 ​ ​ 10.4 Accounts payable ​ 10.3 ​ ​ 12.8 Total accounts payable and accrued liabilities ​ $ 159.2 ​ $ 198.5 ​

DEBT

DEBT	9 Months Ended
	Sep. 30, 2019
DEBT
DEBT	11. DEBT The Company’s debt consisted of the following as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 December 31, 2018 $300 million Term Loan Agreement due December 2021, floating rate ​ $ 222.0 ​ $ 271.1 $650 million fixed rate Senior Notes due January 2027, stated rate of 3.650% ​ 645.1 ​ 644.5 $300 million fixed rate Senior Notes due June 2019, stated rate of 1.950% ​ ​ — ​ ​ 299.8 Revolving Credit Agreement ​ ​ — ​ ​ — Total debt ​ $ 867.1 ​ $ 1,215.4 ​ Term Loan Agreement On March 22, 2018, the Company, as borrower, entered into a new Term Loan Credit Agreement (the “Term Loan Agreement”) with Bank of America, N.A. (“Bank of America”), as administrative agent and initial lender, and the several banks and other financial institutions from time to time party thereto as lenders. Bank of America also acted as sole lead arranger and sole bookrunner with respect to the Term Loan Agreement. The Term Loan Agreement provides for a senior unsecured term loan facility in an aggregate principal amount of $300 million. The proceeds of the loan under the Term Loan Agreement were used to repay the $300 million of outstanding indebtedness under the Prior Term Loan Agreement. Loans under the Term Loan Agreement bear interest, at our option, at either (i) the London Interbank Offered Rate (“LIBOR”) periodically fixed for an interest period (as selected by us) of one, two, three or six months plus a margin (based on our public debt ratings) ranging from 1.00 percent per annum to 1.50 percent per annum or (ii) a daily floating rate based on the agent’s prime rate (subject to certain minimums based upon the federal funds effective rate or LIBOR) plus a margin (based on our public debt ratings) ranging from zero percent per annum to 0.50 percent per annum. The Company was required to pay an up-front fee of 0.05 percent to the agent for the entry into the Term Loan Agreement. The Term Loan Agreement, which matures on December 15, 2021, contains customary representations, warranties and affirmative and negative covenants for facilities of its type, including financial covenants, events of default and indemnification provisions in favor of the lenders thereunder. The negative covenants include restrictions regarding the incurrence of liens, the incurrence of indebtedness by our subsidiaries and fundamental changes, subject to certain exceptions in each case. The financial covenants require us to meet a quarterly financial test with respect to a minimum consolidated interest coverage ratio of not less than 4.00 to 1.00 and a maximum consolidated leverage ratio of not greater than 3.50 to 1.00. At September 30, 2019, the Company was in compliance with these covenants. The Company repaid $50 million of the outstanding indebtedness of the Term Loan Agreement with cash on hand during the quarter ended September 30, 2019. Senior Notes On January 12, 2017, the Company entered into an indenture (the “Indenture”), by and between the Company and Wells Fargo Bank, National Association, as trustee, in connection with the issuance of $650 million aggregate principal amount of the Company’s 3.650% Senior Notes due 2027 ("3.650% Senior Notes" or the “Senior Notes”). The form and terms of the 3.650% Senior Notes were established pursuant to an Officer’s Certificate, dated as of January 12, 2017, supplementing the Indenture. The Company used a portion of the net proceeds from the 3.650% Senior Notes to fund, in part, the Merger, including the payment of related fees and expenses and the repayment of Bats’ existing indebtedness, and the remainder for general corporate purposes. The 3.650% Senior Notes mature on January 12, 2027 and bear interest at the rate of 3.650% per annum, payable semi-annually in arrears on January 12 and July 12 of each year, commencing July 12, 2017. On June 29, 2017, the Company issued $300 million aggregate principal amount of 1.950% Senior Notes due 2019 ("1.950% Senior Notes" and, together with the 3.650% Senior Notes, the "Senior Notes"), which bear interest at the rate of 1.950% per annum, payable semi-annually in arrears on June 28 and December 28 of each year, commencing December 28, 2017. The Senior Notes are unsecured obligations of the Company and rank equally with all of the Company’s other existing and future unsecured, senior indebtedness, but are effectively junior to the Company’s secured indebtedness, to the extent of the value of the assets securing such indebtedness, and will be structurally subordinated to the secured and unsecured indebtedness of the Company’s subsidiaries. The Company has the option to redeem some or all of the Senior Notes, at any time in whole or from time to time in part, at the redemption prices set forth in the applicable Officer’s Certificate. The Company may also be required to offer to repurchase the Senior Notes upon the occurrence of a Change of Control Triggering Event (as such term is defined in the applicable Officer’s Certificate) at a repurchase price equal to 101% of the aggregate principal amount of Senior Notes to be repurchased. The Company repaid the aggregate principal amount of the 1.950% Senior Notes in full with cash on hand upon their maturity on June 28, 2019. Indenture Under the Indenture, the Company may issue debt securities, which includes the Senior Notes, at any time and from time to time, in one or more series without limitation on the aggregate principal amount. The Indenture governing the Senior Notes contains customary restrictions, including a limitation that restricts our ability and the ability of certain of our subsidiaries to create or incur secured debt. Such Indenture also limits certain sale and leaseback transactions and contains customary events of default. At September 30, 2019, the Company was in compliance with these covenants. Revolving Credit Agreement On December 15, 2016, the Company, as borrower, entered into a Credit Agreement (the “Revolving Credit Agreement”) with Bank of America, N.A., as administrative agent and as swing line lender, certain lenders named therein (the “Revolving Lenders”). The Revolving Credit Agreement provides for a senior unsecured $150 million five-year revolving credit facility (the “Revolving Credit Facility”) that includes a $25 million swing line sub-facility. The Company may also, subject to the agreement of the applicable lenders, increase the commitments under the Revolving Credit Facility by up to $100 million, for a total of $250 million. Subject to specified conditions, the Company may designate one or more of its subsidiaries as additional borrowers under the Revolving Credit Agreement provided that the Company guarantees all borrowings and other obligations of any such subsidiaries. As of September 30, 2019, no subsidiaries were designated as additional borrowers. Funds borrowed under the Revolving Credit Agreement may be used to fund working capital and for other general corporate purposes. As of September 30, 2019, no borrowings were outstanding under the Revolving Credit Agreement. Accordingly, at September 30, 2019, $150 million of borrowing capacity was available for the purposes permitted by the Revolving Credit Agreement. Loans under the Revolving Credit Agreement will bear interest, at our option, at either (i) LIBOR periodically fixed for an interest period (as selected by us) of one, two, three or six months plus a margin (based on our public debt ratings) ranging from 1.00 percent per annum to 1.75 percent per annum or (ii) a daily floating rate based on our prime rate (subject to certain minimums based upon the federal funds effective rate or LIBOR) plus a margin (based on our public debt ratings) ranging from zero percent per annum to 0.75 percent per annum. Subject to certain conditions stated in the Revolving Credit Agreement, the Company may borrow, prepay and reborrow amounts under the Revolving Credit Facility at any time during the term of the Revolving Credit Agreement. The Revolving Credit Agreement will terminate and all amounts owing thereunder will be due and payable on December 15, 2021, unless the commitments are terminated earlier, either at our request or, if an event of default occurs, by the Revolving Lenders (or automatically in the case of certain bankruptcy-related events). The Revolving Credit Agreement contains customary representations, warranties and affirmative and negative covenants for facilities of its type, including financial covenants, events of default and indemnification provisions in favor of the Revolving Lenders. The negative covenants include restrictions regarding the incurrence of liens, the incurrence of indebtedness by our subsidiaries and fundamental changes, subject to certain exceptions in each case. The financial covenants require us to meet a quarterly financial test with respect to a minimum consolidated interest coverage ratio of not less than 4.00 to 1.00 and a maximum consolidated leverage ratio of not greater than 3.50 to 1.00. At September 30, 2019, the Company was in compliance with these covenants. Loan and Notes Payments and Contractual Interest The future expected loan repayments related to the Term Loan Agreement and the Senior Notes as of September 30, 2019 are as follows (in millions): ​ ​ ​ ​ 2019 $ — 2020 ​ ​ — 2021 ​ ​ 225.0 2022 ​ ​ — 2023 ​ ​ — Thereafter ​ ​ 650.0 Principal amounts repayable ​ ​ 875.0 Debt issuance cost ​ ​ (3.7) Unamortized discounts on notes ​ ​ (4.2) Total debt outstanding ​ $ 867.1 ​ Interest expense recognized on the Term Loan Agreement and the Senior Notes is included in interest expense, net in the condensed consolidated statements of income, for the three and nine months ended September 30, 2019 and 2018 is as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ September 30, ​ September 30, ​ 2019 2018 2019 2018 Components of interest expense: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contractual interest ​ $ 8.3 ​ $ 10.0 ​ $ 28.0 ​ $ 29.1 Amortization of debt discount ​ 0.2 ​ 0.5 ​ 0.5 ​ 1.3 Amortization of debt issuance costs ​ 0.3 ​ 0.2 ​ 1.2 ​ 0.5 Interest expense ​ $ 8.8 ​ $ 10.7 ​ ​ 29.7 ​ ​ 30.9 Interest income ​ ​ (0.6) ​ ​ (1.1) ​ ​ (1.6) ​ ​ (2.4) Interest expense, net ​ $ 8.2 ​ $ 9.6 ​ $ 28.1 ​ $ 28.5 ​

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME, NET	9 Months Ended
	Sep. 30, 2019
ACCUMULATED OTHER COMPREHENSIVE INCOME, NET
ACCUMULATED OTHER COMPREHENSIVE INCOME, NET	12. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS), NET The following represents the changes in accumulated other comprehensive income (loss) by component (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ​ ​ ​ ​ ​ ​ ​ Total Accumulated ​ ​ Currency Unrealized ​ ​ ​ Other ​ ​ Translation Investment ​ Post-Retirement ​ Comprehensive ​ Adjustment Gain (Loss) Benefits Income (Loss) Balance at December 31, 2018 ​ $ 12.1 ​ $ 0.2 ​ $ (0.8) ​ $ 11.5 Other comprehensive loss ​ (20.6) ​ ​ — ​ ​ — ​ ​ (20.6) Balance at September 30, 2019 ​ $ (8.5) ​ $ 0.2 ​ $ (0.8) ​ $ (9.1) ​

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	9 Months Ended
	Sep. 30, 2019
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS	13. FAIR VALUE MEASUREMENTS Fair value is the price that would be received upon the sale of an asset or paid upon the transfer of a liability in an orderly transaction between market participants at the measurement date and in the principal or most advantageous market for that asset or liability. The fair value should be calculated based on assumptions that market participants would use in pricing the asset or liability, not on assumptions specific to the entity. In addition, the fair value of liabilities should include consideration of non-performance risk, including the Company’s own credit risk. The Company applied FASB ASC 820, Fair Value Measurement and Disclosure ● Level 1—Unadjusted inputs based on quoted markets for identical assets or liabilities. ● Level 2—Observable inputs, either direct or indirect, not including Level 1, corroborated by market data or based upon quoted prices in non-active markets. ● Level 3—Unobservable inputs that reflect management’s best assumptions of what market participants would use in valuing the asset or liability. The Company has included a tabular disclosure for financial assets and liabilities that are measured at fair value on a recurring basis in the condensed consolidated balance sheet as of September 30, 2019 and December 31, 2018. Assets and Liabilities Measured at Fair Value on a Recurring Basis The following tables present the Company’s fair value hierarchy for those assets and liabilities measured at fair value on a recurring basis as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury securities ​ $ 0.5 ​ $ 0.5 ​ $ — ​ $ — Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mutual funds ​ ​ 14.9 ​ ​ 14.9 ​ ​ — ​ ​ — Money market funds ​ 6.0 ​ 6.0 ​ — ​ — Total assets ​ $ 21.4 ​ $ 21.4 ​ $ — ​ $ — Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration liability to related party ​ $ 6.3 ​ $ — ​ $ — ​ $ 6.3 Total Liabilities ​ $ 6.3 ​ $ — ​ $ — ​ $ 6.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury securities ​ $ 35.7 ​ $ 35.7 ​ $ — ​ $ — Total assets ​ $ 35.7 ​ $ 35.7 ​ $ — ​ $ — Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration liability to related party ​ $ 3.9 ​ $ — ​ $ — ​ $ 3.9 Total Liabilities ​ $ 3.9 ​ $ — ​ $ — ​ $ 3.9 ​ The following is a description of the Company’s valuation methodologies used for instruments measured at fair value on a recurring basis: Financial Investments Financial investments consist of highly liquid U.S. Treasury securities and marketable securities held in a rabbi trust for the Company’s non-qualified retirement and benefit plans, also referred to as deferred compensation plan assets. The deferred compensation plan assets have an equal and offsetting deferred compensation plan liability based on the value of the deferred compensation plan assets. These securities are valued by obtaining feeds from a number of live data sources, including active market makers and inter-dealer brokers and therefore categorized as Level 1. See Note 16 (“Employee Benefits”) for more information. Contingent Consideration Liability In connection with the acquisition of the assets of Silexx Financial Systems, LLC (“Silexx”), the Company acquired a contingent consideration arrangement with the former owners of Silexx. The total fair value of this liability at September 30, 2019 was $6.3 million. The fair values are based on estimates of discounted future cash payments, a significant unobservable input, and are considered a Level 3 measurement. Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Certain assets, such as goodwill and intangible assets, are measured at fair value on a non-recurring basis. For goodwill, the process involves using a market approach and income approach (using discounted estimated cash flows) to determine the fair value of each segment on a stand-alone basis. That fair value is compared to the carrying amount of the segment, including its recorded goodwill. Impairment is considered to have occurred if the fair value of the segment is lower than the carrying amount of the segment. For the intangible assets, the process also involves using a discounted estimated cash flow method to determine the fair value of each intangible asset. Impairment is considered to have occurred if the fair value of the intangible asset is lower than its carrying amount. These measurements are considered Level 3 and these assets are recognized at fair value if they are deemed to be impaired. During the nine months ended September 30, 2019, a goodwill impairment charge of $10.5 million was incurred within the Corporate and Other segment. As a result of the impairment and subsequent deconsolidation of Vest, the fair value of the goodwill within the Corporate and Other segment was zero as of September 30, 2019. As of December 31, 2018, none of these assets were recorded at fair value since no impairment indicators were present, see Note 9 (“Goodwill and Intangible Assets, Net”). In addition, property held for sale as of September 30, 2019 was also measured at fair value at September 30, 2019. See Note 7 (“Property and Equipment”) for more information on property held for sale. Fair Value of Assets and Liabilities The following table presents the Company’s fair value hierarchy for certain assets and liabilities held by the Company as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury securities ​ $ 0.5 ​ $ 0.5 ​ $ — ​ $ — Deferred compensation plan assets ​ ​ 20.9 ​ ​ 20.9 ​ ​ — ​ ​ — Total assets ​ $ 21.4 ​ $ 21.4 ​ $ — ​ $ — Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration liability to related party ​ $ 6.3 ​ $ — ​ $ — ​ $ 6.3 Deferred compensation plan liabilities ​ ​ 20.9 ​ ​ 20.9 ​ ​ — ​ ​ — Debt ​ 867.1 ​ — ​ 867.1 ​ — Total liabilities ​ $ 894.3 ​ $ 20.9 ​ $ 867.1 ​ $ 6.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury securities ​ $ 35.7 ​ $ 35.7 ​ $ — ​ $ — Total assets ​ $ 35.7 ​ $ 35.7 ​ $ — ​ $ — Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration liability to related party ​ $ 3.9 ​ $ — ​ $ — ​ $ 3.9 Debt ​ 1,215.4 ​ — ​ 1,215.4 ​ — Total liabilities ​ $ 1,219.3 ​ $ — ​ $ 1,215.4 ​ $ 3.9 ​ Certain financial assets and liabilities, including cash and cash equivalents, accounts receivable, income tax receivable, accounts payable and Section 31 fees payable, are not measured at fair value on a recurring basis, but the carrying values approximate fair value due to their liquid or short-term nature. Debt The carrying amount of debt approximates its fair value based on quoted LIBOR or using a fixed rate at September 30, 2019 and is considered a Level 2 measurement. Information on Level 3 Financial Liabilities The following table sets forth a summary of changes in the fair value of the Company’s Level 3 financial liabilities during the nine months ended September 30, 2019. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 3 Financial Liabilities for the Nine Months Ended September 30, 2019 ​ ​ Balance at ​ Realized (gains) ​ ​ ​ ​ ​ ​ ​ ​ ​ Beginning of ​ losses during ​ ​ ​ ​ ​ Balance at ​ Period ​ period ​ Additions Settlements End of Period Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration liability to related party $ 3.9 ​ $ 2.4 ​ $ — $ — $ 6.3 Total Liabilities ​ $ 3.9 ​ $ 2.4 ​ $ — ​ $ — ​ $ 6.3 ​

REDEEMABLE NONCONTROLLING INTER

REDEEMABLE NONCONTROLLING INTEREST	9 Months Ended
	Sep. 30, 2019
REDEEMABLE NONCONTROLLING INTEREST
REDEEMABLE NONCONTROLLING INTEREST	14. REDEEMABLE NONCONTROLLING INTEREST Redeemable noncontrolling interest is reported on the condensed consolidated balance sheets in mezzanine equity in Redeemable Noncontrolling Interest. The Company recognizes changes to the redemption value of redeemable noncontrolling interest as they occur and adjusts the carrying value to equal the redemption value at the end of each reporting period. The resulting increases or decreases in the estimated redemption amount are affected by corresponding charges or credits against retained earnings, or in the absence of retained earnings, additional paid in capital. The redemption amounts have been estimated based on the fair value of the formerly majority-owned subsidiary Vest. See Note 5 (“Investments”) for more information on the deconsolidation of Vest. For the nine months ended September 30, 2019, the following reflects changes in our redeemable noncontrolling interest (in millions): ​ ​ ​ ​ ​ Redeemable Balance as of December 31, 2018 ​ $ 9.4 Net loss attributable to redeemable noncontrolling interest ​ (4.1) Redemption value adjustment of redeemable noncontrolling interest ​ 0.5 Deconsolidation of former subsidiary with noncontrolling interest ​ ​ (5.8) Balance as of September 30, 2019 ​ $ — ​

SEGMENT REPORTING

SEGMENT REPORTING	9 Months Ended
	Sep. 30, 2019
SEGMENT REPORTING
SEGMENT REPORTING	15. SEGMENT REPORTING The Company reports five business segments: Options, U.S. Equities, Futures, European Equities, and Global FX, which is reflective of how the Company’s chief operating decision-maker reviews and operates the business, as discussed in Note 1 (“Organization and Basis of Presentation”). Segment performance is primarily based on operating income (loss). Our chief operating decision-maker does not review total assets or statements of income below operating income by segments as key performance metrics; therefore, such information is not presented below. The Company has aggregated all of its corporate costs, as well as other business ventures, within the Corporate Items and Eliminations unit based on the decision that those activities should not be used to evaluate the segment’s operating performance; however, operating expenses that relate to activities of a specific segment have been allocated to that segment. The Options segment includes the options exchange business, which lists for trading options on market indexes (index options), mostly on an exclusive basis, as well as on non-exclusive "multiply-listed" options, such as options on the stocks of individual corporations (equity options) and options on other exchange-traded products (ETP options), such as exchange-traded funds (ETF options) and exchange-traded notes (ETN options) that occur on Cboe Options, C2, BZX and EDGX. It also includes the listed equity and ETP options routed transaction services that occur on Cboe Trading. The U.S. Equities segment includes listed cash equities and ETP transaction services that occur on BZX, BYX, EDGX and EDGA. It also includes market data revenue generated from the U.S. tape plans as well as revenue generated from the sale of proprietary market data, ETP listing, listed cash equities and ETPs routed transaction services, connectivity fees, and advertising activity from ETF.com. The Futures segment includes the business of our futures exchange, CFE, which includes offering for trading futures on the VIX Index and other futures products. The European Equities segment includes the pan-European listed cash equities transaction services, ETPs, exchange-traded commodities, and international depository receipts that occur on the RIE, operated by Cboe Europe Limited. It also includes the listings business where ETPs can be listed on Cboe Europe Limited. The Global FX segment includes institutional FX trading services that occur on the Cboe FX platform, as well as non-deliverable forward FX transactions executed on Cboe SEF. ​ Summarized financial data of reportable segments was as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ European ​ ​ ​ ​ Items and ​ ​ ​ ​ Options U.S. Equities Futures Equities Global FX Eliminations Total Three Months Ended September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 266.1 ​ $ 330.7 ​ $ 39.6 ​ $ 25.9 ​ $ 13.1 ​ $ — ​ $ 675.4 Operating income (loss) ​ 85.4 ​ ​ 36.4 ​ ​ 26.2 ​ ​ 4.8 ​ ​ (1.3) ​ ​ (4.1) ​ ​ 147.4 Three Months Ended September 30, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 228.6 ​ $ 271.9 ​ $ 31.2 ​ $ 30.6 ​ $ 13.6 ​ $ — ​ $ 575.9 Operating income (loss) ​ 82.1 ​ ​ 30.6 ​ ​ 20.6 ​ ​ 5.4 ​ ​ (1.9) ​ ​ (10.7) ​ ​ 126.1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ European ​ ​ ​ ​ Items and ​ ​ ​ ​ Options U.S. Equities Futures Equities Global FX Eliminations Total Nine Months Ended September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 743.2 ​ $ 925.2 ​ $ 103.9 ​ $ 84.9 ​ $ 40.1 ​ $ 0.2 ​ $ 1,897.5 Operating income (loss) ​ ​ 252.5 ​ ​ 110.4 ​ ​ 63.9 ​ ​ 16.3 ​ ​ (3.3) ​ ​ (21.8) ​ ​ 418.0 Nine Months Ended September 30, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 766.8 ​ $ 1,005.6 ​ $ 107.7 ​ $ 97.9 ​ $ 42.7 ​ $ 0.4 ​ $ 2,021.1 Operating income (loss) ​ ​ 273.8 ​ ​ 101.9 ​ ​ 63.1 ​ ​ 18.1 ​ ​ (6.6) ​ ​ (27.4) ​ ​ 422.9 ​ ​

EMPLOYEE BENEFITS

EMPLOYEE BENEFITS	9 Months Ended
	Sep. 30, 2019
EMPLOYEE BENEFITS
EMPLOYEE BENEFITS	16. EMPLOYEE BENEFITS Employees are eligible to participate in the Cboe Options SMART Plan (“SMART Plan”). The SMART Plan is a defined contribution plan, which is qualified under Internal Revenue Code Section 401(k). In addition, eligible employees may participate in the Supplemental Employee Retirement Plan, Executive Retirement Plan and Deferred Compensation Plan. Effective January 1, 2017, the Executive Retirement Plan is closed to new executive officers and employees. Each plan is a defined contribution plan that is non-qualified under Internal Revenue Code. The Deferred Compensation Plan assets, held in a rabbi trust, are subject to the claims of general creditors of the Company and totaled $20.9 million at September 30, 2019. Although the value of the plans are recorded as an asset in financial instruments on the condensed consolidated balance sheets, there are equal and offsetting liabilities in other non-current liabilities. The investment results of these plans have no impact on net income as the investment results are recorded in equal amounts to both other income (expense) and compensation and benefits expense. The Company contributed $3.3 million and $2.7 million to the defined contribution plans for the three months ended September 30, 2019 and 2018, respectively, and $8.5 million and $6.7 million to the defined contribution plans for the nine months ended September 30, 2019 and 2018, respectively. For employees of Cboe Europe Limited, the Company contributes to an employee-selected stakeholder contribution plan. The Company’s contribution amounted to $0.2 million and $0.3 million for the three months ended September 30, 2019 and 2018, respectively, and $0.5 and $0.6 million for the nine months ended September 30, 2019 and 2018. This expense is included in compensation and benefits in the condensed consolidated statements of income.

REGULATORY CAPITAL

REGULATORY CAPITAL	9 Months Ended
	Sep. 30, 2019
REGULATORY CAPITAL
REGULATORY CAPITAL	17. REGULATORY CAPITAL As a broker-dealer registered with the SEC, Cboe Trading is subject to the SEC’s Uniform Net Capital Rule (Rule 15c3-1), which requires the maintenance of minimum net capital, as defined therein. The SEC’s requirement also provides that equity capital may not be withdrawn or a cash dividend paid if certain minimum net capital requirements are not met. Cboe Trading computes the net capital requirements under the basic method provided for in Rule 15c3-1. As of September 30, 2019, Cboe Trading is required to maintain net capital equal to the greater of 6.67% of aggregate indebtedness items, as defined, or $0.1 million. At September 30, 2019, Cboe Trading had net capital of $11.8 million, which was $11.4 million in excess of its required net capital of $0.4 million. As entities regulated by the FCA, Cboe Europe Limited is subject to the Financial Resource Requirement ("FRR") and Cboe Chi-X Europe is subject to the Capital Resources Requirement ("CRR"). As a RIE, Cboe Europe Limited computes its FRR in accordance with its Financial Risk Assessment, as agreed by the FCA. This FRR was $20.3 million at September 30, 2019. At September 30, 2019, Cboe Europe Limited had capital in excess of its required FRR of $34.2 million. As a Banks, Investment firms, PRUdential (BIPRU) 50k firm, as defined by the Markets in Financial Instruments Directive of the FCA, Cboe Chi-X Europe computes its CRR as the greater of the base requirement of $0.1 million at September 30, 2019, or the summation of the credit risk, market risk and fixed overheads requirements, as defined. At September 30, 2019, Cboe Chi-X Europe had capital in excess of its required CRR of $0.5 million. Cboe Chi-X Europe Limited is currently dormant having ceased offering its routing service in November 2018. On March 8, 2019, Cboe Europe B.V. received approval from the Dutch Ministry of Finance to operate a RM, a MTF, and an approved publication arrangement (APA) in the Netherlands. As a RM, Cboe Europe B.V. is subject to minimum capital requirements, as established by the Dutch Ministry of Finance in the license of March 8, 2019. As of September 30, 2019, the minimum capital requirement calculated in accordance with the license was $1.8 million. At September 30, 2019, Cboe Europe B.V. had capital in excess of its requirement of $2.9 million. As a designated contract market regulated by the CFTC, CFE is required to meet two capital adequacy tests: (i) its financial resources must be equal to at least twelve months of its projected operating costs and (ii) its unencumbered, liquid financial assets, which may include a line of credit, must be equal to at least six months of its projected operating costs. As of September 30, 2019, CFE had annual projected operating expenses of $55.3 million and had financial resources that exceeded this amount. Additionally, as of September 30, 2019, CFE had projected operating expenses for the upcoming six months of $27.7 million and had unencumbered, liquid financial assets, including a line of credit from Cboe, that exceeded this amount. As a swap execution facility regulated by the CFTC, Cboe SEF is required to meet two capital adequacy tests: (i) its financial resources must be equal to at least twelve months of its projected operating costs and (ii) its unencumbered, liquid financial assets must be equal to at least six months of its projected operating costs. As of September 30, 2019, Cboe SEF had annual projected operating expenses of $0.7 million and had financial resources that exceeded this amount. Additionally, as of September 30, 2019, Cboe SEF had projected operating expenses for the upcoming six months of $0.4 million and had unencumbered, liquid financial assets that exceeded this amount.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	9 Months Ended
	Sep. 30, 2019
STOCK-BASED COMPENSATION
STOCK-BASED COMPENSATION	18. STOCK-BASED COMPENSATION Stock-based compensation is based on the fair value of the award on the date of grant, which is recognized over the related service period, net of actual forfeitures. The service period is the period over which the related service is performed, which is generally the same as the vesting period. Vesting may be accelerated for certain officers and employees as a result of attaining certain age and service based requirements in our long-term incentive plan and award agreements. The Company recognized stock-based compensation expense of $5.3 million and $8.5 million for the three months ended September 30, 2019 and 2018, respectively, and $17.0 million and $29.4 million for the nine months ended September 30, 2019 and 2018, respectively. Stock-based compensation expense is included in compensation and benefits and acquisition-related costs in the condensed consolidated statements of income. ​ The activity in the Company’s stock options, restricted stock and restricted stock units for the nine months ended September 30, 2019 was as follows: ​ Stock Options Summary stock option activity is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ Weighted ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ Number of ​ Exercise ​ Contractual ​ Intrinsic Value ​ Shares Price Term (years) (in millions) Outstanding and exercisable, December 31, 2018 369,483 ​ $ 26.40 ​ ​ ​ ​ ​ Exercised 348,469 ​ 26.77 ​ ​ ​ ​ ​ Outstanding and exercisable, September 30, 2019 ​ 21,014 ​ $ 20.24 ​ 0.5 ​ $ 2.0 ​ The total intrinsic value of stock options exercised was $25.0 million and $4.8 million for the nine months ended September 30, 2019 and 2018, respectively. For the nine months ended September 30, 2019, to satisfy employee’s tax obligations and cash exercise payment due upon the election to exercise 348,469 stock options, the Company purchased 6,323 shares at a cost of $0.6 million. Restricted Stock and Restricted Stock Units The following table summarizes restricted stock award (RSA) and restricted stock unit (RSU) activity during the nine months ended September 30, 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Number of ​ Average Grant ​ Shares Date Fair Value Nonvested stock at December 31, 2018 631,764 ​ $ 85.85 Granted 213,527 ​ ​ 94.92 Vested (274,774) ​ ​ 83.56 Forfeited (92,854) ​ ​ 84.95 Nonvested stock at September 30, 2019 477,663 ​ $ 86.06 ​ RSAs granted to non-employee members of the board of directors have a one-year vesting period and vesting accelerates upon the occurrence of a change in control of the Company. Unvested portions of the RSAs will be forfeited if the director leaves the Company prior to the applicable vesting date. RSUs entitle the holder to one share of common stock upon vesting, typically vest over a three year period, and vesting accelerates upon the occurrence of a change in control or a termination of employment following a change in control. Vesting will also accelerate upon a qualified retirement. Qualified retirement eligibility occurs once satisfying 65 years of age and 5 years of service for grants awarded before 2017 and once satisfying 55 years of age and 10 years of service for grants awarded in and after 2017. Unvested RSUs will be forfeited if the officer, or employee leaves the Company prior to the applicable vesting date, except in limited circumstances. The RSUs have no voting rights but entitle the holder to receive dividend equivalents. Pursuant to the Merger Agreement, each award of restricted Bats common stock (“Bats restricted shares”) granted under any of the Bats Plans that was unvested immediately prior to the effective time of the Merger was assumed by the Company and converted into an award of restricted shares of our common stock, subject to the same terms and conditions (including vesting schedule) that applied to the applicable Bats restricted shares immediately prior to the effective time of the Merger (but taking into account any changes, including any acceleration of vesting of such Bats restricted shares, occurring by reason provided for in the Merger Agreement). In the nine months ended September 30, 2019, to satisfy employees’ tax obligations upon the vesting of restricted stock, the Company purchased 95,597 shares of common stock totaling $9.1 million as the result of the vesting of 274,774 shares of restricted stock. Performance-Based Restricted Stock Units The following table summarizes restricted stock unit contingent upon achievement of performance conditions, or performance-based restricted stock unit (PSU), activity during the nine months ended September 30, 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Number of ​ Average Grant ​ Shares Date Fair Value Nonvested stock at December 31, 2018 151,842 ​ $ 100.81 Granted 86,134 ​ ​ 88.22 Vested (69,372) ​ ​ 74.56 Forfeited (36,356) ​ ​ 97.78 Nonvested stock at September 30, 2019 132,248 ​ $ 107.21 ​ PSUs include shares related to earnings per share during the performance period as well as shares related to total shareholder return during the performance period. The Company used the Monte Carlo valuation model method to estimate the fair value of the total shareholder return PSUs which incorporated the following assumptions: risk-free interest rate (2.54)%, three-year volatility (20.5)% and three year correlation with S&P 500 Index (0.29). Each of these performance shares has a performance condition under which the number of units ultimately awarded will vary from 0% to 200% of the original grant, with each unit representing the contingent right to receive one share of our common stock. The vesting period for the PSUs contingent on the achievement of performance conditions is three years. For each of the performance awards, the PSUs will be settled in shares of our common stock following vesting of the PSU assuming that the participant has been continuously employed during the vesting period, subject to acceleration in the event of a change in control of the Company, or a termination of employment following a change in control, or in the event of a participant’s earlier death or disability. Participants have no voting rights with respect to the PSUs until the issuance of the shares of common stock. Dividends are accrued by the Company and will be paid once the PSUs contingent on the achievement of performance conditions vest. In the nine months ended September 30, 2019, to satisfy employees’ tax obligations upon the vesting of performance stock, the Company purchased 27,477 shares of common stock totaling $2.6 million as the result of the vesting of 69,372 shares of performance stock. As of September 30, 2019, there were $25.1 million in total unrecognized compensation costs related to restricted stock, restricted stock units, and performance stock units. These costs are expected to be recognized over a weighted average period of 1.6 years. Employee Stock Purchase Plan In May 2018, our stockholders approved our Employee Stock Purchase Plan, (“ESPP”), under which a total of 750,000 shares of our common stock will be made available for purchase to employees. The ESPP is a broad-based plan that permits our employees to contribute up to 10% of wages and base salary to purchase shares of our common stock at a discount, subject to applicable annual Internal Revenue Service limitations. Under our ESPP, a participant may not purchase more than a maximum of 312 shares of our common stock during any single offering period. No participant may accrue options to purchase shares of our common stock at a rate that exceeds $25,000 in fair market value of our common stock (determined at the time such options are granted) for each calendar year in which such rights are outstanding at any time. The exercise price per share of common stock shall be 90% (for eligible U.S. employees) or 85% (for eligible international employees) of the lesser of the fair market value of the stock on the first day of the applicable offering period or the applicable exercise date. We record compensation expense over the offering period related to the discount that is given to our employees, which totaled $0.2 million and $0.4 million for the three months and nine months ended September 30, 2019, respectively. As of September 30, 2019, 722,648 shares were reserved for future issuance under the ESPP.

INCOME TAXES

INCOME TAXES	9 Months Ended
	Sep. 30, 2019
INCOME TAXES
INCOME TAXES	19. INCOME TAXES The Company records income tax expense during interim periods based on the best estimate of the full year’s tax rate as adjusted for discrete items, if any, that are taken into account in the relevant interim period. Each quarter, the Company updates its estimate of the annual effective tax rate and any change in the estimated rate is recorded on a cumulative basis. The effective tax rate from continuing operations was 24.8% and 26.3% for the three months ended September 30, 2019 and 2018, respectively, and 26.5% and 27.4% for the nine months ended September 30, 2019 and 2018, respectively. The lower effective tax rate for the three and nine months ended September 30, 2019 was primarily due to benefits related to the Tax Cuts and Jobs Act and recognized upon the completion of our 2018 U.S. federal income tax return. The Company petitioned the U.S. Tax Court on January 13, 2017, May 7, 2018 and November 29, 2018 for a redetermination of IRS notices of deficiency for Cboe and certain of its subsidiaries for tax years 2011 through 2015 related to its Section 199 claims. The Company also filed a complaint on October 5, 2018 with the Court of Federal Claims for a refund of Section 199 claims related to tax years 2008 through 2010. The Company believes the aggregate amount of any additional liabilities that may result from these examinations, if any, will not have a material adverse effect on the financial position, results of operations, or cash flows of the Company. As of September 30, 2019, we have not resolved these matters, and proceedings continue in the U.S. Tax Court and the Court of Federal Claims.

NET INCOME PER COMMON SHARE

NET INCOME PER COMMON SHARE	9 Months Ended
	Sep. 30, 2019
Net Income Per Common Share
Net Income Per Common Share	20. NET INCOME PER COMMON SHARE The computation of basic net income allocated to common stockholders is calculated by reducing net income for the period by dividends paid or declared and undistributed net income for the period that are allocated to participating securities to arrive at net income allocated to common stockholders. Net income allocated to common stockholders is divided by the weighted average number of common shares outstanding during the period to determine net income per share allocated to common stockholders. The computation of diluted earnings per share is calculated by dividing net income allocated to common stockholders by the sum of the weighted average number of common shares outstanding plus all additional common shares that would have been outstanding if the potentially dilutive common shares had been issued. The dilutive effect is calculated using the more dilutive of the two-class or treasury stock method. Additionally, the change in the redemption value for the noncontrolling interest reduces net income allocated to common stockholders. ​ The following table reconciles net income allocated to common stockholders and the number of shares used to calculate the basic and diluted net income per common share for the three and nine months ended September 30, 2019 and 2018: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, (in millions, except per share amounts) 2019 2018 2019 2018 Basic EPS Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Income ​ $ 105.9 ​ $ 85.7 ​ $ 284.5 ​ $ 286.8 Loss attributable to noncontrolling interest ​ ​ 0.1 ​ ​ 0.3 ​ ​ 4.1 ​ ​ 0.9 Net Income excluding noncontrolling interest ​ 106.0 ​ 86.0 ​ 288.6 ​ 287.7 Change in redemption value of noncontrolling interest ​ ​ (0.1) ​ ​ (0.3) ​ ​ (0.5) ​ ​ (0.9) Earnings allocated to participating securities ​ (0.4) ​ (0.7) ​ (1.5) ​ (2.1) Net Income allocated to common stockholders ​ $ 105.5 ​ $ 85.0 ​ $ 286.6 ​ $ 284.7 Basic EPS Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding ​ ​ 111.6 ​ ​ 111.4 ​ ​ 111.6 ​ ​ 112.0 Basic Net Income Per Common Share ​ $ 0.95 ​ $ 0.76 ​ $ 2.57 ​ $ 2.54 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted EPS Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Income ​ $ 105.9 ​ $ 85.7 ​ $ 284.5 ​ $ 286.8 Loss attributable to noncontrolling interest ​ ​ 0.1 ​ ​ 0.3 ​ ​ 4.1 ​ ​ 0.9 Net Income excluding noncontrolling interest ​ 106.0 ​ 86.0 ​ 288.6 ​ 287.7 Change in redemption value of noncontrolling interest ​ ​ (0.1) ​ ​ (0.3) ​ ​ (0.5) ​ ​ (0.9) Earnings allocated to participating securities ​ (0.4) ​ (0.7) ​ (1.5) ​ (2.1) Net Income allocated to common stockholders ​ $ 105.5 ​ $ 85.0 ​ $ 286.6 ​ $ 284.7 Diluted EPS Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding ​ ​ 111.6 ​ ​ 111.4 ​ ​ 111.6 ​ ​ 112.0 Dilutive common shares issued under stock program ​ ​ 0.3 ​ ​ 0.4 ​ ​ 0.4 ​ ​ 0.4 Total dilutive weighted average shares ​ ​ 111.9 ​ ​ 111.8 ​ ​ 112.0 ​ ​ 112.4 Diluted Net Income Per Common Share ​ $ 0.94 ​ $ 0.76 ​ $ 2.56 ​ $ 2.53 ​ For the periods presented, the Company did not have shares of stock-based compensation that would have an anti-dilutive effect on the computation of diluted net income per common share.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2019
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES	21. COMMITMENTS AND CONTINGENCIES Legal Proceedings As of September 30, 2019, the Company was subject to the various legal proceedings and claims discussed below, as well as certain other legal proceedings and claims that have not been fully resolved and that have arisen in the ordinary course of business. The Company reviews its legal proceedings and claims, regulatory reviews and inspections and other legal proceedings on an ongoing basis and follows appropriate accounting guidance when making accrual and disclosure decisions. The Company establishes accruals for those contingencies where the incurrence of a loss is probable and can be reasonably estimated, and the Company discloses the amount accrued and the amount of a reasonably possible loss in excess of the amount accrued, if such disclosure is necessary for our financial statements to not be misleading. The Company does not record liabilities when the likelihood that the liability has been incurred is probable, but the amount cannot be reasonably estimated, or when the liability is believed to be only reasonably possible or remote. The Company’s assessment of whether a loss is reasonably possible or probable is based on its assessment of the ultimate outcome of the matter following all appeals. As of September 30, 2019, the Company does not believe that there is a reasonable possibility that any material loss exceeding the amounts already recognized for these legal proceedings and claims, regulatory reviews, inspections or other legal proceedings, if any, has been incurred. While the consequences of certain unresolved proceedings are not presently determinable, the outcome of any proceeding is inherently uncertain and an adverse outcome from certain matters could have a material effect on our earnings in any given reporting period. Except as set forth herein, there have been no material changes during the period covered by this Form 10-Q from the legal proceedings disclosures in our Annual Report on Form 10-K for the year ended December 31, 2018. SIFMA Securities Industry Financial Markets Association (“SIFMA”) has filed a number of denial of access applications with the SEC to set aside proposed rule changes to establish or modify fees for Cboe Options, C2, BZX, BYX, EDGX and EDGA (the “Exchanges”) market data products and related services (the “Challenged Fees”). The Challenged Fees were held in abeyance pending a decision, which was issued by the SEC on October 16, 2018, on a separate SIFMA denial of access application regarding fees proposed by Nasdaq and the NYSE for their respective market data products. In a second order entered on October 16, 2018, the SEC issued an order (the “Order”) that remanded the stayed Challenged Fees and ordered the Exchanges to: (i) within six months of the Order, provide notice to the SEC of developed or identified fair procedures for assessing the Challenged Fees (the “Procedures”) and (ii) within one year of the Order, apply the Procedures to the Challenged Fees and submit to the SEC a record explaining the Exchanges’ conclusions. On October 26, 2018, the Exchanges filed a motion to reconsider the Order with the SEC. On November 21, 2018, the Exchanges filed with the SEC a joinder motion to NYSE’s prior motion for stay of the Order. On December 3, 2018, SIFMA filed a response to NYSE’s motion for stay. Nasdaq withdrew its motion to reconsider the Order with the SEC on December 4, 2018, and on December 5, 2018, filed a Petition for Review with the Court of Appeals for the D.C. Circuit (the “D.C. Circuit”). On December 14, 2018, the SEC denied the motion for stay but tolled the compliance date set forth in the remand order until ruling is made on the motion to reconsider. The Exchanges and NYSE filed on January 4, 2019 a motion to intervene in the Nasdaq Petition for Review to ensure the ability to participate in the case; the motion to intervene was granted on January 25, 2019. On the same day, SIFMA filed a motion with the D.C. Circuit moving to dismiss or hold in abeyance the Petition for Review. The Exchanges and NYSE submitted on February 6, 2019 a statement of issues for consideration in connection with the Petition for Review pending before the D.C. Circuit. On March 29, 2019, the D.C. Circuit issued an order indicating that SIFMA’s motion to dismiss will be considered with the underlying merits of the Petition for Review. On May 7, 2019, the SEC denied the Exchanges and NYSE’s motion for reconsideration of the Order. The SEC also further tolled the effectiveness of the remand order subject to the resolution of the substantive SIFMA case against Nasdaq and NYSE Arca that is already before the D.C. Circuit. On June 17, 2019, the Exchanges filed a petition for review of the May 7, 2019 SEC order denying reconsideration of the Order with the D.C. Circuit and of the Order. The Exchanges’ joint opening brief was filed on October 23, 2019. An adverse ruling in that matter or a subsequent appeal could adversely affect exchange market data fees. However, the Company believes that the claims are without merit and intends to litigate the matter vigorously. The Company is unable to estimate what, if any, liability may result from this litigation. VIX Litigation On March 20, 2018, a putative class action complaint captioned Tomasulo v. Cboe Exchange, Inc., et al., No. 18-cv-02025 was filed in federal district court for the Northern District of Illinois alleging that the Company intentionally designed its products, operated its platforms, and formulated the method for calculating VIX and the Special Opening Quotation, (i.e., the special VIX value designed by the Company and calculated on the settlement date of VIX derivatives prior to the opening of trading), in a manner that could be collusively manipulated by a group of entities named as John Doe defendants. A number of similar putative class actions, some of which do not name the Company as a party, were filed in federal court in Illinois and New York on behalf of investors in certain volatility-related products. On June 14, 2018, the Judicial Panel on Multidistrict Litigation centralized the putative class actions in the federal district court for the Northern District of Illinois. On September 28, 2018, plaintiffs filed a master, consolidated complaint that is a putative class action alleging various claims against the Company and John Doe defendants in the federal district court for the Northern District of Illinois. The claims asserted against the Company consist of a Securities Exchange Act fraud claim, three Commodity Exchange Act claims and a state law negligence claim. Plaintiffs request a judgment awarding class damages in an unspecified amount, as well as punitive or exemplary damages in an unspecified amount, prejudgment interest, costs including attorneys’ and experts’ fees and expenses and such other relief as the court may deem just and proper. On November 19, 2018, the Company filed a motion to dismiss the master consolidated complaint and the plaintiffs filed their response on January 7, 2019. The Company filed its reply on January 28, 2019. On May 29, 2019, the federal district court for the Northern District of Illinois granted the Company’s motion to dismiss plaintiffs’ entire complaint against the Company. The state law negligence claim was dismissed with prejudice and the other claims were dismissed without prejudice with leave to file an amended complaint, which plaintiffs filed on July 19, 2019. On August 28, 2019, the Company filed its second motion to dismiss the amended consolidated complaint and plaintiffs filed their response on October 8, 2019. Given the preliminary nature of the proceedings, the Company is still evaluating the facts underlying the complaints, however, the Company currently believes that the claims are without merit and intends to litigate the matter vigorously. The Company is unable to estimate what, if any, liability may result from this litigation. Other As self-regulatory organizations under the jurisdiction of the SEC, Cboe Options, C2, BZX, BYX, EDGX and EDGA are subject to routine reviews and inspections by the SEC. As a designated contract market under the jurisdiction of the CFTC, CFE is subject to routine reviews and inspections by the CFTC. Cboe SEF, LLC is a swap execution facility registered with the CFTC and subject to routine reviews and inspections by the CFTC. Cboe Trading is subject to reviews and inspections by FINRA. The Company has from time to time received inquiries and investigative requests from the SEC's Office of Compliance Inspections and Examinations as well as the Division of Enforcement seeking information about our compliance with our obligations as a self-regulatory organization, the federal securities laws as well as our members’ compliance with the federal securities laws. In addition, while Cboe Europe Limited and Cboe Chi-X Europe have not been the subject of any material litigation or regulatory investigation in the past, there is always the possibility of such action in the future. As both companies are domiciled in the U.K., it is likely that any action would be taken in the U.K. courts in relation to litigation or by the FCA in relation to any regulatory enforcement action. The Company is also currently a party to various other legal proceedings in addition to those already mentioned. Management does not believe that the likely outcome of any of these other reviews, inspections, investigations or other legal proceedings is expected to have a material impact on our consolidated financial condition, results of operations, liquidity or capital resources. See also Note 8 (“Other Assets, Net”) for information on promissory notes related to the CAT. See also Note 19 (“Income Taxes”). Contractual Obligations See Note 22 (“Leases”) for information on lease obligations.

LEASES

LEASES	9 Months Ended
	Sep. 30, 2019
LEASES.
LEASES	22. LEASES The Company currently leases office space, data centers and remote network operations centers under non-cancelable operating leases with third parties as of September 30, 2019. Leases with an initial term of 12 months or less are not recorded on the balance sheet and the Company recognizes lease expense for these leases on a straight-line basis over the lease term. Certain leases include one or more options to renew, with renewal terms that can extend the lease term from one to five years or more, and some of which include the Company’s option to terminate the leases within one year. As most of the leases do not provide an implicit rate, the Company applies an incremental borrowing rate based on the information available at the lease commencement date in determining the present value of lease payments. The Company applied an incremental borrowing rate as of January 1, 2019 for operating leases that commenced prior to that date. During the quarter ended September 30, 2019, an additional $2.0 million of right of use assets and lease liabilities were added related to a new operating lease right of use asset and operating lease liability. ​ In September 2019, the Company signed a new lease to secure approximately 185,000 square feet of office space within the Old Post Office building in Chicago, Illinois, which will serve as the Company’s new global headquarters. The initial term of the lease will be 187 months from the accounting commencement date, which is expected to be in the first quarter of 2020. The Company has the option to renew the lease term for an additional 60 months. The total legally binding minimum lease payments for this lease are approximately $98.8 million. See Note 7 (“Property and Equipment”) for information on the current headquarters location. Additionally, in September 2019, the Company signed a new lease to secure approximately 40,000 square feet of office space within the Chicago Board of Trade Building in Chicago, Illinois, where the Company plans to build a new trading floor and office space. The initial term of the lease will be 150 months from the accounting commencement date, which is expected to be in the second quarter of 2020. The Company has the option to renew the lease term for an additional 60 months. The total legally binding minimum lease payments for this lease are approximately $17.1 million. ​ The following table presents the supplemental balance sheet information related to leases for the quarter ended September 30, 2019 (in millions): ​ ​ ​ ​ September 30, ​ 2019 Operating lease right of use assets $ 53.4 Total leased assets $ 53.4 ​ ​ Accrued liabilities $ 8.8 Non-current operating lease liabilities ​ 47.4 Total leased liabilities $ 56.2 ​ The Company has elected to not separate lease components from nonlease components for all office space, data center space and remote network operations centers operating leases. The Company does not have any financing leases as of September 30, 2019. Operating lease expense is recognized on a straight-line basis over the lease term and is reported in the technology support services and facilities cost line items on the condensed consolidated statements of income. The following table presents operating lease costs and other information as of and for the three and nine months ended September 30, 2019 (in millions, except as stated): ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, Nine Months Ended September 30, ​ 2019 2019 Operating lease costs (1) $ 3.4 ​ $ 8.8 ​ ​ ​ ​ ​ ​ ​ ​ Lease term and discount rate information: ​ ​ ​ ​ ​ ​ Weighted average remaining lease term (years) ​ ​ ​ ​ 9.4 ​ Weighted average discount rate ​ ​ ​ ​ 3.5 % ​ ​ ​ ​ ​ ​ ​ Supplemental cash flow information and non-cash activity: ​ ​ ​ ​ ​ ​ Cash paid for amounts included in the measurement of lease liabilities ​ ​ ​ $ 7.5 ​ Right-of-use assets obtained in exchange for lease liabilities ​ ​ ​ ​ 21.0 ​ (1) Includes short-term leases and variable lease costs, which are immaterial. ​ The maturities of the lease liabilities are as follows as of September 30, 2019 (in millions): ​ ​ ​ ​ ​ ​ September 30, ​ 2019 Remainder of 2019 ​ $ 2.8 2020 ​ ​ 10.0 2021 ​ ​ 9.6 2022 ​ ​ 8.9 2023 ​ ​ 7.6 After 2023 (1) ​ 27.8 Total lease payments ​ $ 66.7 Less: Interest ​ ​ (10.5) Present value of lease liabilities ​ $ 56.2 (1) Total lease payments include $ 20.4 million related to options to extend lease terms that are reasonably certain of being exercised and exclude $115.9 million of legally binding lease payments for leases signed but will commence after September 30, 2019.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	9 Months Ended
	Sep. 30, 2019
SUBSEQUENT EVENTS
SUBSEQUENT EVENTS	23. SUBSEQUENT EVENTS On October 30, 2019, the Company announced that its board of directors declared a quarterly cash dividend of $0.36 per share. The dividend is payable December 13, 2019 to stockholders of record at the close of business November 27, 2019. On October 30, 2019, the Company announced that its board of directors authorized an additional $250 million to repurchase shares of its outstanding common stock. This is in addition to any unused amount remaining under prior authorizations. There have been no additional subsequent events that would require disclosure in, or adjustment to, the condensed consolidated financial statements as of and for the nine months ended September 30, 2019.

ORGANIZATION AND BASIS OF PRE_2

ORGANIZATION AND BASIS OF PRESENTATION (Policies)	9 Months Ended
	Sep. 30, 2019
ORGANIZATION AND BASIS OF PRESENTATION
Basis of Presentation	Basis of Presentation These interim unaudited condensed consolidated financial statements have been prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018. The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities, valuation of redeemable noncontrolling interest and reported amounts of revenues and expenses. On an ongoing basis, management evaluates its estimates based upon historical experience, observance of trends, information available from outside sources and various other assumptions that management believes to be reasonable under the circumstances. Actual results may differ from these estimates under different conditions or assumptions. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation of financial position, results of operations and cash flows at the dates and for the periods presented have been included. The results of operations for interim periods are not necessarily indicative of the results of operations for the full year. For those consolidated subsidiaries in which the Company’s ownership is less than 100% and for which the Company has control over the assets and liabilities and the management of the entity, the outside stockholders’ interest is shown as noncontrolling interest.
Segment information	Segment information The Company reports five business segments: Options, U.S. Equities, Futures, European Equities, and Global FX, which is reflective of how the Company’s chief operating decision-maker reviews and operates the business. See Note 15 (“Segment Reporting”) for more information.
Leases	Leases The Company determines if an arrangement contains a lease at inception. For arrangements where the Company is the lessee, operating leases are included in operating lease right of use (“ROU”) assets, accrued liabilities, and non-current operating lease liabilities on the condensed consolidated balance sheet as of September 30, 2019. The Company currently does not have any finance leases. ROU assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. ROU assets also include any initial direct costs incurred and any lease payments made at or before the lease commencement date, less lease incentives received. The Company uses its incremental borrowing rate based on the information available at the lease commencement date in determining the lease liabilities, as the Company’s leases generally do not provide an implicit rate. Lease terms may include options to extend or terminate when the Company is reasonably certain that the option will be exercised. Lease expense is recognized on a straight-line basis over the lease term. The Company also has lease arrangements with lease and non-lease components. The Company elected the practical expedient not to separate non-lease components from lease components for the Company’s leases. The Company elected to apply the short-term lease measurement and recognition exemption in which ROU assets and lease liabilities are not recognized for short-term leases.
Recent Accounting Pronouncements	Recent Accounting Pronouncements - Adopted Recent Accounting Pronouncements - Issued, not yet Adopted In June 2016, the FASB issued ASU 2016-13, Credit Losses. This update replaces the incurred loss impairment methodology in current GAAP with a methodology that requires management to estimate an expected lifetime credit loss on financial assets. For public entities, the update is effective for fiscal years and interim periods within those fiscal years, beginning after December 15, 2019, with early adoption permitted. The Company is in the process of evaluating this guidance and assessing the impact the ASU could have on the consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, interim periods within those fiscal years, beginning after December 15, 2019. Certain disclosures in the new guidance will need to be applied on a retrospective basis and others on a prospective basis. The Company is in the process of evaluating this guidance and assessing the impact the ASU could have on the consolidated financial statements.

REVENUE RECOGNITION (Tables)

REVENUE RECOGNITION (Tables)	9 Months Ended
	Sep. 30, 2019
REVENUE RECOGNITION
Schedule of disaggregation of revenue	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate ​ ​ ​ ​ ​ ​ ​ ​ U.S. ​ ​ ​ ​ European ​ Global ​ Items and ​ ​ ​ ​ Options Equities Futures Equities FX Eliminations Total Three Months Ended September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Transaction fees ​ $ 207.1 ​ $ 199.4 ​ $ 31.2 ​ $ 16.9 ​ $ 11.2 ​ $ — ​ $ 465.8 Access and capacity fees ​ ​ 26.0 ​ ​ 20.1 ​ ​ 4.0 ​ ​ 3.9 ​ ​ 1.7 ​ ​ — ​ ​ 55.7 Market data fees ​ ​ 13.8 ​ ​ 37.7 ​ ​ 1.6 ​ ​ 3.0 ​ ​ 0.2 ​ ​ — ​ ​ 56.3 Regulatory fees ​ ​ 15.9 ​ ​ 72.2 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 88.1 Other revenue ​ ​ 3.3 ​ ​ 1.3 ​ ​ 2.8 ​ ​ 2.1 ​ ​ — ​ ​ — ​ ​ 9.5 ​ ​ $ 266.1 ​ $ 330.7 ​ $ 39.6 ​ $ 25.9 ​ $ 13.1 ​ $ — ​ $ 675.4 Timing of revenue recognition ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Services transferred at a point in time ​ $ 226.3 ​ $ 272.9 ​ $ 34.0 ​ $ 19.0 ​ $ 11.2 ​ $ — ​ $ 563.4 Services transferred over time ​ ​ 39.8 ​ ​ 57.8 ​ ​ 5.6 ​ ​ 6.9 ​ ​ 1.9 ​ ​ — ​ ​ 112.0 ​ ​ $ 266.1 ​ $ 330.7 ​ $ 39.6 ​ $ 25.9 ​ $ 13.1 ​ $ — ​ $ 675.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Transaction fees ​ $ 175.2 ​ $ 176.7 ​ $ 25.7 ​ $ 22.4 ​ $ 11.8 ​ $ — ​ $ 411.8 Access and capacity fees ​ ​ 25.1 ​ ​ 19.5 ​ ​ 3.8 ​ ​ 3.6 ​ ​ 1.6 ​ ​ — ​ ​ 53.6 Market data fees ​ ​ 10.6 ​ ​ 32.0 ​ ​ 1.7 ​ ​ 3.1 ​ ​ 0.2 ​ ​ — ​ ​ 47.6 Regulatory fees ​ ​ 12.6 ​ ​ 42.6 ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ 55.2 Other revenue ​ ​ 5.1 ​ ​ 1.1 ​ ​ — ​ ​ 1.5 ​ ​ — ​ ​ — ​ ​ 7.7 ​ ​ $ 228.6 ​ $ 271.9 ​ $ 31.2 ​ $ 30.6 ​ $ 13.6 ​ $ — ​ $ 575.9 Timing of revenue recognition ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Services transferred at a point in time ​ $ 192.9 ​ $ 220.4 ​ $ 25.7 ​ $ 23.9 ​ $ 11.8 ​ $ — ​ $ 474.7 Services transferred over time ​ ​ 35.7 ​ ​ 51.5 ​ ​ 5.5 ​ ​ 6.7 ​ ​ 1.8 ​ ​ — ​ ​ 101.2 ​ ​ $ 228.6 ​ $ 271.9 ​ $ 31.2 ​ $ 30.6 ​ $ 13.6 ​ $ — ​ $ 575.9 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate ​ ​ ​ ​ ​ ​ ​ U.S. ​ ​ ​ ​ European ​ Global ​ Items and ​ ​ ​ ​ ​ Options ​ Equities ​ Futures ​ Equities ​ FX ​ Eliminations ​ Total Nine Months Ended September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Transaction fees ​ $ 565.7 ​ $ 580.3 ​ $ 84.1 ​ $ 57.5 ​ $ 34.4 ​ $ — ​ $ 1,322.0 Access and capacity fees ​ ​ 77.6 ​ ​ 58.7 ​ ​ 11.5 ​ ​ 11.8 ​ ​ 5.0 ​ ​ — ​ ​ 164.6 Market data fees ​ ​ 41.5 ​ ​ 103.4 ​ ​ 4.9 ​ ​ 9.4 ​ ​ 0.5 ​ ​ — ​ ​ 159.7 Regulatory fees ​ ​ 47.1 ​ ​ 178.9 ​ ​ 0.5 ​ ​ — ​ ​ — ​ ​ — ​ ​ 226.5 Other revenue ​ ​ 11.3 ​ ​ 3.9 ​ ​ 2.9 ​ ​ 6.2 ​ ​ 0.2 ​ ​ 0.2 ​ ​ 24.7 ​ ​ $ 743.2 ​ $ 925.2 ​ $ 103.9 ​ $ 84.9 ​ $ 40.1 ​ $ 0.2 ​ $ 1,897.5 Timing of revenue recognition ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Services transferred at a point in time ​ $ 624.1 ​ $ 763.1 ​ $ 87.5 ​ $ 63.7 ​ $ 34.6 ​ $ 0.2 ​ $ 1,573.2 Services transferred over time ​ ​ 119.1 ​ ​ 162.1 ​ ​ 16.4 ​ ​ 21.2 ​ ​ 5.5 ​ ​ — ​ ​ 324.3 ​ ​ $ 743.2 ​ $ 925.2 ​ $ 103.9 ​ $ 84.9 ​ $ 40.1 ​ $ 0.2 ​ $ 1,897.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Nine Months Ended September 30, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Transaction fees ​ $ 600.0 ​ $ 622.4 ​ $ 91.4 ​ $ 72.3 ​ $ 37.6 ​ $ — ​ $ 1,423.7 Access and capacity fees ​ ​ 73.1 ​ ​ 56.3 ​ ​ 11.3 ​ ​ 11.0 ​ ​ 4.7 ​ ​ — ​ ​ 156.4 Market data fees ​ ​ 32.0 ​ ​ 107.1 ​ ​ 4.9 ​ ​ 9.9 ​ ​ 0.4 ​ ​ — ​ ​ 154.3 Regulatory fees ​ ​ 45.9 ​ ​ 214.8 ​ ​ 0.1 ​ ​ — ​ ​ — ​ ​ — ​ ​ 260.8 Other revenue ​ ​ 15.8 ​ ​ 5.0 ​ ​ — ​ ​ 4.7 ​ ​ — ​ ​ 0.4 ​ ​ 25.9 ​ ​ $ 766.8 ​ $ 1,005.6 ​ $ 107.7 ​ $ 97.9 ​ $ 42.7 ​ $ 0.4 ​ $ 2,021.1 Timing of revenue recognition ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Services transferred at a point in time ​ $ 661.7 ​ $ 842.2 ​ $ 91.5 ​ $ 77.0 ​ $ 37.6 ​ $ 0.4 ​ $ 1,710.4 Services transferred over time ​ ​ 105.1 ​ ​ 163.4 ​ ​ 16.2 ​ ​ 20.9 ​ ​ 5.1 ​ ​ — ​ ​ 310.7 ​ ​ $ 766.8 ​ $ 1,005.6 ​ $ 107.7 ​ $ 97.9 ​ $ 42.7 ​ $ 0.4 ​ $ 2,021.1
Schedule of revenue recognized from contract liabilities and the remaining balance	The revenue recognized from contract liabilities and the remaining balance is shown below (in millions):

SEVERANCE (Tables)

SEVERANCE (Tables)	9 Months Ended
	Sep. 30, 2019
SEVERANCE
Summary of employee termination benefits recognized	The following is a summary of the employee termination benefits recognized within acquisition costs in the condensed consolidated statements of income (in millions): ​ ​ ​ ​ ​ Employee Termination Benefits Balance at December 31, 2018 ​ $ 6.1 Termination benefits accrual adjustment ​ 7.0 Termination payments made ​ (2.9) Balance at September 30, 2019 ​ $ 10.2

INVESTMENTS (Tables)

INVESTMENTS (Tables)	9 Months Ended
	Sep. 30, 2019
INVESTMENTS
Schedule of investments	As of September 30, 2019 and December 31, 2018, the Company’s investments were comprised of the following (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2019 2018 Equity Method Investments: ​ ​ ​ ​ ​ ​ Investment in Signal Trading Systems, LLC ​ $ 13.3 ​ $ 12.4 Investment in EuroCCP ​ 9.4 ​ 9.3 Total equity method investments ​ ​ 22.7 ​ ​ 21.7 ​ ​ ​ ​ ​ ​ ​ Cost Method Investments: ​ ​ ​ ​ ​ ​ Investment in OCC ​ ​ 8.3 ​ ​ 30.3 Investment in Eris Exchange Holdings, LLC ​ ​ 20.8 ​ ​ 20.0 Investment in American Financial Exchange, LLC ​ ​ 8.6 ​ ​ 5.9 Investment in Cboe Vest Financial Group, Inc. ​ ​ 2.9 ​ ​ — Other cost method investments ​ 6.4 ​ 8.3 Total cost method investments ​ ​ 47.0 ​ ​ 64.5 ​ ​ ​ ​ ​ ​ ​ Total investments ​ $ 69.7 ​ $ 86.2

FINANCIAL INVESTMENTS (Tables)

FINANCIAL INVESTMENTS (Tables)	9 Months Ended
	Sep. 30, 2019
INVESTMENTS
Schedule of Financial Investments	The Company’s financial investments are summarized as follows (in millions):

PROPERTY AND EQUIPMENT, NET (Ta

PROPERTY AND EQUIPMENT, NET (Tables)	9 Months Ended
	Sep. 30, 2019
PROPERTY AND EQUIPMENT, NET
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2019 2018 Construction in progress ​ $ — ​ $ 0.1 Building ​ ​ — ​ ​ 81.7 Furniture and equipment ​ 172.6 ​ 161.6 Total property and equipment ​ 172.6 ​ 243.4 Less accumulated depreciation ​ (123.6) ​ (171.7) Property and equipment, net ​ $ 49.0 ​ $ 71.7

OTHER ASSETS, NET (Tables)

OTHER ASSETS, NET (Tables)	9 Months Ended
	Sep. 30, 2019
OTHER ASSETS, NET
Schedule of Other Assets, Net	Other assets, net consisted of the following as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2019 2018 Software development work in progress ​ $ 1.2 ​ $ 8.7 Data processing software ​ ​ 235.8 ​ ​ 219.0 Less accumulated depreciation and amortization ​ (203.8) ​ (193.2) Data processing software, net ​ 33.2 ​ 34.5 Other assets (1) ​ ​ 41.5 ​ ​ 28.4 Data processing software and other assets, net ​ $ 74.7 ​ $ 62.9 (1) At September 30, 2019 and December 31, 2018, the majority of the balance included long-term prepaid assets and notes receivable. The notes receivable included within other assets, net on the condensed consolidated balance sheets relate to the consolidated audit trail NMS plan (“CAT”), which involves the creation of a comprehensive audit trail of orders that enhances the ability to efficiently and accurately track all activity in Regulation NMS securities in the U.S. markets. While the funding of the CAT is ultimately expected to be provided by both the execution venues (which includes the Exchanges) and industry members, until the SEC approves a final funding model, the funding to date has solely been provided by the execution venues. The funding by the execution venues has been done in exchange for promissory notes, which are expected to be repaid once such industry member fees are collected. Until the SEC approves a funding model that shares the cost of the CAT between the execution venues and industry members, the execution venues may continue to incur additional significant costs. Due to circumstances associated with the development of the CAT, the Company believes a loss associated with the uncollectibility of the notes is probable, but is unable to estimate the amount of the loss as of September 30, 2019. As of September 30, 2019 and December 31, 2018, the notes receivable balance was $28.7 million and $20.3 million, respectively. ​

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS, NET (Tables)	9 Months Ended
	Sep. 30, 2019
GOODWILL AND INTANGIBLE ASSETS, NET
Schedule of goodwill details by segment	The following table presents the details of goodwill by segment (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. ​ European ​ ​ ​ ​ Corporate ​ ​ ​ ​ Options Equities Equities Global FX and Other Total Balance as of December 31, 2018 ​ $ 239.4 ​ $ 1,740.4 ​ $ 425.6 ​ $ 267.2 ​ $ 18.8 ​ $ 2,691.4 Additions ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ — Dispositions ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (8.3) ​ ​ (8.3) Impairment ​ ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ (10.5) ​ ​ (10.5) Changes in foreign currency exchange rates ​ — ​ — ​ (9.2) ​ — ​ — ​ (9.2) Balance as of September 30, 2019 ​ $ 239.4 ​ $ 1,740.4 ​ $ 416.4 ​ $ 267.2 ​ $ — ​ $ 2,663.4
Schedule of details of intangible assets	The following table presents the details of the intangible assets (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. ​ European ​ ​ ​ ​ Corporate ​ ​ ​ ​ Options Equities Equities Global FX and Other Total Balance as of December 31, 2018 ​ $ 181.9 ​ $ 990.3 ​ $ 376.9 ​ $ 166.9 ​ $ 4.2 ​ $ 1,720.2 Additions ​ ​ — ​ — ​ — ​ — ​ — ​ ​ — Dispositions ​ — ​ — ​ — ​ — ​ (3.3) ​ (3.3) Amortization ​ (11.6) ​ (52.2) ​ (18.7) ​ ​ (21.7) ​ (0.9) ​ (105.1) Changes in foreign currency exchange rates ​ — ​ — ​ (13.2) ​ — ​ — ​ (13.2) Balance as of September 30, 2019 ​ $ 170.3 ​ $ 938.1 ​ $ 345.0 ​ $ 145.2 ​ $ — ​ $ 1,598.6
Schedule of categories of intangible assets	The following tables present the categories of intangible assets as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ September 30, 2019 ​ Average ​ ​ ​ ​ U.S. ​ European ​ ​ ​ ​ Corporate ​ Amortization ​ Options Equities Equities Global FX and Other Period (in years) Trading registrations and licenses ​ $ 95.5 ​ $ 572.7 ​ $ 169.9 ​ $ — ​ $ — ​ Indefinite Customer relationships ​ 38.8 ​ 222.9 ​ 158.2 ​ 140.0 ​ — ​ 17 Market data customer relationships ​ 53.6 ​ 322.0 ​ 59.4 ​ 64.4 ​ — ​ 12 Technology ​ 24.8 ​ 22.5 ​ 22.3 ​ 22.5 ​ — ​ 4 Trademarks and tradenames ​ 1.7 ​ 6.0 ​ 1.8 ​ 1.2 ​ — ​ 6 Accumulated amortization ​ (44.1) ​ (208.0) ​ (66.6) ​ (82.9) ​ — ​ ​ ​ ​ $ 170.3 ​ $ 938.1 ​ $ 345.0 ​ $ 145.2 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ December 31, 2018 ​ Average ​ ​ ​ ​ U.S. ​ European ​ ​ ​ ​ Corporate ​ Amortization ​ Options Equities Equities Global FX and Other Period (in years) Trading registrations and licenses ​ $ 95.5 ​ $ 572.7 ​ $ 176.0 ​ $ — ​ $ — ​ Indefinite Customer relationships ​ 38.8 ​ 222.9 ​ 163.9 ​ 140.0 ​ 3.0 ​ 18 Market data customer relationships ​ 53.6 ​ 322.0 ​ 61.5 ​ 64.4 ​ — ​ 13 Technology ​ 24.8 ​ 22.5 ​ 23.1 ​ 22.5 ​ 4.0 ​ 5 Trademarks and tradenames ​ 1.7 ​ 6.0 ​ 1.8 ​ 1.2 ​ 1.0 ​ 2 Accumulated amortization ​ (32.5) ​ (155.8) ​ (49.4) ​ (61.2) ​ (3.8) ​ ​ ​ ​ $ 181.9 ​ $ 990.3 ​ $ 376.9 ​ $ 166.9 ​ $ 4.2 ​ ​

ACCOUNTS PAYABLE AND ACCRUED _2

ACCOUNTS PAYABLE AND ACCRUED LIABILITIES (Tables)	9 Months Ended
	Sep. 30, 2019
ACCOUNTS PAYABLE AND ACCRUED LIABILITIES
Schedule of Accounts Payable and Accrued Liabilities	Accounts payable and accrued liabilities consisted of the following as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 December 31, 2018 Compensation and benefit-related liabilities ​ $ 26.0 ​ $ 52.4 Termination benefits ​ ​ 10.2 ​ ​ 6.1 Royalties ​ ​ 20.4 ​ ​ 25.0 Accrued liabilities ​ 82.8 ​ ​ 91.8 Marketing fee payable ​ 9.5 ​ ​ 10.4 Accounts payable ​ 10.3 ​ ​ 12.8 Total accounts payable and accrued liabilities ​ $ 159.2 ​ $ 198.5

DEBT (Tables)

DEBT (Tables)	9 Months Ended
	Sep. 30, 2019
DEBT
Schedule of debt	The Company’s debt consisted of the following as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 December 31, 2018 $300 million Term Loan Agreement due December 2021, floating rate ​ $ 222.0 ​ $ 271.1 $650 million fixed rate Senior Notes due January 2027, stated rate of 3.650% ​ 645.1 ​ 644.5 $300 million fixed rate Senior Notes due June 2019, stated rate of 1.950% ​ ​ — ​ ​ 299.8 Revolving Credit Agreement ​ ​ — ​ ​ — Total debt ​ $ 867.1 ​ $ 1,215.4
Schedule of maturities of long-term debt	The future expected loan repayments related to the Term Loan Agreement and the Senior Notes as of September 30, 2019 are as follows (in millions): ​ ​ ​ ​ 2019 $ — 2020 ​ ​ — 2021 ​ ​ 225.0 2022 ​ ​ — 2023 ​ ​ — Thereafter ​ ​ 650.0 Principal amounts repayable ​ ​ 875.0 Debt issuance cost ​ ​ (3.7) Unamortized discounts on notes ​ ​ (4.2) Total debt outstanding ​ $ 867.1
Schedule of interest expense	Interest expense recognized on the Term Loan Agreement and the Senior Notes is included in interest expense, net in the condensed consolidated statements of income, for the three and nine months ended September 30, 2019 and 2018 is as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ September 30, ​ September 30, ​ 2019 2018 2019 2018 Components of interest expense: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contractual interest ​ $ 8.3 ​ $ 10.0 ​ $ 28.0 ​ $ 29.1 Amortization of debt discount ​ 0.2 ​ 0.5 ​ 0.5 ​ 1.3 Amortization of debt issuance costs ​ 0.3 ​ 0.2 ​ 1.2 ​ 0.5 Interest expense ​ $ 8.8 ​ $ 10.7 ​ ​ 29.7 ​ ​ 30.9 Interest income ​ ​ (0.6) ​ ​ (1.1) ​ ​ (1.6) ​ ​ (2.4) Interest expense, net ​ $ 8.2 ​ $ 9.6 ​ $ 28.1 ​ $ 28.5

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME, NET (Tables)	9 Months Ended
	Sep. 30, 2019
ACCUMULATED OTHER COMPREHENSIVE INCOME, NET
Schedule of Accumulated Other Comprehensive Income, Net	The following represents the changes in accumulated other comprehensive income (loss) by component (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Foreign ​ ​ ​ ​ ​ ​ ​ Total Accumulated ​ ​ Currency Unrealized ​ ​ ​ Other ​ ​ Translation Investment ​ Post-Retirement ​ Comprehensive ​ Adjustment Gain (Loss) Benefits Income (Loss) Balance at December 31, 2018 ​ $ 12.1 ​ $ 0.2 ​ $ (0.8) ​ $ 11.5 Other comprehensive loss ​ (20.6) ​ ​ — ​ ​ — ​ ​ (20.6) Balance at September 30, 2019 ​ $ (8.5) ​ $ 0.2 ​ $ (0.8) ​ $ (9.1)

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Sep. 30, 2019
FAIR VALUE MEASUREMENTS
Schedule of fair value hierarchy for assets measured at fair value on a recurring basis	The following tables present the Company’s fair value hierarchy for those assets and liabilities measured at fair value on a recurring basis as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury securities ​ $ 0.5 ​ $ 0.5 ​ $ — ​ $ — Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Mutual funds ​ ​ 14.9 ​ ​ 14.9 ​ ​ — ​ ​ — Money market funds ​ 6.0 ​ 6.0 ​ — ​ — Total assets ​ $ 21.4 ​ $ 21.4 ​ $ — ​ $ — Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration liability to related party ​ $ 6.3 ​ $ — ​ $ — ​ $ 6.3 Total Liabilities ​ $ 6.3 ​ $ — ​ $ — ​ $ 6.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury securities ​ $ 35.7 ​ $ 35.7 ​ $ — ​ $ — Total assets ​ $ 35.7 ​ $ 35.7 ​ $ — ​ $ — Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration liability to related party ​ $ 3.9 ​ $ — ​ $ — ​ $ 3.9 Total Liabilities ​ $ 3.9 ​ $ — ​ $ — ​ $ 3.9
Schedule of fair value hierarchy of financial instruments held	The following table presents the Company’s fair value hierarchy for certain assets and liabilities held by the Company as of September 30, 2019 and December 31, 2018 (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2019 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury securities ​ $ 0.5 ​ $ 0.5 ​ $ — ​ $ — Deferred compensation plan assets ​ ​ 20.9 ​ ​ 20.9 ​ ​ — ​ ​ — Total assets ​ $ 21.4 ​ $ 21.4 ​ $ — ​ $ — Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration liability to related party ​ $ 6.3 ​ $ — ​ $ — ​ $ 6.3 Deferred compensation plan liabilities ​ ​ 20.9 ​ ​ 20.9 ​ ​ — ​ ​ — Debt ​ 867.1 ​ — ​ 867.1 ​ — Total liabilities ​ $ 894.3 ​ $ 20.9 ​ $ 867.1 ​ $ 6.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2018 ​ Total Level 1 Level 2 Level 3 Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury securities ​ $ 35.7 ​ $ 35.7 ​ $ — ​ $ — Total assets ​ $ 35.7 ​ $ 35.7 ​ $ — ​ $ — Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration liability to related party ​ $ 3.9 ​ $ — ​ $ — ​ $ 3.9 Debt ​ 1,215.4 ​ — ​ 1,215.4 ​ — Total liabilities ​ $ 1,219.3 ​ $ — ​ $ 1,215.4 ​ $ 3.9
Summary of changes in the fair value of level 3 financial liabilities	The following table sets forth a summary of changes in the fair value of the Company’s Level 3 financial liabilities during the nine months ended September 30, 2019. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Level 3 Financial Liabilities for the Nine Months Ended September 30, 2019 ​ ​ Balance at ​ Realized (gains) ​ ​ ​ ​ ​ ​ ​ ​ ​ Beginning of ​ losses during ​ ​ ​ ​ ​ Balance at ​ Period ​ period ​ Additions Settlements End of Period Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration liability to related party $ 3.9 ​ $ 2.4 ​ $ — $ — $ 6.3 Total Liabilities ​ $ 3.9 ​ $ 2.4 ​ $ — ​ $ — ​ $ 6.3

REDEEMABLE NONCONTROLLING INT_2

REDEEMABLE NONCONTROLLING INTEREST (Tables)	9 Months Ended
	Sep. 30, 2019
REDEEMABLE NONCONTROLLING INTEREST
Schedule of Redeemable Noncontrolling Interest	For the nine months ended September 30, 2019, the following reflects changes in our redeemable noncontrolling interest (in millions): ​ ​ ​ ​ ​ Redeemable Balance as of December 31, 2018 ​ $ 9.4 Net loss attributable to redeemable noncontrolling interest ​ (4.1) Redemption value adjustment of redeemable noncontrolling interest ​ 0.5 Deconsolidation of former subsidiary with noncontrolling interest ​ ​ (5.8) Balance as of September 30, 2019 ​ $ —

SEGMENT REPORTING (Tables)

SEGMENT REPORTING (Tables)	9 Months Ended
	Sep. 30, 2019
SEGMENT REPORTING
Summarized Financial Information by Reportable Segment	​ Summarized financial data of reportable segments was as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ European ​ ​ ​ ​ Items and ​ ​ ​ ​ Options U.S. Equities Futures Equities Global FX Eliminations Total Three Months Ended September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 266.1 ​ $ 330.7 ​ $ 39.6 ​ $ 25.9 ​ $ 13.1 ​ $ — ​ $ 675.4 Operating income (loss) ​ 85.4 ​ ​ 36.4 ​ ​ 26.2 ​ ​ 4.8 ​ ​ (1.3) ​ ​ (4.1) ​ ​ 147.4 Three Months Ended September 30, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 228.6 ​ $ 271.9 ​ $ 31.2 ​ $ 30.6 ​ $ 13.6 ​ $ — ​ $ 575.9 Operating income (loss) ​ 82.1 ​ ​ 30.6 ​ ​ 20.6 ​ ​ 5.4 ​ ​ (1.9) ​ ​ (10.7) ​ ​ 126.1 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ European ​ ​ ​ ​ Items and ​ ​ ​ ​ Options U.S. Equities Futures Equities Global FX Eliminations Total Nine Months Ended September 30, 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 743.2 ​ $ 925.2 ​ $ 103.9 ​ $ 84.9 ​ $ 40.1 ​ $ 0.2 ​ $ 1,897.5 Operating income (loss) ​ ​ 252.5 ​ ​ 110.4 ​ ​ 63.9 ​ ​ 16.3 ​ ​ (3.3) ​ ​ (21.8) ​ ​ 418.0 Nine Months Ended September 30, 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Revenues ​ $ 766.8 ​ $ 1,005.6 ​ $ 107.7 ​ $ 97.9 ​ $ 42.7 ​ $ 0.4 ​ $ 2,021.1 Operating income (loss) ​ ​ 273.8 ​ ​ 101.9 ​ ​ 63.1 ​ ​ 18.1 ​ ​ (6.6) ​ ​ (27.4) ​ ​ 422.9 ​

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	9 Months Ended
	Sep. 30, 2019
STOCK-BASED COMPENSATION
Summary of stock option activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ Weighted ​ Average ​ ​ ​ ​ ​ ​ ​ Average ​ Remaining ​ Aggregate ​ ​ Number of ​ Exercise ​ Contractual ​ Intrinsic Value ​ Shares Price Term (years) (in millions) Outstanding and exercisable, December 31, 2018 369,483 ​ $ 26.40 ​ ​ ​ ​ ​ Exercised 348,469 ​ 26.77 ​ ​ ​ ​ ​ Outstanding and exercisable, September 30, 2019 ​ 21,014 ​ $ 20.24 ​ 0.5 ​ $ 2.0
Summary of restricted stock activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Number of ​ Average Grant ​ Shares Date Fair Value Nonvested stock at December 31, 2018 631,764 ​ $ 85.85 Granted 213,527 ​ ​ 94.92 Vested (274,774) ​ ​ 83.56 Forfeited (92,854) ​ ​ 84.95 Nonvested stock at September 30, 2019 477,663 ​ $ 86.06
Summary of performance-based restricted stock unit	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ Number of ​ Average Grant ​ Shares Date Fair Value Nonvested stock at December 31, 2018 151,842 ​ $ 100.81 Granted 86,134 ​ ​ 88.22 Vested (69,372) ​ ​ 74.56 Forfeited (36,356) ​ ​ 97.78 Nonvested stock at September 30, 2019 132,248 ​ $ 107.21

NET INCOME PER COMMON SHARE (Ta

NET INCOME PER COMMON SHARE (Tables)	9 Months Ended
	Sep. 30, 2019
Net Income Per Common Share
Reconciliation of basic and diluted net income per common share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, (in millions, except per share amounts) 2019 2018 2019 2018 Basic EPS Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Income ​ $ 105.9 ​ $ 85.7 ​ $ 284.5 ​ $ 286.8 Loss attributable to noncontrolling interest ​ ​ 0.1 ​ ​ 0.3 ​ ​ 4.1 ​ ​ 0.9 Net Income excluding noncontrolling interest ​ 106.0 ​ 86.0 ​ 288.6 ​ 287.7 Change in redemption value of noncontrolling interest ​ ​ (0.1) ​ ​ (0.3) ​ ​ (0.5) ​ ​ (0.9) Earnings allocated to participating securities ​ (0.4) ​ (0.7) ​ (1.5) ​ (2.1) Net Income allocated to common stockholders ​ $ 105.5 ​ $ 85.0 ​ $ 286.6 ​ $ 284.7 Basic EPS Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding ​ ​ 111.6 ​ ​ 111.4 ​ ​ 111.6 ​ ​ 112.0 Basic Net Income Per Common Share ​ $ 0.95 ​ $ 0.76 ​ $ 2.57 ​ $ 2.54 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted EPS Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net Income ​ $ 105.9 ​ $ 85.7 ​ $ 284.5 ​ $ 286.8 Loss attributable to noncontrolling interest ​ ​ 0.1 ​ ​ 0.3 ​ ​ 4.1 ​ ​ 0.9 Net Income excluding noncontrolling interest ​ 106.0 ​ 86.0 ​ 288.6 ​ 287.7 Change in redemption value of noncontrolling interest ​ ​ (0.1) ​ ​ (0.3) ​ ​ (0.5) ​ ​ (0.9) Earnings allocated to participating securities ​ (0.4) ​ (0.7) ​ (1.5) ​ (2.1) Net Income allocated to common stockholders ​ $ 105.5 ​ $ 85.0 ​ $ 286.6 ​ $ 284.7 Diluted EPS Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding ​ ​ 111.6 ​ ​ 111.4 ​ ​ 111.6 ​ ​ 112.0 Dilutive common shares issued under stock program ​ ​ 0.3 ​ ​ 0.4 ​ ​ 0.4 ​ ​ 0.4 Total dilutive weighted average shares ​ ​ 111.9 ​ ​ 111.8 ​ ​ 112.0 ​ ​ 112.4 Diluted Net Income Per Common Share ​ $ 0.94 ​ $ 0.76 ​ $ 2.56 ​ $ 2.53

LEASES (Tables)

LEASES (Tables)	9 Months Ended
	Sep. 30, 2019
LEASES.
Schedule of supplemental balance sheet	The following table presents the supplemental balance sheet information related to leases for the quarter ended September 30, 2019 (in millions): ​ ​ ​ ​ September 30, ​ 2019 Operating lease right of use assets $ 53.4 Total leased assets $ 53.4 ​ ​ Accrued liabilities $ 8.8 Non-current operating lease liabilities ​ 47.4 Total leased liabilities $ 56.2
Schedule of lease cost and other information	The following table presents operating lease costs and other information as of and for the three and nine months ended September 30, 2019 (in millions, except as stated): ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, Nine Months Ended September 30, ​ 2019 2019 Operating lease costs (1) $ 3.4 ​ $ 8.8 ​ ​ ​ ​ ​ ​ ​ ​ Lease term and discount rate information: ​ ​ ​ ​ ​ ​ Weighted average remaining lease term (years) ​ ​ ​ ​ 9.4 ​ Weighted average discount rate ​ ​ ​ ​ 3.5 % ​ ​ ​ ​ ​ ​ ​ Supplemental cash flow information and non-cash activity: ​ ​ ​ ​ ​ ​ Cash paid for amounts included in the measurement of lease liabilities ​ ​ ​ $ 7.5 ​ Right-of-use assets obtained in exchange for lease liabilities ​ ​ ​ ​ 21.0 ​ (1) Includes short-term leases and variable lease costs, which are immaterial.
Schedule of maturities of lease liabilities	The maturities of the lease liabilities are as follows as of September 30, 2019 (in millions): ​ ​ ​ ​ ​ ​ September 30, ​ 2019 Remainder of 2019 ​ $ 2.8 2020 ​ ​ 10.0 2021 ​ ​ 9.6 2022 ​ ​ 8.9 2023 ​ ​ 7.6 After 2023 (1) ​ 27.8 Total lease payments ​ $ 66.7 Less: Interest ​ ​ (10.5) Present value of lease liabilities ​ $ 56.2 (1) Total lease payments include $ 20.4 million related to options to extend lease terms that are reasonably certain of being exercised and exclude $115.9 million of legally binding lease payments for leases signed but will commence after September 30, 2019.

ORGANIZATION AND BASIS OF PRE_3

ORGANIZATION AND BASIS OF PRESENTATION - Segment information (Details)	9 Months Ended
	Sep. 30, 2019segment
ORGANIZATION AND BASIS OF PRESENTATION
Number of reportable segments	5

REVENUE RECOGNITION - Schedule

REVENUE RECOGNITION - Schedule of revenue by product line and Segment (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)item	Sep. 30, 2018USD ($)
Segment Reporting Information
Number of types of regulatory fees the Company recognizes | item			2
Revenues	$ 675.4	$ 575.9	$ 1,897.5	$ 2,021.1
Services transferred at a point in time
Segment Reporting Information
Revenues	563.4	474.7	1,573.2	1,710.4
Services transferred over time
Segment Reporting Information
Revenues	112	101.2	324.3	310.7
Corporate Items and Eliminations
Segment Reporting Information
Revenues			0.2	0.4
Corporate Items and Eliminations | Services transferred at a point in time
Segment Reporting Information
Revenues			0.2	0.4
Options
Segment Reporting Information
Revenues	266.1	228.6	743.2	766.8
Options | Operating Segments
Segment Reporting Information
Revenues	266.1	228.6	743.2	766.8
Options | Operating Segments | Services transferred at a point in time
Segment Reporting Information
Revenues	226.3	192.9	624.1	661.7
Options | Operating Segments | Services transferred over time
Segment Reporting Information
Revenues	39.8	35.7	119.1	105.1
U.S. Equities
Segment Reporting Information
Revenues	330.7	271.9	925.2	1,005.6
U.S. Equities | Operating Segments
Segment Reporting Information
Revenues	330.7	271.9	925.2	1,005.6
U.S. Equities | Operating Segments | Services transferred at a point in time
Segment Reporting Information
Revenues	272.9	220.4	763.1	842.2
U.S. Equities | Operating Segments | Services transferred over time
Segment Reporting Information
Revenues	57.8	51.5	162.1	163.4
Futures
Segment Reporting Information
Revenues	39.6	31.2	103.9	107.7
Futures | Operating Segments
Segment Reporting Information
Revenues	39.6	31.2	103.9	107.7
Futures | Operating Segments | Services transferred at a point in time
Segment Reporting Information
Revenues	34	25.7	87.5	91.5
Futures | Operating Segments | Services transferred over time
Segment Reporting Information
Revenues	5.6	5.5	16.4	16.2
European Equities
Segment Reporting Information
Revenues	25.9	30.6	84.9	97.9
European Equities | Operating Segments
Segment Reporting Information
Revenues	25.9	30.6	84.9	97.9
European Equities | Operating Segments | Services transferred at a point in time
Segment Reporting Information
Revenues	19	23.9	63.7	77
European Equities | Operating Segments | Services transferred over time
Segment Reporting Information
Revenues	6.9	6.7	21.2	20.9
Global FX
Segment Reporting Information
Revenues	13.1	13.6	40.1	42.7
Global FX | Operating Segments
Segment Reporting Information
Revenues	13.1	13.6	40.1	42.7
Global FX | Operating Segments | Services transferred at a point in time
Segment Reporting Information
Revenues	11.2	11.8	34.6	37.6
Global FX | Operating Segments | Services transferred over time
Segment Reporting Information
Revenues	1.9	1.8	5.5	5.1
Transaction fees
Segment Reporting Information
Revenues	465.8	411.8	1,322	1,423.7
Transaction fees | Options | Operating Segments
Segment Reporting Information
Revenues	207.1	175.2	565.7	600
Transaction fees | U.S. Equities | Operating Segments
Segment Reporting Information
Revenues	199.4	176.7	580.3	622.4
Transaction fees | Futures | Operating Segments
Segment Reporting Information
Revenues	31.2	25.7	84.1	91.4
Transaction fees | European Equities | Operating Segments
Segment Reporting Information
Revenues	16.9	22.4	57.5	72.3
Transaction fees | Global FX | Operating Segments
Segment Reporting Information
Revenues	11.2	11.8	34.4	37.6
Access and capacity fees
Segment Reporting Information
Revenues	55.7	53.6	164.6	156.4
Access and capacity fees | Options | Operating Segments
Segment Reporting Information
Revenues	26	25.1	77.6	73.1
Access and capacity fees | U.S. Equities | Operating Segments
Segment Reporting Information
Revenues	20.1	19.5	58.7	56.3
Access and capacity fees | Futures | Operating Segments
Segment Reporting Information
Revenues	4	3.8	11.5	11.3
Access and capacity fees | European Equities | Operating Segments
Segment Reporting Information
Revenues	3.9	3.6	11.8	11
Access and capacity fees | Global FX | Operating Segments
Segment Reporting Information
Revenues	1.7	1.6	5	4.7
Market data fees
Segment Reporting Information
Revenues	56.3	47.6	159.7	154.3
Market data fees | Options | Operating Segments
Segment Reporting Information
Revenues	13.8	10.6	41.5	32
Market data fees | U.S. Equities | Operating Segments
Segment Reporting Information
Revenues	37.7	32	103.4	107.1
Market data fees | Futures | Operating Segments
Segment Reporting Information
Revenues	1.6	1.7	4.9	4.9
Market data fees | European Equities | Operating Segments
Segment Reporting Information
Revenues	3	3.1	9.4	9.9
Market data fees | Global FX | Operating Segments
Segment Reporting Information
Revenues	0.2	0.2	0.5	0.4
Regulatory fees
Segment Reporting Information
Revenues	88.1	55.2	226.5	260.8
Regulatory fees | Options | Operating Segments
Segment Reporting Information
Revenues	15.9	12.6	47.1	45.9
Regulatory fees | U.S. Equities | Operating Segments
Segment Reporting Information
Revenues	72.2	42.6	178.9	214.8
Regulatory fees | Futures | Operating Segments
Segment Reporting Information
Revenues			0.5	0.1
Other revenue
Segment Reporting Information
Revenues	9.5	7.7	24.7	25.9
Other revenue | Corporate Items and Eliminations
Segment Reporting Information
Revenues			0.2	0.4
Other revenue | Options | Operating Segments
Segment Reporting Information
Revenues	3.3	5.1	11.3	15.8
Other revenue | U.S. Equities | Operating Segments
Segment Reporting Information
Revenues	1.3	1.1	3.9	5
Other revenue | Futures | Operating Segments
Segment Reporting Information
Revenues	2.8		2.9
Other revenue | European Equities | Operating Segments
Segment Reporting Information
Revenues	$ 2.1	$ 1.5	6.2	$ 4.7
Other revenue | Global FX | Operating Segments
Segment Reporting Information
Revenues			$ 0.2

REVENUE RECOGNITION - Rollforwa

REVENUE RECOGNITION - Rollforward of contract liabilities (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)
Revenue recognized from contract liabilities and remaining balance
Beginning Balance	$ 8.5
Cash Additions	33.8
Revenue Recognition	(34.1)
Ending Balance	8.2
Liquidity provider sliding scale
Revenue recognized from contract liabilities and remaining balance
Cash Additions	9.6
Revenue Recognition	(7.2)
Ending Balance	2.4
Other, net
Revenue recognized from contract liabilities and remaining balance
Beginning Balance	8.5
Cash Additions	24.2
Revenue Recognition	(26.9)
Ending Balance	$ 5.8

ACQUISITIONS (Details)

ACQUISITIONS (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2016	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Acquisitions
Purchase price paid in cash	$ 18.9
Payments to former stockholders	14.9
Payments to newly issued shareholders	$ 4
Ownership interest percentage	60.00%
Acquisition-related costs		$ 16.7	$ 5.9	$ 39.8	$ 23.3
Goodwill Impairment Charge				10.5
Compensation and benefits		49.7	51.8	150	168.1
Stock-based compensation expense				17	29.4
Professional fees		17.5	16.6	52.9	51.9
Lease termination costs		0.3
Vest Financial Group Inc.
Acquisitions
Noncontrolling interest percentage	40.00%
Term of put and call options	5 years
Bats Global Markets, Inc.
Acquisitions
General and administrative expenses				2
Bats Global Markets, Inc.
Acquisitions
Acquisition-related costs		16.7	5.9	39.8	23.3
Goodwill Impairment Charge				10.5
Impairment of Facilities Charges				6.1
Compensation and benefits		12.7	4.8	16.1	17.6
Stock-based compensation expense					2.7
General and administrative expenses		2			0.6
Professional fees		$ 1.7	$ 0.9	3.7	$ 2.2
Lease termination costs				$ 1.4

SEVERANCE (Details)

SEVERANCE (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)
Restructuring Reserve
Beginning balance	$ 6.1
Termination benefits accrued	7
Termination payments made	(2.9)
Ending balance	$ 10.2

INVESTMENTS - Schedule of inves

INVESTMENTS - Schedule of investments (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Schedule of Cost and Equity Method Investments
Equity Method	$ 22.7	$ 21.7
Other Equity Investments	47	64.5
Total Investments	69.7	86.2
Investment in Signal Trading Systems, LLC
Schedule of Cost and Equity Method Investments
Equity Method	13.3	12.4
Investment in EuroCCP
Schedule of Cost and Equity Method Investments
Equity Method	9.4	9.3
Investment in OCC
Schedule of Cost and Equity Method Investments
Other Equity Investments	8.3	30.3
Investment in Eris Exchange Holdings, LLC
Schedule of Cost and Equity Method Investments
Other Equity Investments	20.8	20
Investment in American Financial Exchange, LLC
Schedule of Cost and Equity Method Investments
Other Equity Investments	8.6	5.9
Investment in Cboe Vest Financial Group, Inc.
Schedule of Cost and Equity Method Investments
Other Equity Investments	2.9
Other cost method investments
Schedule of Cost and Equity Method Investments
Other Equity Investments	$ 6.4	$ 8.3

INVESTMENTS - Equity method inv

INVESTMENTS - Equity method investments (Details)	Sep. 30, 2019item
Schedule of Equity Method Investments
Number of central counterparties	3
Investment in EuroCCP | Cboe Europe Equities
Schedule of Equity Method Investments
Ownership percentage	20.00%
Number of other investors	4
Investment in Signal Trading Systems, LLC
Schedule of Equity Method Investments
Ownership percentage	50.00%

INVESTMENTS - Other Equity Inve

INVESTMENTS - Other Equity Investments (Details) - USD ($) $ in Millions	Feb. 13, 2019	Mar. 03, 2015	Feb. 26, 2015	Aug. 31, 2019	Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018
Other Equity Investments
Other Equity Investments					$ 47	$ 47	$ 64.5
Contributions					2.7
Proceeds from reimbursement of tax liability					$ 1.1
Decrease in net assets due to deconsolidation				$ 14.5
Noncontrolling Interest, Decrease from Deconsolidation				5.8
Cost Method				2.9
Interest bearing notes receivable				3.7
Deconsolidation gain or loss				$ 2		(2)
Percentage of additional ownership acquired					5.00%
Payments to Acquire Investments, Total					$ 2.7
Maximum
Other Equity Investments
Ownership percentage				20.00%
Percentage of voting interest				5.00%
Investment in OCC
Other Equity Investments
Other Equity Investments					$ 8.3	$ 8.3	$ 30.3
Percentage of equity securities						20.00%
Contribution requirement			$ 150
Contribution requirement, shareholder cap			$ 40
Customer refunds, percent of pre-tax income exceeding capital requirements			50.00%
Contributions		$ 30.3
Retained portion of contributed capital	$ 8.3
Returned portion of contributed capital	22
Reversal of dividend declared	$ 8.8
Payments to Acquire Investments, Total		$ 30.3

FINANCIAL INVESTMENTS (Details)

FINANCIAL INVESTMENTS (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Financial Investments
Cost basis	$ 21.4	$ 35.7
Total Fair Value	21.4	35.7
U.S. Treasury securities
Available-for-sale:
Cost basis	0.5	35.7
Fair value	0.5	$ 35.7
Other securities
Available-for-sale:
Cost basis	20.9
Fair value	$ 20.9

PROPERTY AND EQUIPMENT, NET (De

PROPERTY AND EQUIPMENT, NET (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Property and Equipment, Net
Total property and equipment	$ 172.6		$ 172.6		$ 243.4
Less accumulated depreciation	(123.6)		(123.6)		(171.7)
Property and equipment, net	49		49		71.7
Depreciation expense	5.9	$ 6.2	18.2	$ 19.2
Property classified as property held for sale	21		21
Impairment charge			6.1
Construction in progress
Property and Equipment, Net
Total property and equipment					0.1
Building
Property and Equipment, Net
Total property and equipment					81.7
Furniture and equipment
Property and Equipment, Net
Total property and equipment	$ 172.6		$ 172.6		$ 161.6

OTHER ASSETS, NET - Schedule of

OTHER ASSETS, NET - Schedule of other assets, net (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Finite-Lived Intangible Assets
Less accumulated depreciation and amortization	$ (203.8)		$ (203.8)		$ (193.2)
Data processing software, net	33.2		33.2		34.5
Other assets	41.5		41.5		28.4
Data processing software and other assets, net	74.7		74.7		62.9
Notes receivable	28.7		28.7		20.3
Amortization	33.4	$ 38.8	105.1	$ 120.6
Software development work in progress
Finite-Lived Intangible Assets
Software	1.2		1.2		8.7
Data processing software
Finite-Lived Intangible Assets
Software	235.8		235.8		$ 219
Amortization	$ 3.6	$ 5.3	$ 10.5	$ 15.1

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS, NET - Goodwill by segment (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2016	Sep. 30, 2019
Goodwill
Balance at beginning of the year		$ 2,691.4
Dispositions		(8.3)
Impairment		(10.5)
Changes in foreign currency exchange rates		(9.2)
Balance at end of the year		2,663.4
Impairment of goodwill		10.5
Options
Goodwill
Balance at beginning of the year		239.4
Balance at end of the year		239.4
U.S. Equities
Goodwill
Balance at beginning of the year		1,740.4
Balance at end of the year		1,740.4
European Equities
Goodwill
Balance at beginning of the year		425.6
Changes in foreign currency exchange rates		(9.2)
Balance at end of the year		416.4
Global FX
Goodwill
Balance at beginning of the year		267.2
Balance at end of the year		267.2
Corporate and Other
Goodwill
Balance at beginning of the year		18.8
Dispositions		(8.3)
Impairment	$ (10.5)	(10.5)
Balance at end of the year		0
Impairment of goodwill	$ 10.5	$ 10.5

GOODWILL AND INTANGIBLE ASSET_4

GOODWILL AND INTANGIBLE ASSETS, NET - Schedule of intangible assets by segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Finite-lived Intangible Assets
Balance at beginning of the year			$ 1,720.2
Dispositions			(3.3)
Amortization	$ (33.4)	$ (38.8)	(105.1)	$ (120.6)
Changes in foreign currency exchange rates			(13.2)
Balance at end of the year	1,598.6		1,598.6
Options
Finite-lived Intangible Assets
Balance at beginning of the year			181.9
Amortization			(11.6)
Balance at end of the year	170.3		170.3
U.S. Equities
Finite-lived Intangible Assets
Balance at beginning of the year			990.3
Amortization			(52.2)
Balance at end of the year	938.1		938.1
European Equities
Finite-lived Intangible Assets
Balance at beginning of the year			376.9
Amortization			(18.7)
Changes in foreign currency exchange rates			(13.2)
Balance at end of the year	345		345
Global FX
Finite-lived Intangible Assets
Balance at beginning of the year			166.9
Amortization			(21.7)
Balance at end of the year	145.2		145.2
Corporate and Other
Finite-lived Intangible Assets
Balance at beginning of the year			4.2
Dispositions			(3.3)
Amortization			(0.9)
Futures
Finite-lived Intangible Assets
Balance at end of the year	$ 0		$ 0

GOODWILL AND INTANGIBLE ASSET_5

GOODWILL AND INTANGIBLE ASSETS, NET - Estimated Future Amortization (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
GOODWILL AND INTANGIBLE ASSETS, NET
Amortization	$ 33.4	$ 38.8	$ 105.1	$ 120.6
Amortization expense
Future amortization expense, remainder of 2019	33.2		33.2
2020	119.9		119.9
2021	105.4		105.4
2022	93		93
2023	82.3		82.3
2024	$ 62.1		$ 62.1

GOODWILL AND INTANGIBLE ASSET_6

GOODWILL AND INTANGIBLE ASSETS, NET - Schedule of intangible assets by category (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets
Intangible assets, net	$ 1,598.6	$ 1,720.2
Customer relationships | Weighted Average
Finite-Lived Intangible Assets
Amortization period (in years)	17 years	18 years
Market data customer relationships | Weighted Average
Finite-Lived Intangible Assets
Amortization period (in years)	12 years	13 years
Technology | Weighted Average
Finite-Lived Intangible Assets
Amortization period (in years)	4 years	5 years
Trademarks and tradenames | Weighted Average
Finite-Lived Intangible Assets
Amortization period (in years)	6 years	2 years
Options
Finite-Lived Intangible Assets
Accumulated amortization	$ (44.1)	$ (32.5)
Intangible assets, net	170.3	181.9
Options | Customer relationships
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	38.8	38.8
Options | Market data customer relationships
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	53.6	53.6
Options | Technology
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	24.8	24.8
Options | Trademarks and tradenames
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	1.7	1.7
Options | Trading registrations and licenses
Finite-Lived Intangible Assets
Indefinite-lived intangible assets, gross	95.5	95.5
U.S. Equities
Finite-Lived Intangible Assets
Accumulated amortization	(208)	(155.8)
Intangible assets, net	938.1	990.3
U.S. Equities | Customer relationships
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	222.9	222.9
U.S. Equities | Market data customer relationships
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	322	322
U.S. Equities | Technology
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	22.5	22.5
U.S. Equities | Trademarks and tradenames
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	6	6
U.S. Equities | Trading registrations and licenses
Finite-Lived Intangible Assets
Indefinite-lived intangible assets, gross	572.7	572.7
European Equities
Finite-Lived Intangible Assets
Accumulated amortization	(66.6)	(49.4)
Intangible assets, net	345	376.9
European Equities | Customer relationships
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	158.2	163.9
European Equities | Market data customer relationships
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	59.4	61.5
European Equities | Technology
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	22.3	23.1
European Equities | Trademarks and tradenames
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	1.8	1.8
European Equities | Trading registrations and licenses
Finite-Lived Intangible Assets
Indefinite-lived intangible assets, gross	169.9	176
Global FX
Finite-Lived Intangible Assets
Accumulated amortization	(82.9)	(61.2)
Intangible assets, net	145.2	166.9
Global FX | Customer relationships
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	140	140
Global FX | Market data customer relationships
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	64.4	64.4
Global FX | Technology
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	22.5	22.5
Global FX | Trademarks and tradenames
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross	$ 1.2	1.2
Corporate and Other
Finite-Lived Intangible Assets
Accumulated amortization		(3.8)
Intangible assets, net		4.2
Corporate and Other | Customer relationships
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross		3
Corporate and Other | Technology
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross		4
Corporate and Other | Trademarks and tradenames
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross		$ 1

ACCOUNTS PAYABLE AND ACCRUED _3

ACCOUNTS PAYABLE AND ACCRUED LIABILITIES - Schedule of accounts payable and accrued liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
ACCOUNTS PAYABLE AND ACCRUED LIABILITIES
Compensation and benefit-related liabilities	$ 26	$ 52.4
Termination benefits	10.2	6.1
Royalties	20.4	25
Accrued liabilities	82.8	91.8
Marketing fee payable	9.5	10.4
Accounts payable	10.3	12.8
Total accounts payable and accrued liabilities	$ 159.2	$ 198.5

DEBT - Schedule of long-term de

DEBT - Schedule of long-term debt (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jun. 28, 2019	Dec. 31, 2018	Mar. 22, 2018	Jun. 29, 2017	Jan. 12, 2017
Debt Instrument
Total debt	$ 867.1		$ 1,215.4
Term Loan Agreement
Debt Instrument
Total debt	222		271.1
Debt instrument face amount	300			$ 300
3.650% Senior Notes
Debt Instrument
Total debt	645.1		644.5
Debt instrument face amount	$ 650					$ 650
Interest rate (as a percent)	3.65%					3.65%
1.950% Senior Notes
Debt Instrument
Total debt			$ 299.8
Debt instrument face amount	$ 300				$ 300
Interest rate (as a percent)	1.95%	1.95%			1.95%
Revolving Credit Agreement
Debt Instrument
Total debt	$ 0

DEBT (Details)

DEBT (Details) $ in Millions	Mar. 22, 2018USD ($)	Dec. 15, 2016USD ($)subsidiary	Sep. 30, 2019USD ($)subsidiary	Sep. 30, 2019USD ($)subsidiary	Sep. 30, 2018USD ($)	Jun. 28, 2019	Dec. 31, 2018USD ($)	Jun. 29, 2017USD ($)	Jan. 12, 2017USD ($)
Debt Instrument
Repayments of outstanding indebtedness				$ 350	$ 325
Proceeds from long-term debt					$ 300
Deferred financing costs			$ 3.7	3.7
Borrowings outstanding			867.1	867.1			$ 1,215.4
Line of Credit
Debt Instrument
Credit facility, maximum borrowing capacity		$ 25
Term Loan Agreement
Debt Instrument
Repayments of outstanding indebtedness			50
Debt instrument face amount	$ 300		$ 300	$ 300
Proceeds from long-term debt	$ 300
Up-front fee (as percent)			0.05	0.05
Minimum consolidated interest ratio				4
Maximum consolidated leverage ratio			3.50	3.50
Borrowings outstanding			$ 222	$ 222			271.1
Term Loan Agreement | LIBOR | Minimum
Debt Instrument
Interest rate margin (as a percent)				1.00%
Term Loan Agreement | LIBOR | Maximum
Debt Instrument
Interest rate margin (as a percent)				1.50%
Term Loan Agreement | Prime Rate | Minimum
Debt Instrument
Interest rate margin (as a percent)				0.00%
Term Loan Agreement | Prime Rate | Maximum
Debt Instrument
Interest rate margin (as a percent)				0.50%
3.650% Senior Notes
Debt Instrument
Debt instrument face amount			$ 650	$ 650					$ 650
Interest rate (as a percent)			3.65%	3.65%					3.65%
Redemption price				101.00%
Borrowings outstanding			$ 645.1	$ 645.1			644.5
Revolving Credit Agreement
Debt Instrument
Credit facility, maximum borrowing capacity		$ 150
Minimum consolidated interest ratio				4
Maximum consolidated leverage ratio			3.50	3.50
Term of facility		5 years
Maximum borrowing capacity, increase limit		$ 100
Maximum borrowing capacity, total with increase		$ 250
Number of subsidiaries designated as additional borrowers | subsidiary			0	0
Borrowings outstanding			$ 0	$ 0
Borrowing capacity available			150	$ 150
Revolving Credit Agreement | Minimum
Debt Instrument
Number of subsidiaries that may be designated as additional borrowers | subsidiary		1
Revolving Credit Agreement | LIBOR | Minimum
Debt Instrument
Interest rate margin (as a percent)				1.00%
Revolving Credit Agreement | LIBOR | Maximum
Debt Instrument
Interest rate margin (as a percent)				1.75%
Revolving Credit Agreement | Prime Rate | Minimum
Debt Instrument
Interest rate margin (as a percent)				0.00%
Revolving Credit Agreement | Prime Rate | Maximum
Debt Instrument
Interest rate margin (as a percent)				0.75%
1.950% Senior Notes
Debt Instrument
Debt instrument face amount			$ 300	$ 300				$ 300
Interest rate (as a percent)			1.95%	1.95%		1.95%		1.95%
Borrowings outstanding							$ 299.8

DEBT - Schedule of debt repayme

DEBT - Schedule of debt repayments (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Long-term Debt
2019	$ 0
2020	0
2021	225
2022	0
2023	0
Thereafter	650
Principal amounts repayable	875
Debt issuance cost	(3.7)
Unamortized discount on notes	(4.2)
Total debt outstanding	$ 867.1	$ 1,215.4

DEBT - Schedule of Interest Exp

DEBT - Schedule of Interest Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
DEBT
Contractual interest	$ 8.3	$ 10	$ 28	$ 29.1
Amortization of debt discount	0.2	0.5	0.5	1.3
Amortization of debt issuance cost.	0.3	0.2	1.2	0.5
Interest expense	8.8	10.7	29.7	30.9
Interest income	(0.6)	(1.1)	(1.6)	(2.4)
Interest expense, net	$ 8.2	$ 9.6	$ 28.1	$ 28.5

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE INCOME, NET (Loss) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019
AOCI Attributable to Parent, Net of Tax
Beginning balance	$ 3,327	$ 3,285.4	$ 3,241	$ 3,149.6	$ 3,175.2	$ 3,110.6	$ 3,241
Other comprehensive income	(17.2)	(18.1)	14.7	(8.4)	(41.3)	24.8
Ending balance	3,328.7	3,327	3,285.4	3,151.9	3,149.6	3,175.2	3,328.7
Accumulated Other Comprehensive Income, net
AOCI Attributable to Parent, Net of Tax
Beginning balance	8.1	26.2	11.5	34.2	75.5	50.7	11.5
Other comprehensive income	(17.2)	(18.1)	14.7	(8.4)	(41.3)	24.8	(20.6)
Ending balance	(9.1)	$ 8.1	26.2	$ 25.8	$ 34.2	$ 75.5	(9.1)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax
Beginning balance			12.1				12.1
Other comprehensive income							(20.6)
Ending balance	(8.5)						(8.5)
Unrealized Investment Gain/Loss
AOCI Attributable to Parent, Net of Tax
Beginning balance			0.2				0.2
Ending balance	0.2						0.2
Post-Retirement Benefits
AOCI Attributable to Parent, Net of Tax
Beginning balance			$ (0.8)				(0.8)
Ending balance	$ (0.8)						$ (0.8)

FAIR VALUE MEASUREMENTS - Sched

FAIR VALUE MEASUREMENTS - Schedule of fair value hierarchy for assets measured at fair value on a recurring basis (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Assets:
Total assets	$ 21.4	$ 35.7
Liabilities:
Contingent consideration liability to related party	6.3	3.9
Total liabilities	894.3	1,219.3
Level 1
Assets:
Total assets	21.4	35.7
Liabilities:
Total liabilities	20.9
Level 2
Liabilities:
Total liabilities	867.1	1,215.4
Level 3
Liabilities:
Contingent consideration liability to related party	6.3	3.9
Total liabilities	6.3	3.9
Recurring
Assets:
Total assets	21.4	35.7
Liabilities:
Contingent consideration liability to related party	6.3	3.9
Total liabilities	6.3	3.9
Recurring | U.S. Treasury securities
Assets:
Total assets	0.5	35.7
Recurring | Marketable securities | Mutual funds
Assets:
Total assets	14.9
Recurring | Marketable securities | Money market funds
Assets:
Total assets	6
Recurring | Level 1
Assets:
Total assets	21.4	35.7
Recurring | Level 1 | U.S. Treasury securities
Assets:
Total assets	0.5	35.7
Recurring | Level 1 | Marketable securities | Mutual funds
Assets:
Total assets	14.9
Recurring | Level 1 | Marketable securities | Money market funds
Assets:
Total assets	6
Recurring | Level 3
Liabilities:
Contingent consideration liability to related party	6.3	3.9
Total liabilities	$ 6.3	$ 3.9

FAIR VALUE MEASUREMENTS - Sch_2

FAIR VALUE MEASUREMENTS - Schedule of fair value hierarchy of financial instruments held (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Assets:
Financial investments	$ 0.5	$ 35.7
Deferred compensation assets	20.9
Total assets	21.4	35.7
Liabilities:
Contingent consideration liability to related party	6.3	3.9
Deferred compensation liabilities	20.9
Debt	867.1	1,215.4
Total liabilities	894.3	1,219.3
Level 1
Assets:
Financial investments	0.5	35.7
Deferred compensation assets	20.9
Total assets	21.4	35.7
Liabilities:
Deferred compensation liabilities	20.9
Total liabilities	20.9
Level 2
Liabilities:
Debt	867.1	1,215.4
Total liabilities	867.1	1,215.4
Level 3
Liabilities:
Contingent consideration liability to related party	6.3	3.9
Total liabilities	$ 6.3	$ 3.9

FAIR VALUE MEASUREMENTS - Narra

FAIR VALUE MEASUREMENTS - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Impairment of goodwill	$ 10.5
Fair value of goodwill	2,663.4	$ 2,691.4
Corporate Items and Eliminations
Segment Reporting Information [Line Items]
Impairment of goodwill	10.5
Fair value of goodwill	$ 0

FAIR VALUE MEASUREMENTS - Summa

FAIR VALUE MEASUREMENTS - Summary of changes in the fair value of the company's Level 3 financial liabilities (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)
Changes in fair value of level 3 financial liabilities
Balance at the beginning of the period	$ 3.9
Realized (gains) losses during period	2.4
Balance at the end of the period	6.3
Contingent consideration liability to related party
Changes in fair value of level 3 financial liabilities
Balance at the beginning of the period	3.9
Realized (gains) losses during period	2.4
Balance at the end of the period	$ 6.3

REDEEMABLE NONCONTROLLING INT_3

REDEEMABLE NONCONTROLLING INTEREST (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019
Increase (Decrease) in Redeemable Noncontrolling Interest
Beginning balance			$ 9.4				$ 9.4
Net loss attributable to redeemable noncontrolling interest				$ 0.3	$ 0.6
Redeemable Noncontrolling Interests
Increase (Decrease) in Redeemable Noncontrolling Interest
Beginning balance			9.4				9.4
Net loss attributable to redeemable noncontrolling interest	$ (0.1)	$ (3.8)	$ (0.2)	$ (0.3)	$ (0.3)	$ (0.3)	(4.1)
Redemption value adjustment of redeemable noncontrolling interest							0.5
Deconsolidation of former subsidiary with noncontrolling interest							$ (5.8)

SEGMENT REPORTING - Summarized

SEGMENT REPORTING - Summarized financial information by reportable segment (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)segment	Sep. 30, 2018USD ($)
Segment Reporting Information
Number of reportable segments | segment			5
Revenues	$ 675.4	$ 575.9	$ 1,897.5	$ 2,021.1
Operating income (loss)	147.4	126.1	418	422.9
Options
Segment Reporting Information
Revenues	266.1	228.6	743.2	766.8
Operating income (loss)	85.4	82.1	252.5	273.8
U.S. Equities
Segment Reporting Information
Revenues	330.7	271.9	925.2	1,005.6
Operating income (loss)	36.4	30.6	110.4	101.9
Futures
Segment Reporting Information
Revenues	39.6	31.2	103.9	107.7
Operating income (loss)	26.2	20.6	63.9	63.1
European Equities
Segment Reporting Information
Revenues	25.9	30.6	84.9	97.9
Operating income (loss)	4.8	5.4	16.3	18.1
Global FX
Segment Reporting Information
Revenues	13.1	13.6	40.1	42.7
Operating income (loss)	(1.3)	(1.9)	(3.3)	(6.6)
Operating Segments | Options
Segment Reporting Information
Revenues	266.1	228.6	743.2	766.8
Operating Segments | U.S. Equities
Segment Reporting Information
Revenues	330.7	271.9	925.2	1,005.6
Operating Segments | Futures
Segment Reporting Information
Revenues	39.6	31.2	103.9	107.7
Operating Segments | European Equities
Segment Reporting Information
Revenues	25.9	30.6	84.9	97.9
Operating Segments | Global FX
Segment Reporting Information
Revenues	13.1	13.6	40.1	42.7
Corporate Items and Eliminations
Segment Reporting Information
Revenues			0.2	0.4
Operating income (loss)	$ (4.1)	$ (10.7)	$ (21.8)	$ (27.4)

EMPLOYEE BENEFITS (Details)

EMPLOYEE BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
SMART Plan
Defined Contribution Plan
Company contribution amount	$ 3.3	$ 2.7	$ 8.5	$ 6.7
Balance amount in the plan			20.9
Cboe Europe Equities Employee Selected Stakeholder Contribution Plan
Defined Contribution Plan
Company contribution amount	$ 0.2	$ 0.3	$ 0.5	$ 0.6

REGULATORY CAPITAL (Details)

REGULATORY CAPITAL (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)
Cboe Trading
Regulatory Requirement
Minimum net capital required to be maintained, option 1 - percentage of aggregate indebtedness items	6.67%
Minimum net capital required to be maintained, option 2 - amount	$ 0.1
Net capital	11.8
Excess net capital	11.4
Required net capital	0.4
Cboe Europe Equities
Regulatory Requirement
Financial resources requirement	20.3
Capital in excess of financial resources requirement	34.2
Cboe Chi-X Europe
Regulatory Requirement
Capital resources requirement	0.1
Capital in excess of capital resources requirement	0.5
Cboe Europe B.V
Regulatory Requirement
Capital in excess of financial resources requirement	2.9
Minimum capital requirement	1.8
Cboe SEF
Regulatory Requirement
Annual operating expenses for swap execution facility capital adequacy tests	0.7
XX month operating expenses for swap execution facility capital adequacy tests	0.4
CFE
Regulatory Requirement
Annual operating expenses for registered futures exchange capital adequacy tests	55.3
XX month operating expenses for registered futures exchange capital adequacy tests	$ 27.7

STOCK-BASED COMPENSATION (Detai

STOCK-BASED COMPENSATION (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award
Stock-based compensation expense	$ 5.3	$ 8.5	$ 17	$ 29.4
Options exercised (in shares)			348,469
Payments for the purchase of shares to satisfy the employee income tax withholdings (in shares)			$ 10.7	15.8
Stock options
Share-based Compensation Arrangement by Share-based Payment Award
Total intrinsic value of stock options exercised			$ 25	$ 4.8
Shares purchased to satisfy the employee income tax withholdings (in shares)			6,323
Payments for the purchase of shares to satisfy the employee income tax withholdings (in shares)			$ 0.6
Restricted Stock and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Shares purchased to satisfy the employee income tax withholdings (in shares)			95,597
Payments for the purchase of shares to satisfy the employee income tax withholdings (in shares)			$ 9.1
Number of shares of common stock of which unit is convertible (in shares)	1		1
Vesting period			3 years
Qualified retirement eligibility age for grants awarded prior to 2017			65 years
Qualified retirement eligibility number of years of service for grants awarded prior to 2017			5 years
Qualified retirement eligibility age for grants awarded in and after 2017			55 years
Qualified retirement eligibility number of years of service for grants awarded in and after 2017			10 years
Vested (in shares)			274,774
Restricted Stock and Restricted Stock Units | Director
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period			1 year
Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Payments for the purchase of shares to satisfy the employee income tax withholdings (in shares)			$ 2.6
Number of shares of common stock of which unit is convertible (in shares)	1		1
Vesting period			3 years
Vested (in shares)			69,372
Risk-free interest rate			2.54%
Volatility time period			3 years
Expected volatility			20.50%
Correlation to S&P 500 Index time period			3 years
Correlation with S&P index			0.29%
Unrecognized compensation expense	$ 25.1		$ 25.1
Unrecognized compensation expense, period for recognition			1 year 7 months 6 days
Performance-Based Restricted Stock Units | Minimum
Share-based Compensation Arrangement by Share-based Payment Award
Units ultimately expected to be awarded			0.00%
Performance-Based Restricted Stock Units | Maximum
Share-based Compensation Arrangement by Share-based Payment Award
Units ultimately expected to be awarded			200.00%
Performance Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award
Shares purchased to satisfy the employee income tax withholdings (in shares)			27,477
Vested (in shares)			69,372

STOCK-BASED COMPENSATION - Stoc

STOCK-BASED COMPENSATION - Stock option activity (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)$ / sharesshares
Number of Shares
Beginning balance (in shares) | shares	369,483
Exercised (in shares) | shares	348,469
Ending balance (in shares) | shares	21,014
Weighted Average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 26.40
Exercised (in dollars per share) | $ / shares	26.77
Ending balance (in dollars per share) | $ / shares	$ 20.24
Weighted Average Remaining Contractual Term (years)
Outstanding	6 months
Aggregate Intrinsic Value (in millions)
Ending balance | $	$ 2

STOCK-BASED COMPENSATION - Rest

STOCK-BASED COMPENSATION - Restricted stock activity (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Employee Stock Purchase Plan
Compensation expense		$ 5,300,000	$ 8,500,000	$ 17,000,000	$ 29,400,000
ESPP
Employee Stock Purchase Plan
Number of shares of common stock made available for purchase to employees	750,000
Maximum percentage of annual salary that an employee is permitted to utilize to purchase stock	10.00%
Maximum number of shares that a participant can purchase during any single offering period	312
Maximum fair market value of stock an employee can purchase under the plan per calendar year	$ 25,000
Compensation expense		$ 200,000		$ 400,000
Shares were reserved for future issuance		722,648		722,648
ESPP | US
Employee Stock Purchase Plan
Exercise price per share of common stock as a percent of fair market value	90.00%
ESPP | International
Employee Stock Purchase Plan
Exercise price per share of common stock as a percent of fair market value	85.00%
Restricted Stock and Restricted Stock Units
Number of shares
Beginning balance (in shares)				631,764
Granted (in shares)				213,527
Vested (in shares)				(274,774)
Forfeited (in shares)				(92,854)
Ending balance (in shares)		477,663		477,663
Weighted average grant date fair value
Beginning balance (in USD per share)				$ 85.85
Granted (in dollars per share)				94.92
Vested (in USD per share)				83.56
Forfeited (in USD per share)				84.95
Ending balance (in USD per share)		$ 86.06		$ 86.06
Performance-Based Restricted Stock Units
Number of shares
Beginning balance (in shares)				151,842
Granted (in shares)				86,134
Vested (in shares)				(69,372)
Forfeited (in shares)				(36,356)
Ending balance (in shares)		132,248		132,248
Weighted average grant date fair value
Beginning balance (in USD per share)				$ 100.81
Granted (in dollars per share)				88.22
Vested (in USD per share)				74.56
Forfeited (in USD per share)				97.78
Ending balance (in USD per share)		$ 107.21		$ 107.21

INCOME TAXES - Reconciliation o

INCOME TAXES - Reconciliation of the statutory federal income tax rate to the effective income tax rate (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
INCOME TAXES
Effective tax rate	24.80%	26.30%	26.50%	27.40%

NET INCOME PER COMMON SHARE (De

NET INCOME PER COMMON SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Basic and Diluted EPS Numerator:
Net income	$ 105.9			$ 85.7			$ 284.5	$ 286.8
Net loss attributable to redeemable noncontrolling interest	0.1			0.3			4.1	0.9
Net income excluding redeemable noncontrolling interest	106	$ 88.3	$ 95.4	86	$ 83.3	$ 118.4	288.6	287.7
Change in redemption value of redeemable noncontrolling interest	(0.1)			(0.3)			(0.5)	(0.9)
Earnings allocated to participating securities	(0.4)			(0.7)			(1.5)	(2.1)
Net income allocated to common stockholders	$ 105.5			$ 85			$ 286.6	$ 284.7
Basic EPS Denominator:
Weighted average shares outstanding (in shares)	111.6			111.4			111.6	112
Basic Net Income Per Common Share (in dollars per share)	$ 0.95			$ 0.76			$ 2.57	$ 2.54
Diluted EPS Denominator:
Weighted average shares outstanding (in shares)	111.6			111.4			111.6	112
Dilutive common shares issued under stock program (in shares)	0.3			0.4			0.4	0.4
Total dilutive weighted average shares (in shares)	111.9			111.8			112	112.4
Diluted Net Income Per Common Share (in dollars per share)	$ 0.94			$ 0.76			$ 2.56	$ 2.53

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details)	Sep. 28, 2018item
VIX Litigation | Pending Litigation
Loss Contingencies
Number of Commodity Exchange Act claims	3

LEASES (Details)

LEASES (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)ft²
Leases
Options to renew	true
Option to terminate	true
Additional right of use assets	$ 0.1
Additional operating lease liabilities	2
Additional operating right of use assets	2
Minimum lease payments	$ 66.7
Old Post Office building in Chicago, Illinois
Leases
Area of office space leased | ft²	185,000
Initial term of lease	187 months
Renewal Term	60 months
Minimum lease payments	$ 98.8
Office Space in Chicago Board of Trade Building
Leases
Area of office space leased | ft²	40,000
Initial term of lease	150 months
Renewal Term	60 months
Minimum lease payments	$ 17.1
Minimum
Leases
Renewal term	1 year
Maximum
Leases
Renewal term	5 years
Option to terminate period	1 year

LEASES - Supplemental Balance S

LEASES - Supplemental Balance Sheet (Details) $ in Millions	Sep. 30, 2019USD ($)
LEASES.
Operating lease right of use assets	$ 53.4
Financial position	us-gaap:OtherAssetsNoncurrent
Current operating leased liabilities	$ 8.8
Financial position	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent
Non-current operating lease liabilities	$ 47.4
Financial position	us-gaap:OperatingLeaseLiabilityNoncurrent
Total lease liabilities	$ 56.2
Financial position	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrent us-gaap:OperatingLeaseLiabilityNoncurrent

LEASES - Lease Cost and Other I

LEASES - Lease Cost and Other Information (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)
LEASES.
Operating lease costs	$ 3.4	$ 8.8
Weighted average remaining lease term (years)	9 years 4 months 24 days	9 years 4 months 24 days
Weighted average discount rate	3.50%	3.50%
Cash paid for amounts included in the measurement of lease liabilities		$ 7.5
Right-of-use assets obtained in exchange for lease liabilities		$ 21

LEASES - Maturities (Details)

LEASES - Maturities (Details) $ in Millions	Sep. 30, 2019USD ($)
Maturities of Lease Liabilities
Remainder of 2019	$ 2.8
2020	10
2021	9.6
2022	8.9
2023	7.6
After 2023	27.8
Total lease payments	66.7
Less: Interest	(10.5)
Present value of lease liabilities	$ 56.2

LEASES - Others (Details)

LEASES - Others (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)
LEASES.
Minimum lease payments related to option to extend term	$ 20.4
Minimum lease payments for leases will commence after March 31, 2019	$ 115.9

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Subsequent Events
Dividends (in dollars per share)		$ 0.31	$ 0.31	$ 0.27	$ 0.27	$ 0.36	$ 0.31
Subsequent Event
Subsequent Events
Dividends (in dollars per share)	$ 0.36
Increase in amount of stock repurchase plan authorized	$ 250