DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2021

Schedule of Concentration of Credit Risk

We derived transaction-based revenues from individual market makers in excess of 10% of total revenues, as follows:


	Year ended December 31,
	2019		2020		2021
Market maker:
Citadel Securities, LLC	29	%	34	%	22	%
Tai Mo Shan Limited(1)	—	%	—	%	15	%
Entities affiliated with Susquehanna International Group, LLP(2)	13	%	18	%	12	%

Entities affiliated with Wolverine Holdings, L.P.(3)	12	%	10	%	10	%
All others individually less than 10%	8	%	13	%	18	%
Total as percentage of total revenue:	62	%	75	%	77	%

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(1)Member of Jump Trading Group

(2)Consists of Global Execution Brokers, LP and G1X Execution Services, LLC

(3)Consists of Wolverine Execution Services, LLC and Wolverine Securities LLC

Schedule Of Property, Software and Equipment

Property, software, and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation and amortization is recorded on a straight-line basis over the useful life of the asset, which is as follows:


Property, Software, and Equipment						Useful Life
Computer equipment						3 years
Fixture and furniture						7 years
Tenant improvements						Shorter of estimated useful life or lease term
Internally developed software						3 years

Property, software, and equipment are presented net of accumulated depreciation and amortization and summarized as follows:


	Year ended December 31,
(in thousands)	2020		2021
Tenant improvements	$	18,945	$	64,313
Internally developed software	16,992		31,142
Computer equipment	9,203		23,731
Furniture and fixtures	8,024		21,927
Construction in progress	9,756		44,343
Total	62,920		185,456
Less: accumulated depreciation and amortization	(17,086)		(39,037)
Property, software, and equipment, net	$	45,834	$	146,419