CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating activities:
Net loss	$ (3,263,165)	$ (5,579)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation and amortization	15,734	6,572
Provision for credit losses	61,796	44,339
Share-based compensation	1,252,584	5,348
Change in fair value of convertible notes and warrant liability	2,045,657	0
Other	(121)	2,343
Changes in operating assets and liabilities:
Segregated securities under federal and other regulations	84,994	(4,999)
Increase (Decrease) in Receivables from Brokers-Dealers and Clearing Organizations	(461)	(62,709)
Receivables from users, net	(2,805,032)	(1,662,798)
Deposits with clearing organizations	(90,707)	(121,815)
Other current and non-current assets	(957,222)	(539,103)
Accounts payable and accrued expenses	118,460	109,398
Payables to users	913,927	2,729,643
Securities loaned	1,208,532	487,904
Other current and non-current liabilities	805,883	541,004
Net cash provided by (used in) operating activities	(609,141)	1,529,548
Investing activities:
Purchase of property, software and equipment	(46,107)	(17,582)
Capitalization of internally developed software	(12,619)	(5,708)
Acquisitions of a business, net of cash acquired	(119,161)	0
Other	(1,588)	0
Net cash used in investing activities	(179,475)	(23,290)
Financing activities:
Proceeds from issuance of common stock in connection with initial public offering, net of offering costs	2,057,530	0
Taxes paid related to net share settlement of equity awards	(411,772)	0
Proceeds from issuance of convertible notes and warrants	3,551,975	0
Draws on credit facilities	1,958,276	937,700
Repayments on credit facilities	(1,958,276)	(937,700)
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs	0	1,267,350
Proceeds from exercise of stock options, net of repurchases	11,780	3,587
Net cash provided by financing activities	5,209,513	1,270,937
Effect of foreign exchange rate changes on cash and cash equivalents	(90)	20
Net increase in cash, cash equivalents, segregated cash and restricted cash	4,420,807	2,777,215
Cash, cash equivalents, segregated cash and restricted cash, beginning of the period	6,189,659	3,069,568
Cash, cash equivalents, segregated cash and restricted cash, end of the period	10,610,466	5,846,783
Cash and cash equivalents, end of the period	6,166,705	2,023,654
Segregated cash, end of the period	4,418,298	3,815,765
Restricted cash, end of the period	25,463	7,364
Cash, cash equivalents, segregated cash and restricted cash, end of the period	10,610,466	5,846,783
Supplemental disclosures:
Cash paid for interest	6,183	2,698
Cash paid for income taxes, net of refund received	3,159	2,839
Non-cash financing activities:
Unpaid offering costs in connection with initial public offering	$ 5,150	$ 0