Prosper Marketplace 10-Q 12 Nov 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Nov. 09, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2021
Entity File Number	333-225797-01
Entity Registrant Name	PROSPER MARKETPLACE, INC.
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001416265
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	73-1733867
Entity Address, Address Line One	221 Main Street
Entity Address, Address Line Two	3rd Floor
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94105
City Area Code	415
Local Phone Number	593-5400
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		71,554,898
Prosper Funding LLC
Entity Information [Line Items]
Entity File Number	333-225797
Entity Registrant Name	PROSPER FUNDING LLC
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001542574
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-4526070
Entity Address, Address Line One	221 Main Street
Entity Address, Address Line Two	3rd Floor
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94105
City Area Code	415
Local Phone Number	593-5400
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		0

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands		Sep. 30, 2021	Dec. 31, 2020
Assets:
Cash and Cash Equivalents		$ 55,949	$ 50,145
Restricted Cash	[1]	156,901	163,723
Accounts Receivable	[1]	749	605
Loans Held for Sale, at Fair Value	[1]	285,920	274,621
Borrower loans, at fair value	[1]	254,680	378,263
Property and Equipment, Net		29,696	28,446
Prepaid and Other Assets	[1]	7,358	5,196
Servicing Assets		8,701	9,242
Goodwill		36,368	36,368
Intangible Assets, Net		371	500
Total Assets		836,693	947,109
Liabilities, Convertible Preferred Stock and Stockholders' Deficit:
Accounts Payable and Accrued Liabilities		23,807	17,876
Payable to Investors		141,115	124,094
Notes, at Fair Value		253,242	208,379
Notes Issued by Securitization Trust	[1]	0	156,782
Certificates Issued by Securitization Trust, at Fair Value	[1]	0	22,917
Warehouse Lines	[1]	245,819	242,479
Other Liabilities		24,104	25,057
Convertible Preferred Stock Warrant Liability		249,164	112,319
Total Liabilities		937,251	909,903
Commitments and Contingencies (Note 16)
Convertible Preferred Stock		322,748	322,748
Stockholders' Deficit:
Common Stock – $0.01 par value; 625,000,000 shares authorized; 72,257,653 shares issued and 71,321,718 shares outstanding, as of September 30, 2021; 70,075,307 shares issued and 69,139,372 shares outstanding, as of December 31, 2020.		237	215
Additional Paid-In Capital		156,921	155,952
Less: Treasury Stock		(23,417)	(23,417)
Accumulated Deficit		(554,666)	(415,911)
Total Stockholders' Deficit		(420,925)	(283,161)
Total Liabilities, Convertible Preferred Stock and Stockholders' Deficit		836,693	947,109
Prosper Funding LLC
Assets:
Cash and Cash Equivalents		8,362	8,592
Restricted Cash		147,244	132,332
Borrower loans, at fair value		254,680	209,670
Property and Equipment, Net		8,725	6,928
Servicing Assets		9,968	11,088
Other Assets		282	217
Total Assets		429,261	368,827
Liabilities, Convertible Preferred Stock and Stockholders' Deficit:
Accounts Payable and Accrued Liabilities		1,870	2,361
Payable to Related Party		3,392	4,120
Payable to Investors		142,059	126,266
Notes, at Fair Value		253,242	208,379
Other Liabilities		2,453	2,613
Total Liabilities		403,016	343,739
Stockholders' Deficit:
Member's Equity		11,404	11,404
Accumulated Deficit		14,841	13,684
Total Stockholders' Deficit		26,245	25,088
Total Liabilities, Convertible Preferred Stock and Stockholders' Deficit		429,261	368,827
Primary Beneficiary
Assets:
Restricted Cash		5,805	25,203
Loans Held for Sale, at Fair Value		285,920	274,621
Borrower loans, at fair value		0	168,593
Prepaid and Other Assets		3,068	2,043
Total Assets		294,793	470,460
Liabilities, Convertible Preferred Stock and Stockholders' Deficit:
Notes Issued by Securitization Trust		0	156,782
Certificates Issued by Securitization Trust, at Fair Value		0	22,917
Warehouse Lines		245,819	242,479
Total Liabilities		245,819	422,178
Convertible Preferred Stock		$ 2,381	$ 2,381
[1]	Includes amounts in consolidated variable interest entities (VIEs) presented separately in the table below. The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 6, Securitizations, and Note 10, Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information. September 30, 2021 December 31, 2020 Assets of consolidated VIEs, included in total assets above: Restricted Cash $ 5,805 $ 25,203 Loans Held for Sale, at Fair Value 285,920 274,621 Borrower Loans, at Fair Value — 168,593 Prepaid and Other Assets 3,068 2,043 Total assets of consolidated variable interest entities $ 294,793 $ 470,460 Liabilities of consolidated VIEs, included in total liabilities above: Notes Issued by Securitization Trust $ — $ 156,782 Certificates Issued by Securitization Trust, at Fair Value — 22,917 Warehouse Lines 245,819 242,479 Total liabilities of consolidated variable interest entities $ 245,819 $ 422,178

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 20, 2017
Convertible preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Convertible preferred stock, authorized (in shares)	444,760,848	444,760,848	444,760,848
Convertible preferred stock, issued (in shares)	209,613,570	209,613,570
Convertible preferred stock, outstanding (in shares)	209,613,570	209,613,570
Convertible preferred stock, aggregate liquidation preference	$ 370,456	$ 370,456
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, authorized (in shares)	625,000,000	625,000,000	625,000,000
Common stock, issued (in shares)	72,257,653	70,075,307
Common stock, outstanding (in shares)	71,321,718	69,139,372
Primary Beneficiary
Convertible preferred stock, issued (in shares)	51,247,915	51,247,915
Convertible preferred stock, outstanding (in shares)	51,247,915	51,247,915

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating Revenues:
Gain on Sale of Borrower Loans	$ 1,928,000	$ 786,000	$ 4,917,000	$ 3,147,000
Total Operating Revenues	30,453,000	20,826,000	83,645,000	67,296,000
Interest Income (Expense):
Interest Income on Borrower Loans and Loans Held for Sale	21,495,000	25,693,000	64,441,000	79,982,000
Interest Expense on Financial Instruments	(13,091,000)	(14,519,000)	(38,969,000)	(46,472,000)
Total Interest Income, Net	8,404,000	11,174,000	25,472,000	33,510,000
Change in Fair Value of Financial Instruments, Net	(2,071,000)	4,703,000	(4,481,000)	(34,601,000)
Total Net Revenue	36,786,000	36,703,000	104,636,000	66,205,000
Expenses:
Origination and Servicing	8,983,000	6,871,000	26,038,000	22,682,000
Sales and Marketing	8,860,000	5,362,000	24,486,000	21,626,000
General and Administrative	18,842,000	15,151,000	54,815,000	49,033,000
Impairment Expense	0	0	0	228,000
Change in Fair Value of Convertible Preferred Stock Warrants	86,728,000	11,374,000	136,845,000	(63,624,000)
Loss on Deconsolidation of VIEs (Note 6)	1,494,000	0	1,494,000	0
Other Income, Net	(81,000)	(64,000)	(350,000)	(588,000)
Total Expenses	124,826,000	38,694,000	243,328,000	29,357,000
Net (Loss) Income Before Taxes	(88,040,000)	(1,991,000)	(138,692,000)	36,848,000
Income Tax Expense	(21,000)	(34,000)	(63,000)	(102,000)
Net (Loss) Income	(88,061,000)	(2,025,000)	(138,755,000)	36,746,000
Plus: Return on Share Purchase	0	2,381,000	0	2,381,000
Less: Net Income Allocated to Participating Securities	0	(255,000)	0	(28,814,000)
Net (Loss) Income Attributable to Common Stockholders, Basic	$ (88,061,000)	$ 101,000	$ (138,755,000)	$ 10,313,000
Net (Loss) Income Per Share - Basic (in dollars per share)	$ (1.24)	$ 0	$ (1.97)	$ 0.15
Net (Loss) Income Per Share - Diluted (in dollars per share)	$ (1.24)	$ 0	$ (1.97)	$ 0.03
Weighted-Average Shares - Basic (in shares)	71,068,442	68,485,173	70,433,182	68,465,046
Weighted-Average Shares - Diluted (in shares)	71,068,442	296,652,189	70,433,182	332,508,175
Prosper Funding LLC
Operating Revenues:
Gain on Sale of Borrower Loans	$ 2,404,000	$ 1,247,000	$ 6,078,000	$ 4,429,000
Total Operating Revenues	15,871,000	11,578,000	42,612,000	36,396,000
Interest Income (Expense):
Interest Income on Borrower Loans and Loans Held for Sale	9,574,000	8,979,000	27,130,000	28,126,000
Interest Expense on Financial Instruments	(8,935,000)	(8,419,000)	(25,366,000)	(26,363,000)
Total Interest Income, Net	639,000	560,000	1,764,000	1,763,000
Change in Fair Value of Financial Instruments, Net	371,000	(72,000)	527,000	185,000
Total Net Revenue	16,881,000	12,066,000	44,903,000	38,344,000
Expenses:
Administration Fee - Related Party	13,686,000	10,997,000	38,653,000	32,855,000
Servicing	1,830,000	1,327,000	4,729,000	3,657,000
General and Administrative	108,000	104,000	364,000	271,000
Total Expenses	15,624,000	12,428,000	43,746,000	36,783,000
Income Tax Expense			0	0
Net (Loss) Income	1,257,000	(362,000)	1,157,000	1,561,000
Administration Fee Revenue - Related Party | Prosper Funding LLC
Operating Revenues:
Revenues	9,066,000	5,158,000	24,247,000	14,733,000
Transaction Fees, Net
Operating Revenues:
Revenues	23,626,000	15,075,000	65,397,000	46,889,000
Servicing Fees, Net
Operating Revenues:
Revenues	3,840,000	4,396,000	10,807,000	15,113,000
Servicing Fees, Net | Prosper Funding LLC
Operating Revenues:
Revenues	3,954,000	5,066,000	11,483,000	16,782,000
Other Revenue
Operating Revenues:
Revenues	1,059,000	569,000	2,524,000	2,147,000
Other Revenue | Prosper Funding LLC
Operating Revenues:
Revenues	$ 447,000	$ 107,000	$ 804,000	$ 452,000

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Other Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net (Loss) Income	$ (88,061)	$ (2,025)	$ (138,755)	$ 36,746
Other Comprehensive (Loss) Income, Before Tax:
Other Comprehensive (Loss) Income, Before Tax	0	0	0	0
Other Comprehensive (Loss) Income, Net of Tax:	0	0	0	0
Comprehensive (Loss) Income, Net of Tax	$ (88,061)	$ (2,025)	$ (138,755)	$ 36,746

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Convertible Preferred Stock, Stockholders’ Deficit and Members' Equity (Unaudited) - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Convertible Preferred Stock Held by Consolidated VIE	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Deficit/Retained Earnings	Prosper Funding LLC	Prosper Funding LLCAccumulated Deficit/Retained Earnings	Prosper Funding LLCMember’s Equity
Beginning balance (in shares) at Dec. 31, 2019		209,613,570	0
Beginning balance at Dec. 31, 2019		$ 322,748	$ 0
Ending balance (in shares) at Mar. 31, 2020		209,613,570	0
Ending balance at Mar. 31, 2020		$ 322,748	$ 0
Beginning balance (in shares) at Dec. 31, 2019				73,629,136	(5,177,235)
Beginning balance at Dec. 31, 2019	$ (306,255)			$ 208	$ (23,417)	$ 151,416	$ (434,462)	$ 28,187	$ 12,283	$ 15,904
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of vested stock options (in shares)				3,740
Exercise of vested stock options	1					1
Stock-based compensation expense	557					557
Net (Loss) Income	21,130						21,130	1,548	1,548
Ending balance (in shares) at Mar. 31, 2020				73,632,876	(5,177,235)
Ending balance at Mar. 31, 2020	(284,567)			$ 208	$ (23,417)	151,974	(413,332)	29,735	13,831	15,904
Beginning balance (in shares) at Dec. 31, 2019		209,613,570	0
Beginning balance at Dec. 31, 2019		$ 322,748	$ 0
Increase (Decrease) in Temporary Equity [Roll Forward]
Purchase of convertible preferred stock by consolidated VIE Prosper Grantor Trust (in shares)			(51,247,915)
Purchase of convertible preferred stock by consolidated VIE Prosper Grantor Trust	(2,381)		$ (2,381)			(2,381)
Ending balance (in shares) at Sep. 30, 2020		209,613,570	(51,247,915)
Ending balance at Sep. 30, 2020		$ 322,748	$ (2,381)
Beginning balance (in shares) at Dec. 31, 2019				73,629,136	(5,177,235)
Beginning balance at Dec. 31, 2019	(306,255)			$ 208	$ (23,417)	151,416	(434,462)	28,187	12,283	15,904
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of vested stock options (in shares)				406,685
Exercise of vested stock options	9			$ 4		5
Stock-based compensation expense	1,870					1,870
Distribution To Parent								(4,500)		(4,500)
Net (Loss) Income	36,746						36,746	1,561	1,561
Ending balance (in shares) at Sep. 30, 2020				74,035,821	(5,177,235)
Ending balance at Sep. 30, 2020	(265,249)			$ 212	$ (23,417)	155,672	(397,716)	25,248	13,844	11,404
Beginning balance (in shares) at Mar. 31, 2020		209,613,570	0
Beginning balance at Mar. 31, 2020		$ 322,748	$ 0
Ending balance (in shares) at Jun. 30, 2020		209,613,570	0
Ending balance at Jun. 30, 2020		$ 322,748	$ 0
Beginning balance (in shares) at Mar. 31, 2020				73,632,876	(5,177,235)
Beginning balance at Mar. 31, 2020	(284,567)			$ 208	$ (23,417)	151,974	(413,332)	29,735	13,831	15,904
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	454					454
Distribution To Parent								(4,500)		(4,500)
Net (Loss) Income	17,641						17,641	375	375
Ending balance (in shares) at Jun. 30, 2020				73,632,876	(5,177,235)
Ending balance at Jun. 30, 2020	(266,472)			$ 208	$ (23,417)	152,428	(395,691)	25,610	14,206	11,404
Increase (Decrease) in Temporary Equity [Roll Forward]
Purchase of convertible preferred stock by consolidated VIE Prosper Grantor Trust (in shares)			(51,247,915)
Purchase of convertible preferred stock by consolidated VIE Prosper Grantor Trust	(2,381)		$ (2,381)			(2,381)
Ending balance (in shares) at Sep. 30, 2020		209,613,570	(51,247,915)
Ending balance at Sep. 30, 2020		$ 322,748	$ (2,381)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of vested stock options (in shares)				402,945
Exercise of vested stock options	8			$ 4		4
Stock-based compensation expense	859					859
Net (Loss) Income	(2,025)						(2,025)	(362)	(362)
Ending balance (in shares) at Sep. 30, 2020				74,035,821	(5,177,235)
Ending balance at Sep. 30, 2020	$ (265,249)			$ 212	$ (23,417)	155,672	(397,716)	25,248	13,844	11,404
Beginning balance (in shares) at Dec. 31, 2020	209,613,570	209,613,570	(51,247,915)
Beginning balance at Dec. 31, 2020	$ 322,748	$ 322,748	$ (2,381)
Ending balance (in shares) at Mar. 31, 2021		209,613,570	(51,247,915)
Ending balance at Mar. 31, 2021		$ 322,748	$ (2,381)
Beginning balance (in shares) at Dec. 31, 2020				74,316,607	(5,177,235)
Beginning balance at Dec. 31, 2020	(283,161)			$ 215	$ (23,417)	155,952	(415,911)	25,088	13,684	11,404
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of vested stock options (in shares)				1,624,461
Exercise of vested stock options	34			$ 17		17
Stock-based compensation expense	353					353
Net (Loss) Income	(44,889)						(44,889)	(1,204)	(1,204)
Ending balance (in shares) at Mar. 31, 2021				75,941,068	(5,177,235)
Ending balance at Mar. 31, 2021	$ (327,663)			$ 232	$ (23,417)	156,322	(460,800)	23,884	12,480	11,404
Beginning balance (in shares) at Dec. 31, 2020	209,613,570	209,613,570	(51,247,915)
Beginning balance at Dec. 31, 2020	$ 322,748	$ 322,748	$ (2,381)
Ending balance (in shares) at Sep. 30, 2021	209,613,570	209,613,570	(51,247,915)
Ending balance at Sep. 30, 2021	$ 322,748	$ 322,748	$ (2,381)
Beginning balance (in shares) at Dec. 31, 2020				74,316,607	(5,177,235)
Beginning balance at Dec. 31, 2020	(283,161)			$ 215	$ (23,417)	155,952	(415,911)	25,088	13,684	11,404
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of vested stock options (in shares)				2,182,346
Exercise of vested stock options	44			$ 22		22
Stock-based compensation expense	947					947
Net (Loss) Income	(138,755)						(138,755)	1,157	1,157
Ending balance (in shares) at Sep. 30, 2021				76,498,953	(5,177,235)
Ending balance at Sep. 30, 2021	(420,925)			$ 237	$ (23,417)	156,921	(554,666)	26,245	14,841	11,404
Beginning balance (in shares) at Mar. 31, 2021		209,613,570	(51,247,915)
Beginning balance at Mar. 31, 2021		$ 322,748	$ (2,381)
Ending balance (in shares) at Jun. 30, 2021		209,613,570	(51,247,915)
Ending balance at Jun. 30, 2021		$ 322,748	$ (2,381)
Beginning balance (in shares) at Mar. 31, 2021				75,941,068	(5,177,235)
Beginning balance at Mar. 31, 2021	(327,663)			$ 232	$ (23,417)	156,322	(460,800)	23,884	12,480	11,404
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of vested stock options (in shares)				129,997
Exercise of vested stock options	2			$ 1		1
Stock-based compensation expense	292					292
Net (Loss) Income	(5,805)						(5,805)	1,104	1,104
Ending balance (in shares) at Jun. 30, 2021				76,071,065	(5,177,235)
Ending balance at Jun. 30, 2021	$ (333,174)			$ 233	$ (23,417)	156,615	(466,605)	24,988	13,584	11,404
Ending balance (in shares) at Sep. 30, 2021	209,613,570	209,613,570	(51,247,915)
Ending balance at Sep. 30, 2021	$ 322,748	$ 322,748	$ (2,381)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of vested stock options (in shares)				427,888
Exercise of vested stock options	8			$ 4		4
Stock-based compensation expense	302					302
Net (Loss) Income	(88,061)						(88,061)	1,257	1,257
Ending balance (in shares) at Sep. 30, 2021				76,498,953	(5,177,235)
Ending balance at Sep. 30, 2021	$ (420,925)			$ 237	$ (23,417)	$ 156,921	$ (554,666)	$ 26,245	$ 14,841	$ 11,404

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2021		Sep. 30, 2020
Cash flows from Operating Activities:
Net (Loss) Income	$ (138,755,000)		$ 36,746,000
Adjustments to Reconcile Net (Loss) Income to Net Cash Provided by (Used in) Operating Activities:
Change in Fair Value of Financial Instruments, Net	4,481,000		34,597,000
Depreciation and Amortization	7,224,000		6,196,000
Amortization of Operating Lease Right-of-use Asset	2,811,000		2,599,000
Impairment of Operating Lease Right-of-use Asset	0		228,000
Gain on Sales of Borrower Loans	(5,673,000)		(3,945,000)
Change in Fair Value of Servicing Rights	6,214,000		7,241,000
Stock-Based Compensation Expense	857,000		1,683,000
Change in Fair Value of Convertible Preferred Stock Warrants	136,846,000		(63,624,000)
Loss on Deconsolidation of VIEs (Note 6)	1,494,000		0
Other, Net	1,888,000		1,177,000
Changes in Operating Assets and Liabilities:
Purchase of Loans Held for Sale at Fair Value	(1,248,316,000)		(949,529,000)
Proceeds from Sales and Principal Payments of Loans Held for Sale at Fair Value	1,262,896,000		874,489,000
Accounts Receivable	(144,000)		1,162,000
Prepaid and Other Assets	(475,000)		(437,000)
Accounts Payable and Accrued Liabilities	6,139,000		(5,204,000)
Payable to Investors	17,021,000		(5,205,000)
Other Liabilities	(3,357,000)		(4,101,000)
Net Cash Provided by (Used in) Operating Activities	51,151,000		(65,927,000)
Cash Flows from Investing Activities:
Purchase of Borrower Loans Held at Fair Value	(172,082,000)		(97,406,000)
Proceeds from Sales and Principal Payments of Borrower Loans Held at Fair Value	190,893,000		217,527,000
Purchases of Property and Equipment	(8,881,000)		(6,801,000)
Net Cash Provided by Investing Activities	9,930,000		113,320,000
Cash Flows from Financing Activities:
Proceeds from Issuance of Notes Held at Fair Value	172,231,000		97,303,000
Payments of Notes Held at Fair Value	(126,528,000)		(114,050,000)
Principal Payments on Notes Issued by Securitization Trust	(87,700,000)		(156,377,000)
Principal Payments on Certificates Issued by Securitization Trust	(14,935,000)		(16,608,000)
Net Cash and Restricted Cash Outflows from Deconsolidation of VIEs (Note 6)	(6,821,000)		0
Proceeds from Warehouse Lines	63,250,000		110,499,000
Principal Payments on Warehouse Lines	(59,900,000)		(15,300,000)
Proceeds from Paycheck Protection Program Loan	0		8,447,000
Payments of Debt Issuance Costs	(1,740,000)		0
Proceeds from Exercise of Stock Options	44,000		9,000
Net Cash Used in Financing Activities	(62,099,000)		(86,077,000)
Net Decrease in Cash, Cash Equivalents and Restricted Cash	(1,018,000)		(38,684,000)
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	213,868,000		220,408,000
Cash, Cash Equivalents and Restricted Cash at End of the Period	212,850,000		181,724,000
Supplemental Disclosure of Cash Flow Information:
Cash Paid for Interest	38,236,000		44,647,000
Non-Cash Investing Activity- Accrual for Property and Equipment, Net	625,000		574,000
Non-Cash Investing Activity - Deconsolidation of Borrower Loans, at Fair Value	78,361,000		0
Non-Cash Financing Activity - Deconsolidation of Notes Issued by Securitization Trust	69,709,000		0
Non-Cash Financing Activity - Deconsolidation of Certificates Issued by Securitization Trust, at Fair Value	13,979,000		0
Reconciliation to Amounts on Consolidated Balance Sheets:
Cash and Cash Equivalents	55,949,000		45,898,000
Restricted Cash	156,901,000	[1]	135,826,000
Total Cash, Cash Equivalents and Restricted Cash	212,850,000		181,724,000
Prosper Funding LLC
Cash flows from Operating Activities:
Net (Loss) Income	1,157,000		1,561,000
Adjustments to Reconcile Net (Loss) Income to Net Cash Provided by (Used in) Operating Activities:
Change in Fair Value of Financial Instruments, Net	(527,000)		(186,000)
Other Non-Cash Changes in Borrower Loans, Loans Held for Sale and Notes	18,000		48,000
Depreciation and Amortization	3,540,000		3,132,000
Gain on Sales of Borrower Loans	(6,675,000)		(5,034,000)
Change in Fair Value of Servicing Rights	7,795,000		8,657,000
Changes in Operating Assets and Liabilities:
Purchase of Loans Held for Sale at Fair Value	(1,248,316,000)		(949,529,000)
Proceeds from Sales and Principal Payments of Loans Held for Sale at Fair Value	1,248,316,000		949,529,000
Other Assets	(65,000)		504,000
Accounts Payable and Accrued Liabilities	(491,000)		261,000
Payable to Investors	15,793,000		(7,266,000)
Net Related Party Receivable/Payable	(704,000)		7,910,000
Other Liabilities	(160,000)		(1,027,000)
Net Cash Provided by (Used in) Operating Activities	19,681,000		8,560,000
Cash Flows from Investing Activities:
Purchase of Borrower Loans Held at Fair Value	(172,082,000)		(97,406,000)
Proceeds from Sales and Principal Payments of Borrower Loans Held at Fair Value	126,741,000		114,145,000
Purchases of Property and Equipment	(5,361,000)		(2,942,000)
Net Cash Provided by Investing Activities	(50,702,000)		13,797,000
Cash Flows from Financing Activities:
Proceeds from Issuance of Notes Held at Fair Value	172,231,000		97,303,000
Payments of Notes Held at Fair Value	(126,528,000)		(114,051,000)
Payments of Distributions to Affiliates	0		(4,500,000)
Net Cash Used in Financing Activities	45,703,000		(21,248,000)
Net Decrease in Cash, Cash Equivalents and Restricted Cash	14,682,000		1,109,000
Cash, Cash Equivalents and Restricted Cash at Beginning of the Period	140,924,000		117,861,000
Cash, Cash Equivalents and Restricted Cash at End of the Period	155,606,000		118,970,000
Supplemental Disclosure of Cash Flow Information:
Cash Paid for Interest	25,571,000		26,353,000
Non-Cash Investing Activity- Accrual for Property and Equipment, Net	480,000		238,000
Reconciliation to Amounts on Consolidated Balance Sheets:
Cash and Cash Equivalents	8,362,000		7,950,000
Restricted Cash	147,244,000		111,020,000
Total Cash, Cash Equivalents and Restricted Cash	$ 155,606,000		$ 118,970,000
[1]	Includes amounts in consolidated variable interest entities (VIEs) presented separately in the table below. The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 6, Securitizations, and Note 10, Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information. September 30, 2021 December 31, 2020 Assets of consolidated VIEs, included in total assets above: Restricted Cash $ 5,805 $ 25,203 Loans Held for Sale, at Fair Value 285,920 274,621 Borrower Loans, at Fair Value — 168,593 Prepaid and Other Assets 3,068 2,043 Total assets of consolidated variable interest entities $ 294,793 $ 470,460 Liabilities of consolidated VIEs, included in total liabilities above: Notes Issued by Securitization Trust $ — $ 156,782 Certificates Issued by Securitization Trust, at Fair Value — 22,917 Warehouse Lines 245,819 242,479 Total liabilities of consolidated variable interest entities $ 245,819 $ 422,178

BASIS OF PRESENTATION

BASIS OF PRESENTATION	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
BASIS OF PRESENTATION	Basis of Presentation Prosper Marketplace, Inc. (“PMI”) was incorporated in the state of Delaware on March 22, 2005. Except as the context requires otherwise, as used in these notes to the condensed consolidated financial statements of PMI, “Prosper,” “we,” “us,” and “our” refer to PMI and its wholly-owned subsidiaries, on a consolidated basis. The unaudited interim condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”) and disclosure requirements for interim financial information and the requirements of Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by US GAAP for complete financial statements. The unaudited interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2020. The balance sheet at December 31, 2020 has been derived from the audited financial statements at that date. Management believes these unaudited interim condensed consolidated financial statements reflect all adjustments, consisting of a normal recurring nature, which are necessary for a fair presentation of the results for the interim periods presented. The results of operations for the interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period. The preparation of Prosper’s condensed consolidated financial statements and related disclosures in conformity with US GAAP requires management to make judgments, assumptions and estimates that affect the amounts reported in Prosper’s financial statements and accompanying notes. Management bases its estimates on historical experience and on various other factors it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of certain assets and liabilities. These judgments, estimates and assumptions are inherently subjective in nature and actual results may differ from these estimates and assumptions. The accompanying interim condensed consolidated financial statements include the accounts of PMI, its wholly-owned subsidiaries and consolidated variable interest entities (“VIEs”). All intercompany balances have been eliminated in consolidation. Securitization Notes are Notes held by certain third-party investors pursuant to Prosper’s securitization transactions, and are distinguishable from the borrower payment dependent Notes available to investors through the Company’s Note Channel.
Prosper Funding LLC
Entity Information [Line Items]
BASIS OF PRESENTATION	Basis of Presentation Prosper Funding LLC (“PFL”) was formed in the state of Delaware in February 2012 as a limited liability company with Prosper Marketplace, Inc. (“PMI”) as its sole equity member. Except as the context otherwise requires, as used in these Notes to the condensed consolidated financial statements of Prosper Funding LLC, “PFL”, and the “Company” refers to Prosper Funding LLC and its wholly owned subsidiary, Prosper Depositor LLC, a Delaware limited liability company, on a consolidated basis. The unaudited interim condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“US GAAP”) and disclosure requirements for interim financial information and the requirements of Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by US GAAP for complete financial statements. The unaudited interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2020. The balance sheet at December 31, 2020 has been derived from the audited financial statements at that date. Management believes these unaudited interim condensed consolidated financial statements reflect all adjustments, consisting of a normal recurring nature, which are necessary for a fair presentation of the results for the interim periods presented. The results of operations for the interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period. PFL did not have any items of other comprehensive income or loss for any of the periods presented in the condensed consolidated financial statements as of and for the nine months ended September 30, 2021 and September 30, 2020. The preparation of PFL's condensed consolidated financial statements and related disclosures in conformity with US GAAP requires management to make judgments, assumptions and estimates that affect the amounts reported in its condensed consolidated financial statements and accompanying notes. Management bases its estimates on historical experience and on various other factors it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of certain assets and liabilities. These judgments, estimates and assumptions are inherently subjective in nature and actual results may differ from these estimates and assumptions, and the differences could be material.

SUMMARY OF SIGNIFICANT ACCOUNT

SUMMARY OF SIGNIFICANT ACCOUNT POLICIES	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
SUMMARY OF SIGNIFICANT ACCOUNT POLICIES	Summary of Significant Accounting Policies Prosper’s significant accounting policies are included in Note 2, Summary of Significant Accounting Policies, in Prosper’s Annual Report on Form 10-K for the year ended December 31, 2020. There have been no changes to these accounting policies during the first nine months of 2021. Fair Value Measurements Financial instruments measured at fair value consist principally of Borrower Loans, Loans Held for Sale, Servicing Assets, Loan Trailing Fee Liabilities (Note 9), Notes, Certificates Issued by Securitization Trust (Note 6) and Convertible Preferred Stock Warrant Liability. The estimated fair values of other financial instruments, including Cash and Cash Equivalents, Restricted Cash, Accounts Receivable, Accounts Payable and Accrued Liabilities, and Payable to Investors approximate their carrying values because of their short-term nature. The estimated fair values of the Paycheck Protection Program loan (Note 9 and 10), Notes Issued by Securitization Trust (Note 6) and Warehouse Lines do not approximate their carrying values due primarily to differences in the stated and market rates associated with these instruments. Refer to Note 7, Fair Value of Assets and Liabilities, for additional fair value disclosures. Restricted Cash Restricted Cash consists primarily of cash deposits, money market funds and short-term certificate of deposit accounts held as collateral as required for long term leases, loan funding and servicing activities, and cash that investors have on our marketplace that has not yet been invested in Borrower Loans or disbursed to the investor. Borrower Loans, Loans Held for Sale, Notes and Certificates Issued by Securitization Trust Borrower Loans are funded either through the Note Channel or through the Whole Loan Channel. Through the Note Channel, Prosper purchases Borrower Loans from WebBank, then issues Notes and holds the Borrower Loans until maturity. The obligation to repay a series of Notes issued through the Note Channel is dependent upon the repayment of the associated Borrower Loan. Borrower Loans funded and Notes issued through the Note Channel are carried on Prosper’s condensed consolidated balance sheets as assets and liabilities, respectively. In 2019, Prosper began refinancing the purchase of Borrower Loans through the Whole Loan Channel through securitization transactions, which issue senior notes, risk retention interests and residual certificates. These securitization trusts were deemed consolidated VIEs until September 2021, when the Company sold its share of the residual certificates issued by these securitization trusts and deconsolidated the VIEs. Prior to their deconsolidation, the Borrower Loans held in the securitization trusts were included in “Borrower Loans, at Fair Value”. Senior notes sold to third party investors were included in “Notes Issued by Securitization Trust,” and the risk retention interest and residual certificates held by third party investors were included in “Certificates Issued by Securitization Trust, at Fair Value” on the accompanying condensed consolidated balance sheets. Refer to Note 6, Securitization for additional disclosures and details on the deconsolidation of these securitization trust VIEs. Prosper uses Warehouse Lines to purchase Loans Held for Sale that may be subsequently contributed to securitization transactions or sold to investors. Loans Held for Sale are included in “Loans Held for Sale, at Fair Value” on the Consolidated Balance Sheets. See Note 10, Debt for more details on Warehouse Lines. Borrower Loans and Loans Held for Sale are purchased from WebBank. Prosper places Borrower Loans and Loans Held for Sale on non-accrual status when they are 120 days past due. When a loan is placed on non-accrual status, Prosper stops accruing interest and reverses all accrued but unpaid interest as of such date. Additionally, Prosper charges-off Borrower Loans and Loans Held for Sale when they are 120 days past due. The fair value of loans 120 or more days past due generally consists of the expected recovery from debt sales in subsequent periods. Prosper has elected the fair value option for Borrower Loans, Loans Held for Sale, Notes, and Certificates Issued by Securitization Trust. Changes in fair value of Borrower Loans funded through the Note Channel are largely offset by the changes in fair value of Notes due to the borrower payment-dependent design of the Notes. Changes in the fair value of Borrower Loans held in consolidated securitization trusts are partially offset by changes in fair value of the Certificates Issued by Securitization Trust, prior to the deconsolidation of these securitization trusts in September 2021. Changes in fair value of Loans Held for Sale are recorded through Proper's earnings and Prosper collects interest on Loans Held for Sale. Changes in the fair values of Borrower Loans, Loans Held for Sale, Notes, and Certificates Issued by Securitization Trust are included in “Change in Fair Value of Financial Instruments, Net” on the Consolidated Statements of Operations. Prosper primarily uses a discounted cash flow model to estimate the fair value of Borrower Loans, Loans Held for Sale, Notes, and Certificates Issued by Securitization Trust. The key assumptions used in the valuation include default rates and prepayment rates derived primarily from historical performance, and discount rates based on estimates of the rates of return that investors would require when investing in financial instruments with similar characteristics. Leases Management determines if an arrangement is a lease at inception. Operating lease right-of-use (“ROU”) assets and operating lease liabilities are included on the Consolidated Balance Sheets in Property and Equipment, Net and in Other Liabilities, respectively. For certain leases with original terms of twelve months or less, PMI recognizes the lease expense as incurred and does not record ROU assets and lease liabilities. If a contract contains a lease, management evaluates whether it should be classified as an operating or finance lease. Operating lease ROU assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. As most of PMI's leases do not provide an implicit rate, management uses an incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. The operating lease ROU asset also includes any lease payments made and excludes lease incentives and initial direct costs incurred. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. The operating lease ROU assets are evaluated for impairment utilizing the same impairment model used for Property and Equipment. Consolidation of Variable Interest Entities The determination of whether to consolidate a VIE in which we have a variable interest requires a significant amount of analysis and judgment regarding whether we are the primary beneficiary of a VIE due to our holding a controlling financial interest in the VIE. A controlling financial interest in a VIE exists if we have both the power to direct the VIE’s activities that most significantly affect the VIE’s economic performance and a potentially significant economic interest in the VIE. The determination of whether an entity is a VIE considers factors, such as (i) whether the entity’s equity investment at risk is insufficient to allow the entity to finance its activities without additional subordinated financial support and (ii) whether a holder’s equity investment at risk lacks any of the following characteristics of a controlling financial interest: the direct or indirect ability through voting rights or similar rights to make decisions about a legal entity’s activities that have a significant effect on the entity’s success, the obligation to absorb the expected losses of the entity or the right to receive the expected residual returns of the legal entity. Management regularly reviews and reconsiders its previous conclusions regarding the status of an entity as a VIE and whether we are required to consolidate or deconsolidate such VIE in the consolidated financial statements. Recent Accounting Pronouncements Accounting Standards Adopted by the Company in the Current Period In December 2019, the FASB issued ASU No. 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.” This ASU simplifies the accounting for income taxes by removing certain exceptions related to the incremental approach for intraperiod tax allocation, the requirement to recognize or derecognize deferred tax liabilities related to equity method investments that are also foreign subsidiaries and the methodology for calculating income taxes in an interim period. The guidance also clarifies and simplifies other aspects of the accounting for income taxes, including a modification in the guidance for franchise taxes that are partially based on income and recognizing deferred taxes for a subsequent step-up in the tax basis of goodwill. The ASU is effective for the Company beginning in the first quarter of 2021. The Company has adopted ASU 2019-12 and concluded that the impact on its condensed consolidated financial statements was immaterial. Accounting Standards Issued, to be Adopted by the Company in Future Periods In March 2020, the FASB issued ASU No. 2020-04, “Reference Rate Reform (Topic 848),” which provides optional expedients and exceptions for applying GAAP on contract modifications and hedge accounting, in order to ease the financial reporting burdens of the expected market transition from LIBOR and other interbank offered rates to alternative referenced rates, such as the Secured Overnight Financing Rate. This ASU can be adopted after its issuance date through December 31, 2022. The Company is currently evaluating the impact reference rate reform will have on its contracts that reference LIBOR in order to determine whether to adopt this guidance.
Prosper Funding LLC
Entity Information [Line Items]
SUMMARY OF SIGNIFICANT ACCOUNT POLICIES	Summary of Significant Accounting Policies PFL's significant accounting policies are included in Note 2, Summary of Significant Accounting Policies, in PFL’s Annual Report on Form 10-K for the year ended December 31, 2020. There have been no changes to these accounting policies during the first nine months of 2021. Fair Value Measurements Financial instruments consist principally of Cash and Cash Equivalents, Restricted Cash, Borrower Loans, Loans Held for Sale, Accounts Receivable, Accounts Payable and Accrued Liabilities, Payable to Investors and Notes. The estimated fair values of Cash and Cash Equivalents, Restricted Cash, Accounts Receivable, Accounts Payable and Accrued Liabilities, and Payable to Investors approximate their carrying values because of their short-term nature. Refer to Note 7 for additional fair value disclosures. Restricted Cash Restricted Cash consists primarily of cash deposits, money market funds and short-term certificate of deposit accounts held as collateral as required for long term leases, loan funding and servicing activities, and cash that investors have on our marketplace that has not yet been invested in Borrower Loans or disbursed to the investor. Borrower Loans, Loans Held for Sale and Notes With respect to the Note Channel, PFL purchases Borrower Loans from WebBank, then issues Notes and holds the Borrower Loans until maturity. The obligation to repay a series of Notes funded through the Note Channel is dependent upon the repayment of the associated Borrower Loan. Borrower Loans and Notes funded through the Note Channel are carried on PFL’s condensed consolidated balance sheets as assets and liabilities, respectively. PFL places Borrower Loans and Loans Held for Sale on non-accrual status when they are 120 days past due. When a loan is placed on non-accrual status, PFL stops accruing interest and reverses all accrued but unpaid interest as of such date. Additionally, PFL charges-off Borrower Loans and Loans Held for Sale when they are 120 days past due. The fair value of loans 120 days past due generally consists of the expected recovery from debt sales in subsequent periods. Management has elected the fair value option for Borrower Loans, Loans Held for Sale, and Notes. Changes in fair value of Borrower Loans are largely offset by the changes in fair value of Notes due to the borrower payment-dependent design of the Notes. Changes in fair value of Borrower Loans, Loans Held for Sale and Notes are included in “Change in Fair Value of Borrower Loans, Loans Held for Sale and Notes, Net” on the condensed consolidated statements of operations. PFL primarily uses a discounted cash flow model to estimate the fair value of Borrower Loans, Loans Held for Sale and Notes. The key assumptions used in the valuation include default rates and prepayment rates derived primarily from historical performance and discount rates based on estimates of the rates of return that investors would require when investing in financial instruments with similar characteristics. Recent Accounting Pronouncements Accounting Standards Adopted In The Current Period No accounting standards were adopted in the current period for PFL. Accounting Standards Issued, To Be Adopted By PFL In Future Periods No issued and pending accounting standards were identified that are expected to have an impact on PFL.

PROPERTY AND EQUIPMENT, NET

PROPERTY AND EQUIPMENT, NET	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
PROPERTY AND EQUIPMENT, NET	Property and Equipment, Net Property and Equipment consists of the following at the dates presented (in thousands): September 30, 2021 December 31, 2020 Operating lease right-of-use assets $ 17,485 $ 15,767 Computer equipment 14,276 13,841 Internal-use software and website development costs 38,630 33,176 Office equipment and furniture 2,929 2,872 Leasehold improvements 7,167 7,167 Assets not yet placed in service 6,207 5,035 Property and equipment 86,694 77,858 Less: Accumulated depreciation and amortization (56,998) (49,412) Total Property and Equipment, Net $ 29,696 $ 28,446 Depreciation and amortization expense for Property and Equipment, Net for the three months ended September 30, 2021 and September 30, 2020 wa s $2.5 million an d $2.1 million, respectively. Depreciation and amortization expense for Property and Equipment, Net for the nine months ended September 30, 2021 and September 30, 2020 wa s $7.1 million an d $6.0 million, respectively. These charges are included in General and Administrative expenses on the condensed consolidated statements of operations. PMI capitalized internal-use software and website development costs in the amount of $2.6 million and $1.8 million for the three months ended September 30, 2021 and September 30, 2020, respectively. PMI capitalized internal-use software and website development costs in the amount of $7.1 million and $6.5 million for the nine months ended September 30, 2021 and September 30, 2020, respectively. Additionally, disclosures around the operating lease right-of-use assets are included in Note 15.
Prosper Funding LLC
Entity Information [Line Items]
PROPERTY AND EQUIPMENT, NET	Property and Equipment, Net Property and equipment consist of the following as of the dates presented (in thousands): September 30, 2021 December 31, 2020 Internal-use software and web site development costs $ 31,920 $ 26,953 Less accumulated depreciation and amortization (23,195) (20,025) Total property and equipment, net $ 8,725 $ 6,928

BORROWER LOANS, LOANS HELD FOR

BORROWER LOANS, LOANS HELD FOR SALE AND NOTES, AT FAIR VALUE	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
BORROWER LOANS, LOANS HELD FOR SALE AND NOTES, AT FAIR VALUE	Borrower Loans, Loans Held for Sale and Notes, at Fair Value The aggregate principal balances outstanding and fair values of Borrower Loans, Loans Held for Sale, and Notes as of September 30, 2021 and December 31, 2020, are presented in the following table (in thousands): Borrower Loans Loans Held for Sale Notes September 30, 2021 December 31, 2020 September 30, 2021 December 31, 2020 September 30, 2021 December 31, 2020 Aggregate principal balance outstanding $ 253,760 $ 393,642 $ 285,646 $ 279,113 $ 255,848 $ 217,110 Fair value adjustments 920 (15,379) 274 (4,492) (2,606) (8,731) Fair value $ 254,680 $ 378,263 $ 285,920 $ 274,621 $ 253,242 $ 208,379 PMI has offered assistance to qualified borrowers who are facing financial hardship as a result of the COVID-19 pandemic. These relief options include, among other things, the ability to delay up to four monthly loan payments, the ability to reduce minimum monthly payments for up to 12 months and extend the term of the loan by up to 11 months, and waived late and non-sufficient funds fees. Since COVID-19 relief was first offered in March 2020 and through September 30, 2021, approximately 10% of the total outstanding balances of all loans originated on our platform on a cumulative basis have enrolled in at least one of these COVID-19 relief programs. Approximately 1% of the total outstanding balances of all loans originated on our platform are actively enrolled in at least one relief program as of September 30, 2021. Borrower Loans On September 27, 2021, Borrower Loans held by the securitization trusts consolidated by PMI as VIEs were removed from the balance sheet as part of the deconsolidation of those entities. Refer to Note 6 for additional details on this deconsolidation. As of September 30, 2021, outstanding Borrower Loans had original terms to maturity of either 36 or 60 months, had monthly payments with fixed interest rates ranging from 5.31% to 31.82%, and h a d various original maturity dates through September 2026. At December 31, 2020, outstanding Borrower Loans had original maturities of either 36 or 60 months, had monthly payments with fixed interest rates ranging from 5.31% to 31.82%, and had various original maturity dates through December 2025. As of September 30, 2021, Borrower Loans that were 90 days or more delinquent ha d an aggregate principal amount of $0.8 million and a fair value of $0.1 million . As of December 31, 2020, Borrower Loans that were 90 days or more delinquent had an aggregate principal amount of $2.8 million and a fair value of $0.3 million . Prosper places loans on non-accrual status when they are over 120 days past due. As of September 30, 2021 and December 31, 2020, Borrower Loans in non-accrual status had a fair value of $0.1 million a nd $0.4 million, respectively. Loans Held for Sale As of September 30, 2021, outstanding Loans Held for Sale had original terms to maturity between 36 months and 60 months, had mont hly payments with fixed interest rates ranging from 5.31% to 31.82% and had various original maturity dates through September 2026. At December 31, 2020, outstanding Loans Held for Sale had original terms to maturity between 36 months and 60 months , had monthly payments with fixed interest rates ranging from 5.31% to 31.82% and had various original maturity dates through December 2025. Interest income earned on Loans Held for Sale by the Company was $23.7 million and $19.2 million for the nine months e nded September 30, 2021 and September 30, 2020, respectively. As of September 30, 2021, Loans Held for Sale that were 90 days or more delinquent had an aggregate principal amount of $0.8 million and a fair value of $0.1 million. As of December 31, 2020, Loans Held for S ale that were 90 days or more delinquent had an aggregate principal amount of $0.8 million and a fair value of $0.1 million . Prosper places loans on non-accrual status when they are over 120 days past due. As of September 30, 2021 and December 31, 2020, Loans Held for Sale in non-accrual status had a fair value of $0.1 million (for both periods).
Prosper Funding LLC
Entity Information [Line Items]
BORROWER LOANS, LOANS HELD FOR SALE AND NOTES, AT FAIR VALUE	Borrower Loans and Notes, at Fair Value The aggregate principal balances outstanding and fair values of Borrower Loans and Notes as of September 30, 2021 and December 31, 2020, are presented in the following table (in thousands): Borrower Loans Notes September 30, 2021 December 31, 2020 September 30, 2021 December 31, 2020 Aggregate principal balance outstanding $ 253,760 $ 215,373 $ 255,848 $ 217,110 Fair value adjustments 920 (5,703) (2,606) (8,731) Fair value $ 254,680 $ 209,670 $ 253,242 $ 208,379 At September 30, 2021, outstanding Borrower Loans had original terms to maturity of either 36 or 60 months, had monthly payments with fixed interest rates ranging from 5.31% to 31.82% and had various original maturity dates through September 2026. At December 31, 2020, outstanding Borrower Loans had original maturities of either 36 or 60 months, monthly payments with fixed interest rates ranging from 5.31% to 31.82%, and had various original maturity da tes through December 2025. Since COVID-19 relief was first offered in March 2020 and through September 30, 2021, approximately 10% of the total outstanding balances of all loans originated on our platform on a cumulative basis have enrolled in at least one of these COVID-19 relief programs. Approximately 1% of the total outstanding balances of all loans originated on our platform are actively enrolled in at least one relief program as of September 30, 2021. As of September 30, 2021, Borrower Loans that were 90 days or more delinquent had an aggregate principal amount of $0.8 million and a fair value of $0.1 million. As of December 31, 2020, Borrower Loans that were 90 days or more delinquent had an aggregate principal amount of $1.4 million and a fair value of $0.1 million. PFL places loans on non-accrual status when they are over 120 days past due. As of September 30, 2021 and December 31, 2020, Borrower Loans in non-accrual status had a fair value of $0.1 million and $0.2 million, respectively.

SERVICING ASSETS

SERVICING ASSETS	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
SERVICING ASSETS	Servicing AssetsProsper accounts for Servicing Assets at their estimated fair values with changes in fair values recorded in Servicing Fees. The initial asset or liability is recognized when Prosper sells Borrower Loans to unrelated third-party buyers through the Whole Loan Channel and the servicing rights are retained. The Servicing Assets are measured at fair value throughout the servicing period. The total gains recognized on the sale of such Borrower Loans for the three months ended September 30, 2021 and 2020 were $1.9 million and $0.8 million, respectively, recognized in Gain on Sale of Borrower Loans on the condensed consolidated statements of operations. The total gains recognized on the sale of such Borrower Loans for the nine months ended September 30, 2021 and 2020 were $4.9 million and $3.1 million, respe ctively, recognized in Gain on Sale of Borrower Loans on the condensed consolidated statements of operations . As of September 30, 2021, Borrower Loans that were sold but for which Prosper retained servicing rights had a total outstanding principal balance of $2.3 billion , original terms of either 36 or 60 months, monthly payments with fixed interest rates ranging fr om 5.31% to 31.82%, and various original maturity dates through September 2026 . A t December 31, 2020, Borrower Loans that were sold but for which Prosper retained servicing rights had a total outstanding principal balance of $2.4 billion, original terms of either 36 or 60 months, monthly payments with fixed interest rates ranging from 5.31% to 31.82%, and various original maturity dates through December 2025. Contractually-specified servicing fees and ancillary fees tota ling $6.3 million a nd $6.7 million for the three months ended September 30, 2021 and 2020 , respectively, and $18.1 million and $23.2 million for the nine months ended September 30, 2021 and 2020 , respectively, are included on the condensed consolidated statements of operations in Servicing Fees, Net. Fair Value Valuation Method Prosper uses a discounted cash flow valuation methodology generally consisting of developing an estimate of future cash flows that are expected to occur over the life of a financial instrument and then discounting those cash flows at a rate of return that results in the fair value amount. Significant unobservable inputs presented in the table within Note 7 below are those that Prosper considers significant to the estimated fair values of the Level 3 Servicing Assets. The following is a description of the significant unobservable inputs provided in the table. Market Servicing Rate Prosper estimates adequate market servicing rates that would fairly compensate a substitute servicer should one be required, which includes the profit that would be demanded in the marketplace. This rate is stated as a fixed percentage of outstanding principal balance on a per annum basis. With the assistance of a valuation specialist, Prosper estimated these market servicing rates based on observable market rates for other loan types in the industry and bids from subservicing providers, adjusted for the unique loan attributes that are present in the specific loans that Prosper sells and services and information from backup service providers. Discount Rate The discount rate is a rate of return used to discount future expected cash flows to arrive at a present value, which represents the fair value of the loan servicing rights. We used a range of discount rates for the Servicing Assets based on comparable observed valuations of similar assets and publicly available disclosures related to servicing valuations, with comparability adjustments made to account for differences with Prosper’s servicing assets. Default Rate The default rate presented in Note 7 is an annualized, average estimate considering all Borrower Loan categories (i.e., risk ratings and duration), and represents an aggregate of conditional default rate curves for each credit grade or Borrower Loan category. Each point on a particular Borrower Loan category’s curve represents the percentage of principal expected to default per period based on the term and age of the underlying Borrower Loans. The assumption regarding defaults directly reduces servicing revenues because the amount of servicing revenues received is based on the amount collected each period. Prepayment Rate The prepayment rate presented in Note 7 is an annualized, average estimate considering all Borrower Loan categories (i.e., risk ratings and duration), and represents an aggregate of conditional prepayment rate curves for each credit grade or Borrower Loan category. Each point on a particular Borrower Loan category’s curve represents the percentage of principal expected to prepay per period based on the term and age of the underlying Borrower Loans. Prepayments reduce servicing revenues as they shorten the period over which we expect to collect fees on the Borrower Loans, which is used to project future servicing revenues.
Prosper Funding LLC
Entity Information [Line Items]
SERVICING ASSETS	Servicing Assets PFL accounts for Servicing Assets at their estimated fair values with changes in fair values recorded in Servicing Fees, Net on the condensed consolidated statements of operations. The initial asset or liability is recognized when PFL sells Borrower Loans to unrelated third-party buyers through the Whole Loa n Channel and the servicing rights are retained. The total recognized gains on the sale of such Borrow er Loans was $2.4 million and $1.2 million for the three months ended September 30, 2021 and September 30, 2020, respectively, and $6.1 million and $4.4 million for the nine mont hs ended September 30, 2021 and September 30, 2020, respectively. As of September 30, 2021, Borrower Loans that were sold, but for which PFL retained servicing rights, had a total outstanding principal balance of $2.5 billion, origi nal ter ms of either 36 or 60 months, monthly payments with fixed interest rates ranging from 5.31% to 31.82%, and various original maturity dates through September 2026. At December 31, 2020, Borrower Loans that were sold, but for which PFL retained servicing rights, had a total outstanding principal balance of $2.4 billion, original terms of either 36 or 60 months, monthly payments with fixed interest rates ranging from 5.31% to 31.82%, and various original maturity dates through December 2025. Contractually-specified servicing fees and ancillary fees tot aled $8.8 million and $10.3 million for the three months ended September 30, 2021 and September 30, 2020, respectively, and $27.1 million and $33.3 million for the nine months ended September 30, 2021 and September 30, 2020, respectively, and are included on the condensed consolidated statements of operations in Servicing Fees, Net. Fair Value Valuation Method PFL uses a discounted cash flow valuation methodology generally consisting of developing an estimate of future cash flows that are expected to occur over the life of a financial instrument and then discounting those cash flows at a rate of return that results in the fair value amount. Significant unobservable inputs presented in the table within Note 7 are those that PFL considers significant to the estimated fair values of the Level 3 Servicing Assets. The following is a description of the significant unobservable inputs provided in the table. Market Servicing Rate PFL estimates adequate market servicing rates that would fairly compensate a substitute servicer should one be required, which includes the profit that would be demanded in the marketplace. This rate is stated as a fixed percentage of outstanding principal balance on a per annum basis. With the assistance of a valuation specialist, PFL estimates these market servicing rates based on observable market rates for other loan types in the industry and bids from sub-servicing providers, adjusted for the unique loan attributes that are present in the specific loans that PFL sells and services and information from backup service providers. Discount Rate The discount rate is a rate of return used to discount future expected cash flows to arrive at a present value, which represents the fair value of the loan servicing rights. Management used a range of discount rates for the Servicing Assets based on comparable observed valuations of similar assets and publicly available disclosures related to servicing valuations, with comparability adjustments made to account for differences with PFL’s Servicing Assets. Default Rate The default rate presented in Note 7 is an annualized, average estimate considering all Borrower Loan categories (i.e., risk ratings and duration), and represents an aggregate of conditional default rate curves for each credit grade or Borrower Loan category. Each point on a particular Borrower Loan category’s curve represents the percentage of principal expected to default per period based on the term and age of the underlying Borrower Loans. The assumption regarding defaults directly reduces servicing revenues because the amount of servicing revenues received is based on the amount collected each period. Prepayment Rate The prepayment rate presented in Note 7 is an annualized, average estimate considering all Borrower Loan categories (i.e., risk ratings and duration), and represents an aggregate of conditional prepayment rate curves for each credit grade or Borrower Loan category. Each point on a particular Borrower Loan category’s curve represents the percentage of principal expected to prepay per period based on the term and age of the underlying Borrower Loans. Prepayments reduce servicing revenues as they shorten the period over which PFL expects to collect fees on the Borrower Loans, which is used to project future servicing revenues.

SECURITIZATIONS

SECURITIZATIONS	9 Months Ended
	Sep. 30, 2021
Transfers and Servicing [Abstract]
SECURITIZATIONS	SecuritizationsIn 2019, Prosper co-sponsored and retained residual certificates in securitizations of unsecured personal whole loans facilitated through our marketplace with an aggregate outstanding principal balance of $573.0 million through three securitization trusts (PMIT 2019-1, PMIT 2019-2, and PMIT 2019-4). Each securitization trust issued senior notes, a risk retention interest and residual certificates to finance the purchase of Borrower Loans. The risk retention interest represents the right to receive 5.0% of all amounts collected on the Borrower Loans held by the securitization trusts. The resulting senior notes were sold to third party investors. Prosper retained 65.5%, 16.4%, and 19.6% of the residual certificates issued by PMIT 2019-1, PMIT 2019-2, and PMIT 2019-4, respectively. The remaining residual certificates and all the risk retention interests were held by third-party investors. In addition to the retained residual certificates, Prosper's continued involvement includes loan servicing responsibilities over the life of the underlying loans. PMIT 2019-1, 2019-2 and 2019-4 were deemed VIEs. Prosper consolidated the VIEs as the primary beneficiary because Prosper, through its role as the servicer, had both the power to direct the activities that most significantly affect the VIEs’ economic performance and a variable interest that could potentially be significant to the VIEs through holding the retained residual certificates. In evaluating whether Prosper was the primary beneficiary, management considered both qualitative and quantitative factors regarding the nature, size and form of the Company’s involvement with the VIEs. For these VIEs, the creditors have no recourse to the general credit of Prosper and the liabilities of the VIEs can only be settled by the respective VIEs’ assets. Additionally, the assets of the VIEs can be used only to settle obligations of the VIEs. Because Prosper consolidated the securitization trusts, the loans held in the securitization trusts were included in “Borrower Loans, at Fair Value”, the notes sold to third party investors recorded in “Notes Issued by Securitization Trust”, and the risk retention interests and residual certificates held by third party investors in “Certificates Issued by Securitization Trust, at Fair Value” in the condensed consolidated balance sheets. Management assesses whether Prosper is the primary beneficiary of its VIEs on an on-going basis. On September 27, 2021, PMI sold its retained residual certificates issued by PMIT 2019-1, 2019-2 and 2019-4 to an unrelated third party for $4.1 million in cash. As a result of this sale, management determined that the Company was no longer the primary beneficiary of these entities as it no longer held a variable interest that could potentially be significant to the VIEs. Accordingly, the net assets of PMIT 2019-1, 2019-2 and 2019-4 were deconsolidated from Prosper’s balance sheet on September 27, 2021, resulting in a loss on deconsolidation of $1.5 million, consisting of the following (in thousands): PMIT 2019-1 PMIT 2019-2 PMIT 2019-4 Total Consideration received for residual certificates: Cash $ 2,259 $ 836 $ 981 $ 4,076 Net assets deconsolidated: Restricted Cash $ 2,485 $ 4,324 $ 4,088 $ 10,897 Borrower Loans (1) 15,133 29,989 33,239 78,361 Notes Issued by Securitization Trust (13,022) (26,712) (29,975) (69,709) Certificates Issued by Securitization Trust, at Fair Value (1) (2,057) (5,990) (5,932) (13,979) Total net assets deconsolidated $ 2,539 $ 1,611 $ 1,420 $ 5,570 Total loss on deconsolidation $ (280) $ (775) $ (439) $ (1,494) (1) Because Borrower Loans and Certificates Issued by Securitization Trust are measured at fair value on the Company’s condensed consolidated balance sheets, the balances above reflect the fair values of these financial instruments as of September 27, 2021, the deconsolidation date. This loss on deconsolidation is presented on the accompanying condensed consolidated statement of operations as “Loss on Deconsolidation of VIEs.” Prosper will continue to service the underlying borrower loans, but otherwise will have no continuing involvement with PMIT 2019-1, 2019-2 and 2019-4. In conjunction with the deconsolidation of the VIEs, the Company recognized Servicing Assets totaling $0.2 million, the impact of which is included in Servicing Fees, Net on the accompanying condensed consolidated statement of operations. Consideration received from the sale of the residual certificates, net of Restricted Cash of $10.9 million retained by PMIT 2019-1, 2019-2 and 2019-4, is presented as a financing activity on the Company’s condensed consolidated statement of cash flows, while the loss on deconsolidation is presented as an operating activity.

FAIR VALUE OF ASSETS AND LIABIL

FAIR VALUE OF ASSETS AND LIABILITIES	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
FAIR VALUE OF ASSETS AND LIABILITIES	Fair Value of Assets and LiabilitiesProsper measures the fair value of assets and liabilities in accordance with its fair value hierarchy which prioritizes information used to measure fair value and the effect of fair value measurements on earnings and provides for enhanced disclosures determined by the level within the hierarchy of information used in the valuation. The Company applies this framework whenever other standards require (or permit) assets or liabilities to be measured at fair value. Assets and liabilities carried at fair value on the balance sheets are classified among three levels based on the observability of the inputs used to determine fair value: Level 1 — The valuation is based on quoted prices in active markets for identical instruments. Level 2 — The valuation is based on observable inputs such as quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation methodologies for which all significant assumptions are observable in the market. Level 3 — The valuation is based on unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the instrument. Level 3 valuations are typically performed using pricing models, discounted cash flow methodologies, or similar methodologies, which incorporate management’s own estimates of assumptions that market participants would use in pricing the instrument or valuations that require significant management judgment or estimation. Fair values of assets or liabilities are determined based on the fair value hierarchy, which requires an entity to maximize the use of quoted prices and observable inputs and to minimize the use of unobservable inputs when measuring fair value. Various valuation methodologies are utilized, depending on the nature of the financial instrument, including the use of market prices for identical or similar instruments, or discounted cash flow models. When possible, active and observable market data for identical or similar financial instruments are utilized. Alternatively, fair value is determined using assumptions that management believes a market participant would use in pricing the asset or liability. Prosper did not transfer any assets or liabilities in or out of Level 3 for the nine months ended September 30, 2021 or September 30, 2020. Financial Instruments Recorded at Fair Value The fair value of the Borrower Loans, Loans Held for Sale, Notes, Certificates Issued by Securitization Trust, Servicing Rights and loan trailing fee liability are estimated using discounted cash flow methodologies based upon a set of valuation assumptions. The primary assumptions used in the discounted cash flow model include default and prepayment rates primarily derived from historical performance and discount rates applied to each credit grade based on the perceived credit risk of each credit grade. The Convertible Preferred Stock Warrant Liability is valued using a Black-Scholes option pricing model. Refer to Note 12 for further details. The following tables present the fair value hierarchy for assets and liabilities measured at fair value (in thousands): September 30, 2021 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans, at Fair Value $ — $ — $ 254,680 $ 254,680 Loans Held for Sale at Fair Value — — 285,920 285,920 Servicing Assets — — 8,701 8,701 Total Assets $ — $ — $ 549,301 $ 549,301 Liabilities: Notes, at Fair Value $ — $ — $ 253,242 $ 253,242 Convertible Preferred Stock Warrant Liability — — 249,164 249,164 Loan Trailing Fee Liability — — 2,183 2,183 Total Liabilities $ — $ — $ 504,589 $ 504,589 December 31, 2020 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans, at Fair Value $ — $ — $ 378,263 $ 378,263 Loans Held for Sale at Fair Value — — 274,621 274,621 Servicing Assets — — 9,242 9,242 Total Assets $ — $ — $ 662,126 $ 662,126 Liabilities: Notes, at Fair Value $ — $ — $ 208,379 $ 208,379 Certificates Issued by Securitization Trust, at Fair Value — — 22,917 22,917 Convertible Preferred Stock Warrant Liability — — 112,319 112,319 Loan Trailing Fee Liability — — 2,233 2,233 Total Liabilities $ — $ — $ 345,848 $ 345,848 As PMI’s Borrower Loans, Loans Held for Sale, Notes, Certificates Issued by Securitization Trust, Convertible Preferred Stock Warrant Liability, servicing assets and loan trailing fee liability do not trade in an active market with readily observable prices, the Company uses significant unobservable inputs to measure the fair value of these assets and liabilities. Financial instruments are categorized in the Level 3 valuation hierarchy based on the significance of unobservable factors in the overall fair value measurement. These fair value estimates may also include observable, actively quoted components derived from external sources. As a result, gains and losses for assets and liabilities within the Level 3 category may include changes in fair value that were attributable to both observable and unobservable inputs. Prosper did not transfer any assets or liabilities in or out of Level 3 for the nine months ended September 30, 2021 and September 30, 2020. Significant Unobservable Inputs The following tables present quantitative information about the ranges of significant unobservable inputs used for the Company’s Level 3 fair value measurements at September 30, 2021 and December 31, 2020: Range Borrower Loans, Loans Held for Sale and Notes: September 30, 2021 December 31, 2020 Discount rate 4.6% - 15.1% 4.5% - 17.7% Default rate 2.0% - 16.9% 2.3% - 17.9% Range Certificates Issued by Securitization Trust: December 31, 2020 Discount rate 3.3% - 16.0% Default rate 3.2% - 15.3% Prepayment rate 7.6% - 35.4% Borrower Loans held in consolidated securitization trusts and the associated Certificates Issued by Securitization Trust were deconsolidated from the Company’s balance sheet as of September 27, 2021 (Note 6), and as a result the tables above exclude these financial instruments. Refer to the section below for information about the inputs used to measure the fair value of these Borrower Loans and Certificates Issued by Securitization Trust. Range Servicing Assets: September 30, 2021 December 31, 2020 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.6% - 14.7% 1.9% - 17.7% Prepayment rate 10.3% - 29.1% 12.4% - 28.9% Market servicing rate (1) (2) 0.648% - 0.842% 0.625% - 0.818% (1) Servicing assets associated with loans enrolled in a relief program offered by the Company in response to the COVID-19 pandemic as of September 30, 2021 and December 31, 2020 were measured using a market servicing rate assumption of 84.2 basis points. This rate was estimated using a multiplier consistent with observable market rates for other loan types, applied to the base market servicing rate assumption of 64.8 basis points. (2) Excludes collection fees that would be passed on to a hypothetical third-party servicer. As of September 30, 2021 and December 31, 2020, the market rate for collection fees and non-sufficient fund fees was assumed to be 6 basis points and 7 basis points, respectively, for a total market servicing rate range of 70.8 - 90.2 basis points and a total market servicing rate of 69.5 - 88.8 basis points, respectively. Range Loan Trailing Fee Liability September 30, 2021 December 31, 2020 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.6% - 14.7% 1.9% - 17.7% Prepayment rate 10.3% - 29.1% 12.4% - 28.9% At September 30, 2021 and December 31, 2020, the discounted cash flow methodology used to estimate the Notes fair values used the same projected cash flows as the related Borrower Loans. Deconsolidated Assets and Liabilities As discussed in Note 6, the Company deconsolidated its Borrower Loans held in securitization trusts and Certificates Issued by Securitization Trust on September 27, 2021. The amounts deconsolidated for these financial instruments represent their estimated fair value on that date. Borrower Loan fair value measurements were determined using significant unobservable inputs, as described in the previous section. Key assumptions for the valuation of Borrower Loans are presented in the following table (in thousands, except percentages): Borrower Loans September 27, 2021 Fair value, using the following assumptions: $ 78,361 Weighted-average discount rate 9.26 % Weighted-average default rate 8.13 % Because the residual certificates held by the Company were sold in a market transaction to an unrelated third party, it was determined that the sales price was a fair representation of their fair value. Market assumptions were derived from the sale and utilized to estimate the fair value of the risk retention interests as well. Key assumptions for the valuation of Certificates Issued by Securitization Trust are presented in the following table (in thousands, except percentages): Certificates Issued by Securitization Trust September 27, 2021 Fair value, using the following assumptions: $ 13,979 Weighted-average discount rate 7.99 % Weighted-average default rate 7.68 % Weighted-average prepayment rate 17.94 % Changes in Level 3 Fair Value Assets and Liabilities on a Recurring Basis The following tables present additional information about Level 3 Borrower Loans, Loans Held for Sale, Notes and Certificates Issued by Securitization Trust measured at fair value on a recurring basis (in thousands): Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held For Sale Notes Certificates Issued by Securitization Trust Total Balance at January 1, 2021 $ 378,263 $ 274,621 $ (208,379) $ (22,917) $ 421,588 Purchase of Borrower Loans/Issuance of Notes 172,082 1,248,316 (172,231) — 1,248,167 Principal repayments (215,076) (117,876) 126,528 14,935 (191,489) Borrower Loans sold to third parties (2,311) (1,118,526) — — (1,120,837) Other changes (1,545) (34) 205 113 (1,261) Change in fair value 1,628 (581) 635 (6,110) (4,428) Deconsolidation of VIEs (Note 6) (78,361) — — 13,979 (64,382) Balance at September 30, 2021 $ 254,680 $ 285,920 $ (253,242) $ — $ 287,358 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held for Sale Notes Certificates Issued by Securitization Trust Total Balance at January 1, 2020 $ 634,019 $ 142,026 $ (244,171) $ (52,168) $ 479,706 Purchase of Borrower Loans/Issuance of Notes 97,406 949,529 (97,303) — 949,632 Principal repayments (259,210) (72,885) 114,050 16,608 (201,437) Borrower Loans sold to third parties (5,637) (754,284) — — (759,921) Other changes (1,084) 943 (24) 390 225 Change in fair value (50,617) (12,886) 20,517 8,389 (34,597) Balance at September 30, 2020 $ 414,877 $ 252,443 $ (206,931) $ (26,781) $ 433,608 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held For Sale Notes Certificates Issued by Securitization Trust Total Balance at July 1, 2021 $ 338,939 $ 249,955 $ (236,041) $ (15,295) $ 337,558 Purchase of Borrower Loans/Issuance of Notes 64,473 455,642 (64,028) — 456,087 Principal repayments (69,094) (44,422) 45,486 4,042 (63,988) Borrower Loans sold to third parties (587) (375,192) — — (375,779) Other changes (353) 233 (14) 41 (93) Change in fair value (337) (296) 1,355 (2,767) (2,045) Deconsolidation of VIEs (Note 6) (78,361) — — 13,979 (64,382) Balance at September 30, 2021 $ 254,680 $ 285,920 $ (253,242) $ — $ 287,358 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held for Sale Notes Certificates Issued by Securitization Trust Total Balance at July 1, 2020 $ 457,487 $ 216,243 $ (209,987) $ (31,571) $ 432,172 Purchase of Borrower Loans/Issuance of Notes 31,742 327,407 (32,260) — 326,889 Principal repayments (79,658) (29,809) 36,943 6,733 (65,791) Borrower Loans sold to third parties (1,383) (262,502) — — (263,885) Other changes (926) 164 233 49 (480) Change in fair value 7,615 940 (1,860) (1,992) 4,703 Balance at September 30, 2020 $ 414,877 $ 252,443 $ (206,931) $ (26,781) $ 433,608 The following tables present additional information about Level 3 Servicing Assets measured at fair value on a recurring basis for the three and nine month periods ending September 30, 2021 and 2020 (in thousands): Servicing Assets Fair Value at January 1, 2021 $ 9,242 Additions 5,674 Recognition of Servicing Assets upon deconsolidation of VIEs (Note 6) 215 Less: Changes in fair value (6,430) Fair Value at September 30, 2021 $ 8,701 Servicing Assets Fair Value at January 1, 2020 $ 12,602 Additions 3,945 Less: Changes in fair value (7,241) Fair Value at September 30, 2020 $ 9,306 Servicing Assets Fair Value at July 1, 2021 $ 8,944 Additions 1,895 Recognition of Servicing Assets upon deconsolidation of VIEs (Note 6) 215 Less: Changes in fair value (2,353) Fair Value at September 30, 2021 $ 8,701 Servicing Assets Fair Value at July 1, 2020 $ 10,073 Additions 1,242 Less: Changes in fair value (2,009) Fair Value at September 30, 2020 $ 9,306 The following tables present additional information about the Level 3 Convertible Preferred Stock Warrant Liability measured at fair value on a recurring basis for the nine month periods ending September 30, 2021 and 2020 (in thousands): Convertible Preferred Stock Balance as of January 1, 2021 $ 112,319 Change in fair value 136,845 Balance as of September 30, 2021 $ 249,164 Convertible Preferred Stock Balance as of January 1, 2020 $ 149,996 Change in fair value (63,624) Balance as of September 30, 2020 $ 86,372 Convertible Preferred Stock Balance as of July 1, 2021 $ 162,436 Change in fair value 86,728 Balance as of September 30, 2021 $ 249,164 Convertible Preferred Stock Balance as of July 1, 2020 $ 74,998 Change in fair value 11,374 Balance as of September 30, 2020 $ 86,372 Loan Trailing Fee The fair value of the Loan Trailing Fee represents the present value of the expected monthly Loan Trailing Fee payments, which takes into consideration certain assumptions related to expected prepayment rates and default rates using a discounted cash flow model. The assumptions used are the same as those used for the valuation of Servicing Assets, as described below. The following tables present additional information about the Level 3 Loan Trailing Fee Liability measured at fair value on a recurring basis for the nine month periods ending September 30, 2021 and 2020 (in thousands): Loan Trailing Fee Liability Balance at January 1, 2021 $ 2,233 Issuances 1,289 Cash Payment of Loan Trailing Fee (1,587) Change in Fair Value 248 Balance at September 30, 2021 $ 2,183 Loan Trailing Fee Liability Balance at January 1, 2020 $ 2,997 Issuances 938 Cash Payment of Loan Trailing Fee (1,867) Change in Fair Value 194 Balance at September 30, 2020 $ 2,262 Loan Trailing Fee Liability Balance at July 1, 2021 $ 2,145 Issuances 472 Cash Payment of Loan Trailing Fee (521) Change in Fair Value 87 Balance at September 30, 2021 $ 2,183 Loan Trailing Fee Liability Balance at July 1, 2020 $ 2,403 Issuances 313 Cash Payment of Loan Trailing Fee (596) Change in Fair Value 142 Balance at September 30, 2020 $ 2,262 Significant Recurring Level 3 Fair Value Input Sensitivity Key economic assumptions and the sensitivity of the fair value to immediate changes in those assumptions at September 30, 2021 and December 31, 2020 for Borrower Loans and Loans Held for Sale are presented in the following table (in thousands, except percentages). Borrower Loans and Loans Held for Sale September 30, 2021 December 31, 2020 Fair value, using the following assumptions: $ 540,600 $ 652,884 Weighted-average discount rate 6.50 % 8.26 % Weighted-average default rate 9.78 % 11.58 % Fair value resulting from: 100 basis point increase in discount rate $ 535,208 $ 647,093 200 basis point increase in discount rate $ 529,952 $ 641,437 Fair value resulting from: 100 basis point decrease in discount rate $ 546,133 $ 658,817 200 basis point decrease in discount rate $ 551,813 $ 664,895 Fair value resulting from: 10 percent increase in default rate $ 535,886 $ 646,421 20 percent increase in default rate $ 531,204 $ 639,987 Fair value resulting from: 10 percent decrease in default rate $ 545,341 $ 659,377 20 percent decrease in default rate $ 550,113 $ 665,904 Key economic assumptions and the sensitivity of the fair value to immediate changes in those assumptions at September 30, 2021 and December 31, 2020 for Notes are presented in the following table (in thousands, except percentages). Notes September 30, 2021 December 31, 2020 Fair value, using the following assumptions: $ 253,242 $ 208,379 Weighted-average discount rate 6.71 % 8.93 % Weighted-average default rate 10.66 % 12.26 % Fair value resulting from: 100 basis point increase in discount rate $ 250,713 $ 206,528 200 basis point increase in discount rate $ 248,247 $ 204,720 Fair value resulting from: 100 basis point decrease in discount rate $ 255,838 $ 210,274 200 basis point decrease in discount rate $ 258,503 $ 212,217 Fair value resulting from: 10 percent increase in default rate $ 251,021 $ 206,304 20 percent increase in default rate $ 248,814 $ 204,238 Fair value resulting from: 10 percent decrease in default rate $ 255,477 $ 210,463 20 percent decrease in default rate $ 257,727 $ 212,558 Key economic assumptions and the sensitivity of the fair value to immediate changes in those assumptions at September 30, 2021 and December 31, 2020 for Servicing Assets is presented in the following table (in thousands, except percentages). Servicing Assets September 30, 2021 December 31, 2020 Fair value, using the following assumptions $ 8,701 $ 9,242 Weighted-average market servicing rate 0.650 % 0.631 % Weighted-average prepayment rate 18.89 % 19.84 % Weighted-average default rate 12.18 % 12.78 % Fair value resulting from: Market servicing rate increase of 0.025% $ 8,148 $ 8,689 Market servicing rate decrease of 0.025% $ 9,255 $ 9,796 Fair value resulting from: Applying a 1.1 multiplier to prepayment rate $ 8,532 $ 9,064 Applying a 0.9 multiplier to prepayment rate $ 8,872 $ 9,423 Fair value resulting from: Applying a 1.1 multiplier to default rate $ 8,586 $ 9,116 Applying a 0.9 multiplier to default rate $ 8,817 $ 9,369 These sensitivities are hypothetical and should be evaluated with care. The effect on fair value of a variation in assumptions generally cannot be determined because the relationship of the change in assumptions to the fair value may not be linear. Additionally, the impact of a variation in a particular assumption on the fair value is calculated while holding other assumptions constant. In reality, changes in one factor may lead to changes in other factors, which could impact the above hypothetical effects. Assets and Liabilities Not Recorded at Fair Value The following table presents the fair value hierarchy for assets, and liabilities not recorded at fair value (in thousands): September 30, 2021 Carrying Amount Level 1 Inputs Level 2 Inputs Level 3 Inputs Balance at Fair Value Assets: Cash and Cash Equivalents $ 55,949 $ 55,949 $ — $ — $ 55,949 Restricted Cash - Cash and Cash Equivalents 152,024 152,024 — — 152,024 Restricted Cash - Certificates of Deposit 4,877 — 4,877 — 4,877 Accounts Receivable 749 — 749 — 749 Total Assets $ 213,599 $ 207,973 $ 5,626 $ — $ 213,599 Liabilities: Accounts Payable and Accrued Liabilities $ 23,807 $ — $ 23,807 $ — $ 23,807 Payable to Investors 141,115 — 141,115 — 141,115 Warehouse Lines 245,819 — 247,769 — 247,769 Paycheck Protection Program loan (Note 10) 8,568 — 8,557 — 8,557 Total Liabilities $ 419,309 $ — $ 421,248 $ — $ 421,248 December 31, 2020 Carrying Amount Level 1 Inputs Level 2 Inputs Level 3 Inputs Balance at Fair Value Assets: Cash and Cash Equivalents $ 50,145 $ 50,145 $ — $ — $ 50,145 Restricted Cash - Cash and Cash Equivalents 158,846 158,846 — — 158,846 Restricted Cash - Certificates of Deposit 4,877 — 4,877 — 4,877 Accounts Receivable 605 — 605 — 605 Total Assets $ 214,473 $ 208,991 $ 5,482 $ — $ 214,473 Liabilities: Accounts Payable and Accrued Liabilities $ 17,876 $ — $ 17,876 $ — $ 17,876 Payable to Investors 124,094 — 124,094 — 124,094 Notes Issued by Securitization Trust 156,782 — 158,951 — 158,951 Warehouse Lines 242,479 — 242,261 — 242,261 Paycheck Protection Program loan (Note 10) 8,505 — 8,540 — 8,540 Total Liabilities $ 549,736 $ — $ 551,722 $ — $ 551,722 The estimated fair values of Cash and Cash Equivalents, Restricted Cash, Accounts Receivable, Accounts Payable and Accrued Liabilities and Payable to Investors approximate their carrying values because of their short-term nature.
Prosper Funding LLC
Entity Information [Line Items]
FAIR VALUE OF ASSETS AND LIABILITIES	Fair Value of Assets and Liabilities PFL has elected to record certain financial instruments at fair value on the balance sheet. PFL classifies Borrower Loans, Loans Held for Sale and Notes as financial instruments and assesses their fair value each on a quarterly basis for financial statement presentation purposes. Gains and losses on these financial instruments are shown separately on the condensed consolidated statements of operations. As of September 30, 2021 and December 31, 2020, the discounted cash flow methodology used to estimate the Notes fair values used the same projected cash flows as the related Borrower Loans. As demonstrated in the table below, the fair value adjustments for Borrower Loans were largely offset by the fair value adjustments of the Notes due to the borrower payment dependent design of the Notes and because the principal balances of the Borrower Loans approximated the principal balances of the Notes. Assets and liabilities carried at fair value on the balance sheets are classified among three levels based on the observability of the inputs used to determine fair value: Level 1 — The valuation is based on quoted prices in active markets for identical instruments. Level 2 — The valuation is based on observable inputs such as quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation methodologies for which all significant assumptions are observable in the market. Level 3 — The valuation is based on unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the instrument. Level 3 valuations are typically performed using pricing models, discounted cash flow methodologies, or similar methodologies, which incorporate management’s own estimates of assumptions that market participants would use in pricing the instrument or valuations that require significant management judgment or estimation. Fair values of assets or liabilities are determined based on the fair value hierarchy, which requires an entity to maximize the use of quoted prices and observable inputs and to minimize the use of unobservable inputs when measuring fair value. Various valuation methodologies are utilized, depending on the nature of the financial instrument, including the use of market prices for identical or similar instruments, or discounted cash flow models. When possible, active and observable market data for identical or similar financial instruments are utilized. Alternatively, fair value is determined using assumptions that management believes a market participant would use in pricing the asset or liability. PFL did not transfer any assets or liabilities in or out of Level 3 for the nine months ended September 30, 2021 or 2020. Financial Instruments Recorded at Fair Value The fair value of the Borrower Loans and Notes are estimated using discounted cash flow methodologies based upon a set of valuation assumptions. The primary cash flow assumptions used to value such Borrower Loans and Notes include default and prepayment rates derived primarily from historical performance and discount rates that reflect estimates of the rates of return that investors would require when investing in financial instruments with similar characteristics. The following tables present the fair value hierarchy for assets and liabilities measured at fair value (in thousands): September 30, 2021 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans, at Fair Value $ — $ — $ 254,680 $ 254,680 Servicing Assets — — 9,968 9,968 Total Assets $ — $ — $ 264,648 $ 264,648 Liabilities: Notes, at Fair Value $ — $ — $ 253,242 $ 253,242 Loan Trailing Fee Liability — — 2,183 2,183 Total Liabilities $ — $ — $ 255,425 $ 255,425 December 31, 2020 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans, at Fair Value $ — $ — $ 209,670 $ 209,670 Servicing Assets — — 11,088 11,088 Total Assets $ — $ — $ 220,758 $ 220,758 Liabilities: Notes, at Fair Value $ — $ — $ 208,379 $ 208,379 Loan Trailing Fee Liability — — 2,233 2,233 Total Liabilities $ — $ — $ 210,612 $ 210,612 As PFL’s Borrower Loans, Notes, Servicing Assets and loan trailing fee liability do not trade in an active market with readily observable prices, PFL uses significant unobservable inputs to measure the fair value of these assets and liabilities. Financial instruments are categorized in the Level 3 valuation hierarchy based on the significance of unobservable factors in the overall fair value measurement. These fair value estimates may also include observable, actively quoted components derived from external sources. As a result, the realized and unrealized gains and losses for assets and liabilities within the Level 3 category may include changes in fair value that were attributable to both observable and unobservable inputs. Significant Unobservable Inputs The following tables present quantitative information about the significant unobservable inputs used for PFL’s Level 3 fair value measurements at the dates presented: Range Borrower Loans and Notes September 30, 2021 December 31, 2020 Discount rate 4.6% - 15.0% 5.3% - 16.1% Default rate 2.0% - 14.0% 2.6% - 16.2% Range Servicing Assets September 30, 2021 December 31, 2020 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.6% - 14.7% 1.9% - 17.7% Prepayment rate 10.3% - 29.1% 12.4% - 28.9% Market servicing rate (1) (2) 0.648% - 0.842% 0.625% - 0.818% (1) Servicing assets associated with loans enrolled in a relief program offered by the Company in response to the COVID-19 pandemic as of September 30, 2021 and December 31, 2020 were measured using a market servicing rate assumption of 84.2 basis points. This rate was estimated using a multiplier consistent with observable market rates for other loan types, applied to the base market servicing rate assumption of 64.8 basis points. (2) Excludes collection fees that would be passed on to a hypothetical third-party servicer. As of September 30, 2021 and December 31, 2020, the market rate for collection fees and non-sufficient fund fees was assumed to be 6 basis points and 7 basis points, respectively, for a total market servicing rate range of 70.8 - 90.2 basis points and a total market servicing rate of 69.5 - 88.8 basis points, respectively. Range Loan Trailing Fee Liability September 30, 2021 December 31, 2020 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.6% - 14.7% 1.9% - 17.7% Prepayment rate 10.3% - 29.1% 12.4% - 28.9% Changes in Level 3 Fair Value Assets and Liabilities on a Recurring Basis The following tables present additional information about Level 3 Borrower Loans, Loans Held for Sale and Notes measured at fair value on a recurring basis (in thousands): Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held for Sale Notes Total Balance at January 1, 2021 $ 209,670 $ — $ (208,379) $ 1,291 Originations 172,082 1,248,316 (172,231) 1,248,167 Principal repayments (125,672) — 126,528 856 Borrower Loans sold to third parties (1,069) (1,248,316) — (1,249,385) Other changes (223) — 205 (18) Change in fair value (108) — 635 527 Balance at September 30, 2021 $ 254,680 $ — $ (253,242) $ 1,438 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held for Sale Notes Total Balance at January 1, 2020 $ 245,137 $ — $ (244,171) $ 966 Originations 97,406 949,529 (97,303) 949,632 Principal repayments (112,034) — 114,051 2,017 Borrower Loans sold to third parties (2,111) (949,529) — (951,640) Other changes (23) — (25) (48) Change in fair value (20,331) — 20,517 186 Balance at September 30, 2020 $ 208,044 $ — $ (206,931) $ 1,113 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held for Sale Notes Total Balance at July 1, 2021 $ 236,844 $ — $ (236,041) $ 803 Originations 64,473 455,642 (64,028) 456,087 Principal repayments (45,338) — 45,486 148 Borrower Loans sold to third parties (300) (455,642) — (455,942) Other changes (15) — (14) (29) Change in fair value (984) — 1,355 371 Balance at September 30, 2021 $ 254,680 $ — $ (253,242) $ 1,438 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held for Sale Notes Total Balance at July 1, 2020 $ 211,775 $ — $ (209,986) $ 1,789 Originations 31,742 327,407 (32,260) 326,889 Principal repayments (36,438) — 36,943 505 Borrower Loans sold to third parties (547) (327,407) — (327,954) Other changes (276) — 232 (44) Change in fair value 1,788 — (1,860) (72) Balance at September 30, 2020 $ 208,044 $ — $ (206,931) $ 1,113 The following tables present additional information about Level 3 Servicing Assets recorded at fair value (in thousands): Servicing Assets Fair Value at January 1, 2021 $ 11,088 Additions 6,676 Less: Changes in fair value (7,796) Fair Value at September 30, 2021 $ 9,968 Servicing Assets Fair Value at January 1, 2020 $ 14,888 Additions 5,034 Less: Changes in fair value (8,657) Fair Value at September 30, 2020 $ 11,265 Servicing Assets Fair Value at July 1, 2021 $ 10,389 Additions 2,300 Less: Changes in fair value (2,721) Fair Value at September 30, 2021 $ 9,968 Servicing Assets Fair Value at July 1, 2020 $ 12,063 Additions 1,632 Less: Changes in fair value (2,430) Fair Value at September 30, 2020 $ 11,265 Loan Trailing Fee Liability The fair value of the Loan Trailing Fee Liability represents the present value of the expected monthly Loan Trailing Fee payments, which takes into consideration certain assumptions related to expected prepayment rates and default rates using a discounted cash flow model. The assumptions used are the same as those used for the valuation of Servicing Assets, as described below. The following tables present additional information about Level 3 Loan Trailing Fee Liability measured at fair value on a recurring basis (in thousands): Loan Trailing Fee Liability Fair Value at January 1, 2021 $ 2,233 Issuances 1,289 Cash payment of Loan Trailing Fee (1,587) Change in fair value 248 Fair Value at September 30, 2021 $ 2,183 Loan Trailing Fee Liability Fair Value at January 1, 2020 $ 2,997 Issuances 938 Cash payment of Loan Trailing Fee (1,867) Change in fair value 194 Fair Value at September 30, 2020 $ 2,262 Loan Trailing Fee Liability Fair Value at July 1, 2021 $ 2,145 Issuances 472 Cash payment of Loan Trailing Fee (521) Change in fair value 87 Fair Value at September 30, 2021 $ 2,183 Loan Trailing Fee Liability Fair Value at July 1, 2020 $ 2,403 Issuances 313 Cash payment of Loan Trailing Fee (596) Change in fair value 142 Fair Value at September 30, 2020 $ 2,262 Significant Recurring Level 3 Fair Value Asset and Liability Input Sensitivity Key economic assumptions are used to compute the fair value of Borrower Loans. The sensitivity of the fair value to immediate changes in assumptions at September 30, 2021 and December 31, 2020 for Borrower Loans are presented in the following table (in thousands, except percentages). Borrower Loans: September 30, 2021 December 31, 2020 Fair value, using the following assumptions: $ 254,680 $ 209,670 Weighted-average discount rate 6.71 % 8.93 % Weighted-average default rate 10.66 % 12.26 % Fair value resulting from: 100 basis point increase in discount rate $ 252,139 $ 207,810 200 basis point increase in discount rate $ 249,663 $ 205,994 Fair value resulting from: 100 basis point decrease in discount rate $ 257,286 $ 211,575 200 basis point decrease in discount rate $ 259,962 $ 213,527 Fair value resulting from: 10 percent increase in default rate $ 252,459 $ 207,594 20 percent increase in default rate $ 250,253 $ 205,528 Fair value resulting from: 10 percent decrease in default rate $ 256,914 $ 211,755 20 percent decrease in default rate $ 259,161 $ 213,851 Key economic assumptions are used to compute the fair value of Notes. The sensitivity of the fair value to immediate changes in assumptions at September 30, 2021 and December 31, 2020 for Notes funded through the Note Channel are presented in the following table (in thousands, except percentages). Notes September 30, 2021 December 31, 2020 Fair value, using the following assumptions: $ 253,242 $ 208,379 Weighted-average discount rate 6.71 % 8.93 % Weighted-average default rate 10.66 % 12.26 % Fair value resulting from: 100 basis point increase in discount rate $ 250,713 $ 206,528 200 basis point increase in discount rate $ 248,247 $ 204,720 Fair value resulting from: 100 basis point decrease in discount rate $ 255,838 $ 210,274 200 basis point decrease in discount rate $ 258,503 $ 212,217 Fair value resulting from: 10 percent increase in default rate $ 251,021 $ 206,304 20 percent increase in default rate $ 248,814 $ 204,238 Fair value resulting from: 10 percent decrease in default rate $ 255,477 $ 210,463 20 percent decrease in default rate $ 257,727 $ 212,558 Key economic assumptions are used to compute the fair value of Servicing Assets. The sensitivity of the current fair value to immediate changes in assumptions at September 30, 2021 and December 31, 2020 for Servicing Assets are presented in the following table (in thousands, except percentages). Servicing Assets September 30, 2021 December 31, 2020 Fair value, using the following assumptions: $ 9,968 $ 11,088 Weighted-average market servicing rate 0.650 % 0.631 % Weighted-average prepayment rate 18.89 % 19.84 % Weighted-average default rate 11.83 % 12.78 % Fair value resulting from: Market servicing rate increase of 0.025% $ 9,333 $ 10,424 Market servicing rate decrease of 0.025% $ 10,602 $ 11,752 Fair value resulting from: Applying a 1.1 multiplier to prepayment rate $ 9,774 $ 10,874 Applying a 0.9 multiplier to prepayment rate $ 10,164 $ 11,304 Fair value resulting from: Applying a 1.1 multiplier to default rate $ 9,836 $ 10,936 Applying a 0.9 multiplier to default rate $ 10,100 $ 11,239 These sensitivities are hypothetical and should be evaluated with care. The effect on fair value of a variation in assumptions generally cannot be determined because the relationship of the change in assumptions to the fair value may not be linear. Additionally, the impact of a variation in a particular assumption on the fair value is calculated while holding other assumptions constant. In reality, changes in one factor may lead to changes in other factors, which could impact the above hypothetical effects.

GOODWILL AND OTHER INTANGIBLE A

GOODWILL AND OTHER INTANGIBLE ASSETS, NET	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND OTHER INTANGIBLE ASSETS, NET	Goodwill and Other Intangible Assets, Net Goodwill Prosper’s goodwill balance of $36.4 million at December 31, 2020 did not change during the nine months ended September 30, 2021. The Company recorded no goodwill impairment for the nine months ended September 30, 2021 and 2020. Other Intangible Assets The following table presents the detail of other intangible assets subject to amortization as of the following date (dollars in thousands): September 30, 2021 Gross Carrying Value Accumulated Amortization Net Carrying Value Remaining Useful Life (In Years) Developed technology $ 3,060 $ (3,060) $ — — User base and customer relationships 5,050 (4,679) 371 3.6 Brand name 60 (60) — — Total Intangible Assets subject to amortization $ 8,170 $ (7,799) $ 371 Prosper’s intangible asset balance w as $0.4 million and $0.5 million at September 30, 2021 and December 31, 2020, respectively. The user base and customer relationships intangible assets are being amortized on an accelerated basis over a three Amortization expense for the three months ended September 30, 2021 and 2020 was not material and $0.1 million, respectively. Amortization expense for the nine months ended September 30, 2021 and 2020 was $0.1 million and $0.2 million, respectively. Estimated amortization of purchased intangible assets for future periods is as follows (in thousands): Year Ending December 31, 2021 (remainder thereof) $ 43 2022 136 2023 107 2024 85 Total $ 371

OTHER LIABILITIES

OTHER LIABILITIES	9 Months Ended
	Sep. 30, 2021
Other Liabilities [Abstract]
OTHER LIABILITIES	Other Liabilities Other Liabilities consist of the following (in thousands): September 30, 2021 December 31, 2020 Operating lease liabilities $ 12,316 $ 13,342 Paycheck Protection Program loan (Note 10) 8,568 8,505 Loan trailing fee liability 2,183 2,233 Deferred income tax liability 552 489 Financing lease liabilities 155 — Deferred revenue 50 63 Other 280 425 Total Other Liabilities $ 24,104 $ 25,057 Additionally, disclosures around the operating lease liabilities are included in Note 15.

DEBT

DEBT	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
DEBT	Debt PWIT Warehouse Trust Agreements Prosper’s consolidated VIEs, PWIT and PWIIT (together, “Warehouse VIEs”), each entered into an agreement (together, “Warehouse Agreements”) with certain lenders for committed revolving lines of credit (“Warehouse Lines”) during 2018 and 2019, respectively. In connection with the Warehouse Agreements, the Warehouse VIEs each entered into a security agreement with a bank as administrative agent and a national banking association as collateral trustee and paying agent. Proceeds under the Warehouse Lines may only be used to purchase certain unsecured consumer loans and related rights and documents from Prosper and to pay fees and expenses related to the Warehouse Lines. Both Warehouse VIEs are consolidated because Prosper is the primary beneficiary of the VIEs. The assets of the VIEs can be used only to settle obligations of the VIEs. Additionally, the creditors of the Warehouse Lines have no recourse to the general credit of Prosper. The loans held in the Warehouse VIEs are included in Loans Held for Sale, at Fair Value and Warehouse Lines are in Warehouse Lines in the condensed consolidated balance sheets. Both Warehouse Agreements contain the same certain covenants including restrictions on each Warehouse VIE's ability to incur indebtedness, pledge assets, merge or consolidate and enter into certain affiliate transactions. Each Warehouse Agreement also requires Prosper to maintain a minimum tangible net worth of $25 million, minimum net liquidity of $15 million and a maximum leverage ratio of 5:1. Tangible net worth is defined as the sum of (i) (A) Convertible Preferred Stock, (B) total Stockholders’ Deficit and (C) Convertible Preferred Stock Warrant Liability, less the sum of (ii) (A) goodwill and (B) intangible assets. Net liquidity is defined as the sum of cash, cash equivalents and Available for Sale Investments. The leverage ratio is defined as the ratio of total consolidated indebtedness other than non-recourse securitization indebtedness, non-recourse or limited recourse warehouse indebtedness and borrower dependent notes, to tangible net worth. As of September 30, 2021, Prosper was in compliance with the covenants under each Warehouse Agreement. PWIT Warehouse Line On January 19, 2018, through PWIT, Prosper entered into a Warehouse Agreement for a Warehouse Line. Effective June 12, 2018, the Warehouse Agreement was amended. The amendments included increasing the committed line of credit from $100 million to $200 million, extending the term of the PWIT Warehouse Line (including the final maturity date), amending the monthly unused commitment fee and reducing the rate at which the PWIT Warehouse Line bears interest. Subsequently the Warehouse Agreement was amended on June 20, 2019 to extend the facility, to reduce the interest rate and unused commitment fee and to expand the eligibility criteria for unsecured consumer loans that can be financed through the PWIT Warehouse Line. It was amended again on May 19, 2021 to extend the facility, to reduce the interest and advance rates and to include provisions for an alternative benchmark rate in light of the ongoing phaseout of LIBOR. Under the amended agreement, proceeds of loans made under the PWIT Warehouse Line may be borrowed, repaid and reborrowed until the earlier of June 20, 2023 or the occurrence of any accelerated amortization event or event of default. Repayment of any outstanding proceeds will be made over the 24 month period ending June 20, 2025, excluding the occurrence of any accelerated amortization event or event of default. Under the amended agreement, the PWIT Warehouse Line bears interest at a rate of an established benchmark rate (currently LIBOR) plus 2.75% and has an advance rate of 87%. Additionally, the PWIT Warehouse Line bears a monthly unused commitment fee of 0.50% per annum on the undrawn portion available under the PWIT Warehouse Line. As of September 30, 2021, Prosper had $114.6 million in debt and accrued interest outstanding under the PWIT Warehouse Line. This debt is secured by an aggregate outstanding principal balance of $134.9 million included in “Loans Held for Sale, at Fair Value” on the condensed consolidated balance sheets. At September 30, 2021 the undrawn portion available under the Warehouse Line was $85.4 million. Prosper incurred $2.2 million of deferred debt issuance costs associated with the PWIT Warehouse Line, including $0.3 million from the amendment signed on May 19, 2021, which are included in “Prepaids and Other Assets” and amortized to interest expense over the term of the revolving arrangement. Prosper purchased a swaption to limit the Company's exposure to increases in LIBOR. The swaption is recorded on the consolidated balance sheet at fair value in Prepaids and Other Assets. Any changes in the fair value are recorded in the Change in Fair Value of Financial Instruments, Net on the Consolidated Statement of Operations. The fair value of the swaption was $0.1 million at September 30, 2021. PWIIT Warehouse Line On March 28, 2019, through PWIIT, Prosper entered into a second Warehouse Agreement for a $300 million Warehouse Line with a national banking association different than that of PWIT. Under the PWIIT Warehouse Agreement, proceeds of loans made under the PWIIT Warehouse Line may be borrowed, repaid, and reborrowed until the earlier of March 28, 2021 and at the occurrence of any accelerated amortization event or event of default. Repayment of any outstanding proceeds will be made over the 24-month period ending March 28, 2023, excluding the occurrence of any accelerated amortization event or event of default. On March 4, 2021, PMI extended its $300 million PWIIT Warehouse Line (“PWIIT Extension”). The PWIIT Extension consists of a $230 million Class A loan with the existing PWIIT Warehouse Line national banking association and a $70 million Class B loan with an asset manager. The advance rate on the PWIIT Extension is 90%. Under the PWIIT Extension, proceeds of loans made under the PWIIT Warehouse Line may be borrowed, repaid and reborrowed until the earlier of March 3, 2023 or the occurrence of any accelerated amortization event or event of default. Repayment of any outstanding proceeds will be made over a 24-month period ending March 4, 2025, excluding the occurrence of any accelerated amortization event or event of default. Under the PWIIT Extension, the Class A loan bears interest at a rate of the national banking association's asset-backed commercial paper rate, plus a spread of 2.05%. The spread increases by 0.375% during the first 12 months immediately following the termination of the revolving period with an additional increase of 0.375% one year later. Additionally, the Class A loan bears a monthly unused commitment fee of 0.50% per annum on the undrawn portion available under the Class A loan. The Class B loan bears interest at a rate of one-month LIBOR, plus a spread of 8.75%. The spread increases by 0.375% during the first twelve months immediately following the termination of the revolving period with an additional increase of 0.375% one year later. Additionally, the Class B loan bears a monthly unused commitment fee of 0.50% or 1.00% per annum on the undrawn portion available under the Class B loan, depending on the Class B loan utilization percentage. As of September 30, 2021, Prosper had $131.2 million in debt and accrued interest outstanding under the PWIIT Warehouse Line. This debt is secured by an aggregate outstanding principal balance of $148.6 million included in Loans Held for Sale, at Fair Value on the Consolidated Balance Sheets. At September 30, 2021 the undrawn portion available under the PWIIT Warehouse Line was $168.8 million. PMI incurred $1.3 million of debt issuance costs for the extension in March 2021, which are included in Prepaids and Other Assets and will be amortized to interest expense over the term of the revolving arrangement. Phaseout of LIBOR A portion of the interest rate charged on our Warehouse Lines is currently based on LIBOR. LIBOR has been the subject of reform and was expected to phase out by the end of fiscal 2021; however, on November 30, 2020, the ICE Benchmark Administration Limited (“ICE”) announced plans to delay the phase out of LIBOR to June 30, 2023. The consequences of the discontinuation of LIBOR cannot be entirely predicted but could impact the interest expense incurred on these debt instruments. We have negotiated alternatives to LIBOR on the PWIT and PWIIT Warehouse Lines, which we may renegotiate before LIBOR ceases to be a widely available reference rate. Paycheck Protection Program Loan The Paycheck Protection Program (“PPP”), established by the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) and sponsored by the U.S. Small Business Administration (“SBA”), provides small businesses – sole proprietors, independent contractors, and, with certain industry exceptions, businesses with fewer than 500 employees – the opportunity to apply for a loan of up to $10 million to cover up to 24 weeks (the “covered period”) of payroll costs, including benefits. Funds may also be used to cover interest on mortgage obligations, leases, and utilities incurred or in place before February 15, 2020. PPP loan payments are deferred as described below, and, based on SBA guidance, will be forgiven as long as (i) loan proceeds are used for covered expenses, (ii) full-time employee headcount is maintained during the eight-week period covered by the PPP loan and (iii) compensation for employees who earned less than $100,000 on an annualized basis in 2019 is not reduced by more than 25% during the covered period. For purposes of calculating maximum loan eligibility, payroll costs per employee are capped at $100,000 on an annualized basis. In April 2020, the Company obtained an $8.4 million loan under the PPP. The loan accrues interest at one percent per annum and has a two-year term through April 2022. PMI has formally applied for forgiveness with the lender and the SBA, and that application remains under review. Pursuant to the Paycheck Protection Flexibility Act of 2020, PMI is permitted to defer monthly payments of principal and interest until such time as an approval or denial of forgiveness is received from the SBA. The Company used the PPP Loan proceeds to cover payroll costs, rent and utilities in accordance with the relevant terms and conditions of the CARES Act. As of September 30, 2021, principal and interest outstanding under the PPP loan totaled $8.6 million and is included in Other Liabilities on the accompanying condensed consolidated balance sheet.

NET INCOME (LOSS) PER SHARE

NET INCOME (LOSS) PER SHARE	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
NET INCOME (LOSS) PER SHARE	Net Income (Loss) Per Share PMI computes its net income (loss) per share in accordance with ASC Topic 260, Earnings Per Share (“ASC Topic 260”). Under ASC Topic 260, basic net income (loss) per share is computed by dividing net income (loss) available to common stockholders by the weighted average number of common shares outstanding for the period and excludes the effects of any potentially dilutive securities. Net income (loss) per share is calculated using the two-class method in accordance with ASC Topic 260. The two-class method allocates earnings that otherwise would have been available to common shareholders to holders of participating securities. Management considers all series of our Convertible Preferred Stock to be participating securities due to their rights to participate in dividends with Common Stock. As such, earnings allocated to these participating securities, which include participation rights in undistributed earnings, are subtracted from net income to determine total undistributed earnings to be allocated to common stockholders. All participating securities are excluded from basic weighted-average common shares outstanding. Prior to any conversion to common shares, each series of Prosper’s Convertible Preferred Stock is entitled to participate on an if-converted basis in distributions of earnings, when and if declared by the board of directors, that are made to common stockholders and consequently, these shares were considered participating securities. During the nine months ended September 30, 2021 and September 30, 2020, certain shares issued as a result of the early exercise of stock options which are subject to a repurchase right by PMI were entitled to receive non-forfeitable dividends during the vesting period and consequently, are considered participating securities. The weighted average shares used in calculating basic and diluted net income (loss) per share excludes certain shares that are disclosed as outstanding shares in the condensed consolidated balance sheets because such shares are restricted as they were associated with options that were early exercised and continue to remain unvested. Basic and diluted income (loss) per share were calculated as follows for the periods presented (in thousands, except share and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2021 2021 2020 2021 2020 Numerator: Net (Loss) Income $ (88,061) $ (2,025) $ (138,755) $ 36,746 Plus: Return on Share Purchase — 2,381 — 2,381 Less: Net Income Allocated to Participating Securities — (255) — (28,814) Net (Loss) Income Attributable to Common Stockholders $ (88,061) $ 101 $ (138,755) $ 10,313 Denominator: Weighted average shares used in computing basic net (loss) income per share 71,068,442 68,485,173 70,433,182 68,465,046 Effect of dilutive securities: Stock options — 14,902,171 — 50,778,284 Convertible preferred stock warrants — 213,264,845 — 213,264,845 Weighted average shares used in computing diluted Net (Loss) Income per Share 71,068,442 296,652,189 70,433,182 332,508,175 Net (Loss) Income Per Share – Basic $ (1.24) $ — $ (1.97) $ 0.15 Net (Loss) Income Per Share – Diluted $ (1.24) $ — $ (1.97) $ 0.03 The following common stock equivalents were excluded from the computation of diluted net (loss) income per share for the periods presented because including them would have been anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (shares) (shares) (shares) (shares) Excluded securities: Convertible preferred stock issued and outstanding, excluding shares held by consolidated VIE 158,365,655 181,761,442 158,365,655 200,261,761 Stock options issued and outstanding 70,601,482 58,390,141 72,845,826 22,127,694 Warrants issued and outstanding 1,080,349 1,080,349 1,080,349 1,080,349 Series E-1 convertible preferred stock warrants 35,544,141 — 35,544,141 — Series F convertible preferred stock warrants 177,720,704 — 177,720,704 — Total common stock equivalents excluded from diluted net (loss) income per common share computation 443,312,331 241,231,932 445,556,675 223,469,804

CONVERTIBLE PREFERRED STOCK, CO

CONVERTIBLE PREFERRED STOCK, CONVERTIBLE PREFERRED STOCK WARRANT LIABILITY AND COMMON STOCK	9 Months Ended
	Sep. 30, 2021
Stockholders' Equity Note [Abstract]
CONVERTIBLE PREFERRED STOCK, CONVERTIBLE PREFERRED STOCK WARRANT LIABILITY AND COMMON STOCK	Convertible Preferred Stock, Convertible Preferred Stock Warrant Liability and Common Stock Convertible Preferred Stock and Warrants Under PMI’s amended and restated certificate of incorporation, preferred stock is issuable in series, and the Board of Directors is authorized to determine the rights, preferences, and terms of each series. On July 13, 2020, the Company established Prosper Grantor Trust (“PGT”), a revocable grantor trust administered by an independent trustee, with the intention of contributing assets to PGT for the benefit of PMI employees in the event of a change in control through an Eligible Employee Retention Plan. PGT was determined to be a VIE and PMI was determined to be its primary beneficiary due to the fact that the Company, through its role as the grantor, has both (a) the power to direct the activities that most significantly affect the VIE’s economic performance, including its funding decisions and investment strategy, and (b) the obligation to absorb losses that could be potentially significant to the economic performance of the VIE by virtue of the Company’s requirement to fund PGT in the event that it is unable to meet its obligations to PMI’s employees. PMI also maintains a contingent call liability on PGT’s assets in the event of a bankruptcy. As a result, PGT is fully consolidated into PMI’s consolidated financial statements. On July 21, 2020, PGT entered into a Stock Transfer Agreement with a PMI investor to purchase 34,670,420 shares of Series A Convertible Preferred Stock and 16,577,495 shares of Series B Convertible Preferred Stock for nominal consideration. Upon execution of the Stock Transfer Agreement, these shares were purchased by a consolidated VIE of the Company, and thus the difference between the fair value of the repurchased stock and the purchase price is included in Convertible Preferred Stock Held by Consolidated VIE on PMI’s accompanying condensed consolidated balance sheets. These shares remain outstanding for legal purposes and retain their voting rights, but are excluded from the earnings per share calculation. The number of authorized, issued and outstanding shares, their par value and liquidation preference for each series of convertible preferred stock as of September 30, 2021 are disclosed in the table below (amounts in thousands except share and par value amounts): Convertible Preferred Stock Par Value Authorized Shares Outstanding and Issued Shares Liquidation Preference, Outstanding Shares Series A $ 0.01 68,558,220 66,428,185 * $ 19,160 Series A-1 $ 0.01 24,760,915 22,515,315 45,031 Series B $ 0.01 35,775,880 35,127,160 * 21,190 Series C $ 0.01 24,404,770 24,404,770 70,075 Series D $ 0.01 23,888,640 23,888,640 165,000 Series E-1 $ 0.01 35,544,141 — — Series E-2 $ 0.01 16,858,078 — — Series F $ 0.01 177,720,707 3 — Series G $ 0.01 37,249,497 37,249,497 50,000 Total 444,760,848 209,613,570 $ 370,456 * Series A and Series B Convertible Preferred Stock totals are inclusive of 34,670,420 and 16,577,495 shares, respectively, held by PGT, a consolidated VIE. Dividends Dividends on shares of the Series A, Series B, Series C, Series D, Series E-1, Series E-2, Series F and Series G convertible preferred stock are payable only when, as, and if declared by the Board of Directors. No dividends will be paid with respect to the common stock until any declared dividends on the Series A, Series B, Series C, Series D, Series E-1, Series E-2, Series F, and Series G convertible preferred stock have been paid or set aside for payment to the Series A, Series B, Series C, Series D, Series E-1, Series E-2, Series F, and Series G convertible preferred stockholders. After payment of any such dividends, any additional dividends or distributions will be distributed among all holders of common stock and preferred stock in proportion to the number of shares of common stock that would be held by each such holder if all shares of preferred stock were converted to common stock at the then-effective conversion rate. The Series A-1 convertible preferred shares have no dividend rights. To date, no dividends have been declared on any of PMI’s preferred stock or common stock. Conversion Under the terms of PMI’s amended and restated certificate of incorporation, the holders of preferred stock have the right to convert such preferred stock into common stock at any time. In addition, all preferred stock automatically converts into common stock (i) immediately prior to the closing of an initial public offering that values Prosper at least at $2 billion and that results in aggregate proceeds to Prosper of at least $100 million or (ii) upon a written request from the holders of at least 60% of the voting power of the outstanding preferred stock (on an as-converted basis), provided that (i) the Series A-1 convertible preferred stock shall not be converted without at least 14% of the voting power of the outstanding Series A-1 convertible preferred stock; (ii) the Series D shall not be converted without at least 60% of the voting power of the outstanding Series D; (iii) the Series E-1 and Series E-2 shall not be converted without at least 60% of the voting power of the outstanding Series E-1 and Series E-2, voting together as a single class; (iv) the Series F shall not be converted without at least 60% of the voting power of the outstanding Series F, and (v) the shares of Series G Preferred Stock will not be automatically converted unless the holders of at least 60% of the outstanding shares of Series G Preferred Stock approve such conversion. In addition, if a holder of the Series A convertible preferred stock has converted any of the Series A convertible preferred stock, then all of such holder’s shares of Series A-1 convertible preferred stock also will be converted upon a liquidation event. In lieu of any fractional shares of common stock to which a holder would otherwise be entitled, PMI shall pay such holder cash in an amount equal to the fair market value of such fractional shares, as determined by its Board of Directors. At present, each of the Series A, Series B, Series C, Series D, Series E-1, Series E-2, and Series F convertible preferred stock converts into PMI common stock at a 1:1 ratio. The Series A-1 convertible preferred stock converts into common stock at a 1,000,000:1 ratio and the Series G convertible preferred stock converts into common stock at a 1:1.36 ratio. The Series G convertible preferred stock conversion ratio reflects the Series G true-up that occurred at end of the vesting period for the Series E-2 and Series F Preferred Stock warrants. For the Series G true-up, the conversion price of the Series G Convertible Preferred Stock was reduced to a number equal to the Series G Preferred Stock original issuance price, divided by the quotient obtained by dividing the Series G true-up amount by the total number of Series G Preferred Stock issued as of the Series G closing date. The Series G true-up amount means the aggregate number of shares of Series G Preferred Stock that would have been issued to the purchasers of the Series G Preferred Stock on the Series G closing date, if warrants to purchase shares of Series E-2 Preferred Stock or Series F Preferred Stock that were exercisable or exercised as of the true-up time (end of vesting period) had been exercisable or exercised as of such Series G closing date. Liquidation Rights PMI’s convertible preferred stock has been classified as temporary equity on the condensed consolidated balance sheets. The preferred stock is not redeemable; however, in the event of a voluntary or involuntary liquidation, dissolution, change in control or winding up of PMI, holders of the convertible preferred stock may have the right to receive its liquidation preference under the terms of PMI’s certificate of incorporation. Each holder of Series E-1, Series E-2, and Series F convertible preferred stock is entitled to receive prior and in preference to any distribution of proceeds from a liquidation event to the holders of Series A, Series B, Series C, Series D, Series G and Series A-1 convertible preferred stock or common stock, an amount per share for (i) each share of Series E-1 convertible preferred stock equal to the sum of the liquidation preference specified for such share and all declared but unpaid dividends, if any, on such share, (ii) each share of Series E-2 convertible preferred stock equal to the sum of two-thirds the liquidation preference specified for such share and all declared but unpaid dividends, if any, on such share, and (iii) each share of Series F convertible preferred stock equal to the sum of two-thirds of the liquidation preference specified for such share and all declared but unpaid dividends, if any, on such share. After the payment or setting aside for payment to the holders of Series E-1, Series E-2, and Series F convertible preferred stock, each holder of Series A, Series B, Series C and Series D, Series E-2, Series F, and Series G convertible preferred stock is entitled to receive, on a pari passu basis, prior to and in preference to any distribution of proceeds from a liquidation event to the holders of Series A-1 convertible preferred stock or common stock, (i) an amount per share for each share of Series E-2 and Series F convertible preferred stock equal to the sum of one-third of the liquidation preference specified for such share and all declared but unpaid dividends, if any, on such share, and (ii) an amount per share for each share of Series A, Series B, Series C, Series D and Series G convertible preferred stock equal to the sum of the liquidation preference specified for such share and all declared but unpaid dividends, if any, on such share. After the payment or setting aside for payment to the holders of Series A, Series B, Series C, Series D, Series E-1, Series E-2, Series F, and Series G convertible preferred stock, the holders of Series A-1 convertible preferred stock are entitled to receive, prior and in preference to any distribution of proceeds to the holders of common stock, an amount per share for each such share of Series A-1 convertible preferred stock equal to the sum of the liquidation preference specified for such share and all declared but unpaid dividends, if any, on such share. After the payment or setting aside for payment to the holders of Series A, Series B, Series C, Series D, Series E-1, Series E-2, Series F, Series G, and Series A-1 convertible preferred stock, the entire remaining proceeds legally available for distribution will be distributed pro rata to the holders of Series A convertible preferred stock and common stock in proportion to the number of shares of common stock held by them assuming the Series A convertible preferred stock has been converted into shares of common stock at the then effective conversion rate, provided that the maximum aggregate amount per share of Series A convertible preferred stock which the holders of Series A convertible preferred stock shall be entitled to receive is three times the original issue price for the Series A convertible preferred stock. At present, the liquidation preferences are equal to $0.29 per share for the Series A convertible preferred stock, $2.00 per share for the Series A-1 convertible preferred stock, $0.60 per share for the Series B convertible preferred stock, $2.87 per share for the Series C convertible preferred stock, $6.91 per share for the Series D convertible preferred stock, $0.84 per share for the Series E-1 convertible preferred stock, $0.84 per share for the Series E-2 convertible preferred stock, $0.84 per share for the Series F convertible preferred stock and $1.34 per share for the Series G convertible preferred stock. Voting Each holder of shares of convertible preferred stock is entitled to the number of votes equal to the number of shares of common stock into which such shares of convertible preferred stock could be converted and has voting rights and powers equal to the voting rights and powers of the common stock. The holders of convertible preferred stock and the holders of common stock vote together as a single class (except with respect to certain matters that require separate votes or as required by law), and are entitled to notice of any stockholders’ meeting in accordance with the Bylaws of PMI. Convertible Preferred Stock Warrant Liability Series E-1 Warrants In connection with the Settlement and Release Agreement dated November 17, 2016 among PMI, its wholly owned subsidiary Prosper Funding LLC (“PFL”) and Colchis, on December 16, 2016, PMI issued the First Series E-1 Warrant. The Second Series E-1 Warrant for an additional 15,277,006 shares of Series E-1 convertible preferred stock was granted on the signing of the Consortium Purchase Agreement (as defined in Note 15) on February 27, 2017. The warrants expire ten years from the dat e of issuance. For the three months ended September 30, 2021 and 2020, Prosper recognized $13.9 million and $2.5 million of expense, respectively, from the re-measurement of the fair value of the warrants. For the nine months ended September 30, 2021 and 2020, Prosper recognized $21.3 million of expense and $10.3 million of income, respectively, from the re-measurement of the fair value of the warrants. The income or expense resulted from the remeasurement of the fair value of the warrants is recorded in Change in Fair Value of Convertible Preferred Stock Warrants on the condensed consolidated statements of operations. To determine the fair value of the Series E-1 Warrants, the Company first determined the value of a share of a Series E-1 Convertible Preferred Stock. To determine the fair value of the Convertible Preferred Stock, the Company first derived the business enterprise value (“BEV”) of the Company using a variety of valuation methods, including discounted cash flow models and market based methods, as deemed appropriate under the circumstances applicable at the valuation date. Once the Company determined an estimated BEV, the option pricing method ("OPM") was used to allocate the BEV to the various classes of our equity, including our preferred stock. The concluded per share value for the Series E-1 Convertible Preferred Stock was utilized as an input to the Black-Scholes option pricing model. The Company determined the fair value of the outstanding Series E-1 Warrants utilizing the following assumptions as of the following dates: September 30, 2021 December 31, 2020 Volatility 59.0 % 60.0 % Risk-free interest rate 0.50 % 0.20 % Expected term (in years) 2.75 2.75 Dividend yield — % — % The above assumptions were determined as follows: Volatility: The volatility is derived from historical volatilities of several unrelated publicly listed peer companies over a period approximately equal to the term of the warrant as the Company has limited information on the volatility of its preferred stock since there is currently no trading history. When making the selections of industry peer companies to be used in the volatility calculation, the Company considered the size, operational, and economic similarities to the Company’s principal business operations. Risk-Free Interest Rate: The risk-free interest rate is based on the U.S. Treasury yield in effect as of September 30, 2021, and for zero coupon U.S. Treasury notes with maturities approximately equal to the term of the warrant. Expected Term: The expected term is the period of time for which the warrants are expected to be outstanding. Dividend Yield: The expected dividend assumption is based on the Company’s current expectations about the Company’s anticipated dividend policy. Series F Warrants In connection with the Consortium Purchase Agreement (as described in Note 16 of PMI’s 10-K for the year ended December 31, 2021) on February 27, 2017, PMI issued warrants to purchase up to 177,720,706 shares of PMI's Series F convertible preferred stock at $0.01 per share. The warrants expire ten years from the date of issuance. For the three months ended September 30, 2021 and 2020, Prosper recognized $72.9 million and $8.9 million of expense, respectively, from the re-measurement of the fair value of the warrants. For the nine months ended September 30, 2021 and 2020, Prosper recognized $115.5 million of expense and $53.3 million of income, respectively, from the re-measurement of the fair value of the warrants. The income or expense resulting from changes in the fair value of the warrant is recorded through Change in Fair Value of Convertible Preferred Stock Warrants on the condensed consolidated statements of operations . To determine the fair value of the Series F Warrants, the Company first determined the value of a share of a Series F Convertible Preferred Stock. To determine the fair value of the Convertible Preferred Stock, the Company first derived the BEV using valuation methods, including a combination of methods, as deemed appropriate under the circumstances applicable at the valuation date. Once the Company determined an estimated BEV, the OPM was used to allocate the BEV to the various classes of Prosper's equity, including our preferred stock. The concluded per share value for the Series F Convertible Preferred Stock warrants utilized the Black-Scholes option pricing model. The Company determined the fair value of the outstanding Series F Warrants utilizing the following assumptions as of the following dates: September 30, 2021 December 31, 2020 Volatility 59.0 % 60.0 % Risk-free interest rate 0.50 % 0.20 % Expected term (in years) 2.75 2.75 Dividend yield — % — % The above assumptions were determined using the same criteria described above for the Series E-1 Warrants. The combined activity of the Convertible Preferred Stock Warrant Liability for the nine months ended September 30, 2021 and 2020 are as follows (in thousands): Warrant Activity Balance at January 1, 2021 $ 112,319 Change in fair value 136,845 Balance at September 30, 2021 $ 249,164 Warrant Activity Balance at January 1, 2020 $ 149,996 Change in fair value (63,624) Balance at September 30, 2020 $ 86,372 Common Stock PMI, through its Amended and Restated Certificate of Incorporation, is the sole issuer of common stock and related options, restricted stock units ("RSUs") and warrants. On February 16, 2016, PMI amended and restated its Certificate of Incorporation to, among other things, effect a 5-for-1 forward stock split. On September 20, 2017, PMI further amended its Amended and Restated Certificate of Incorporation to increase the number of shares of common stock authorized for issuance. The total number of shares of stock which PMI has the authority to issue is 1,069,760,848, consisting of 625,000,000 shares of common stock, $0.01 par value per share, and 444,760,848 shares of preferred stock, $0.01 par value per share. As of September 30, 2021, 72,257,653 shares of common stock were issued and 71,321,718 shares of common stock were outstanding. As of December 31, 2020, 70,075,307 shares of common stock were issued and 69,139,372 shares of common stock were outstanding. Each holder of common stock is entitled to one vote for each share of common stock held. Common Stock Issued upon Exercise of Stock Options

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
STOCK-BASED COMPENSATION	Stock-Based CompensationPMI grants equity awards primarily through its Amended and Restated 2005 Stock Option Plan (the “2005 Plan”), which was approved as amended and restated by its stockholders on December 1, 2010; and its 2015 Equity Incentive Plan, which was approved by its stockholders on April 7, 2015 and subsequently amended by an Amendment No. 1, Amendment No. 2 and Amendment No. 3, which were approved by PMI's stockholders effective as of February 15, 2016, May 31, 2016, and September 5, 2018 respectively (as amended, the “2015 Plan”). In March 2015, the 2005 Plan expired, except that any awards granted under the 2005 Plan prior to its expiration remain in effect pursuant to their terms. Stock Option Reprice On May 3, 2016 and March 17, 2017, the Compensation Committee of the Board of Directors of PMI approved two separate stock option repricing programs authorizing PMI’s officers to reprice certain outstanding stock options held by employees and directors that had exercise prices above the current fair market value of PMI’s Common Stock on those respective dates. On August 11, 2020, the Compensation Committee of the Board of Directors of PMI approved a stock option repricing program (the “2020 Repricing” and together with the 2016 Repricing and the 2017 Repricing, the “Repricings”) authorizing PMI’s officers to reprice certain outstanding stock options held by employees and directors that have exercise prices above the current fair market value of PMI’s common stock. The repricing was effected on August 11, 2020 for eligible directors and employees. PMI believes that the Repricings encourage the continued service of valued employees and directors, and motivate such service providers to perform at high levels, both of which are critical to the Company’s continued success. PMI expects to incur additional stock based compensation charges as a result of the Repricings. The financial statement impact of the above Repricings was not material for the nine months ended September 30, 2021. As of September 30, 2021, the unamortized Repricings expense (net of forfeitures) of $34 thousand will be recognized over the remaining weighted-average vesting period of 1.7 years. Stock Option Activity Stock option activity under the 2005 Plan and 2015 Plan is summarized for the nine months ended September 30, 2021 below: Options Issued and Outstanding Weighted Average Exercise Price Balance as of January 1, 2021 72,915,449 $ 0.02 Options issued 15,431,359 $ 0.16 Options exercised (2,182,346) $ 0.02 Options forfeited (13,815,422) $ 0.02 Options expired (30,190) $ 0.02 Balance as of September 30, 2021 72,318,850 $ 0.05 Options vested and expected to vest as of September 30, 2021 54,681,009 $ 0.05 Options vested and exercisable as of September 30, 2021 48,617,301 $ 0.02 Other Information Regarding Stock Options The weighted-average remaining life for options outstanding as of September 30, 2021 was 6.90 years. The fair value of options granted to employees is estimated on the grant date using the Black-Scholes option valuation model. This valuation model for stock-based compensation expense requires PMI to make assumptions and judgments about the variables used in the calculation, including the fair value of PMI’s common stock, the expected term (the period of time that the options granted are expected to be outstanding), the volatility of PMI’s common stock, a risk-free interest rate, and expected dividends. Given the absence of a publicly traded market, the Company considered numerous objective and subjective factors to determine the fair value of PMI’s common stock at each grant date. These factors included, but were not limited to: (i) contemporaneous valuations of common stock performed by unrelated third-party specialists, (ii) the prices for PMI’s preferred stock sold to outside investors, (iii) the rights, preferences and privileges of PMI’s preferred stock relative to PMI’s common stock, (iv) the lack of marketability of PMI’s common stock, (v) developments in the business, (vi) secondary transactions of PMI’s common and preferred shares, and (vii) the likelihood of achieving a liquidity event, such as an initial public offering or a merger or acquisition of Prosper, given prevailing market conditions. As PMI’s stock is not publicly traded, volatility for stock options is based on an average of the historical volatilities of the common stock of several entities with characteristics similar to those of PMI. The expected term assumptions were determined based on the vesting terms, exercise terms and contractual lives of the options using the simplified method. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option. PMI uses an expected dividend yield of zero as it does not anticipate paying any dividends in the foreseeable future. PMI also estimates forfeitures of unvested stock options. Expected forfeitures are based on the Company’s historical experience. To the extent actual forfeitures differ from the estimates, the difference will be recorded as a cumulative adjustment in the period estimates are revised. No compensation cost is recorded for options that do not vest. The fair value of PMI’s stock option awards granted during the three and nine months ended September 30, 2021 and 2020 was estimated at the date of grant using the Black-Scholes model with the following average assumptions: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Volatility of common stock 64.84 % 57.32 % 64.37 % 52.66 % Risk-free interest rate 0.97 % 0.37 % 0.99 % 0.51 % Expected life 6.0 years 6.0 years 6.0 years 6.0 years Dividend yield — % — % — % — % Restricted Stock Unit Activity For the nine months ended September 30, 2021, PMI did not grant any RSUs. In previous years, PMI granted RSUs to certain employees that are subject to three-year or four-year vesting terms and the occurrence of a liquidity event. The following table summarizes the number of PMI’s RSU activity for the nine months ended September 30, 2021: Number of Shares Weighted-Average Grant Date Fair Value Unvested at January 1, 2021 4,661,141 $ 0.91 Forfeited (1,786,793) $ 0.54 Unvested at September 30, 2021 2,874,348 $ 1.14 Share Based Compensation The following table presents the amount of stock-based compensation related to stock-based awards granted to employees recognized in Prosper’s condensed consolidated statements of operations for the periods presented (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Origination and servicing $ 30 $ 53 $ 92 $ 124 Sales and marketing 15 25 47 51 General and administrative 225 708 718 1,508 Total stock-based compensation $ 270 $ 786 $ 857 $ 1,683 Prosper capitalized stock-based compensation as internal-use software and website development costs of an immaterial amount and $0.1 million for the three months ended September 30, 2021 and 2020, respectively, and $0.1 million and $0.2 million for the nine months ended September 30, 2021 and 2020, respectively. As of September 30, 2021 , the unamortized stock-based compensation expense, adjusted for forfeiture estimates, related to unvested stock-based awards was approximately $1.4 million, which will be recognized over a remaining weighted-average vesting period of approximately 2.5 years.

INCOME TAXES

INCOME TAXES	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
INCOME TAXES	Income Taxes For the three months ended September 30, 2021 and 2020, PMI recognized $21 thousand and $34 thousand of income tax expense, respectively. For the nine months ended September 30, 2021 and 2020, PMI recognized $63 thousand and $102 thousand of income tax expense, respectively. The income tax expense relates to state income tax expense and the amortization of tax deductible goodwill which gives rise to an indefinite-lived deferred tax liability. No other income tax expense or benefit was recorded for the nine month periods ended September 30, 2021 and 2020 due to a full valuation allowance recorded against the Company’s deferred tax assets . Management assesses the available positive and negative evidence to estimate if sufficient future taxable income will be generated to utilize our existing deferred tax assets. On the basis of this evaluation, it is not more likely than not that our deferred tax assets will be realized and therefore a full valuation allowance has been recorded.
Prosper Funding LLC
Entity Information [Line Items]
INCOME TAXES	Income TaxesPFL incurred no income tax provision for the nine months ended September 30, 2021 and September 30, 2020. PFL is a U.S. disregarded entity and its income and loss are included in the income tax reporting of its parent, PMI. Since PMI is in a taxable loss position, is not currently subject to income taxes, and has fully reserved against its deferred tax asset, the net effective tax rate for PFL is 0%.

LEASES

LEASES	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
LEASES	Leases Prosper has operating leases for corporate offices and datacenters. These leases have remaining lease terms of one year to five years. Some o f the lease agreem ents include options to extend the lease term for up to an additional five years. Rental expense under operating lease arrangements was $1.1 million and $1.2 million for the three months ended September 30, 2021 and 2020, respectively, and $3.4 million an d $4.2 million for the nine months ended September 30, 2021 and 2020, respectively. Additionally, Prosper subleases certain leased office space to third parties when it determines there is excess leased capacity. Sublease income from operating lease arrangements was $0.1 million and $0.1 million for the three months ended September 30, 2021 and 2020, respectively, and $0.2 million and $0.4 million for the nine months ended September 30, 2021 and 2020, respectively. Operating Lease Right-of-Use (“ROU”) Assets The following table summarizes the operating lease right-of-use assets as of September 30, 2021, which are included in “Property and Equipment, Net” on the condensed consolidated balance sheets. September 30, 2021 Gross Carrying Value Accumulated Amortization Net Carrying Value ROU Assets - Office buildings $ 16,709 $ 8,581 $ 8,128 ROU Assets - Other 776 252 524 Total right-of-use assets subject to amortization $ 17,485 $ 8,833 $ 8,652 The Company identified certain impairment triggers related to its ROU assets in the second quarter of 2020, primarily due to the non-renewal of certain sublease agreements and the time expected to find new subtenants. As a result of impairment testing performed on these ROU assets, the Company recorded an impairment charge of $0.2 million for the three months ended June 30, 2020. No impairment was identified in 2021. Lease Liabilities Future maturities of operating lease liabilities as of September 30, 2021 were as follows (in thousands). The present value of the future minimum lease payments represent our operating lease liabilities as of September 30, 2021 and are included in " Other Liabilities September 30, 2021 Remainder of 2021 $ 1,439 2022 5,833 2023 2,124 2024 1,360 2025 1,395 Thereafter 1,218 Total future minimum lease payments $ 13,369 Less imputed interest (1,053) Present value of future minimum lease payments $ 12,316 Because the rate implicit in each lease is not readily determinable, we use our incremental borrowing rate to determine the present value of the lease payments. Other information related to leases was as follows (dollars in thousands): September 30, 2021 Cash paid for operating leases year-to-date $ 3,955 ROU assets obtained in exchange for new operating lease obligations year-to-date $ 1,773 Weighted average remaining lease term (in years) 3.24 years Weighted average discount rate 5.48 %

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
COMMITMENTS AND CONTINGENCIES	Commitments and Contingencies In the normal course of its operations, Prosper becomes involved in various legal actions. Prosper maintains provisions it considers to be adequate for such actions. Prosper does not believe it is probable that the ultimate liability, if any, arising out of any such matters will have a material effect on Prosper's financial condition, results of operations or cash flows. Operating Commitments Prosper has entered into an agreement with WebBank, under which all Borrower Loans originated through the marketplace are made by WebBank under its bank charter. On June 25, 2021, PMI, along with its wholly-owned subsidiary Prosper Funding LLC, and WebBank entered into: (i) a Fifth Amendment (the “Sale Agreement Amendment”) to the Asset Sale Agreement, dated July 1, 2016, between Prosper Funding LLC and WebBank (the “Sale Agreement”); (ii) a Sixth Amendment (the “Marketing Agreement Amendment”) to the Marketing Agreement, dated July 1, 2016, between PMI and WebBank (the “Marketing Agreement”); and (iii) a Third Amendment (the “Purchase Agreement Amendment”) to the Stand By Purchase Agreement, dated July 1, 2016, between PMI and WebBank (the “Purchase Agreement” and, collectively with the Sale Agreement and the Marketing Agreement, the “Origination and Sale Agreements”). The Sale Agreement Amendment, the Marketing Agreement Amendment, and the Purchase Agreement Amendment, collectively, are hereinafter referred to as the “Amendments.” The Sale Agreement Amendment, among other things, extends the term of the Sale Agreement to February 1, 2025 and amends certain collateral requirements under the Sale Agreement. The Marketing Agreement Amendment, among other things, extends the term of the Marketing Agreement to February 1, 2025 and sets forth the amended terms and conditions of certain fees owed by the Registrants to WebBank under the Marketing Agreement. The Purchase Agreement Amendment amends certain collateral requirements of PMI under the Purchase Agreement. Pursuant to the Marketing Agreement Amendment, the marketing fee that Prosper receives in connection with the origination of each loan is partially reduced by an amount (the “Designated Amount”) calculated as a percentage of the principal amount of such loan based on the aggregate principal amount of loans originated for the applicable month. To the extent the aggregate Designated Amount for all loans originated during any month is less than $143,500 through February 1, 2022, and $100,000 thereafter through February 1, 2025, Prosper is required to pay WebBank an amount equal to such deficiency. Accordingly, the minimum fee for the remaining three months of 2021 is $0.4 million . The minimum fee is then $1.2 million for each year from 2022 through 2024, and $0.1 million in 2025. Additionally, under the agreement with WebBank, Prosper is required to maintain minimum net liquidity of $15.0 million at all times during the term of the agreement. Net liquidity is defined as the sum of Cash, Cash Equivalents and Available for Sale Investments. Violation of this covenan t can result in termination of the contract with WebBank. As of September 30, 2021, Prosper was in compliance with the covenant. Loan Purchase Commitments Prosper entered into an agreement with WebBank to purchase $13.9 million of Borrower Loans that WebBank originated during the last two business days of the quarter ended September 30, 2021. Prosper will purchase these Borrower Loans within the first three business days of the quarter ending December 31, 2021. Repurchase Obligation Under the terms of the loan purchase agreements between Prosper and investors that participate in the Whole Loan Channel, Prosper may, in certain circumstances, become obligated to repurchase a Borrower Loan from an investor. Generally, these circumstances include the occurrence of verifiable identity theft, the failure to properly follow loan listing or bidding protocols or a violation of the applicable federal, state or local lending laws. Prosper recognizes a liability at fair value for the repurchase obligation when the Borrower Loans are sold. The fair value of the repurchase obligation is estimated based on historical experience. Repurchased Borrower Loans associated with violations of federal, state or local lending laws or verifiable identity theft are written off at the time of repurchase. The maximum potential amount of future payments associated with this obligation is the outstanding balances of the Borrower Loans issued through the Whole Loan Channel, which at September 30, 2021 is $2.5 billion. Prosper has accrued $0.3 million and $0.2 million as of September 30, 2021 and December 31, 2020, respectively, in regard to this obligation. Regulatory Contingencies Prosper accrues for contingencies when a loss from such contingencies is probable and the amount of loss can be reasonably estimated. In determining whether a loss is probable and if it is possible to quantify the amount of the estimated loss, Prosper reviews and evaluates its litigation and regulatory matters on at least a quarterly basis in light of potentially relevant factual and legal developments. If Prosper determines that an unfavorable outcome is not probable or that the amount of a loss cannot be reasonably estimated, Prosper does not accrue for a potential litigation loss. If an unfavorable outcome is probable and Prosper can estimate a range of outcomes, an amount is recorded which management considers to be the best estimate within the range of potential losses that are both probable and estimable; however, if management cannot quantify the amount of the estimated loss, then the low end of the range of the potential losses is recorded. West Virginia Matter In January 2018, the Attorney General of the State of West Virginia (the “Attorney General”) initiated discussions regarding certain acts and practices of PMI and PFL that the Attorney General asserts may have violated the West Virginia Consumer Credit and Protection Act (the “Consumer Act”), to which Prosper responded with such information as was requested by the Attorney General. Following a period of more than a year with limited to no communication, in February 2020, Prosper received a proposed Assurance of Discontinuance (an “AOD”) from the Attorney General requesting that, without in any way admitting that any of its prior practices were in violation of the Consumer Act, Prosper agree to certain terms and conditions regarding its past and potential future conduct of its business with respect to customers in West Virginia, including a release by the Attorney General of any claims it may have related to the matters identified in the AOD. Prosper is evaluating and intends to discuss the proposed terms in the AOD with the Attorney General. We cannot predict the outcome of the matter and any potential fines or penalties, if any, that may arise from the matter. Further, we are unable to estimate a range of outcomes and as a result no accrual has been made. No loans have been originated through the Prosper platform to West Virginians since June 2016.
Prosper Funding LLC
Entity Information [Line Items]
COMMITMENTS AND CONTINGENCIES	Commitments and Contingencies Operating Commitments Prosper has entered into an agreement with WebBank, under which all Borrower Loans originated through the marketplace are made by WebBank under its bank charter. On June 25, 2021, PMI, along with PFL, and WebBank entered into: (i) a Fifth Amendment (the “Sale Agreement Amendment”) to the Asset Sale Agreement, dated July 1, 2016, between PFL and WebBank (the “Sale Agreement”); (ii) a Sixth Amendment (the “Marketing Agreement Amendment”) to the Marketing Agreement, dated July 1, 2016, between PMI and WebBank (the “Marketing Agreement”); and (iii) a Third Amendment (the “Purchase Agreement Amendment”) to the Stand By Purchase Agreement, dated July 1, 2016, between PMI and WebBank (the “Purchase Agreement” and, collectively with the Sale Agreement and the Marketing Agreement, the “Origination and Sale Agreements”). The Sale Agreement Amendment, the Marketing Agreement Amendment, and the Purchase Agreement Amendment, collectively, are hereinafter referred to as the “Amendments.” The Sale Agreement Amendment, among other things, extends the term of the Sale Agreement to February 1, 2025 and amends certain collateral requirements under the Sale Agreement. The Marketing Agreement Amendment, among other things, extends the term of the Marketing Agreement to February 1, 2025 and sets forth the amended terms and conditions of certain fees owed by the Registrants to WebBank under the Marketing Agreement. The Purchase Agreement Amendment amends certain collateral requirements of Prosper under the Purchase Agreement. Pursuant to the Marketing Agreement Amendment, the marketing fee that Prosper receives in connection with the origination of each loan is partially reduced by an amount (the “Designated Amount”) calculated as a percentage of the principal amount of such loan based on the aggregate principal amount of loans originated for the applicable month. To the extent the aggregate Designated Amount for all loans originated during any month is less than $143,500 through February 1, 2022, and $100,000 thereafter through February 1, 2025, Prosper is required to pay WebBank an amount equal to such deficiency. Accordingly, the minimum fee for the remaining three months of 2021 is $0.4 million. The minimum fee is then $1.2 million for each year from 2022 through 2024, and $0.1 million in 2025. Additionally, under the agreement with WebBank, Prosper is required to maintain minimum net liquidity of $15 million at all times during the term of the agreement. Net liquidity is defined as the sum of Cash, Cash Equivalents and Available for Sale Investments. Violation of this covenant can result in termination of the contract with WebBank. As of September 30, 2021, the Company was in compliance with the covenant. Loan Purchase Commitments Under the terms of PFL’s agreement with WebBank, PFL is committed to purchase $13.9 million of Borrower Loans that WebBank originated during the last two business days of the quarter ended September 30, 2021. PFL will purchase these Borrower Loans within the first three business days of the quarter ending December 31, 2021. Repurchase Obligation Under the terms of the loan purchase agreements between PFL and investors that participate in the Whole Loan Channel, PFL may, in certain circumstances, become obligated to repurchase a Borrower Loan from an investor. Generally, these circumstances include the occurrence of verifiable identity theft, the failure to properly follow loan listing or bidding protocols, or a violation of the applicable federal, state, or local lending laws. The fair value of the indemnification and repurchase obligation is estimated based on historical experience. PFL recognizes a liability for the repurchase and indemnification obligation when the Borrower Loans are issued. Indemnified or repurchased Borrower Loans associated with violations of federal, state, or local lending laws or verifiable identity theft are written off at the time of repurchase or at the time an indemnification payment is made. The maximum potential amount of future payments associated under this obligation is the outstanding balances of the Borrower Loans issued through the Whole Loan Channel, which as of September 30, 2021 is $2.5 billion. PFL has acc rued $0.3 million and $0.2 million as of September 30, 2021 and December 31, 2020, respectively, in regard to this obligation. Regulatory Contingencies PFL accrues for contingencies when a loss from such contingencies is probable and the amount of loss can be reasonably estimated. In determining whether a loss is probable and if it is possible to quantify the amount of the estimated loss, PFL reviews and evaluates its litigation and regulatory matters on at least a quarterly basis in light of potentially relevant factual and legal developments. If PFL determines that an unfavorable outcome is not probable or that the amount of a loss cannot be reasonably estimated, PFL does not accrue for a potential litigation loss. If an unfavorable outcome is probable and PFL can estimate a range of outcomes, PFL record the amount management considers to be the best estimate within the range of potential losses that are both probable and estimable; however, if management cannot quantify the amount of the estimated loss, then PFL records the low end of the range of those potential losses. West Virginia Matter In January 2018, the Attorney General of the State of West Virginia (the “Attorney General”) initiated discussions regarding certain acts and practices of PMI and PFL that the Attorney General asserts may have violated the West Virginia Consumer Credit and Protection Act (the “Consumer Act”), to which PMI responded with such information as was requested by the Attorney General. Following a period of more than a year with limited to no communication, in February 2020, PMI received a proposed Assurance of Discontinuance (an “AOD”) from the Attorney General requesting that, without in any way admitting that any of its prior practices were in violation of the Consumer Act, PMI agreed to certain terms and conditions regarding its past and potential future conduct of its business with respect to customers in West Virginia, including a release by the Attorney General of any claims it may have related to the matters identified in the AOD. PMI is evaluating and intends to discuss the proposed terms in the AOD with the Attorney General. We cannot predict the outcome of the matter and any potential fines or penalties, if any, that may arise from the matter. Further, we are unable to estimate a range of outcomes and as a result no accrual has been made. No loans have been originated through the PFL platform to West Virginians since June 2016.

RELATED PARTIES

RELATED PARTIES	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
RELATED PARTIES	Related Parties Since Prosper’s inception, it has engaged in various transactions with its directors, executive officers, and holders of more than 10% of its voting securities, and immediate family members and other affiliates of its directors, executive officers, and 10% stockholders. Prosper believes that all of the transactions described below were made on terms no less favorable to Prosper than could have been obtained from unaffiliated third parties. Prosper’s executive officers, directors who are not executive officers, and certain affiliates participate in its marketplace by placing bids and purchasing Notes. The aggregate amount of the Notes purchased and the income earned by parties deemed to be affiliates and related parties of Prosper for the three and nine months ended September 30, 2021 and September 30, 2020, as well as the Notes outstanding as of September 30, 2021 and December 31, 2020 are summarized below (in thousands): Aggregate Amount of Interest Earned on Notes Related Party 2021 2020 2021 2020 Executive officers and management $ 9 $ 7 $ 2 $ 1 Directors (excluding executive officers and management) 4 41 1 14 Total $ 13 $ 48 $ 3 $ 15 Aggregate Amount of Interest Earned on Notes Related Party 2021 2020 2021 2020 Executive officers and management $ 26 $ 19 $ 5 $ 4 Directors (excluding executive officers and management) 24 272 1 43 Total $ 50 $ 291 $ 6 $ 47 Notes Balance as of Related Party September 30, 2021 December 31, Executive officers and management $ 40 $ 41 Directors (excluding executive officers and management) 18 — Total $ 58 $ 41
Prosper Funding LLC
Entity Information [Line Items]
RELATED PARTIES	Related PartiesSince inception, PFL has engaged in various transactions with its directors, executive officers, PMI, and immediate family members and other affiliates of its directors, executive officers, and PMI. PFL believes that all of the transactions described below were made on terms no less favorable to PFL than could have been obtained from unaffiliated third parties. PFL’s executive officers and directors who are not executive officers participate in its marketplace by placing bids and purchasing Notes. The aggregate amount of the Notes purchased and the income earned by parties deemed to be related parties of PFL for the nine months ended September 30, 2021 and 2020 are summarized below (in thousands): Aggregate Amount of Notes Purchased Interest Earned on Notes Three Months Ended September 30, Three Months Ended September 30, Related Party 2021 2020 2021 2020 Executive officers and management $ 9 $ 7 $ 2 $ 1 Directors (excluding executive officers and management) — — — — Total $ 9 $ 7 $ 2 $ 1 Aggregate Amount of Notes Purchased Interest Earned on Notes Nine Months Ended September 30, Nine Months Ended September 30, Related Party 2021 2020 2021 2020 Executive officers and management $ 26 $ 19 $ 5 $ 4 Directors (excluding executive officers and management) — — — — Total $ 26 $ 19 $ 5 $ 4 The balance of Notes held by officers and directors who are not executive officers are as follows (in thousands): Notes Balance as of Related Party September 30, 2021 December 31, 2020 Executive officers and management $ 40 $ 41 Directors (excluding executive officers and management) — — Total $ 40 $ 41

SIGNIFICANT CONCENTRATIONS

SIGNIFICANT CONCENTRATIONS	9 Months Ended
	Sep. 30, 2021
Risks and Uncertainties [Abstract]
SIGNIFICANT CONCENTRATIONS	Significant Concentrations Prosper is dependent on third-party funding sources such as banks, asset managers, investment funds and Warehouse Lines to provide the funds to allow WebBank to originate Borrower Loans that the third party funding sources will later purchase. Of all Borrower Loans originated in the three months ended September 30, 2021, one individual party purchased 24.7% of such loans, and the Company’s Warehouse VIEs purchased 15.7% of such loans. For the three months ended September 30, 2020, two individual parties purchased 26.7% and 15.0% of all Borrower Loans originated, and the Company’s Warehouse VIEs purchased 23.1% of such loans. Of all Borrower Loans originated in the nine months ended September 30, 2021, one individual party purchased 27.0% of such loans, and the Company’s Warehouse VIEs purchased 13.4% of such loans. For the nine months ended September 30, 2020, two individual parties purchased 17.7% and 16.4%, respectively, of all Borrower Loans originated, and the Company’s Warehouse VIEs purchased 21.1% of such loans. These purchases reflect that a significant portion of Prosper’s business is dependent on funding through the Whole Loan Channel, through which 88% and 91% of Borrower Loans were originated in the nine months ended September 30, 2021 and September 30, 2020, respectively. Prosper receives all of its transaction fee revenue from WebBank. Prosper earns a transaction fee from WebBank for its services in facilitating originations of Borrower Loans issued by WebBank. The rate of the transaction fee for each individual Borrower Loan is based on the term and credit grade of the Borrower Loan. No individual borrower or investor accounted for 10% or more of consolidated net revenue for any of the periods presented .

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNT POLICIES (Policies)	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
Basis of Presentation	Prosper Marketplace, Inc. (“PMI”) was incorporated in the state of Delaware on March 22, 2005. Except as the context requires otherwise, as used in these notes to the condensed consolidated financial statements of PMI, “Prosper,” “we,” “us,” and “our” refer to PMI and its wholly-owned subsidiaries, on a consolidated basis. The unaudited interim condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”) and disclosure requirements for interim financial information and the requirements of Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by US GAAP for complete financial statements. The unaudited interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2020. The balance sheet at December 31, 2020 has been derived from the audited financial statements at that date. Management believes these unaudited interim condensed consolidated financial statements reflect all adjustments, consisting of a normal recurring nature, which are necessary for a fair presentation of the results for the interim periods presented. The results of operations for the interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period. The preparation of Prosper’s condensed consolidated financial statements and related disclosures in conformity with US GAAP requires management to make judgments, assumptions and estimates that affect the amounts reported in Prosper’s financial statements and accompanying notes. Management bases its estimates on historical experience and on various other factors it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of certain assets and liabilities. These judgments, estimates and assumptions are inherently subjective in nature and actual results may differ from these estimates and assumptions. The accompanying interim condensed consolidated financial statements include the accounts of PMI, its wholly-owned subsidiaries and consolidated variable interest entities (“VIEs”). All intercompany balances have been eliminated in consolidation. Securitization Notes are Notes held by certain third-party investors pursuant to Prosper’s securitization transactions, and are distinguishable from the borrower payment dependent Notes available to investors through the Company’s Note Channel.
Fair Value Measurements	Fair Value Measurements Financial instruments measured at fair value consist principally of Borrower Loans, Loans Held for Sale, Servicing Assets, Loan Trailing Fee Liabilities (Note 9), Notes, Certificates Issued by Securitization Trust (Note 6) and Convertible Preferred Stock Warrant Liability. The estimated fair values of other financial instruments, including Cash and Cash Equivalents, Restricted Cash, Accounts Receivable, Accounts Payable and Accrued Liabilities, and Payable to Investors approximate their carrying values because of their short-term nature. The estimated fair values of the Paycheck Protection Program loan (Note 9 and 10), Notes Issued by Securitization Trust (Note 6) and Warehouse Lines do not approximate their carrying values due primarily to differences in the stated and market rates associated with these instruments.
Restricted Cash	Restricted Cash Restricted Cash consists primarily of cash deposits, money market funds and short-term certificate of deposit accounts held as collateral as required for long term leases, loan funding and servicing activities, and cash that investors have on our marketplace that has not yet been invested in Borrower Loans or disbursed to the investor.
Borrower Loans, Loans Held for Sale, Notes and Certificates Issued by Securitization Trust	Borrower Loans, Loans Held for Sale, Notes and Certificates Issued by Securitization Trust Borrower Loans are funded either through the Note Channel or through the Whole Loan Channel. Through the Note Channel, Prosper purchases Borrower Loans from WebBank, then issues Notes and holds the Borrower Loans until maturity. The obligation to repay a series of Notes issued through the Note Channel is dependent upon the repayment of the associated Borrower Loan. Borrower Loans funded and Notes issued through the Note Channel are carried on Prosper’s condensed consolidated balance sheets as assets and liabilities, respectively. In 2019, Prosper began refinancing the purchase of Borrower Loans through the Whole Loan Channel through securitization transactions, which issue senior notes, risk retention interests and residual certificates. These securitization trusts were deemed consolidated VIEs until September 2021, when the Company sold its share of the residual certificates issued by these securitization trusts and deconsolidated the VIEs. Prior to their deconsolidation, the Borrower Loans held in the securitization trusts were included in “Borrower Loans, at Fair Value”. Senior notes sold to third party investors were included in “Notes Issued by Securitization Trust,” and the risk retention interest and residual certificates held by third party investors were included in “Certificates Issued by Securitization Trust, at Fair Value” on the accompanying condensed consolidated balance sheets. Refer to Note 6, Securitization for additional disclosures and details on the deconsolidation of these securitization trust VIEs. Prosper uses Warehouse Lines to purchase Loans Held for Sale that may be subsequently contributed to securitization transactions or sold to investors. Loans Held for Sale are included in “Loans Held for Sale, at Fair Value” on the Consolidated Balance Sheets. See Note 10, Debt for more details on Warehouse Lines. Borrower Loans and Loans Held for Sale are purchased from WebBank. Prosper places Borrower Loans and Loans Held for Sale on non-accrual status when they are 120 days past due. When a loan is placed on non-accrual status, Prosper stops accruing interest and reverses all accrued but unpaid interest as of such date. Additionally, Prosper charges-off Borrower Loans and Loans Held for Sale when they are 120 days past due. The fair value of loans 120 or more days past due generally consists of the expected recovery from debt sales in subsequent periods. Prosper has elected the fair value option for Borrower Loans, Loans Held for Sale, Notes, and Certificates Issued by Securitization Trust. Changes in fair value of Borrower Loans funded through the Note Channel are largely offset by the changes in fair value of Notes due to the borrower payment-dependent design of the Notes. Changes in the fair value of Borrower Loans held in consolidated securitization trusts are partially offset by changes in fair value of the Certificates Issued by Securitization Trust, prior to the deconsolidation of these securitization trusts in September 2021. Changes in fair value of Loans Held for Sale are recorded through Proper's earnings and Prosper collects interest on Loans Held for Sale. Changes in the fair values of Borrower Loans, Loans Held for Sale, Notes, and Certificates Issued by Securitization Trust are included in “Change in Fair Value of Financial Instruments, Net” on the Consolidated Statements of Operations. Prosper primarily uses a discounted cash flow model to estimate the fair value of Borrower Loans, Loans Held for Sale, Notes, and Certificates Issued by Securitization Trust. The key assumptions used in the valuation include default rates and prepayment rates derived primarily from historical performance, and discount rates based on estimates of the rates of return that investors would require when investing in financial instruments with similar characteristics.
Leases	Leases Management determines if an arrangement is a lease at inception. Operating lease right-of-use (“ROU”) assets and operating lease liabilities are included on the Consolidated Balance Sheets in Property and Equipment, Net and in Other Liabilities, respectively. For certain leases with original terms of twelve months or less, PMI recognizes the lease expense as incurred and does not record ROU assets and lease liabilities. If a contract contains a lease, management evaluates whether it should be classified as an operating or finance lease. Operating lease ROU assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. As most of PMI's leases do not provide an implicit rate, management uses an incremental borrowing rate based on the information available at commencement date in determining the present value of future payments. The operating lease ROU asset also includes any lease payments made and excludes lease incentives and initial direct costs incurred. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term. The operating lease ROU assets are evaluated for impairment utilizing the same impairment model used for Property and Equipment.
Consolidation of Variable Interest Entities	Consolidation of Variable Interest Entities The determination of whether to consolidate a VIE in which we have a variable interest requires a significant amount of analysis and judgment regarding whether we are the primary beneficiary of a VIE due to our holding a controlling financial interest in the VIE. A controlling financial interest in a VIE exists if we have both the power to direct the VIE’s activities that most significantly affect the VIE’s economic performance and a potentially significant economic interest in the VIE. The determination of whether an entity is a VIE considers factors, such as (i) whether the entity’s equity investment at risk is insufficient to allow the entity to finance its activities without additional subordinated financial support and (ii) whether a holder’s equity investment at risk lacks any of the following characteristics of a controlling financial interest: the direct or indirect ability through voting rights or similar rights to make decisions about a legal entity’s activities that have a significant effect on the entity’s success, the obligation to absorb the expected losses of the entity or the right to receive the expected residual returns of the legal entity. Management regularly reviews and reconsiders its previous conclusions regarding the status of an entity as a VIE and whether we are required to consolidate or deconsolidate such VIE in the consolidated financial statements.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Standards Adopted by the Company in the Current Period In December 2019, the FASB issued ASU No. 2019-12, “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.” This ASU simplifies the accounting for income taxes by removing certain exceptions related to the incremental approach for intraperiod tax allocation, the requirement to recognize or derecognize deferred tax liabilities related to equity method investments that are also foreign subsidiaries and the methodology for calculating income taxes in an interim period. The guidance also clarifies and simplifies other aspects of the accounting for income taxes, including a modification in the guidance for franchise taxes that are partially based on income and recognizing deferred taxes for a subsequent step-up in the tax basis of goodwill. The ASU is effective for the Company beginning in the first quarter of 2021. The Company has adopted ASU 2019-12 and concluded that the impact on its condensed consolidated financial statements was immaterial. Accounting Standards Issued, to be Adopted by the Company in Future Periods In March 2020, the FASB issued ASU No. 2020-04, “Reference Rate Reform (Topic 848),” which provides optional expedients and exceptions for applying GAAP on contract modifications and hedge accounting, in order to ease the financial reporting burdens of the expected market transition from LIBOR and other interbank offered rates to alternative referenced rates, such as the Secured Overnight Financing Rate. This ASU can be adopted after its issuance date through December 31, 2022. The Company is currently evaluating the impact reference rate reform will have on its contracts that reference LIBOR in order to determine whether to adopt this guidance.
Prosper Funding LLC
Entity Information [Line Items]
Basis of Presentation	Prosper Funding LLC (“PFL”) was formed in the state of Delaware in February 2012 as a limited liability company with Prosper Marketplace, Inc. (“PMI”) as its sole equity member. Except as the context otherwise requires, as used in these Notes to the condensed consolidated financial statements of Prosper Funding LLC, “PFL”, and the “Company” refers to Prosper Funding LLC and its wholly owned subsidiary, Prosper Depositor LLC, a Delaware limited liability company, on a consolidated basis. The unaudited interim condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“US GAAP”) and disclosure requirements for interim financial information and the requirements of Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by US GAAP for complete financial statements. The unaudited interim condensed consolidated financial statements should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2020. The balance sheet at December 31, 2020 has been derived from the audited financial statements at that date. Management believes these unaudited interim condensed consolidated financial statements reflect all adjustments, consisting of a normal recurring nature, which are necessary for a fair presentation of the results for the interim periods presented. The results of operations for the interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period. PFL did not have any items of other comprehensive income or loss for any of the periods presented in the condensed consolidated financial statements as of and for the nine months ended September 30, 2021 and September 30, 2020. The preparation of PFL's condensed consolidated financial statements and related disclosures in conformity with US GAAP requires management to make judgments, assumptions and estimates that affect the amounts reported in its condensed consolidated financial statements and accompanying notes. Management bases its estimates on historical experience and on various other factors it believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of certain assets and liabilities. These judgments, estimates and assumptions are inherently subjective in nature and actual results may differ from these estimates and assumptions, and the differences could be material.
Fair Value Measurements	Fair Value Measurements Financial instruments consist principally of Cash and Cash Equivalents, Restricted Cash, Borrower Loans, Loans Held for Sale, Accounts Receivable, Accounts Payable and Accrued Liabilities, Payable to Investors and Notes. The estimated fair values of Cash and Cash Equivalents, Restricted Cash, Accounts Receivable, Accounts Payable and Accrued Liabilities, and Payable to Investors approximate their carrying values because of their short-term nature.
Restricted Cash	Restricted Cash Restricted Cash consists primarily of cash deposits, money market funds and short-term certificate of deposit accounts held as collateral as required for long term leases, loan funding and servicing activities, and cash that investors have on our marketplace that has not yet been invested in Borrower Loans or disbursed to the investor.
Borrower Loans, Loans Held for Sale, Notes and Certificates Issued by Securitization Trust	Borrower Loans, Loans Held for Sale and Notes With respect to the Note Channel, PFL purchases Borrower Loans from WebBank, then issues Notes and holds the Borrower Loans until maturity. The obligation to repay a series of Notes funded through the Note Channel is dependent upon the repayment of the associated Borrower Loan. Borrower Loans and Notes funded through the Note Channel are carried on PFL’s condensed consolidated balance sheets as assets and liabilities, respectively. PFL places Borrower Loans and Loans Held for Sale on non-accrual status when they are 120 days past due. When a loan is placed on non-accrual status, PFL stops accruing interest and reverses all accrued but unpaid interest as of such date. Additionally, PFL charges-off Borrower Loans and Loans Held for Sale when they are 120 days past due. The fair value of loans 120 days past due generally consists of the expected recovery from debt sales in subsequent periods. Management has elected the fair value option for Borrower Loans, Loans Held for Sale, and Notes. Changes in fair value of Borrower Loans are largely offset by the changes in fair value of Notes due to the borrower payment-dependent design of the Notes. Changes in fair value of Borrower Loans, Loans Held for Sale and Notes are included in “Change in Fair Value of Borrower Loans, Loans Held for Sale and Notes, Net” on the condensed consolidated statements of operations. PFL primarily uses a discounted cash flow model to estimate the fair value of Borrower Loans, Loans Held for Sale and Notes. The key assumptions used in the valuation include default rates and prepayment rates derived primarily from historical performance and discount rates based on estimates of the rates of return that investors would require when investing in financial instruments with similar characteristics.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Standards Adopted In The Current Period No accounting standards were adopted in the current period for PFL. Accounting Standards Issued, To Be Adopted By PFL In Future Periods No issued and pending accounting standards were identified that are expected to have an impact on PFL.

PROPERTY AND EQUIPMENT, NET (Ta

PROPERTY AND EQUIPMENT, NET (Tables)	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
Property and Equipment, Net	Property and Equipment consists of the following at the dates presented (in thousands): September 30, 2021 December 31, 2020 Operating lease right-of-use assets $ 17,485 $ 15,767 Computer equipment 14,276 13,841 Internal-use software and website development costs 38,630 33,176 Office equipment and furniture 2,929 2,872 Leasehold improvements 7,167 7,167 Assets not yet placed in service 6,207 5,035 Property and equipment 86,694 77,858 Less: Accumulated depreciation and amortization (56,998) (49,412) Total Property and Equipment, Net $ 29,696 $ 28,446
Prosper Funding LLC
Entity Information [Line Items]
Property and Equipment, Net	Property and equipment consist of the following as of the dates presented (in thousands): September 30, 2021 December 31, 2020 Internal-use software and web site development costs $ 31,920 $ 26,953 Less accumulated depreciation and amortization (23,195) (20,025) Total property and equipment, net $ 8,725 $ 6,928

BORROWER LOANS, LOANS HELD FO_2

BORROWER LOANS, LOANS HELD FOR SALE AND NOTES, AT FAIR VALUE (Tables)	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
Aggregate Principal Balances Outstanding and Fair Values of Borrower Loans, Notes and Loans Held for Sale	The aggregate principal balances outstanding and fair values of Borrower Loans, Loans Held for Sale, and Notes as of September 30, 2021 and December 31, 2020, are presented in the following table (in thousands): Borrower Loans Loans Held for Sale Notes September 30, 2021 December 31, 2020 September 30, 2021 December 31, 2020 September 30, 2021 December 31, 2020 Aggregate principal balance outstanding $ 253,760 $ 393,642 $ 285,646 $ 279,113 $ 255,848 $ 217,110 Fair value adjustments 920 (15,379) 274 (4,492) (2,606) (8,731) Fair value $ 254,680 $ 378,263 $ 285,920 $ 274,621 $ 253,242 $ 208,379
Prosper Funding LLC
Entity Information [Line Items]
Aggregate Principal Balances Outstanding and Fair Values of Borrower Loans, Notes and Loans Held for Sale	The aggregate principal balances outstanding and fair values of Borrower Loans and Notes as of September 30, 2021 and December 31, 2020, are presented in the following table (in thousands): Borrower Loans Notes September 30, 2021 December 31, 2020 September 30, 2021 December 31, 2020 Aggregate principal balance outstanding $ 253,760 $ 215,373 $ 255,848 $ 217,110 Fair value adjustments 920 (5,703) (2,606) (8,731) Fair value $ 254,680 $ 209,670 $ 253,242 $ 208,379

SECURITIZATIONS (Tables)

SECURITIZATIONS (Tables)	9 Months Ended
	Sep. 30, 2021
Transfers and Servicing [Abstract]
Securitizations	Accordingly, the net assets of PMIT 2019-1, 2019-2 and 2019-4 were deconsolidated from Prosper’s balance sheet on September 27, 2021, resulting in a loss on deconsolidation of $1.5 million, consisting of the following (in thousands): PMIT 2019-1 PMIT 2019-2 PMIT 2019-4 Total Consideration received for residual certificates: Cash $ 2,259 $ 836 $ 981 $ 4,076 Net assets deconsolidated: Restricted Cash $ 2,485 $ 4,324 $ 4,088 $ 10,897 Borrower Loans (1) 15,133 29,989 33,239 78,361 Notes Issued by Securitization Trust (13,022) (26,712) (29,975) (69,709) Certificates Issued by Securitization Trust, at Fair Value (1) (2,057) (5,990) (5,932) (13,979) Total net assets deconsolidated $ 2,539 $ 1,611 $ 1,420 $ 5,570 Total loss on deconsolidation $ (280) $ (775) $ (439) $ (1,494) (1) Because Borrower Loans and Certificates Issued by Securitization Trust are measured at fair value on the Company’s condensed consolidated balance sheets, the balances above reflect the fair values of these financial instruments as of September 27, 2021, the deconsolidation date.

FAIR VALUE OF ASSETS AND LIAB_2

FAIR VALUE OF ASSETS AND LIABILITIES (Tables)	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value	The following tables present the fair value hierarchy for assets and liabilities measured at fair value (in thousands): September 30, 2021 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans, at Fair Value $ — $ — $ 254,680 $ 254,680 Loans Held for Sale at Fair Value — — 285,920 285,920 Servicing Assets — — 8,701 8,701 Total Assets $ — $ — $ 549,301 $ 549,301 Liabilities: Notes, at Fair Value $ — $ — $ 253,242 $ 253,242 Convertible Preferred Stock Warrant Liability — — 249,164 249,164 Loan Trailing Fee Liability — — 2,183 2,183 Total Liabilities $ — $ — $ 504,589 $ 504,589 December 31, 2020 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans, at Fair Value $ — $ — $ 378,263 $ 378,263 Loans Held for Sale at Fair Value — — 274,621 274,621 Servicing Assets — — 9,242 9,242 Total Assets $ — $ — $ 662,126 $ 662,126 Liabilities: Notes, at Fair Value $ — $ — $ 208,379 $ 208,379 Certificates Issued by Securitization Trust, at Fair Value — — 22,917 22,917 Convertible Preferred Stock Warrant Liability — — 112,319 112,319 Loan Trailing Fee Liability — — 2,233 2,233 Total Liabilities $ — $ — $ 345,848 $ 345,848
Quantitative Information About Significant Unobservable Inputs	The following tables present quantitative information about the ranges of significant unobservable inputs used for the Company’s Level 3 fair value measurements at September 30, 2021 and December 31, 2020: Range Borrower Loans, Loans Held for Sale and Notes: September 30, 2021 December 31, 2020 Discount rate 4.6% - 15.1% 4.5% - 17.7% Default rate 2.0% - 16.9% 2.3% - 17.9% Range Certificates Issued by Securitization Trust: December 31, 2020 Discount rate 3.3% - 16.0% Default rate 3.2% - 15.3% Prepayment rate 7.6% - 35.4% Borrower Loans held in consolidated securitization trusts and the associated Certificates Issued by Securitization Trust were deconsolidated from the Company’s balance sheet as of September 27, 2021 (Note 6), and as a result the tables above exclude these financial instruments. Refer to the section below for information about the inputs used to measure the fair value of these Borrower Loans and Certificates Issued by Securitization Trust. Range Servicing Assets: September 30, 2021 December 31, 2020 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.6% - 14.7% 1.9% - 17.7% Prepayment rate 10.3% - 29.1% 12.4% - 28.9% Market servicing rate (1) (2) 0.648% - 0.842% 0.625% - 0.818% (1) Servicing assets associated with loans enrolled in a relief program offered by the Company in response to the COVID-19 pandemic as of September 30, 2021 and December 31, 2020 were measured using a market servicing rate assumption of 84.2 basis points. This rate was estimated using a multiplier consistent with observable market rates for other loan types, applied to the base market servicing rate assumption of 64.8 basis points. (2) Excludes collection fees that would be passed on to a hypothetical third-party servicer. As of September 30, 2021 and December 31, 2020, the market rate for collection fees and non-sufficient fund fees was assumed to be 6 basis points and 7 basis points, respectively, for a total market servicing rate range of 70.8 - 90.2 basis points and a total market servicing rate of 69.5 - 88.8 basis points, respectively. Range Loan Trailing Fee Liability September 30, 2021 December 31, 2020 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.6% - 14.7% 1.9% - 17.7% Prepayment rate 10.3% - 29.1% 12.4% - 28.9%
Deconsolidated Assets and Liabilities	Key assumptions for the valuation of Borrower Loans are presented in the following table (in thousands, except percentages): Borrower Loans September 27, 2021 Fair value, using the following assumptions: $ 78,361 Weighted-average discount rate 9.26 % Weighted-average default rate 8.13 % Certificates Issued by Securitization Trust September 27, 2021 Fair value, using the following assumptions: $ 13,979 Weighted-average discount rate 7.99 % Weighted-average default rate 7.68 % Weighted-average prepayment rate 17.94 %
Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following tables present additional information about Level 3 Borrower Loans, Loans Held for Sale, Notes and Certificates Issued by Securitization Trust measured at fair value on a recurring basis (in thousands): Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held For Sale Notes Certificates Issued by Securitization Trust Total Balance at January 1, 2021 $ 378,263 $ 274,621 $ (208,379) $ (22,917) $ 421,588 Purchase of Borrower Loans/Issuance of Notes 172,082 1,248,316 (172,231) — 1,248,167 Principal repayments (215,076) (117,876) 126,528 14,935 (191,489) Borrower Loans sold to third parties (2,311) (1,118,526) — — (1,120,837) Other changes (1,545) (34) 205 113 (1,261) Change in fair value 1,628 (581) 635 (6,110) (4,428) Deconsolidation of VIEs (Note 6) (78,361) — — 13,979 (64,382) Balance at September 30, 2021 $ 254,680 $ 285,920 $ (253,242) $ — $ 287,358 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held for Sale Notes Certificates Issued by Securitization Trust Total Balance at January 1, 2020 $ 634,019 $ 142,026 $ (244,171) $ (52,168) $ 479,706 Purchase of Borrower Loans/Issuance of Notes 97,406 949,529 (97,303) — 949,632 Principal repayments (259,210) (72,885) 114,050 16,608 (201,437) Borrower Loans sold to third parties (5,637) (754,284) — — (759,921) Other changes (1,084) 943 (24) 390 225 Change in fair value (50,617) (12,886) 20,517 8,389 (34,597) Balance at September 30, 2020 $ 414,877 $ 252,443 $ (206,931) $ (26,781) $ 433,608 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held For Sale Notes Certificates Issued by Securitization Trust Total Balance at July 1, 2021 $ 338,939 $ 249,955 $ (236,041) $ (15,295) $ 337,558 Purchase of Borrower Loans/Issuance of Notes 64,473 455,642 (64,028) — 456,087 Principal repayments (69,094) (44,422) 45,486 4,042 (63,988) Borrower Loans sold to third parties (587) (375,192) — — (375,779) Other changes (353) 233 (14) 41 (93) Change in fair value (337) (296) 1,355 (2,767) (2,045) Deconsolidation of VIEs (Note 6) (78,361) — — 13,979 (64,382) Balance at September 30, 2021 $ 254,680 $ 285,920 $ (253,242) $ — $ 287,358 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held for Sale Notes Certificates Issued by Securitization Trust Total Balance at July 1, 2020 $ 457,487 $ 216,243 $ (209,987) $ (31,571) $ 432,172 Purchase of Borrower Loans/Issuance of Notes 31,742 327,407 (32,260) — 326,889 Principal repayments (79,658) (29,809) 36,943 6,733 (65,791) Borrower Loans sold to third parties (1,383) (262,502) — — (263,885) Other changes (926) 164 233 49 (480) Change in fair value 7,615 940 (1,860) (1,992) 4,703 Balance at September 30, 2020 $ 414,877 $ 252,443 $ (206,931) $ (26,781) $ 433,608
Schedule of Servicing Assets and Liabilities Measured at Fair Value	The following tables present additional information about Level 3 Servicing Assets measured at fair value on a recurring basis for the three and nine month periods ending September 30, 2021 and 2020 (in thousands): Servicing Assets Fair Value at January 1, 2021 $ 9,242 Additions 5,674 Recognition of Servicing Assets upon deconsolidation of VIEs (Note 6) 215 Less: Changes in fair value (6,430) Fair Value at September 30, 2021 $ 8,701 Servicing Assets Fair Value at January 1, 2020 $ 12,602 Additions 3,945 Less: Changes in fair value (7,241) Fair Value at September 30, 2020 $ 9,306 Servicing Assets Fair Value at July 1, 2021 $ 8,944 Additions 1,895 Recognition of Servicing Assets upon deconsolidation of VIEs (Note 6) 215 Less: Changes in fair value (2,353) Fair Value at September 30, 2021 $ 8,701 Servicing Assets Fair Value at July 1, 2020 $ 10,073 Additions 1,242 Less: Changes in fair value (2,009) Fair Value at September 30, 2020 $ 9,306 The following tables present additional information about the Level 3 Convertible Preferred Stock Warrant Liability measured at fair value on a recurring basis for the nine month periods ending September 30, 2021 and 2020 (in thousands): Convertible Preferred Stock Balance as of January 1, 2021 $ 112,319 Change in fair value 136,845 Balance as of September 30, 2021 $ 249,164 Convertible Preferred Stock Balance as of January 1, 2020 $ 149,996 Change in fair value (63,624) Balance as of September 30, 2020 $ 86,372 Convertible Preferred Stock Balance as of July 1, 2021 $ 162,436 Change in fair value 86,728 Balance as of September 30, 2021 $ 249,164 Convertible Preferred Stock Balance as of July 1, 2020 $ 74,998 Change in fair value 11,374 Balance as of September 30, 2020 $ 86,372
Fair Value, Liabilities Measured on Recurring Basis	The following tables present additional information about the Level 3 Loan Trailing Fee Liability measured at fair value on a recurring basis for the nine month periods ending September 30, 2021 and 2020 (in thousands): Loan Trailing Fee Liability Balance at January 1, 2021 $ 2,233 Issuances 1,289 Cash Payment of Loan Trailing Fee (1,587) Change in Fair Value 248 Balance at September 30, 2021 $ 2,183 Loan Trailing Fee Liability Balance at January 1, 2020 $ 2,997 Issuances 938 Cash Payment of Loan Trailing Fee (1,867) Change in Fair Value 194 Balance at September 30, 2020 $ 2,262 Loan Trailing Fee Liability Balance at July 1, 2021 $ 2,145 Issuances 472 Cash Payment of Loan Trailing Fee (521) Change in Fair Value 87 Balance at September 30, 2021 $ 2,183 Loan Trailing Fee Liability Balance at July 1, 2020 $ 2,403 Issuances 313 Cash Payment of Loan Trailing Fee (596) Change in Fair Value 142 Balance at September 30, 2020 $ 2,262
Fair Value Assumptions for Loans Held for Sale, Borrower Loans and Notes	Key economic assumptions and the sensitivity of the fair value to immediate changes in those assumptions at September 30, 2021 and December 31, 2020 for Borrower Loans and Loans Held for Sale are presented in the following table (in thousands, except percentages). Borrower Loans and Loans Held for Sale September 30, 2021 December 31, 2020 Fair value, using the following assumptions: $ 540,600 $ 652,884 Weighted-average discount rate 6.50 % 8.26 % Weighted-average default rate 9.78 % 11.58 % Fair value resulting from: 100 basis point increase in discount rate $ 535,208 $ 647,093 200 basis point increase in discount rate $ 529,952 $ 641,437 Fair value resulting from: 100 basis point decrease in discount rate $ 546,133 $ 658,817 200 basis point decrease in discount rate $ 551,813 $ 664,895 Fair value resulting from: 10 percent increase in default rate $ 535,886 $ 646,421 20 percent increase in default rate $ 531,204 $ 639,987 Fair value resulting from: 10 percent decrease in default rate $ 545,341 $ 659,377 20 percent decrease in default rate $ 550,113 $ 665,904 Key economic assumptions and the sensitivity of the fair value to immediate changes in those assumptions at September 30, 2021 and December 31, 2020 for Notes are presented in the following table (in thousands, except percentages). Notes September 30, 2021 December 31, 2020 Fair value, using the following assumptions: $ 253,242 $ 208,379 Weighted-average discount rate 6.71 % 8.93 % Weighted-average default rate 10.66 % 12.26 % Fair value resulting from: 100 basis point increase in discount rate $ 250,713 $ 206,528 200 basis point increase in discount rate $ 248,247 $ 204,720 Fair value resulting from: 100 basis point decrease in discount rate $ 255,838 $ 210,274 200 basis point decrease in discount rate $ 258,503 $ 212,217 Fair value resulting from: 10 percent increase in default rate $ 251,021 $ 206,304 20 percent increase in default rate $ 248,814 $ 204,238 Fair value resulting from: 10 percent decrease in default rate $ 255,477 $ 210,463 20 percent decrease in default rate $ 257,727 $ 212,558
Schedule of Prosper's and Prosper Funding's Estimated Fair Value of Servicing Assets and Liabilities	Key economic assumptions and the sensitivity of the fair value to immediate changes in those assumptions at September 30, 2021 and December 31, 2020 for Servicing Assets is presented in the following table (in thousands, except percentages). Servicing Assets September 30, 2021 December 31, 2020 Fair value, using the following assumptions $ 8,701 $ 9,242 Weighted-average market servicing rate 0.650 % 0.631 % Weighted-average prepayment rate 18.89 % 19.84 % Weighted-average default rate 12.18 % 12.78 % Fair value resulting from: Market servicing rate increase of 0.025% $ 8,148 $ 8,689 Market servicing rate decrease of 0.025% $ 9,255 $ 9,796 Fair value resulting from: Applying a 1.1 multiplier to prepayment rate $ 8,532 $ 9,064 Applying a 0.9 multiplier to prepayment rate $ 8,872 $ 9,423 Fair value resulting from: Applying a 1.1 multiplier to default rate $ 8,586 $ 9,116 Applying a 0.9 multiplier to default rate $ 8,817 $ 9,369
Financial Instruments, Assets And Liabilities Not Recorded At Fair Value	The following table presents the fair value hierarchy for assets, and liabilities not recorded at fair value (in thousands): September 30, 2021 Carrying Amount Level 1 Inputs Level 2 Inputs Level 3 Inputs Balance at Fair Value Assets: Cash and Cash Equivalents $ 55,949 $ 55,949 $ — $ — $ 55,949 Restricted Cash - Cash and Cash Equivalents 152,024 152,024 — — 152,024 Restricted Cash - Certificates of Deposit 4,877 — 4,877 — 4,877 Accounts Receivable 749 — 749 — 749 Total Assets $ 213,599 $ 207,973 $ 5,626 $ — $ 213,599 Liabilities: Accounts Payable and Accrued Liabilities $ 23,807 $ — $ 23,807 $ — $ 23,807 Payable to Investors 141,115 — 141,115 — 141,115 Warehouse Lines 245,819 — 247,769 — 247,769 Paycheck Protection Program loan (Note 10) 8,568 — 8,557 — 8,557 Total Liabilities $ 419,309 $ — $ 421,248 $ — $ 421,248 December 31, 2020 Carrying Amount Level 1 Inputs Level 2 Inputs Level 3 Inputs Balance at Fair Value Assets: Cash and Cash Equivalents $ 50,145 $ 50,145 $ — $ — $ 50,145 Restricted Cash - Cash and Cash Equivalents 158,846 158,846 — — 158,846 Restricted Cash - Certificates of Deposit 4,877 — 4,877 — 4,877 Accounts Receivable 605 — 605 — 605 Total Assets $ 214,473 $ 208,991 $ 5,482 $ — $ 214,473 Liabilities: Accounts Payable and Accrued Liabilities $ 17,876 $ — $ 17,876 $ — $ 17,876 Payable to Investors 124,094 — 124,094 — 124,094 Notes Issued by Securitization Trust 156,782 — 158,951 — 158,951 Warehouse Lines 242,479 — 242,261 — 242,261 Paycheck Protection Program loan (Note 10) 8,505 — 8,540 — 8,540 Total Liabilities $ 549,736 $ — $ 551,722 $ — $ 551,722
Prosper Funding LLC
Entity Information [Line Items]
Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value	The following tables present the fair value hierarchy for assets and liabilities measured at fair value (in thousands): September 30, 2021 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans, at Fair Value $ — $ — $ 254,680 $ 254,680 Servicing Assets — — 9,968 9,968 Total Assets $ — $ — $ 264,648 $ 264,648 Liabilities: Notes, at Fair Value $ — $ — $ 253,242 $ 253,242 Loan Trailing Fee Liability — — 2,183 2,183 Total Liabilities $ — $ — $ 255,425 $ 255,425 December 31, 2020 Level 1 Inputs Level 2 Inputs Level 3 Inputs Total Assets: Borrower Loans, at Fair Value $ — $ — $ 209,670 $ 209,670 Servicing Assets — — 11,088 11,088 Total Assets $ — $ — $ 220,758 $ 220,758 Liabilities: Notes, at Fair Value $ — $ — $ 208,379 $ 208,379 Loan Trailing Fee Liability — — 2,233 2,233 Total Liabilities $ — $ — $ 210,612 $ 210,612
Quantitative Information About Significant Unobservable Inputs	The following tables present quantitative information about the significant unobservable inputs used for PFL’s Level 3 fair value measurements at the dates presented: Range Borrower Loans and Notes September 30, 2021 December 31, 2020 Discount rate 4.6% - 15.0% 5.3% - 16.1% Default rate 2.0% - 14.0% 2.6% - 16.2% Range Servicing Assets September 30, 2021 December 31, 2020 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.6% - 14.7% 1.9% - 17.7% Prepayment rate 10.3% - 29.1% 12.4% - 28.9% Market servicing rate (1) (2) 0.648% - 0.842% 0.625% - 0.818% (1) Servicing assets associated with loans enrolled in a relief program offered by the Company in response to the COVID-19 pandemic as of September 30, 2021 and December 31, 2020 were measured using a market servicing rate assumption of 84.2 basis points. This rate was estimated using a multiplier consistent with observable market rates for other loan types, applied to the base market servicing rate assumption of 64.8 basis points. (2) Excludes collection fees that would be passed on to a hypothetical third-party servicer. As of September 30, 2021 and December 31, 2020, the market rate for collection fees and non-sufficient fund fees was assumed to be 6 basis points and 7 basis points, respectively, for a total market servicing rate range of 70.8 - 90.2 basis points and a total market servicing rate of 69.5 - 88.8 basis points, respectively. Range Loan Trailing Fee Liability September 30, 2021 December 31, 2020 Discount rate 15.0% - 25.0% 15.0% - 25.0% Default rate 1.6% - 14.7% 1.9% - 17.7% Prepayment rate 10.3% - 29.1% 12.4% - 28.9%
Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following tables present additional information about Level 3 Borrower Loans, Loans Held for Sale and Notes measured at fair value on a recurring basis (in thousands): Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held for Sale Notes Total Balance at January 1, 2021 $ 209,670 $ — $ (208,379) $ 1,291 Originations 172,082 1,248,316 (172,231) 1,248,167 Principal repayments (125,672) — 126,528 856 Borrower Loans sold to third parties (1,069) (1,248,316) — (1,249,385) Other changes (223) — 205 (18) Change in fair value (108) — 635 527 Balance at September 30, 2021 $ 254,680 $ — $ (253,242) $ 1,438 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held for Sale Notes Total Balance at January 1, 2020 $ 245,137 $ — $ (244,171) $ 966 Originations 97,406 949,529 (97,303) 949,632 Principal repayments (112,034) — 114,051 2,017 Borrower Loans sold to third parties (2,111) (949,529) — (951,640) Other changes (23) — (25) (48) Change in fair value (20,331) — 20,517 186 Balance at September 30, 2020 $ 208,044 $ — $ (206,931) $ 1,113 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held for Sale Notes Total Balance at July 1, 2021 $ 236,844 $ — $ (236,041) $ 803 Originations 64,473 455,642 (64,028) 456,087 Principal repayments (45,338) — 45,486 148 Borrower Loans sold to third parties (300) (455,642) — (455,942) Other changes (15) — (14) (29) Change in fair value (984) — 1,355 371 Balance at September 30, 2021 $ 254,680 $ — $ (253,242) $ 1,438 Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Assets Liabilities Borrower Loans Loans Held for Sale Notes Total Balance at July 1, 2020 $ 211,775 $ — $ (209,986) $ 1,789 Originations 31,742 327,407 (32,260) 326,889 Principal repayments (36,438) — 36,943 505 Borrower Loans sold to third parties (547) (327,407) — (327,954) Other changes (276) — 232 (44) Change in fair value 1,788 — (1,860) (72) Balance at September 30, 2020 $ 208,044 $ — $ (206,931) $ 1,113
Schedule of Servicing Assets and Liabilities Measured at Fair Value	The following tables present additional information about Level 3 Servicing Assets recorded at fair value (in thousands): Servicing Assets Fair Value at January 1, 2021 $ 11,088 Additions 6,676 Less: Changes in fair value (7,796) Fair Value at September 30, 2021 $ 9,968 Servicing Assets Fair Value at January 1, 2020 $ 14,888 Additions 5,034 Less: Changes in fair value (8,657) Fair Value at September 30, 2020 $ 11,265 Servicing Assets Fair Value at July 1, 2021 $ 10,389 Additions 2,300 Less: Changes in fair value (2,721) Fair Value at September 30, 2021 $ 9,968 Servicing Assets Fair Value at July 1, 2020 $ 12,063 Additions 1,632 Less: Changes in fair value (2,430) Fair Value at September 30, 2020 $ 11,265 Loan Trailing Fee Liability The fair value of the Loan Trailing Fee Liability represents the present value of the expected monthly Loan Trailing Fee payments, which takes into consideration certain assumptions related to expected prepayment rates and default rates using a discounted cash flow model. The assumptions used are the same as those used for the valuation of Servicing Assets, as described below. The following tables present additional information about Level 3 Loan Trailing Fee Liability measured at fair value on a recurring basis (in thousands): Loan Trailing Fee Liability Fair Value at January 1, 2021 $ 2,233 Issuances 1,289 Cash payment of Loan Trailing Fee (1,587) Change in fair value 248 Fair Value at September 30, 2021 $ 2,183 Loan Trailing Fee Liability Fair Value at January 1, 2020 $ 2,997 Issuances 938 Cash payment of Loan Trailing Fee (1,867) Change in fair value 194 Fair Value at September 30, 2020 $ 2,262 Loan Trailing Fee Liability Fair Value at July 1, 2021 $ 2,145 Issuances 472 Cash payment of Loan Trailing Fee (521) Change in fair value 87 Fair Value at September 30, 2021 $ 2,183 Loan Trailing Fee Liability Fair Value at July 1, 2020 $ 2,403 Issuances 313 Cash payment of Loan Trailing Fee (596) Change in fair value 142 Fair Value at September 30, 2020 $ 2,262
Fair Value Assumptions for Loans Held for Sale, Borrower Loans and Notes	Key economic assumptions are used to compute the fair value of Borrower Loans. The sensitivity of the fair value to immediate changes in assumptions at September 30, 2021 and December 31, 2020 for Borrower Loans are presented in the following table (in thousands, except percentages). Borrower Loans: September 30, 2021 December 31, 2020 Fair value, using the following assumptions: $ 254,680 $ 209,670 Weighted-average discount rate 6.71 % 8.93 % Weighted-average default rate 10.66 % 12.26 % Fair value resulting from: 100 basis point increase in discount rate $ 252,139 $ 207,810 200 basis point increase in discount rate $ 249,663 $ 205,994 Fair value resulting from: 100 basis point decrease in discount rate $ 257,286 $ 211,575 200 basis point decrease in discount rate $ 259,962 $ 213,527 Fair value resulting from: 10 percent increase in default rate $ 252,459 $ 207,594 20 percent increase in default rate $ 250,253 $ 205,528 Fair value resulting from: 10 percent decrease in default rate $ 256,914 $ 211,755 20 percent decrease in default rate $ 259,161 $ 213,851 Key economic assumptions are used to compute the fair value of Notes. The sensitivity of the fair value to immediate changes in assumptions at September 30, 2021 and December 31, 2020 for Notes funded through the Note Channel are presented in the following table (in thousands, except percentages). Notes September 30, 2021 December 31, 2020 Fair value, using the following assumptions: $ 253,242 $ 208,379 Weighted-average discount rate 6.71 % 8.93 % Weighted-average default rate 10.66 % 12.26 % Fair value resulting from: 100 basis point increase in discount rate $ 250,713 $ 206,528 200 basis point increase in discount rate $ 248,247 $ 204,720 Fair value resulting from: 100 basis point decrease in discount rate $ 255,838 $ 210,274 200 basis point decrease in discount rate $ 258,503 $ 212,217 Fair value resulting from: 10 percent increase in default rate $ 251,021 $ 206,304 20 percent increase in default rate $ 248,814 $ 204,238 Fair value resulting from: 10 percent decrease in default rate $ 255,477 $ 210,463 20 percent decrease in default rate $ 257,727 $ 212,558
Schedule of Prosper's and Prosper Funding's Estimated Fair Value of Servicing Assets and Liabilities	Key economic assumptions are used to compute the fair value of Servicing Assets. The sensitivity of the current fair value to immediate changes in assumptions at September 30, 2021 and December 31, 2020 for Servicing Assets are presented in the following table (in thousands, except percentages). Servicing Assets September 30, 2021 December 31, 2020 Fair value, using the following assumptions: $ 9,968 $ 11,088 Weighted-average market servicing rate 0.650 % 0.631 % Weighted-average prepayment rate 18.89 % 19.84 % Weighted-average default rate 11.83 % 12.78 % Fair value resulting from: Market servicing rate increase of 0.025% $ 9,333 $ 10,424 Market servicing rate decrease of 0.025% $ 10,602 $ 11,752 Fair value resulting from: Applying a 1.1 multiplier to prepayment rate $ 9,774 $ 10,874 Applying a 0.9 multiplier to prepayment rate $ 10,164 $ 11,304 Fair value resulting from: Applying a 1.1 multiplier to default rate $ 9,836 $ 10,936 Applying a 0.9 multiplier to default rate $ 10,100 $ 11,239

GOODWILL AND OTHER INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLE ASSETS, NET (Tables)	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Other Intangible Assets for the Period Presented	The following table presents the detail of other intangible assets subject to amortization as of the following date (dollars in thousands): September 30, 2021 Gross Carrying Value Accumulated Amortization Net Carrying Value Remaining Useful Life (In Years) Developed technology $ 3,060 $ (3,060) $ — — User base and customer relationships 5,050 (4,679) 371 3.6 Brand name 60 (60) — — Total Intangible Assets subject to amortization $ 8,170 $ (7,799) $ 371
Summary of Estimated Amortization of Purchased Intangible Assets	Estimated amortization of purchased intangible assets for future periods is as follows (in thousands): Year Ending December 31, 2021 (remainder thereof) $ 43 2022 136 2023 107 2024 85 Total $ 371

OTHER LIABILITIES (Tables)

OTHER LIABILITIES (Tables)	9 Months Ended
	Sep. 30, 2021
Other Liabilities [Abstract]
Schedule of Other Liabilities	Other Liabilities consist of the following (in thousands): September 30, 2021 December 31, 2020 Operating lease liabilities $ 12,316 $ 13,342 Paycheck Protection Program loan (Note 10) 8,568 8,505 Loan trailing fee liability 2,183 2,233 Deferred income tax liability 552 489 Financing lease liabilities 155 — Deferred revenue 50 63 Other 280 425 Total Other Liabilities $ 24,104 $ 25,057

NET INCOME (LOSS) PER SHARE (Ta

NET INCOME (LOSS) PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Basic and Diluted Net Income (Loss) per Share	Basic and diluted income (loss) per share were calculated as follows for the periods presented (in thousands, except share and per share amounts): Three Months Ended September 30, Nine Months Ended September 30, 2021 2021 2020 2021 2020 Numerator: Net (Loss) Income $ (88,061) $ (2,025) $ (138,755) $ 36,746 Plus: Return on Share Purchase — 2,381 — 2,381 Less: Net Income Allocated to Participating Securities — (255) — (28,814) Net (Loss) Income Attributable to Common Stockholders $ (88,061) $ 101 $ (138,755) $ 10,313 Denominator: Weighted average shares used in computing basic net (loss) income per share 71,068,442 68,485,173 70,433,182 68,465,046 Effect of dilutive securities: Stock options — 14,902,171 — 50,778,284 Convertible preferred stock warrants — 213,264,845 — 213,264,845 Weighted average shares used in computing diluted Net (Loss) Income per Share 71,068,442 296,652,189 70,433,182 332,508,175 Net (Loss) Income Per Share – Basic $ (1.24) $ — $ (1.97) $ 0.15 Net (Loss) Income Per Share – Diluted $ (1.24) $ — $ (1.97) $ 0.03
Common Stock Equivalents Excluded from Computation of Diluted Net Income (Loss) per Share	The following common stock equivalents were excluded from the computation of diluted net (loss) income per share for the periods presented because including them would have been anti-dilutive: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (shares) (shares) (shares) (shares) Excluded securities: Convertible preferred stock issued and outstanding, excluding shares held by consolidated VIE 158,365,655 181,761,442 158,365,655 200,261,761 Stock options issued and outstanding 70,601,482 58,390,141 72,845,826 22,127,694 Warrants issued and outstanding 1,080,349 1,080,349 1,080,349 1,080,349 Series E-1 convertible preferred stock warrants 35,544,141 — 35,544,141 — Series F convertible preferred stock warrants 177,720,704 — 177,720,704 — Total common stock equivalents excluded from diluted net (loss) income per common share computation 443,312,331 241,231,932 445,556,675 223,469,804

CONVERTIBLE PREFERRED STOCK, _2

CONVERTIBLE PREFERRED STOCK, CONVERTIBLE PREFERRED STOCK WARRANT LIABILITY AND COMMON STOCK (Tables)	9 Months Ended
	Sep. 30, 2021
Stockholders' Equity Note [Abstract]
Summary of Shares Authorized, Issued, Outstanding, Par Value and Liquidation Preference of Convertible Preferred Stock	The number of authorized, issued and outstanding shares, their par value and liquidation preference for each series of convertible preferred stock as of September 30, 2021 are disclosed in the table below (amounts in thousands except share and par value amounts): Convertible Preferred Stock Par Value Authorized Shares Outstanding and Issued Shares Liquidation Preference, Outstanding Shares Series A $ 0.01 68,558,220 66,428,185 * $ 19,160 Series A-1 $ 0.01 24,760,915 22,515,315 45,031 Series B $ 0.01 35,775,880 35,127,160 * 21,190 Series C $ 0.01 24,404,770 24,404,770 70,075 Series D $ 0.01 23,888,640 23,888,640 165,000 Series E-1 $ 0.01 35,544,141 — — Series E-2 $ 0.01 16,858,078 — — Series F $ 0.01 177,720,707 3 — Series G $ 0.01 37,249,497 37,249,497 50,000 Total 444,760,848 209,613,570 $ 370,456 * Series A and Series B Convertible Preferred Stock totals are inclusive of 34,670,420 and 16,577,495 shares, respectively, held by PGT, a consolidated VIE.
Schedule of Assumptions Used	The Company determined the fair value of the outstanding Series E-1 Warrants utilizing the following assumptions as of the following dates: September 30, 2021 December 31, 2020 Volatility 59.0 % 60.0 % Risk-free interest rate 0.50 % 0.20 % Expected term (in years) 2.75 2.75 Dividend yield — % — % The Company determined the fair value of the outstanding Series F Warrants utilizing the following assumptions as of the following dates: September 30, 2021 December 31, 2020 Volatility 59.0 % 60.0 % Risk-free interest rate 0.50 % 0.20 % Expected term (in years) 2.75 2.75 Dividend yield — % — %
Schedule of Stockholders' Equity Note, Warrants or Rights	The combined activity of the Convertible Preferred Stock Warrant Liability for the nine months ended September 30, 2021 and 2020 are as follows (in thousands): Warrant Activity Balance at January 1, 2021 $ 112,319 Change in fair value 136,845 Balance at September 30, 2021 $ 249,164 Warrant Activity Balance at January 1, 2020 $ 149,996 Change in fair value (63,624) Balance at September 30, 2020 $ 86,372

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Summarized Option Activity under Option Plan	Stock option activity under the 2005 Plan and 2015 Plan is summarized for the nine months ended September 30, 2021 below: Options Issued and Outstanding Weighted Average Exercise Price Balance as of January 1, 2021 72,915,449 $ 0.02 Options issued 15,431,359 $ 0.16 Options exercised (2,182,346) $ 0.02 Options forfeited (13,815,422) $ 0.02 Options expired (30,190) $ 0.02 Balance as of September 30, 2021 72,318,850 $ 0.05 Options vested and expected to vest as of September 30, 2021 54,681,009 $ 0.05 Options vested and exercisable as of September 30, 2021 48,617,301 $ 0.02
Fair Value of Stock Option Awards	The fair value of PMI’s stock option awards granted during the three and nine months ended September 30, 2021 and 2020 was estimated at the date of grant using the Black-Scholes model with the following average assumptions: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Volatility of common stock 64.84 % 57.32 % 64.37 % 52.66 % Risk-free interest rate 0.97 % 0.37 % 0.99 % 0.51 % Expected life 6.0 years 6.0 years 6.0 years 6.0 years Dividend yield — % — % — % — %
Summarized Activities for RSU's	The following table summarizes the number of PMI’s RSU activity for the nine months ended September 30, 2021: Number of Shares Weighted-Average Grant Date Fair Value Unvested at January 1, 2021 4,661,141 $ 0.91 Forfeited (1,786,793) $ 0.54 Unvested at September 30, 2021 2,874,348 $ 1.14
Stock Based Compensation Included in Consolidated Statements of Operations	The following table presents the amount of stock-based compensation related to stock-based awards granted to employees recognized in Prosper’s condensed consolidated statements of operations for the periods presented (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Origination and servicing $ 30 $ 53 $ 92 $ 124 Sales and marketing 15 25 47 51 General and administrative 225 708 718 1,508 Total stock-based compensation $ 270 $ 786 $ 857 $ 1,683

LEASES (Tables)

LEASES (Tables)	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Summary of Operating Lease Right-of-Use Assets	The following table summarizes the operating lease right-of-use assets as of September 30, 2021, which are included in “Property and Equipment, Net” on the condensed consolidated balance sheets. September 30, 2021 Gross Carrying Value Accumulated Amortization Net Carrying Value ROU Assets - Office buildings $ 16,709 $ 8,581 $ 8,128 ROU Assets - Other 776 252 524 Total right-of-use assets subject to amortization $ 17,485 $ 8,833 $ 8,652
Schedule of Future Minimum Lease Payments	Future maturities of operating lease liabilities as of September 30, 2021 were as follows (in thousands). The present value of the future minimum lease payments represent our operating lease liabilities as of September 30, 2021 and are included in " Other Liabilities September 30, 2021 Remainder of 2021 $ 1,439 2022 5,833 2023 2,124 2024 1,360 2025 1,395 Thereafter 1,218 Total future minimum lease payments $ 13,369 Less imputed interest (1,053) Present value of future minimum lease payments $ 12,316
Summary of Other Information Related to Leases	Other information related to leases was as follows (dollars in thousands): September 30, 2021 Cash paid for operating leases year-to-date $ 3,955 ROU assets obtained in exchange for new operating lease obligations year-to-date $ 1,773 Weighted average remaining lease term (in years) 3.24 years Weighted average discount rate 5.48 %

RELATED PARTIES (Tables)

RELATED PARTIES (Tables)	9 Months Ended
	Sep. 30, 2021
Entity Information [Line Items]
Aggregate Amount of Notes Purchased and the Income Earned	The aggregate amount of the Notes purchased and the income earned by parties deemed to be affiliates and related parties of Prosper for the three and nine months ended September 30, 2021 and September 30, 2020, as well as the Notes outstanding as of September 30, 2021 and December 31, 2020 are summarized below (in thousands): Aggregate Amount of Interest Earned on Notes Related Party 2021 2020 2021 2020 Executive officers and management $ 9 $ 7 $ 2 $ 1 Directors (excluding executive officers and management) 4 41 1 14 Total $ 13 $ 48 $ 3 $ 15 Aggregate Amount of Interest Earned on Notes Related Party 2021 2020 2021 2020 Executive officers and management $ 26 $ 19 $ 5 $ 4 Directors (excluding executive officers and management) 24 272 1 43 Total $ 50 $ 291 $ 6 $ 47 Notes Balance as of Related Party September 30, 2021 December 31, Executive officers and management $ 40 $ 41 Directors (excluding executive officers and management) 18 — Total $ 58 $ 41
Prosper Funding LLC
Entity Information [Line Items]
Aggregate Amount of Notes Purchased and the Income Earned	The aggregate amount of the Notes purchased and the income earned by parties deemed to be related parties of PFL for the nine months ended September 30, 2021 and 2020 are summarized below (in thousands): Aggregate Amount of Notes Purchased Interest Earned on Notes Three Months Ended September 30, Three Months Ended September 30, Related Party 2021 2020 2021 2020 Executive officers and management $ 9 $ 7 $ 2 $ 1 Directors (excluding executive officers and management) — — — — Total $ 9 $ 7 $ 2 $ 1 Aggregate Amount of Notes Purchased Interest Earned on Notes Nine Months Ended September 30, Nine Months Ended September 30, Related Party 2021 2020 2021 2020 Executive officers and management $ 26 $ 19 $ 5 $ 4 Directors (excluding executive officers and management) — — — — Total $ 26 $ 19 $ 5 $ 4 The balance of Notes held by officers and directors who are not executive officers are as follows (in thousands): Notes Balance as of Related Party September 30, 2021 December 31, 2020 Executive officers and management $ 40 $ 41 Directors (excluding executive officers and management) — — Total $ 40 $ 41

PROPERTY AND EQUIPMENT, NET (De

PROPERTY AND EQUIPMENT, NET (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Total Property and Equipment, Net	Total Property and Equipment, Net
Property and equipment	$ 86,694	$ 77,858
Less: Accumulated depreciation and amortization	(56,998)	(49,412)
Total Property and Equipment, Net	29,696	28,446
Prosper Funding LLC
Property, Plant and Equipment [Line Items]
Less: Accumulated depreciation and amortization	(23,195)	(20,025)
Total Property and Equipment, Net	8,725	6,928
Operating lease right-of-use assets
Property, Plant and Equipment [Line Items]
Operating lease right-of-use assets	17,485	15,767
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment	14,276	13,841
Internal-use software and website development costs
Property, Plant and Equipment [Line Items]
Property and equipment	38,630	33,176
Internal-use software and website development costs | Prosper Funding LLC
Property, Plant and Equipment [Line Items]
Property and equipment	31,920	26,953
Office equipment and furniture
Property, Plant and Equipment [Line Items]
Property and equipment	2,929	2,872
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	7,167	7,167
Assets not yet placed in service
Property, Plant and Equipment [Line Items]
Property and equipment	$ 6,207	$ 5,035

PROPERTY AND EQUIPMENT, NET - A

PROPERTY AND EQUIPMENT, NET - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Property, Plant and Equipment [Line Items]
Depreciation and Amortization			$ 7,224	$ 6,196
Prosper Funding LLC
Property, Plant and Equipment [Line Items]
Depreciation and Amortization	$ 1,300	$ 1,100	3,540	3,132
Property Plant And Equipment
Property, Plant and Equipment [Line Items]
Depreciation and Amortization	2,500	2,100	7,100	6,000
Internal-use software and website development costs
Property, Plant and Equipment [Line Items]
Capitalized internal-use software and website development costs	$ 2,600	$ 1,800	$ 7,100	$ 6,500

BORROWER LOANS, LOANS HELD FO_3

BORROWER LOANS, LOANS HELD FOR SALE AND NOTES, AT FAIR VALUE - Aggregate Principal Balances Outstanding and Fair Values of Borrower Loans, Notes and Loans Held for Sale (Details) - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2021	Dec. 31, 2020
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Borrower Loans, at Fair Value	[1]	$ 254,680	$ 378,263
Loans Held for Sale, at Fair Value	[1]	285,920	274,621
Notes, at Fair Value		253,242	208,379
Prosper Funding LLC
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Borrower Loans, at Fair Value		254,680	209,670
Notes, at Fair Value		253,242	208,379
Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Notes, Aggregate principal balance outstanding		255,848	217,110
Notes, Fair value adjustments		(2,606)	(8,731)
Notes, at Fair Value		253,242	208,379
Notes | Prosper Funding LLC
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Notes, Aggregate principal balance outstanding		255,848	217,110
Notes, Fair value adjustments		(2,606)	(8,731)
Notes, at Fair Value		253,242	208,379
Borrower Loans
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Borrower Loans, Aggregate principal balance outstanding		253,760	393,642
Fair value adjustments		920	(15,379)
Borrower Loans, at Fair Value		254,680	378,263
Borrower Loans | Prosper Funding LLC
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Borrower Loans, Aggregate principal balance outstanding		253,760	215,373
Fair value adjustments		920	(5,703)
Borrower Loans, at Fair Value		254,680	209,670
Loans Held for Sale
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Loans Held for Sale, Aggregate principal balance outstanding		285,646	279,113
Fair value adjustments		274	(4,492)
Loans Held for Sale, at Fair Value		$ 285,920	$ 274,621
[1]	Includes amounts in consolidated variable interest entities (VIEs) presented separately in the table below. The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 6, Securitizations, and Note 10, Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information. September 30, 2021 December 31, 2020 Assets of consolidated VIEs, included in total assets above: Restricted Cash $ 5,805 $ 25,203 Loans Held for Sale, at Fair Value 285,920 274,621 Borrower Loans, at Fair Value — 168,593 Prepaid and Other Assets 3,068 2,043 Total assets of consolidated variable interest entities $ 294,793 $ 470,460 Liabilities of consolidated VIEs, included in total liabilities above: Notes Issued by Securitization Trust $ — $ 156,782 Certificates Issued by Securitization Trust, at Fair Value — 22,917 Warehouse Lines 245,819 242,479 Total liabilities of consolidated variable interest entities $ 245,819 $ 422,178

BORROWER LOANS, LOANS HELD FO_4

BORROWER LOANS, LOANS HELD FOR SALE AND NOTES, AT FAIR VALUE - Additional Information (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Non accrual status past due date				120 days
Interest income		$ 8,404	$ 11,174	$ 25,472	$ 33,510
COVID-19 Relief
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Percent of loans in relief program, cumulative		10.00%		10.00%
Percent of loans in relief program, active		1.00%		1.00%
Borrower Loans
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Fixed interest rate, minimum	5.31%			5.31%
Fixed interest rate, maximum	31.82%			31.82%
Fair value of loans originated that are 90 days or more delinquent	$ 300	$ 100		$ 100		$ 300
Loans in non-accrual status	400	100		100		400
Borrower Loans | 90 days or more past due
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Aggregate principal amount	$ 2,800	800		$ 800		2,800
Loans Held for Sale
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Fixed interest rate, minimum	5.31%			5.31%
Fixed interest rate, maximum	31.82%			31.82%
Fair value of loans originated that are 90 days or more delinquent	$ 100	100		$ 100		100
Loans in non-accrual status	100	100		100		100
Interest income				23,700	19,200
Loans Held for Sale | 90 days or more past due
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Aggregate principal amount	800	800		800		$ 800
Prosper Funding LLC
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Interest income		$ 639	$ 560	$ 1,764	$ 1,763
Prosper Funding LLC | COVID-19 Relief
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Percent of loans in relief program, cumulative		10.00%		10.00%
Percent of loans in relief program, active		1.00%		1.00%
Prosper Funding LLC | Borrower Loans
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Fixed interest rate, minimum				5.31%		5.31%
Fixed interest rate, maximum				31.82%		31.82%
Fair value of loans originated that are 90 days or more delinquent	100	$ 100		$ 100		$ 100
Non accrual status past due date				120 days
Loans in non-accrual status	200	100		$ 100		200
Prosper Funding LLC | Borrower Loans | 90 days or more past due
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Aggregate principal amount	$ 1,400	$ 800		$ 800		$ 1,400
Minimum | Borrower Loans
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Maturity, in months	36 months			36 months
Minimum | Loans Held for Sale
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Maturity, in months	36 months			36 months
Minimum | Prosper Funding LLC | Borrower Loans
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Maturity, in months				36 months		36 months
Maximum | Borrower Loans
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Maturity, in months	60 months			60 months
Maximum | Loans Held for Sale
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Maturity, in months	60 months			60 months
Maximum | Prosper Funding LLC | Borrower Loans
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Maturity, in months				60 months		60 months

SERVICING ASSETS (Details)

SERVICING ASSETS (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Servicing Assets And Liabilities Fair Value [Line Items]
Gain (loss) on sale of borrower loans		$ 1,928	$ 786	$ 4,917	$ 3,147
Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Gain (loss) on sale of borrower loans		2,404	1,247	6,078	4,429
Servicing Assets
Servicing Assets And Liabilities Fair Value [Line Items]
Outstanding principle	$ 2,400,000	2,300,000		$ 2,300,000
Fixed interest rate, minimum	5.31%			5.31%
Fixed interest rate, maximum	31.82%			31.82%
Contractually specified servicing fees, late charges and ancillary fees		6,300	6,700	$ 18,100	23,200
Servicing Assets | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Outstanding principle	$ 2,400,000	2,500,000		$ 2,500,000
Fixed interest rate, minimum	5.31%			5.31%
Fixed interest rate, maximum	31.82%			31.82%
Contractually specified servicing fees, late charges and ancillary fees		$ 8,800	$ 10,300	$ 27,100	$ 33,300
Minimum | Servicing Assets
Servicing Assets And Liabilities Fair Value [Line Items]
Maturity, in months	36 months			36 months
Minimum | Servicing Assets | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Maturity, in months	36 months			36 months
Maximum | Servicing Assets
Servicing Assets And Liabilities Fair Value [Line Items]
Maturity, in months	60 months			60 months
Maximum | Servicing Assets | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Maturity, in months	60 months			60 months

SECURITIZATIONS (Narrative) (De

SECURITIZATIONS (Narrative) (Detail) - USD ($) $ in Thousands	Sep. 27, 2021	Sep. 30, 2021		Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2021		Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2020
Variable Interest Entity [Line Items]
Proceeds from sale of certificate issued by securitization trust	$ 4,100
Total loss on deconsolidation		$ 1,494		$ 0		$ 1,494		$ 0
Servicing assets	200
Restricted Cash		156,901	[1]	$ 135,826		156,901	[1]	$ 135,826		$ 163,723	[1]
Primary Beneficiary
Variable Interest Entity [Line Items]
Risk retention interest percentage									5.00%
Total loss on deconsolidation	1,494
Restricted Cash	10,897	$ 5,805				$ 5,805				$ 25,203
PMIT 2019 Securitization Trusts | Primary Beneficiary
Variable Interest Entity [Line Items]
Securitization amount					$ 573,000				$ 573,000
PMIT 2019-1 | Primary Beneficiary
Variable Interest Entity [Line Items]
Ownership percentage					65.50%
Total loss on deconsolidation	280
Restricted Cash	2,485
PMIT 2019-2 | Primary Beneficiary
Variable Interest Entity [Line Items]
Ownership percentage					16.40%
Total loss on deconsolidation	775
Restricted Cash	4,324
PMIT 2019-4 | Primary Beneficiary
Variable Interest Entity [Line Items]
Ownership percentage					19.60%
Total loss on deconsolidation	439
Restricted Cash	$ 4,088
[1]	Includes amounts in consolidated variable interest entities (VIEs) presented separately in the table below. The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 6, Securitizations, and Note 10, Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information. September 30, 2021 December 31, 2020 Assets of consolidated VIEs, included in total assets above: Restricted Cash $ 5,805 $ 25,203 Loans Held for Sale, at Fair Value 285,920 274,621 Borrower Loans, at Fair Value — 168,593 Prepaid and Other Assets 3,068 2,043 Total assets of consolidated variable interest entities $ 294,793 $ 470,460 Liabilities of consolidated VIEs, included in total liabilities above: Notes Issued by Securitization Trust $ — $ 156,782 Certificates Issued by Securitization Trust, at Fair Value — 22,917 Warehouse Lines 245,819 242,479 Total liabilities of consolidated variable interest entities $ 245,819 $ 422,178

SECURITIZATIONS (Summary of Dec

SECURITIZATIONS (Summary of Deconsolidation) (Detail) - USD ($) $ in Thousands		Sep. 27, 2021	Sep. 30, 2021		Sep. 30, 2020	Sep. 30, 2021		Sep. 30, 2020	Dec. 31, 2020
Variable Interest Entity [Line Items]
Restricted Cash			$ 156,901	[1]	$ 135,826	$ 156,901	[1]	$ 135,826	$ 163,723	[1]
Borrower Loans	[1]		254,680			254,680			378,263
Notes Issued by Securitization Trust	[1]		0			0			(156,782)
Certificates Issued by Securitization Trust, at Fair Value (1)	[1]		0			0			(22,917)
Total loss on deconsolidation			(1,494)		$ 0	(1,494)		$ 0
Primary Beneficiary
Variable Interest Entity [Line Items]
Cash		$ 4,076
Restricted Cash		10,897	5,805			5,805			25,203
Borrower Loans		78,361	0			0			168,593
Notes Issued by Securitization Trust		(69,709)	0			0			(156,782)
Certificates Issued by Securitization Trust, at Fair Value (1)		(13,979)	$ 0			$ 0			$ (22,917)
Total net assets deconsolidated		5,570
Total loss on deconsolidation		(1,494)
PMIT 2019-1 | Primary Beneficiary
Variable Interest Entity [Line Items]
Cash		2,259
Restricted Cash		2,485
Borrower Loans		15,133
Notes Issued by Securitization Trust		(13,022)
Certificates Issued by Securitization Trust, at Fair Value (1)		(2,057)
Total net assets deconsolidated		2,539
Total loss on deconsolidation		(280)
PMIT 2019-2 | Primary Beneficiary
Variable Interest Entity [Line Items]
Cash		836
Restricted Cash		4,324
Borrower Loans		29,989
Notes Issued by Securitization Trust		(26,712)
Certificates Issued by Securitization Trust, at Fair Value (1)		(5,990)
Total net assets deconsolidated		1,611
Total loss on deconsolidation		(775)
PMIT 2019-4 | Primary Beneficiary
Variable Interest Entity [Line Items]
Cash		981
Restricted Cash		4,088
Borrower Loans		33,239
Notes Issued by Securitization Trust		(29,975)
Certificates Issued by Securitization Trust, at Fair Value (1)		(5,932)
Total net assets deconsolidated		1,420
Total loss on deconsolidation		$ (439)
[1]	Includes amounts in consolidated variable interest entities (VIEs) presented separately in the table below. The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 6, Securitizations, and Note 10, Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information. September 30, 2021 December 31, 2020 Assets of consolidated VIEs, included in total assets above: Restricted Cash $ 5,805 $ 25,203 Loans Held for Sale, at Fair Value 285,920 274,621 Borrower Loans, at Fair Value — 168,593 Prepaid and Other Assets 3,068 2,043 Total assets of consolidated variable interest entities $ 294,793 $ 470,460 Liabilities of consolidated VIEs, included in total liabilities above: Notes Issued by Securitization Trust $ — $ 156,782 Certificates Issued by Securitization Trust, at Fair Value — 22,917 Warehouse Lines 245,819 242,479 Total liabilities of consolidated variable interest entities $ 245,819 $ 422,178

FAIR VALUE OF ASSETS AND LIAB_3

FAIR VALUE OF ASSETS AND LIABILITIES - Fair Value Hierarchy for Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands		Sep. 30, 2021	Dec. 31, 2020
Assets:
Borrower Loans	[1]	$ 254,680	$ 378,263
Loans Held for Sale at Fair Value	[1]	285,920	274,621
Servicing Assets		8,701	9,242
Total Assets		549,301	662,126
Liabilities:
Notes, at Fair Value		253,242	208,379
Certificates Issued by Securitization Trust, at Fair Value	[1]	0	22,917
Convertible Preferred Stock Warrant Liability		249,164	112,319
Loan Trailing Fee Liability		2,183	2,233
Total Liabilities		504,589	345,848
Prosper Funding LLC
Assets:
Borrower Loans		254,680	209,670
Servicing Assets		9,968	11,088
Total Assets		264,648	220,758
Liabilities:
Notes, at Fair Value		253,242	208,379
Loan Trailing Fee Liability		2,183	2,233
Total Liabilities		255,425	210,612
Level 1 Inputs
Assets:
Borrower Loans		0	0
Loans Held for Sale at Fair Value		0	0
Servicing Assets		0	0
Total Assets		0	0
Liabilities:
Notes, at Fair Value		0	0
Certificates Issued by Securitization Trust, at Fair Value			0
Convertible Preferred Stock Warrant Liability		0	0
Loan Trailing Fee Liability		0	0
Total Liabilities		0	0
Level 1 Inputs | Prosper Funding LLC
Assets:
Borrower Loans		0	0
Servicing Assets		0	0
Total Assets		0	0
Liabilities:
Notes, at Fair Value		0	0
Loan Trailing Fee Liability		0	0
Total Liabilities		0	0
Level 2 Inputs
Assets:
Borrower Loans		0	0
Loans Held for Sale at Fair Value		0	0
Servicing Assets		0	0
Total Assets		0	0
Liabilities:
Notes, at Fair Value		0	0
Certificates Issued by Securitization Trust, at Fair Value			0
Convertible Preferred Stock Warrant Liability		0	0
Loan Trailing Fee Liability		0	0
Total Liabilities		0	0
Level 2 Inputs | Prosper Funding LLC
Assets:
Borrower Loans		0	0
Servicing Assets		0	0
Total Assets		0	0
Liabilities:
Notes, at Fair Value		0	0
Loan Trailing Fee Liability		0	0
Total Liabilities		0	0
Level 3 Inputs
Assets:
Borrower Loans		254,680	378,263
Loans Held for Sale at Fair Value		285,920	274,621
Servicing Assets		8,701	9,242
Total Assets		549,301	662,126
Liabilities:
Notes, at Fair Value		253,242	208,379
Certificates Issued by Securitization Trust, at Fair Value			22,917
Convertible Preferred Stock Warrant Liability		249,164	112,319
Loan Trailing Fee Liability		2,183	2,233
Total Liabilities		504,589	345,848
Level 3 Inputs | Prosper Funding LLC
Assets:
Borrower Loans		254,680	209,670
Servicing Assets		9,968	11,088
Total Assets		264,648	220,758
Liabilities:
Notes, at Fair Value		253,242	208,379
Loan Trailing Fee Liability		2,183	2,233
Total Liabilities		$ 255,425	$ 210,612
[1]	Includes amounts in consolidated variable interest entities (VIEs) presented separately in the table below. The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 6, Securitizations, and Note 10, Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information. September 30, 2021 December 31, 2020 Assets of consolidated VIEs, included in total assets above: Restricted Cash $ 5,805 $ 25,203 Loans Held for Sale, at Fair Value 285,920 274,621 Borrower Loans, at Fair Value — 168,593 Prepaid and Other Assets 3,068 2,043 Total assets of consolidated variable interest entities $ 294,793 $ 470,460 Liabilities of consolidated VIEs, included in total liabilities above: Notes Issued by Securitization Trust $ — $ 156,782 Certificates Issued by Securitization Trust, at Fair Value — 22,917 Warehouse Lines 245,819 242,479 Total liabilities of consolidated variable interest entities $ 245,819 $ 422,178

FAIR VALUE OF ASSETS AND LIAB_4

FAIR VALUE OF ASSETS AND LIABILITIES - Significant Unobservable Inputs - Borrower Loans, Loans Held For Sale and Notes (Details)	Sep. 30, 2021	Dec. 31, 2020
Discount rate | Minimum
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.046	0.045
Discount rate | Minimum | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.046	0.053
Discount rate | Maximum
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.151	0.177
Discount rate | Maximum | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.150	0.161
Default rate | Minimum
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.020	0.023
Default rate | Minimum | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.020	0.026
Default rate | Maximum
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.169	0.179
Default rate | Maximum | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value measurement inputs	0.140	0.162

FAIR VALUE OF ASSETS AND LIAB_5

FAIR VALUE OF ASSETS AND LIABILITIES - Significant Unobservable Inputs - Certificates Issued by Securitization Trust (Details)	12 Months Ended
	Dec. 31, 2020
Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	3.30%
Default rate	3.20%
Prepayment rate	7.60%
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	16.00%
Default rate	15.30%
Prepayment rate	35.40%

FAIR VALUE OF ASSETS AND LIAB_6

FAIR VALUE OF ASSETS AND LIABILITIES - Significant Unobservable Inputs - Servicing Rights (Details)	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2020	Sep. 30, 2021	Dec. 31, 2020
Servicing Rights at Fair Value [Line Items]
Collection fee market rate	0.06%		0.07%
Prosper Funding LLC
Servicing Rights at Fair Value [Line Items]
Collection fee market rate	0.06%		0.07%
Minimum
Servicing Rights at Fair Value [Line Items]
Discount rate				15.00%	15.00%
Default rate				1.60%	1.90%
Prepayment rate				10.30%	12.40%
Market servicing rate	0.648%		0.648%	0.648%	0.625%
Weighted-average market servicing rate	0.708%		0.695%
Minimum | Prosper Funding LLC
Servicing Rights at Fair Value [Line Items]
Discount rate				15.00%	15.00%
Default rate				1.60%	1.90%
Prepayment rate				10.30%	12.40%
Market servicing rate	0.648%	0.648%		0.648%	0.625%
Weighted-average market servicing rate	0.708%		0.695%
Maximum
Servicing Rights at Fair Value [Line Items]
Discount rate				25.00%	25.00%
Default rate				14.70%	17.70%
Prepayment rate				29.10%	28.90%
Market servicing rate	0.842%		0.842%	0.842%	0.818%
Weighted-average market servicing rate	0.902%		0.888%
Maximum | Prosper Funding LLC
Servicing Rights at Fair Value [Line Items]
Discount rate				25.00%	25.00%
Default rate				14.70%	17.70%
Prepayment rate				29.10%	28.90%
Market servicing rate	0.842%	0.842%		0.842%	0.818%
Weighted-average market servicing rate	0.902%		0.888%

FAIR VALUE OF ASSETS AND LIAB_7

FAIR VALUE OF ASSETS AND LIABILITIES - Significant Unobservable Inputs - Loan Trailing Fee Liability (Details)	Sep. 30, 2021	Dec. 31, 2020
Discount rate | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.046	0.045
Discount rate | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.151	0.177
Discount rate | Prosper Funding LLC | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.046	0.053
Discount rate | Prosper Funding LLC | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.150	0.161
Discount rate | Obligations | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.150	0.150
Discount rate | Obligations | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.250	0.250
Discount rate | Obligations | Prosper Funding LLC | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.150	0.150
Discount rate | Obligations | Prosper Funding LLC | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.250	0.250
Default rate | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.020	0.023
Default rate | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.169	0.179
Default rate | Prosper Funding LLC | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.020	0.026
Default rate | Prosper Funding LLC | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.140	0.162
Default rate | Obligations | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.016	0.019
Default rate | Obligations | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.147	0.177
Default rate | Obligations | Prosper Funding LLC | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.016	0.019
Default rate | Obligations | Prosper Funding LLC | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.147	0.177
Prepayment rate | Obligations | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.103	0.124
Prepayment rate | Obligations | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.291	0.289
Prepayment rate | Obligations | Prosper Funding LLC | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.103	0.124
Prepayment rate | Obligations | Prosper Funding LLC | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement inputs	0.291	0.289

FAIR VALUE OF ASSETS AND LIAB_8

FAIR VALUE OF ASSETS AND LIABILITIES - Deconsolidated Assets and Liabilities- Borrower Loans (Details) $ in Thousands		Sep. 30, 2021USD ($)	Sep. 27, 2021USD ($)	Dec. 31, 2020USD ($)
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower Loans, at Fair Value	[1]	$ 254,680		$ 378,263
Borrower Loans
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower Loans, at Fair Value			$ 78,361
Discount rate | Weighted Average | Borrower Loans
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans, measurement input			0.0926
Default rate | Weighted Average | Borrower Loans
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans, measurement input			0.0813
[1]	Includes amounts in consolidated variable interest entities (VIEs) presented separately in the table below. The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 6, Securitizations, and Note 10, Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information. September 30, 2021 December 31, 2020 Assets of consolidated VIEs, included in total assets above: Restricted Cash $ 5,805 $ 25,203 Loans Held for Sale, at Fair Value 285,920 274,621 Borrower Loans, at Fair Value — 168,593 Prepaid and Other Assets 3,068 2,043 Total assets of consolidated variable interest entities $ 294,793 $ 470,460 Liabilities of consolidated VIEs, included in total liabilities above: Notes Issued by Securitization Trust $ — $ 156,782 Certificates Issued by Securitization Trust, at Fair Value — 22,917 Warehouse Lines 245,819 242,479 Total liabilities of consolidated variable interest entities $ 245,819 $ 422,178

FAIR VALUE OF ASSETS AND LIAB_9

FAIR VALUE OF ASSETS AND LIABILITIES - Deconsolidated Assets and Liabilities- Certificates issued by Securitization Trust (Details) $ in Thousands		Sep. 30, 2021USD ($)	Sep. 27, 2021USD ($)	Dec. 31, 2020USD ($)
Fair Value Inputs Assets Quantitative Information [Line Items]
Certificates issued by Securitization Trust, fair value	[1]	$ 0		$ 22,917
Certificates Issued by Securitization Trust
Fair Value Inputs Assets Quantitative Information [Line Items]
Certificates issued by Securitization Trust, fair value			$ 13,979
Discount rate | Weighted Average | Certificates Issued by Securitization Trust
Fair Value Inputs Assets Quantitative Information [Line Items]
Certificates issued by Securitization Trust, measurement input			0.0799
Default rate | Weighted Average | Certificates Issued by Securitization Trust
Fair Value Inputs Assets Quantitative Information [Line Items]
Certificates issued by Securitization Trust, measurement input			0.0768
Prepayment rate | Weighted Average | Certificates Issued by Securitization Trust
Fair Value Inputs Assets Quantitative Information [Line Items]
Certificates issued by Securitization Trust, measurement input			0.1794
[1]	Includes amounts in consolidated variable interest entities (VIEs) presented separately in the table below. The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 6, Securitizations, and Note 10, Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information. September 30, 2021 December 31, 2020 Assets of consolidated VIEs, included in total assets above: Restricted Cash $ 5,805 $ 25,203 Loans Held for Sale, at Fair Value 285,920 274,621 Borrower Loans, at Fair Value — 168,593 Prepaid and Other Assets 3,068 2,043 Total assets of consolidated variable interest entities $ 294,793 $ 470,460 Liabilities of consolidated VIEs, included in total liabilities above: Notes Issued by Securitization Trust $ — $ 156,782 Certificates Issued by Securitization Trust, at Fair Value — 22,917 Warehouse Lines 245,819 242,479 Total liabilities of consolidated variable interest entities $ 245,819 $ 422,178

FAIR VALUE OF ASSETS AND LIA_10

FAIR VALUE OF ASSETS AND LIABILITIES - Changes in Level 3 Fair Value Assets and Liabilities on a Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Total
Beginning balance, Total	$ 337,558	$ 432,172	$ 421,588	$ 479,706
Purchase of Borrower Loans/Issuance of Notes	456,087	326,889	1,248,167	949,632
Principal repayments	(63,988)	(65,791)	(191,489)	(201,437)
Borrower Loans sold to third parties	(375,779)	(263,885)	(1,120,837)	(759,921)
Other changes	(93)	(480)	(1,261)	225
Change in fair value	(2,045)	4,703	(4,428)	(34,597)
Deconsolidation of VIEs (Note 6)	(64,382)		(64,382)
Ending balance, Total	287,358	433,608	287,358	433,608
Prosper Funding LLC
Total
Beginning balance, Total	803	1,789	1,291	966
Purchase of Borrower Loans/Issuance of Notes	456,087	326,889	1,248,167	949,632
Principal repayments	(148)	(505)	(856)	(2,017)
Borrower Loans sold to third parties	(455,942)	(327,954)	(1,249,385)	(951,640)
Other changes	(29)	(44)	(18)	(48)
Change in fair value	371	(72)	527	186
Ending balance, Total	1,438	1,113	1,438	1,113
Notes
Liabilities
Beginning balance, Liabilities	(236,041)	(209,987)	(208,379)	(244,171)
Purchase of Borrower Loans/Issuance of Notes	(64,028)	(32,260)	(172,231)	(97,303)
Principal repayments	45,486	36,943	126,528	114,050
Borrower Loans sold to third parties	0	0	0	0
Other changes	(14)	233	205	(24)
Change in fair value	1,355	(1,860)	635	20,517
Deconsolidation of VIEs (Note 6)	0		0
Ending balance, Liabilities	(253,242)	(206,931)	(253,242)	(206,931)
Notes | Prosper Funding LLC
Liabilities
Beginning balance, Liabilities	(236,041)	(209,986)	(208,379)	(244,171)
Purchase of Borrower Loans/Issuance of Notes	(64,028)	(32,260)	(172,231)	(97,303)
Principal repayments	45,486	36,943	126,528	114,051
Borrower Loans sold to third parties	0	0	0	0
Other changes	(14)	232	205	(25)
Change in fair value	1,355	(1,860)	635	20,517
Ending balance, Liabilities	(253,242)	(206,931)	(253,242)	(206,931)
Certificates Issued by Securitization Trust
Liabilities
Beginning balance, Liabilities	(15,295)	(31,571)	(22,917)	(52,168)
Purchase of Borrower Loans/Issuance of Notes	0	0	0	0
Principal repayments	4,042	6,733	14,935	16,608
Borrower Loans sold to third parties	0	0	0	0
Other changes	41	49	113	390
Change in fair value	(2,767)	(1,992)	(6,110)	8,389
Deconsolidation of VIEs (Note 6)	13,979		13,979
Ending balance, Liabilities	0	(26,781)	0	(26,781)
Borrower Loans
Assets
Beginning balance, Assets	338,939	457,487	378,263	634,019
Purchase of Borrower Loans/Issuance of Notes	64,473	31,742	172,082	97,406
Principal repayments	(69,094)	(79,658)	(215,076)	(259,210)
Borrower Loans sold to third parties	(587)	(1,383)	(2,311)	(5,637)
Other changes	(353)	(926)	(1,545)	(1,084)
Change in fair value	(337)	7,615	1,628	(50,617)
Deconsolidation of VIEs (Note 6)	(78,361)		(78,361)
Ending balance, Assets	254,680	414,877	254,680	414,877
Borrower Loans | Prosper Funding LLC
Assets
Beginning balance, Assets	236,844	211,775	209,670	245,137
Purchase of Borrower Loans/Issuance of Notes	64,473	31,742	172,082	97,406
Principal repayments	(45,338)	(36,438)	(125,672)	(112,034)
Borrower Loans sold to third parties	(300)	(547)	(1,069)	(2,111)
Other changes	(15)	(276)	(223)	(23)
Change in fair value	(984)	1,788	(108)	(20,331)
Ending balance, Assets	254,680	208,044	254,680	208,044
Loans Held for Sale
Assets
Beginning balance, Assets	249,955	216,243	274,621	142,026
Purchase of Borrower Loans/Issuance of Notes	455,642	327,407	1,248,316	949,529
Principal repayments	(44,422)	(29,809)	(117,876)	(72,885)
Borrower Loans sold to third parties	(375,192)	(262,502)	(1,118,526)	(754,284)
Other changes	233	164	(34)	943
Change in fair value	(296)	940	(581)	(12,886)
Deconsolidation of VIEs (Note 6)	0		0
Ending balance, Assets	285,920	252,443	285,920	252,443
Loans Held for Sale | Prosper Funding LLC
Assets
Beginning balance, Assets	0	0	0	0
Purchase of Borrower Loans/Issuance of Notes	455,642	327,407	1,248,316	949,529
Principal repayments	0	0	0	0
Borrower Loans sold to third parties	(455,642)	(327,407)	(1,248,316)	(949,529)
Other changes	0	0	0	0
Change in fair value	0	0	0	0
Ending balance, Assets	$ 0	$ 0	$ 0	$ 0

FAIR VALUE OF ASSETS AND LIA_11

FAIR VALUE OF ASSETS AND LIABILITIES - Summary of Additional Information for Level 3 Fair Value Balances (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Servicing Assets
Beginning balance			$ 9,242
Ending balance	$ 8,701		8,701
Prosper Funding LLC
Servicing Assets
Beginning balance			11,088
Ending balance	9,968		9,968
Servicing Assets
Servicing Assets
Beginning balance			9,242
Ending balance	8,701		8,701
Servicing Assets | Prosper Funding LLC
Servicing Assets
Beginning balance			11,088
Ending balance	9,968		9,968
Level 3 Inputs
Servicing Assets
Beginning balance			9,242
Ending balance	8,701		8,701
Level 3 Inputs | Prosper Funding LLC
Servicing Assets
Beginning balance			11,088
Ending balance	9,968		9,968
Level 3 Inputs | Servicing Assets
Servicing Assets
Beginning balance	8,944	$ 10,073	9,242	$ 12,602
Additions	1,895	1,242	5,674	3,945
Recognition of Servicing Assets upon deconsolidation of VIEs (Note 6)	215		215
Less: Changes in fair value	(2,353)	(2,009)	(6,430)	(7,241)
Ending balance	8,701	9,306	8,701	9,306
Level 3 Inputs | Servicing Assets | Prosper Funding LLC
Servicing Assets
Beginning balance	10,389	12,063	11,088	14,888
Additions	2,300	1,632	6,676	5,034
Less: Changes in fair value	(2,721)	(2,430)	(7,796)	(8,657)
Ending balance	9,968	11,265	9,968	11,265
Level 3 Inputs | Mandatorily Redeemable Preferred Stock
Liabilities
Beginning balance	162,436	74,998	112,319	149,996
Change in fair value	86,728	11,374	136,845	(63,624)
Ending balance	249,164	86,372	249,164	86,372
Level 3 Inputs | Loan Trailing Fee Liability
Liabilities
Beginning balance	2,145	2,403	2,233	2,997
Issuances	472	313	1,289	938
Principal repayments	(521)	(596)	(1,587)	(1,867)
Change in fair value	87	142	248	194
Ending balance	2,183	2,262	2,183	2,262
Level 3 Inputs | Loan Trailing Fee Liability | Prosper Funding LLC
Liabilities
Beginning balance	2,145	2,403	2,233	2,997
Issuances	472	313	1,289	938
Principal repayments	(521)	(596)	(1,587)	(1,867)
Change in fair value	87	142	248	194
Ending balance	$ 2,183	$ 2,262	$ 2,183	$ 2,262

FAIR VALUE OF ASSETS AND LIA_12

FAIR VALUE OF ASSETS AND LIABILITIES - Fair Value Assumptions for Borrower Loans, Loans Held for Sale and Notes (Details) $ in Thousands		Sep. 30, 2021USD ($)	Dec. 31, 2020USD ($)
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower Loans, at Fair Value	[1]	$ 254,680	$ 378,263
Notes, at Fair Value		253,242	208,379
Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower Loans, at Fair Value		254,680	209,670
Notes, at Fair Value		253,242	208,379
Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes, at Fair Value		253,242	208,379
Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower Loans, at Fair Value			209,670
Notes, at Fair Value		253,242	208,379
Borrower loans and loans held for sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower Loans, at Fair Value		540,600	652,884
Borrower loans and loans held for sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower Loans, at Fair Value		254,680	209,670
Discount rate assumption | 100 basis point increase | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes		250,713	206,528
Discount rate assumption | 100 basis point increase | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans			207,810
Notes		250,713	206,528
Discount rate assumption | 100 basis point increase | Borrower loans and loans held for sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		535,208	647,093
Discount rate assumption | 100 basis point increase | Borrower loans and loans held for sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		252,139	207,810
Discount rate assumption | 200 basis point incease | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes		248,247	204,720
Discount rate assumption | 200 basis point incease | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans			205,994
Notes		248,247	204,720
Discount rate assumption | 200 basis point incease | Borrower loans and loans held for sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		529,952	641,437
Discount rate assumption | 200 basis point incease | Borrower loans and loans held for sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		249,663	205,994
Discount rate assumption | 100 basis point decrease | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes		255,838	210,274
Discount rate assumption | 100 basis point decrease | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans			211,575
Notes		255,838	210,274
Discount rate assumption | 100 basis point decrease | Borrower loans and loans held for sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		546,133	658,817
Discount rate assumption | 100 basis point decrease | Borrower loans and loans held for sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		257,286	211,575
Discount rate assumption | 200 basis point decrease | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes		258,503	212,217
Discount rate assumption | 200 basis point decrease | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans			213,527
Notes		258,503	212,217
Discount rate assumption | 200 basis point decrease | Borrower loans and loans held for sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		551,813	664,895
Discount rate assumption | 200 basis point decrease | Borrower loans and loans held for sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		259,962	213,527
Default rate assumption | 10 percent increase | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes		251,021	206,304
Default rate assumption | 10 percent increase | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans			207,594
Notes		251,021	206,304
Default rate assumption | 10 percent increase | Borrower loans and loans held for sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		535,886	646,421
Default rate assumption | 10 percent increase | Borrower loans and loans held for sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		252,459	207,594
Default rate assumption | 20 percent increase | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes		248,814	204,238
Default rate assumption | 20 percent increase | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans			205,528
Notes		248,814	204,238
Default rate assumption | 20 percent increase | Borrower loans and loans held for sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		531,204	639,987
Default rate assumption | 20 percent increase | Borrower loans and loans held for sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		250,253	205,528
Default rate assumption | 10 percent decrease | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes		255,477	210,463
Default rate assumption | 10 percent decrease | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans			211,755
Notes		255,477	210,463
Default rate assumption | 10 percent decrease | Borrower loans and loans held for sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		545,341	659,377
Default rate assumption | 10 percent decrease | Borrower loans and loans held for sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		256,914	211,755
Default rate assumption | 20 percent decrease | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Notes		257,727	212,558
Default rate assumption | 20 percent decrease | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans			213,851
Notes		257,727	212,558
Default rate assumption | 20 percent decrease | Borrower loans and loans held for sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		550,113	665,904
Default rate assumption | 20 percent decrease | Borrower loans and loans held for sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Borrower loans		$ 259,161	$ 213,851
Discount rate | Discount rate assumption | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions		0.0671	0.0893
Discount rate | Discount rate assumption | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions		0.0671	0.0893
Discount rate | Discount rate assumption | Borrower loans and loans held for sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions		0.0650	0.0826
Discount rate | Discount rate assumption | Borrower loans and loans held for sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions		0.0671	0.0893
Default rate | Default rate assumption | Notes
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions		0.1066	0.1226
Default rate | Default rate assumption | Notes | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions		0.1066	0.1226
Default rate | Default rate assumption | Borrower loans and loans held for sale
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions		0.0978	0.1158
Default rate | Default rate assumption | Borrower loans and loans held for sale | Prosper Funding LLC
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair value assumptions		0.1066	0.1226
[1]	Includes amounts in consolidated variable interest entities (VIEs) presented separately in the table below. The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 6, Securitizations, and Note 10, Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information. September 30, 2021 December 31, 2020 Assets of consolidated VIEs, included in total assets above: Restricted Cash $ 5,805 $ 25,203 Loans Held for Sale, at Fair Value 285,920 274,621 Borrower Loans, at Fair Value — 168,593 Prepaid and Other Assets 3,068 2,043 Total assets of consolidated variable interest entities $ 294,793 $ 470,460 Liabilities of consolidated VIEs, included in total liabilities above: Notes Issued by Securitization Trust $ — $ 156,782 Certificates Issued by Securitization Trust, at Fair Value — 22,917 Warehouse Lines 245,819 242,479 Total liabilities of consolidated variable interest entities $ 245,819 $ 422,178

FAIR VALUE OF ASSETS AND LIA_13

FAIR VALUE OF ASSETS AND LIABILITIES - Fair Value Assumptions for Certificates Issued by Securitization Trust (Details) - USD ($) $ in Thousands		Sep. 30, 2021	Dec. 31, 2020
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Certificates Issued by Securitization Trust, at Fair Value	[1]	$ 0	$ 22,917
Level 3 Inputs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Certificates Issued by Securitization Trust, at Fair Value			$ 22,917
[1]	Includes amounts in consolidated variable interest entities (VIEs) presented separately in the table below. The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 6, Securitizations, and Note 10, Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information. September 30, 2021 December 31, 2020 Assets of consolidated VIEs, included in total assets above: Restricted Cash $ 5,805 $ 25,203 Loans Held for Sale, at Fair Value 285,920 274,621 Borrower Loans, at Fair Value — 168,593 Prepaid and Other Assets 3,068 2,043 Total assets of consolidated variable interest entities $ 294,793 $ 470,460 Liabilities of consolidated VIEs, included in total liabilities above: Notes Issued by Securitization Trust $ — $ 156,782 Certificates Issued by Securitization Trust, at Fair Value — 22,917 Warehouse Lines 245,819 242,479 Total liabilities of consolidated variable interest entities $ 245,819 $ 422,178

FAIR VALUE OF ASSETS AND LIA_14

FAIR VALUE OF ASSETS AND LIABILITIES - Schedule of Prosper's and Prosper Funding's Estimated Fair Value of Servicing Assets and Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Servicing Assets And Liabilities Fair Value [Line Items]
Servicing Assets	$ 8,701	$ 9,242
Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Servicing Assets	9,968	11,088
Servicing Assets
Servicing Assets And Liabilities Fair Value [Line Items]
Servicing Assets	8,701	9,242
Servicing Assets | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Servicing Assets	9,968	11,088
Market servicing rate | Servicing Assets | Market servicing rate increase of 0.025%
Servicing Assets And Liabilities Fair Value [Line Items]
Expected fair value with change in assumptions	8,148	8,689
Market servicing rate | Servicing Assets | Market servicing rate increase of 0.025% | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Expected fair value with change in assumptions	9,333	10,424
Market servicing rate | Servicing Assets | Market servicing rate decrease of 0.025%
Servicing Assets And Liabilities Fair Value [Line Items]
Expected fair value with change in assumptions	9,255	9,796
Market servicing rate | Servicing Assets | Market servicing rate decrease of 0.025% | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Expected fair value with change in assumptions	10,602	11,752
Prepayment rate assumption | Servicing Assets | Applying a 1.1 multiplier to prepayment rate
Servicing Assets And Liabilities Fair Value [Line Items]
Expected fair value with change in assumptions	8,532	9,064
Prepayment rate assumption | Servicing Assets | Applying a 1.1 multiplier to prepayment rate | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Expected fair value with change in assumptions	9,774	10,874
Prepayment rate assumption | Servicing Assets | Applying a 0.9 multiplier to prepayment rate
Servicing Assets And Liabilities Fair Value [Line Items]
Expected fair value with change in assumptions	8,872	9,423
Prepayment rate assumption | Servicing Assets | Applying a 0.9 multiplier to prepayment rate | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Expected fair value with change in assumptions	10,164	11,304
Default rate assumption | Servicing Assets | Applying a 1.1 multiplier to default rate
Servicing Assets And Liabilities Fair Value [Line Items]
Expected fair value with change in assumptions	8,586	9,116
Default rate assumption | Servicing Assets | Applying a 1.1 multiplier to default rate | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Expected fair value with change in assumptions	9,836	10,936
Default rate assumption | Servicing Assets | Applying a 0.9 multiplier to default rate
Servicing Assets And Liabilities Fair Value [Line Items]
Expected fair value with change in assumptions	8,817	9,369
Default rate assumption | Servicing Assets | Applying a 0.9 multiplier to default rate | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Expected fair value with change in assumptions	$ 10,100	$ 11,239
Market servicing rate | Servicing Assets
Servicing Assets And Liabilities Fair Value [Line Items]
Valuation techniques	0.65%	0.631%
Market servicing rate | Servicing Assets | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Valuation techniques	0.65%	0.631%
Prepayment rate | Servicing Assets
Servicing Assets And Liabilities Fair Value [Line Items]
Valuation techniques	18.89%	19.84%
Prepayment rate | Servicing Assets | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Valuation techniques	18.89%	19.84%
Default rate | Servicing Assets
Servicing Assets And Liabilities Fair Value [Line Items]
Valuation techniques	12.18%	12.78%
Default rate | Servicing Assets | Prosper Funding LLC
Servicing Assets And Liabilities Fair Value [Line Items]
Valuation techniques	11.83%	12.78%

FAIR VALUE OF ASSETS AND LIA_15

FAIR VALUE OF ASSETS AND LIABILITIES - Schedule of Prosper's and Prosper Funding's Estimated Fair Value of Servicing Assets and Liabilities - Additional Information (Details)	9 Months Ended
	Sep. 30, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing rate increase	0.025%
Servicing rate decrease	0.025%
Prepayment rate assumption
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Prepayment rate increase	1.10%
Prepayment rate decrease	0.90%
Default rate assumption
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Default rate increase	1.10%
Default rate decrease	0.90%

FAIR VALUE OF ASSETS AND LIA_16

FAIR VALUE OF ASSETS AND LIABILITIES - Financial Instruments, Assets and Liabilities not Recorded at Fair Value (Details) - USD ($) $ in Thousands		Sep. 30, 2021		Dec. 31, 2020		Sep. 30, 2020
Assets:
Cash and Cash Equivalents		$ 55,949		$ 50,145		$ 45,898
Restricted Cash		156,901	[1]	163,723	[1]	$ 135,826
Accounts Receivable	[1]	749		605
Total Assets		836,693		947,109
Liabilities:
Accounts Payable and Accrued Liabilities		23,807		17,876
Payable to Investors		141,115		124,094
Notes Issued by Securitization Trust	[1]	0		156,782
Warehouse Lines	[1]	245,819		242,479
Paycheck Protection Program loan (Note 10)		8,568		8,505
Total Liabilities		937,251		909,903
Carrying Amount
Assets:
Cash and Cash Equivalents		55,949		50,145
Accounts Receivable		749		605
Total Assets		213,599		214,473
Liabilities:
Accounts Payable and Accrued Liabilities		23,807		17,876
Payable to Investors		141,115		124,094
Notes Issued by Securitization Trust				156,782
Warehouse Lines		245,819		242,479
Paycheck Protection Program loan (Note 10)		8,568		8,505
Total Liabilities		419,309		549,736
Carrying Amount | Cash and Cash Equivalents
Assets:
Restricted Cash		152,024		158,846
Carrying Amount | Certificates of Deposit
Assets:
Restricted Cash		4,877		4,877
Balance at Fair Value
Assets:
Cash and Cash Equivalents		55,949		50,145
Accounts Receivable		749		605
Total Assets		213,599		214,473
Liabilities:
Accounts Payable and Accrued Liabilities		23,807		17,876
Payable to Investors		141,115		124,094
Notes Issued by Securitization Trust				158,951
Warehouse Lines		247,769		242,261
Paycheck Protection Program loan (Note 10)		8,557		8,540
Total Liabilities		421,248		551,722
Balance at Fair Value | Cash and Cash Equivalents
Assets:
Restricted Cash		152,024		158,846
Balance at Fair Value | Certificates of Deposit
Assets:
Restricted Cash		4,877		4,877
Level 1 Inputs
Assets:
Cash and Cash Equivalents		55,949		50,145
Accounts Receivable		0		0
Total Assets		207,973		208,991
Liabilities:
Accounts Payable and Accrued Liabilities		0		0
Payable to Investors		0		0
Notes Issued by Securitization Trust				0
Warehouse Lines		0		0
Paycheck Protection Program loan (Note 10)		0		0
Total Liabilities		0		0
Level 1 Inputs | Cash and Cash Equivalents
Assets:
Restricted Cash		152,024		158,846
Level 1 Inputs | Certificates of Deposit
Assets:
Restricted Cash		0		0
Level 2 Inputs
Assets:
Cash and Cash Equivalents		0		0
Accounts Receivable		749		605
Total Assets		5,626		5,482
Liabilities:
Accounts Payable and Accrued Liabilities		23,807		17,876
Payable to Investors		141,115		124,094
Notes Issued by Securitization Trust				158,951
Warehouse Lines		247,769		242,261
Paycheck Protection Program loan (Note 10)		8,557		8,540
Total Liabilities		421,248		551,722
Level 2 Inputs | Cash and Cash Equivalents
Assets:
Restricted Cash		0		0
Level 2 Inputs | Certificates of Deposit
Assets:
Restricted Cash		4,877		4,877
Level 3 Inputs
Assets:
Cash and Cash Equivalents		0		0
Accounts Receivable		0		0
Total Assets		0		0
Liabilities:
Accounts Payable and Accrued Liabilities		0		0
Payable to Investors		0		0
Notes Issued by Securitization Trust				0
Warehouse Lines		0		0
Paycheck Protection Program loan (Note 10)		0		0
Total Liabilities		0		0
Level 3 Inputs | Cash and Cash Equivalents
Assets:
Restricted Cash		0		0
Level 3 Inputs | Certificates of Deposit
Assets:
Restricted Cash		$ 0		$ 0
[1]	Includes amounts in consolidated variable interest entities (VIEs) presented separately in the table below. The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 6, Securitizations, and Note 10, Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information. September 30, 2021 December 31, 2020 Assets of consolidated VIEs, included in total assets above: Restricted Cash $ 5,805 $ 25,203 Loans Held for Sale, at Fair Value 285,920 274,621 Borrower Loans, at Fair Value — 168,593 Prepaid and Other Assets 3,068 2,043 Total assets of consolidated variable interest entities $ 294,793 $ 470,460 Liabilities of consolidated VIEs, included in total liabilities above: Notes Issued by Securitization Trust $ — $ 156,782 Certificates Issued by Securitization Trust, at Fair Value — 22,917 Warehouse Lines 245,819 242,479 Total liabilities of consolidated variable interest entities $ 245,819 $ 422,178

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLE ASSETS, NET - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Goodwill And Other Intangible Assets [Line Items]
Goodwill	$ 36,368,000		$ 36,368,000		$ 36,368,000
Goodwill impairment			0	$ 0
Intangible assets, net	371,000		371,000		$ 500,000
Amortization of intangible assets	100,000	$ 100,000	100,000	$ 200,000
User base and customer relationships
Goodwill And Other Intangible Assets [Line Items]
Intangible assets, net	$ 371,000		$ 371,000
Intangible assets amortized period			3 years 7 months 6 days
User base and customer relationships | Minimum
Goodwill And Other Intangible Assets [Line Items]
Intangible assets amortized period			3 years
User base and customer relationships | Maximum
Goodwill And Other Intangible Assets [Line Items]
Intangible assets amortized period			10 years

GOODWILL AND OTHER INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLE ASSETS, NET - Summary of Other Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 8,170
Accumulated Amortization	(7,799)
Net Carrying Value	371	$ 500
Developed technology
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	3,060
Accumulated Amortization	(3,060)
Net Carrying Value	0
User base and customer relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	5,050
Accumulated Amortization	(4,679)
Net Carrying Value	$ 371
Remaining Useful Life (In Years)	3 years 7 months 6 days
Brand name
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 60
Accumulated Amortization	(60)
Net Carrying Value	$ 0

GOODWILL AND OTHER INTANGIBLE_5

GOODWILL AND OTHER INTANGIBLE ASSETS, NET - Summary of Estimated Amortization of Purchased Intangible Assets (Details) $ in Thousands	Sep. 30, 2021USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2021 (remainder thereof)	$ 43
2022	136
2023	107
2024	85
Total	$ 371

OTHER LIABILITIES (Details)

OTHER LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Other Liabilities [Abstract]
Operating lease liabilities	$ 12,316	$ 13,342
Paycheck Protection Program loan (Note 10)	8,568	8,505
Loan trailing fee liability	2,183	2,233
Deferred income tax liability	552	489
Financing lease liabilities	155	0
Deferred revenue	50	63
Other	280	425
Total Other Liabilities	$ 24,104	$ 25,057
Operating lease liability, location	Total Other Liabilities	Total Other Liabilities
Finance lease liability, location	Total Other Liabilities	Total Other Liabilities

DEBT (Details)

DEBT (Details)		Mar. 04, 2021USD ($)	Jun. 20, 2019	Mar. 28, 2019USD ($)	Apr. 30, 2020USD ($)	Sep. 30, 2021USD ($)	May 19, 2021USD ($)	Dec. 31, 2020USD ($)	Jun. 12, 2018USD ($)	Jan. 19, 2018USD ($)
Line of Credit Facility [Line Items]
Warehouse Lines	[1]					$ 245,819,000		$ 242,479,000
Loans Held for Sale at Fair Value	[1]					285,920,000		274,621,000
Paycheck protection program loan						8,568,000		$ 8,505,000
Swaptation
Line of Credit Facility [Line Items]
Derivative asset						100,000
Warehouse Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Minimum tangible net worth						25,000,000
Minimum net liquidity						$ 15,000,000
Maximum leverage ratio						5
PWIT | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity									$ 200,000,000	$ 100,000,000
Repayment period			24 months
Advance rate			87.00%
Commitment fee percent			0.50%
Warehouse Lines						$ 114,600,000
Loans Held for Sale at Fair Value						134,900,000
Undrawn portion						85,400,000
Capitalized debt issuance cost						2,200,000	$ 300,000
PWIIT | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity				$ 300,000,000
Repayment period		24 months		24 months
Advance rate		90.00%
Warehouse Lines						131,200,000
Loans Held for Sale at Fair Value						148,600,000
Undrawn portion						168,800,000
Capitalized debt issuance cost						1,300,000
PWIIT Class A | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 230,000,000
Commitment fee percent		0.50%
PWIIT Class B | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 70,000,000
PWIIT Class B | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Commitment fee percent		0.50%
PWIIT Class B | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Commitment fee percent		1.00%
PPP Loan
Line of Credit Facility [Line Items]
Loan at time of issuance					$ 8,400,000
Stated interest rate					1.00%
Remaining contractual term (in years)					2 years
Paycheck protection program loan						$ 8,600,000
LIBOR | PWIT | Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest rate			2.75%
LIBOR | PWIIT Class A | Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest rate		2.05%
Increase to basis spread		0.375%
LIBOR | PWIIT Class B | Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest rate		8.75%
Increase to basis spread		0.375%
[1]	Includes amounts in consolidated variable interest entities (VIEs) presented separately in the table below. The following table presents the assets and liabilities of consolidated variable interest entities (VIEs), which are included in the condensed consolidated balance sheets above. The assets in the table below may only be used to settle obligations of consolidated VIEs and are in excess of those obligations. Additionally, the assets and liabilities in the table below include third-party assets and liabilities of consolidated VIEs only and exclude intercompany balances that eliminate in consolidation. See Note 6, Securitizations, and Note 10, Debt, to our Notes to Condensed Consolidated Financial Statements for add itional information. September 30, 2021 December 31, 2020 Assets of consolidated VIEs, included in total assets above: Restricted Cash $ 5,805 $ 25,203 Loans Held for Sale, at Fair Value 285,920 274,621 Borrower Loans, at Fair Value — 168,593 Prepaid and Other Assets 3,068 2,043 Total assets of consolidated variable interest entities $ 294,793 $ 470,460 Liabilities of consolidated VIEs, included in total liabilities above: Notes Issued by Securitization Trust $ — $ 156,782 Certificates Issued by Securitization Trust, at Fair Value — 22,917 Warehouse Lines 245,819 242,479 Total liabilities of consolidated variable interest entities $ 245,819 $ 422,178

NET INCOME (LOSS) PER SHARE - B

NET INCOME (LOSS) PER SHARE - Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator:
Net (Loss) Income	$ (88,061)	$ (5,805)	$ (44,889)	$ (2,025)	$ 17,641	$ 21,130	$ (138,755)	$ 36,746
Plus: Return on Share Purchase	0			2,381			0	2,381
Less: Net Income Allocated to Participating Securities	0			(255)			0	(28,814)
Net (Loss) Income Attributable to Common Stockholders, Basic	(88,061)			101			(138,755)	10,313
Net (Loss) Income Attributable to Common Stockholders, Diluted	$ (88,061)			$ 101			$ (138,755)	$ 10,313
Denominator:
Weighted average shares used in computing basic net (loss) income per share	71,068,442			68,485,173			70,433,182	68,465,046
Effect of dilutive securities:
Stock options (in shares)	0			14,902,171			0	50,778,284
Convertible preferred stock warrants (in shares)	0			213,264,845			0	213,264,845
Weighted average shares used in computing diluted Net (Loss) Income per Share	71,068,442			296,652,189			70,433,182	332,508,175
Net (Loss) Income Per Share - Basic (in dollars per share)	$ (1.24)			$ 0			$ (1.97)	$ 0.15
Net (Loss) Income Per Share - Diluted (in dollars per share)	$ (1.24)			$ 0			$ (1.97)	$ 0.03

NET INCOME (LOSS) PER SHARE - C

NET INCOME (LOSS) PER SHARE - Common Stock Equivalents Excluded from Computation of Diluted Net Income (Loss) Per Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents excluded from diluted net (loss) income per common share computation (in shares)	443,312,331	241,231,932	445,556,675	223,469,804
Convertible preferred stock issued and outstanding, excluding shares held by consolidated VIE
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents excluded from diluted net (loss) income per common share computation (in shares)	158,365,655	181,761,442	158,365,655	200,261,761
Stock options issued and outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents excluded from diluted net (loss) income per common share computation (in shares)	70,601,482	58,390,141	72,845,826	22,127,694
Warrants issued and outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents excluded from diluted net (loss) income per common share computation (in shares)	1,080,349	1,080,349	1,080,349	1,080,349
Series E-1 convertible preferred stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents excluded from diluted net (loss) income per common share computation (in shares)	35,544,141	0	35,544,141	0
Series F convertible preferred stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total common stock equivalents excluded from diluted net (loss) income per common share computation (in shares)	177,720,704	0	177,720,704	0

CONVERTIBLE PREFERRED STOCK, _3

CONVERTIBLE PREFERRED STOCK, CONVERTIBLE PREFERRED STOCK WARRANT LIABILITY AND COMMON STOCK - Additional Information (Details)	Jul. 21, 2020shares	Feb. 27, 2017$ / sharesshares	Dec. 16, 2016	Feb. 16, 2016	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2020USD ($)shares	Sep. 30, 2021USD ($)time$ / sharesshares	Sep. 30, 2020USD ($)shares	Dec. 31, 2020$ / sharesshares	Sep. 20, 2017$ / sharesshares
Class of Stock [Line Items]
Common and preferred stock, shares authorized (in shares)										1,069,760,848
Common stock, authorized (in shares)					625,000,000		625,000,000		625,000,000	625,000,000
Common stock, par value (in dollars per share) | $ / shares					$ 0.01		$ 0.01		$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)					444,760,848		444,760,848		444,760,848	444,760,848
Preferred stock, par value (in dollars per share) | $ / shares										$ 0.01
Common stock, issued (in shares)					72,257,653		72,257,653		70,075,307
Common stock, outstanding (in shares)					71,321,718		71,321,718		69,139,372
Convertible Preferred Stock Held by Consolidated VIE
Class of Stock [Line Items]
Purchase of convertible preferred stock by consolidated VIE Prosper Grantor Trust (in shares)						51,247,915		51,247,915
Common Stock
Class of Stock [Line Items]
Stock split conversion ratio				5
Exercise of stock options (in shares)							2,182,346
Cash proceeds | $							$ 44,000
Series A
Class of Stock [Line Items]
Conversion ratio					1		1
Times the original issue | time							3
Liquidation preference (in dollars per share) | $ / shares					$ 0.29		$ 0.29
Preferred stock, shares authorized (in shares)					68,558,220		68,558,220
Series A | Convertible Preferred Stock Held by Consolidated VIE
Class of Stock [Line Items]
Purchase of convertible preferred stock by consolidated VIE Prosper Grantor Trust (in shares)	34,670,420
Series B
Class of Stock [Line Items]
IPO value (at least) | $							$ 2,000,000,000
Aggregate proceeds (at least) | $							$ 100,000,000
Voting power (at least)							60.00%
Liquidation preference (in dollars per share) | $ / shares					$ 0.60		$ 0.60
Preferred stock, shares authorized (in shares)					35,775,880		35,775,880
Series B | Convertible Preferred Stock Held by Consolidated VIE
Class of Stock [Line Items]
Purchase of convertible preferred stock by consolidated VIE Prosper Grantor Trust (in shares)	16,577,495
Series A-1
Class of Stock [Line Items]
Voting power (at least)							14.00%
Conversion ratio					1,000,000		1,000,000
Liquidation preference (in dollars per share) | $ / shares					$ 2		$ 2
Preferred stock, shares authorized (in shares)					24,760,915		24,760,915
Series D
Class of Stock [Line Items]
Voting power (at least)							60.00%
Liquidation preference (in dollars per share) | $ / shares					$ 6.91		$ 6.91
Series E1 and E2 Preferred Stock
Class of Stock [Line Items]
Voting power (at least)							60.00%
Series F
Class of Stock [Line Items]
Voting power (at least)							60.00%
Preferred stock, liquidation preference, conversion basis							0.6667
Preferred stock, liquidation preference, conversion basis, after payment							0.3333
Liquidation preference (in dollars per share) | $ / shares					$ 0.84		$ 0.84
Warrant to purchase (in shares)		177,720,706
Warrant expiration period		10 years
Change in fair value | $					$ (72,900,000)	$ (8,900,000)	$ (115,500,000)	$ 53,300,000
Exercise price (in dollars per share) | $ / shares		$ 0.01
Preferred stock, shares authorized (in shares)					177,720,707		177,720,707
Series G
Class of Stock [Line Items]
Voting power (at least)							60.00%
Conversion ratio					1.36		1.36
Liquidation preference (in dollars per share) | $ / shares					$ 1.34		$ 1.34
Preferred stock, shares authorized (in shares)					37,249,497		37,249,497
Series C
Class of Stock [Line Items]
Liquidation preference (in dollars per share) | $ / shares					$ 2.87		$ 2.87
Preferred stock, shares authorized (in shares)					24,404,770		24,404,770
Series E-1
Class of Stock [Line Items]
Liquidation preference (in dollars per share) | $ / shares					$ 0.84		$ 0.84
Warrant to purchase (in shares)		15,277,006
Warrant expiration period			10 years
Change in fair value | $					$ (13,900,000)	$ (2,500,000)	$ (21,300,000)	$ 10,300,000
Preferred stock, shares authorized (in shares)					35,544,141		35,544,141
Series E-2
Class of Stock [Line Items]
Preferred stock, liquidation preference, conversion basis							0.6667
Preferred stock, liquidation preference, conversion basis, after payment							0.3333
Liquidation preference (in dollars per share) | $ / shares					$ 0.84		$ 0.84
Preferred stock, shares authorized (in shares)					16,858,078		16,858,078

CONVERTIBLE PREFERRED STOCK, _4

CONVERTIBLE PREFERRED STOCK, CONVERTIBLE PREFERRED STOCK WARRANT LIABILITY AND COMMON STOCK - Summary of Shares Authorized, Issued, Outstanding, Par Value and Liquidation Preference of Convertible Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 20, 2017
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01			$ 0.01
Convertible preferred stock, authorized (in shares)	444,760,848			444,760,848					444,760,848
Convertible preferred stock, issued (in shares)	209,613,570			209,613,570
Convertible preferred stock, outstanding (in shares)	209,613,570			209,613,570
Liquidation Preference, Outstanding Shares	$ 370,456			$ 370,456
Convertible Preferred Stock Held by Consolidated VIE
Class of Stock [Line Items]
Convertible preferred stock, outstanding (in shares)	(51,247,915)	(51,247,915)	(51,247,915)	(51,247,915)	(51,247,915)	0	0	0
Series A
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, authorized (in shares)	68,558,220
Convertible preferred stock, issued (in shares)	66,428,185
Convertible preferred stock, outstanding (in shares)	66,428,185
Liquidation Preference, Outstanding Shares	$ 19,160
Series A | Convertible Preferred Stock Held by Consolidated VIE
Class of Stock [Line Items]
Convertible preferred stock, issued (in shares)	34,670,420
Convertible preferred stock, outstanding (in shares)	34,670,420
Series A-1
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, authorized (in shares)	24,760,915
Convertible preferred stock, issued (in shares)	22,515,315
Convertible preferred stock, outstanding (in shares)	22,515,315
Liquidation Preference, Outstanding Shares	$ 45,031
Series B
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, authorized (in shares)	35,775,880
Convertible preferred stock, issued (in shares)	35,127,160
Convertible preferred stock, outstanding (in shares)	35,127,160
Liquidation Preference, Outstanding Shares	$ 21,190
Series B | Convertible Preferred Stock Held by Consolidated VIE
Class of Stock [Line Items]
Convertible preferred stock, issued (in shares)	16,577,495
Convertible preferred stock, outstanding (in shares)	16,577,495
Series C
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, authorized (in shares)	24,404,770
Convertible preferred stock, issued (in shares)	24,404,770
Convertible preferred stock, outstanding (in shares)	24,404,770
Liquidation Preference, Outstanding Shares	$ 70,075
Series D
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, authorized (in shares)	23,888,640
Convertible preferred stock, issued (in shares)	23,888,640
Convertible preferred stock, outstanding (in shares)	23,888,640
Liquidation Preference, Outstanding Shares	$ 165,000
Series E-1
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, authorized (in shares)	35,544,141
Convertible preferred stock, issued (in shares)	0
Convertible preferred stock, outstanding (in shares)	0
Liquidation Preference, Outstanding Shares	$ 0
Series E-2
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, authorized (in shares)	16,858,078
Convertible preferred stock, issued (in shares)	0
Convertible preferred stock, outstanding (in shares)	0
Liquidation Preference, Outstanding Shares	$ 0
Series F
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, authorized (in shares)	177,720,707
Convertible preferred stock, issued (in shares)	3
Convertible preferred stock, outstanding (in shares)	3
Liquidation Preference, Outstanding Shares	$ 0
Series G
Class of Stock [Line Items]
Convertible preferred stock, par value (in dollars per share)	$ 0.01
Convertible preferred stock, authorized (in shares)	37,249,497
Convertible preferred stock, issued (in shares)	37,249,497
Convertible preferred stock, outstanding (in shares)	37,249,497
Liquidation Preference, Outstanding Shares	$ 50,000

CONVERTIBLE PREFERRED STOCK, _5

CONVERTIBLE PREFERRED STOCK, CONVERTIBLE PREFERRED STOCK WARRANT LIABILITY AND COMMON STOCK - Schedule of Assumptions Used (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Volatility | Series E-1
Class of Stock [Line Items]
Fair value assumptions	0.590	0.600
Volatility | Series F
Class of Stock [Line Items]
Fair value assumptions	0.590	0.600
Risk-free interest rate | Series E-1
Class of Stock [Line Items]
Fair value assumptions	0.0050	0.0020
Risk-free interest rate | Series F
Class of Stock [Line Items]
Fair value assumptions	0.0050	0.0020
Expected term (in years) | Series E-1
Class of Stock [Line Items]
Remaining contractual term (in years)	2 years 9 months	2 years 9 months
Expected term (in years) | Series F
Class of Stock [Line Items]
Remaining contractual term (in years)	2 years 9 months	2 years 9 months
Dividend yield | Series E-1
Class of Stock [Line Items]
Fair value assumptions	0	0
Dividend yield | Series F
Class of Stock [Line Items]
Fair value assumptions	0	0

CONVERTIBLE PREFERRED STOCK, _6

CONVERTIBLE PREFERRED STOCK, CONVERTIBLE PREFERRED STOCK WARRANT LIABILITY AND COMMON STOCK - Warrant Liability (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Warrants or Rights [Roll Forward]
Change in fair value	$ 136,846	$ (63,624)
Convertible Preferred Stock Warrant
Warrants or Rights [Roll Forward]
Beginning balance	112,319	149,996
Change in fair value	136,845	(63,624)
Ending balance	$ 249,164	$ 86,372

STOCK-BASED COMPENSATION - Addi

STOCK-BASED COMPENSATION - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Plan repricing, unamortized cost	$ 34,000		$ 34,000
Plan repricing, unamortized cost, vesting period			1 year 8 months 12 days
Options outstanding, term			6 years 10 months 24 days
Dividend yield	0.00%	0.00%	0.00%	0.00%
Internal-use software and website development costs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation capitalized	$ 100,000	$ 100,000	$ 100,000	$ 200,000
Stock options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized cost of unvested share-based compensation awards.	0		0
RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unamortized expense related to unvested stock-based awards	$ 1,400,000		$ 1,400,000
Weighted average vesting period			2 years 6 months
RSUs | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			3 years
RSUs | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period			4 years

STOCK-BASED COMPENSATION - Summ

STOCK-BASED COMPENSATION - Summarized Option Activity under Option Plan (Details) - 2005 Stock Plan and 2015 Stock Option Plan	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Options Issued and Outstanding
Beginning Balance (in shares) | shares	72,915,449
Options issued (in shares) | shares	15,431,359
Options exercised (in shares) | shares	(2,182,346)
Options forfeited (in shares) | shares	(13,815,422)
Options expired (in shares) | shares	(30,190)
Ending balance (in shares) | shares	72,318,850
Options vested and expected to vest (in shares) | shares	54,681,009
Options vested and exercisable (in shares) | shares	48,617,301
Weighted Average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 0.02
Options issued (in dollars per share) | $ / shares	0.16
Options exercised (in dollars per share) | $ / shares	0.02
Options forfeited (in dollars per share) | $ / shares	0.02
Options expired (in dollars per share) | $ / shares	0.02
Ending balance (in dollars per share) | $ / shares	0.05
Options vested and expected to vest (in dollars per share) | $ / shares	0.05
Options vested and exercisable (in dollars per share) | $ / shares	$ 0.02

STOCK-BASED COMPENSATION - Fair

STOCK-BASED COMPENSATION - Fair Value of Stock Option Awards (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Fair value of stock option awards [Abstract]
Volatility of common stock	64.84%	57.32%	64.37%	52.66%
Risk-free interest rate	0.97%	0.37%	0.99%	0.51%
Expected life	6 years	6 years	6 years	6 years
Dividend yield	0.00%	0.00%	0.00%	0.00%

STOCK-BASED COMPENSATION - Su_2

STOCK-BASED COMPENSATION - Summarized Activities for the Company's RSU's (Details) - RSUs	9 Months Ended
	Sep. 30, 2021$ / sharesshares
Number of Shares
Unvested, beginning balance (in shares) | shares	4,661,141
Forfeited (in shares) | shares	(1,786,793)
Unvested, ending balance (in shares) | shares	2,874,348
Weighted-Average Grant Date Fair Value
Unvested, beginning balance (in dollars per share) | $ / shares	$ 0.91
Forfeited (in dollars per share) | $ / shares	0.54
Unvested, ending balance (in dollars per share) | $ / shares	$ 1.14

STOCK-BASED COMPENSATION - Stoc

STOCK-BASED COMPENSATION - Stock Based Compensation Included in Consolidated Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 270	$ 786	$ 857	$ 1,683
Origination and servicing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	30	53	92	124
Sales and marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	15	25	47	51
General and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 225	$ 708	$ 718	$ 1,508

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Taxes [Line Items]
Income tax expense	$ 21,000	$ 34,000	$ 63,000	$ 102,000
Prosper Funding LLC
Income Taxes [Line Items]
Income tax expense			$ 0	$ 0
Net effective tax rate			0.00%

LEASES - Additional Information

LEASES - Additional Information (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Renewal term	5 years			5 years
Rental expense under operating lease arrangements	$ 1,100,000	$ 1,200,000		$ 3,400,000	$ 4,200,000
Sublease income	$ 100,000	$ 100,000		200,000	400,000
Impairment of Operating Lease Right-of-use Asset			$ 200,000	$ 0	$ 228,000
Operating lease liability, location	Other Liabilities			Other Liabilities		Other Liabilities
Minimum
Lessee, Lease, Description [Line Items]
Operating lease contract term	1 year			1 year
Maximum
Lessee, Lease, Description [Line Items]
Operating lease contract term	5 years			5 years

LEASES - Operating Lease Right-

LEASES - Operating Lease Right-of-Use Assets (Details) $ in Thousands	Sep. 30, 2021USD ($)
Lessee, Lease, Description [Line Items]
Gross Carrying Value	$ 17,485
Accumulated Amortization	8,833
Net Carrying Value	8,652
ROU Assets - Office buildings
Lessee, Lease, Description [Line Items]
Gross Carrying Value	16,709
Accumulated Amortization	8,581
Net Carrying Value	8,128
ROU Assets - Other
Lessee, Lease, Description [Line Items]
Gross Carrying Value	776
Accumulated Amortization	252
Net Carrying Value	$ 524

LEASES - Schedule of Lease Matu

LEASES - Schedule of Lease Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Schedule of Lease Maturity
Remainder of 2021	$ 1,439
2022	5,833
2023	2,124
2024	1,360
2025	1,395
Thereafter	1,218
Total future minimum lease payments	13,369
Less imputed interest	(1,053)
Present value of future minimum lease payments	$ 12,316	$ 13,342

LEASES - Other Information Rela

LEASES - Other Information Related to Leases (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Leases [Abstract]
Cash paid for operating leases year-to-date	$ 3,955
ROU assets obtained in exchange for new operating lease obligations year-to-date	$ 1,773
Weighted average remaining lease term (in years)	3 years 2 months 26 days
Weighted average discount rate	5.48%

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Commitments And Contingencies [Line Items]
Designated Amount for loans (less than), through February 2022	$ 143,500
Designated Amount for loans (less than), through February 2025	100,000
Minimum fee, remaining in current year	400,000
Minimum fee, 2022	1,200,000
Minimum fee, 2023	1,200,000
Minimum fee, 2024	1,200,000
Minimum fee, 2025	100,000
Minimum liquidity covenant	15,000,000
Purchase commitment of borrower loans	13,900,000
Maximum potential future payments	2,500,000,000
Accrued repurchase and indemnification obligation	300,000	$ 200,000
Prosper Funding LLC
Commitments And Contingencies [Line Items]
Designated Amount for loans (less than), through February 2022	143,500
Designated Amount for loans (less than), through February 2025	100,000
Minimum fee, remaining in current year	400,000
Minimum fee, 2022	1,200,000
Minimum fee, 2023	1,200,000
Minimum fee, 2024	1,200,000
Minimum fee, 2025	100,000
Minimum liquidity covenant	15,000,000
Purchase commitment of borrower loans	13,900,000
Maximum potential future payments	2,500,000,000
Accrued repurchase and indemnification obligation	$ 300,000	$ 200,000

RELATED PARTIES - Additional In

RELATED PARTIES - Additional Information (Details)	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Minimum percentage of voting securities considered for related parties	10.00%
Minimum percentage of stockholders considered for related parties	10.00%

RELATED PARTIES - Aggregate Amo

RELATED PARTIES - Aggregate Amount of Notes Purchased and the Income Earned (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Related Party Transaction [Line Items]
Aggregate Amount of Notes Purchased	$ 13	$ 48	$ 50	$ 291
Interest Earned on Notes and Borrower Loans	3	15	6	47
Notes Balance	58		58		$ 41
Prosper Funding LLC
Related Party Transaction [Line Items]
Aggregate Amount of Notes Purchased	9	7	26	19
Interest Earned on Notes and Borrower Loans	2	1	5	4
Notes Balance	40		40		41
Executive officers and management
Related Party Transaction [Line Items]
Aggregate Amount of Notes Purchased	9	7	26	19
Interest Earned on Notes and Borrower Loans	2	1	5	4
Notes Balance	40		40		41
Executive officers and management | Prosper Funding LLC
Related Party Transaction [Line Items]
Aggregate Amount of Notes Purchased	9	7	26	19
Interest Earned on Notes and Borrower Loans	2	1	5	4
Notes Balance	40		40		41
Directors (excluding executive officers and management)
Related Party Transaction [Line Items]
Aggregate Amount of Notes Purchased	4	41	24	272
Interest Earned on Notes and Borrower Loans	1	14	1	43
Notes Balance	18		18		0
Directors (excluding executive officers and management) | Prosper Funding LLC
Related Party Transaction [Line Items]
Aggregate Amount of Notes Purchased	0	0	0	0
Interest Earned on Notes and Borrower Loans	0	$ 0	0	$ 0
Notes Balance	$ 0		$ 0		$ 0

SIGNIFICANT CONCENTRATIONS (Det

SIGNIFICANT CONCENTRATIONS (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Concentration Risk [Line Items]
Percentage of funds originating in channel			88.00%	91.00%
Party One
Concentration Risk [Line Items]
Percentage of loan purchased	24.70%	26.70%	27.00%	17.70%
Warehouse VIE
Concentration Risk [Line Items]
Percentage of loan purchased	15.70%	23.10%	13.40%	21.10%
Party Two
Concentration Risk [Line Items]
Percentage of loan purchased		15.00%		16.40%