00100 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION link:presentationLink link:calculationLink link:definitionLink 00200 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS link:presentationLink link:calculationLink link:definitionLink 00300 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME link:presentationLink link:calculationLink link:definitionLink 00500 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS link:presentationLink link:calculationLink link:definitionLink 40602 - Disclosure - DEBT - Maturities of the notes (Details) link:presentationLink link:calculationLink link:definitionLink 00090 - Document - Document and Entity Information link:presentationLink link:calculationLink link:definitionLink 00105 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 00400 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY link:presentationLink link:calculationLink link:definitionLink 40201 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Share-Based Compensation (Details) link:presentationLink link:calculationLink link:definitionLink 40204 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Goodwill and Other Intangible Assets (Details) link:presentationLink link:calculationLink link:definitionLink 40301 - Disclosure - MERGER AND RECAPITALIZATION (Details) link:presentationLink link:calculationLink link:definitionLink 40401 - Disclosure - REVENUES FROM CONTRACTS WITH CUSTOMERS (Details) link:presentationLink link:calculationLink link:definitionLink 40601 - Disclosure - DEBT (Details) link:presentationLink link:calculationLink link:definitionLink 40701 - Disclosure - PROMISSORY NOTES - AFFILIATES (Details) link:presentationLink link:calculationLink link:definitionLink 40801 - Disclosure - SERIES A REDEEMABLE CONVERTIBLE PREFERRED STOCK (Details) link:presentationLink link:calculationLink link:definitionLink 40901 - Disclosure - SERIES B CONVERTIBLE PREFERRED STOCK (Details) link:presentationLink link:calculationLink link:definitionLink 41001 - Disclosure - SHARE-BASED COMPENSATION - Narratives (Details) link:presentationLink link:calculationLink link:definitionLink 41002 - Disclosure - SHARE-BASED COMPENSATION - Stock options (Details) link:presentationLink link:calculationLink link:definitionLink 41003 - Disclosure - SHARE-BASED COMPENSATION - Restricted Stock and Stock Units (Details) link:presentationLink link:calculationLink link:definitionLink 41101 - Disclosure - WARRANTS - Warrant outstanding (Details) link:presentationLink link:calculationLink link:definitionLink 41501 - Disclosure - COMMON STOCK, PREFERRED STOCK AND STOCKHOLDERS' EQUITY (Details) link:presentationLink link:calculationLink link:definitionLink 00505 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 10101 - Disclosure - ORGANIZATION, DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION link:presentationLink link:calculationLink link:definitionLink 10201 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES link:presentationLink link:calculationLink link:definitionLink 10301 - Disclosure - MERGER AND RECAPITALIZATION link:presentationLink link:calculationLink link:definitionLink 10401 - Disclosure - REVENUES FROM CONTRACTS WITH CUSTOMERS link:presentationLink link:calculationLink link:definitionLink 10501 - Disclosure - FAIR VALUE link:presentationLink link:calculationLink link:definitionLink 10601 - Disclosure - DEBT link:presentationLink link:calculationLink link:definitionLink 10701 - Disclosure - PROMISSORY NOTES - AFFILIATES link:presentationLink link:calculationLink link:definitionLink 10801 - Disclosure - SERIES A REDEEMABLE CONVERTIBLE PREFERRED STOCK link:presentationLink link:calculationLink link:definitionLink 10901 - Disclosure - SERIES B CONVERTIBLE PREFERRED STOCK link:presentationLink link:calculationLink link:definitionLink 11001 - Disclosure - SHARE-BASED COMPENSATION link:presentationLink link:calculationLink link:definitionLink 11101 - Disclosure - WARRANTS link:presentationLink link:calculationLink link:definitionLink 11201 - Disclosure - INCOME TAXES link:presentationLink link:calculationLink link:definitionLink 11301 - Disclosure - NET INCOME (LOSS) PER SHARE link:presentationLink link:calculationLink link:definitionLink 11401 - Disclosure - COMMITMENTS AND CONTINGENCIES link:presentationLink link:calculationLink link:definitionLink 11501 - Disclosure - COMMON STOCK, PREFERRED STOCK AND STOCKHOLDERS' EQUITY link:presentationLink link:calculationLink link:definitionLink 11601 - Disclosure - NET CAPITAL REQUIREMENTS link:presentationLink link:calculationLink link:definitionLink 11701 - Disclosure - CREDIT RISK AND CONCENTRATIONS link:presentationLink link:calculationLink link:definitionLink 11801 - Disclosure - SEGMENT INFORMATION link:presentationLink link:calculationLink link:definitionLink 11901 - Disclosure - SUBSEQUENT EVENTS link:presentationLink link:calculationLink link:definitionLink 20202 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies) link:presentationLink link:calculationLink link:definitionLink 30403 - Disclosure - REVENUES FROM CONTRACTS WITH CUSTOMERS (Tables) link:presentationLink link:calculationLink link:definitionLink 30603 - Disclosure - DEBT (Tables) link:presentationLink link:calculationLink link:definitionLink 31003 - Disclosure - SHARE-BASED COMPENSATION (Tables) link:presentationLink link:calculationLink link:definitionLink 31103 - Disclosure - WARRANTS (Tables) link:presentationLink link:calculationLink link:definitionLink 31303 - Disclosure - NET INCOME (LOSS) PER SHARE (Tables) link:presentationLink link:calculationLink link:definitionLink 40101 - Disclosure - ORGANIZATION, DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (Details) link:presentationLink link:calculationLink link:definitionLink 40202 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Cash, Cash Equivalents and Restricted Cash (Details) link:presentationLink link:calculationLink link:definitionLink 40203 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Financial Instruments - Credit Losses (Details) link:presentationLink link:calculationLink link:definitionLink 41102 - Disclosure - WARRANTS (Details) link:presentationLink link:calculationLink link:definitionLink 41201 - Disclosure - INCOME TAXES (Details) link:presentationLink link:calculationLink link:definitionLink 41301 - Disclosure - NET INCOME (LOSS) PER SHARE - Computation of loss per share and weighted average of the company's common stock outstanding (Details) link:presentationLink link:calculationLink link:definitionLink 41302 - Disclosure - NET INCOME (LOSS) PER SHARE - Securities that have been excluded from the calculation of weighted-average shares for diluted earnings per share (Details) link:presentationLink link:calculationLink link:definitionLink 41401 - Disclosure - COMMITMENTS AND CONTINGENCIES (Details) link:presentationLink link:calculationLink link:definitionLink 41801 - Disclosure - SEGMENT INFORMATION (Details) link:presentationLink link:calculationLink link:definitionLink 99900 - Disclosure - Standard And Custom Axis Domain Defaults link:presentationLink link:calculationLink link:definitionLink