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Disclosure - LEASES - Maturities of lease liabilities (Details) link:presentationLink link:calculationLink link:definitionLink 41305 - Disclosure - LEASES - Maturities of lease liabilities (Details)calc2 link:presentationLink link:calculationLink link:definitionLink 99941701 - Disclosure - INCOME TAXES - Income tax provision (benefit) (Details) link:presentationLink link:calculationLink link:definitionLink 99941702 - Disclosure - INCOME TAXES - Reconciliation between the U.S. statutory federal income tax rate and the Company's effective tax rate (Details) link:presentationLink link:calculationLink link:definitionLink 99941703 - Disclosure - INCOME TAXES - Deferred tax assets and liabilities (Details) link:presentationLink link:calculationLink link:definitionLink 995200090 - Document - Document and Entity Information link:presentationLink link:calculationLink link:definitionLink 995200105 - Statement - CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) link:presentationLink link:calculationLink link:definitionLink 995200300 - 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Disclosure - DEBT - Subsequent information (Details) link:presentationLink link:calculationLink link:definitionLink 99941101 - Disclosure - PROMISSORY NOTES - AFFILIATES (Details) link:presentationLink link:calculationLink link:definitionLink 99941201 - Disclosure - DUE TO MEMBERS (Details) link:presentationLink link:calculationLink link:definitionLink 99941301 - Disclosure - LEASES (Details) link:presentationLink link:calculationLink link:definitionLink 99941401 - Disclosure - SERIES A REDEEMABLE CONVERTIBLE PREFERRED STOCK (Details) link:presentationLink link:calculationLink link:definitionLink 99941501 - Disclosure - SERIES B CONVERTIBLE PREFERRED STOCK (Details) link:presentationLink link:calculationLink link:definitionLink 99941601 - Disclosure - WARRANTS - Warrant outstanding (Details) link:presentationLink link:calculationLink link:definitionLink 99941704 - Disclosure - INCOME TAXES - Net Operating Losses and Valuation Allowance (Details) link:presentationLink link:calculationLink link:definitionLink 99942001 - 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Disclosure - DUE FROM CLEARING BROKER AND CLEARING DEPOSIT link:presentationLink link:calculationLink link:definitionLink 995210701 - Disclosure - FAIR VALUE link:presentationLink link:calculationLink link:definitionLink 995210801 - Disclosure - PROPERTY AND EQUIPMENT, NET link:presentationLink link:calculationLink link:definitionLink 995210901 - Disclosure - INTANGIBLE ASSETS link:presentationLink link:calculationLink link:definitionLink 995211001 - Disclosure - DEBT link:presentationLink link:calculationLink link:definitionLink 995211101 - Disclosure - PROMISSORY NOTES - AFFILIATES link:presentationLink link:calculationLink link:definitionLink 995211201 - Disclosure - DUE TO MEMBERS link:presentationLink link:calculationLink link:definitionLink 995211301 - Disclosure - LEASES link:presentationLink link:calculationLink link:definitionLink 995211401 - Disclosure - SERIES A REDEEMABLE CONVERTIBLE PREFERRED STOCK link:presentationLink link:calculationLink link:definitionLink 995211501 - Disclosure - SERIES B CONVERTIBLE PREFERRED STOCK link:presentationLink link:calculationLink link:definitionLink 995211601 - Disclosure - WARRANTS link:presentationLink link:calculationLink link:definitionLink 995211701 - Disclosure - INCOME TAXES link:presentationLink link:calculationLink link:definitionLink 995211801 - Disclosure - NET LOSS PER SHARE link:presentationLink link:calculationLink link:definitionLink 995211901 - Disclosure - COMMITMENTS AND CONTINGENCIES link:presentationLink link:calculationLink link:definitionLink 995212001 - Disclosure - RELATED-PARTY TRANSACTIONS link:presentationLink link:calculationLink link:definitionLink 995212101 - Disclosure - STOCKHOLDERS' EQUITY link:presentationLink link:calculationLink link:definitionLink 995212201 - Disclosure - RETIREMENT PLAN link:presentationLink link:calculationLink link:definitionLink 995212301 - Disclosure - NET CAPITAL REQUIREMENTS link:presentationLink link:calculationLink link:definitionLink 995212401 - Disclosure - CREDIT RISK AND CONCENTRATIONS link:presentationLink link:calculationLink link:definitionLink 995212501 - Disclosure - SEGMENT INFORMATION link:presentationLink link:calculationLink link:definitionLink 995212601 - Disclosure - SUBSEQUENT EVENTS link:presentationLink link:calculationLink link:definitionLink 99920302 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies) link:presentationLink link:calculationLink link:definitionLink 99930503 - Disclosure - REVENUES FROM CONTRACTS WITH CUSTOMERS (Tables) link:presentationLink link:calculationLink link:definitionLink 99930603 - Disclosure - DUE FROM CLEARING BROKER AND CLEARING DEPOSIT (Tables) link:presentationLink link:calculationLink link:definitionLink 99930803 - Disclosure - PROPERTY AND EQUIPMENT, NET (Tables) link:presentationLink link:calculationLink link:definitionLink 99930903 - Disclosure - INTANGIBLE ASSETS (Tables) link:presentationLink link:calculationLink link:definitionLink 99931003 - Disclosure - DEBT (Tables) link:presentationLink link:calculationLink link:definitionLink 99931303 - 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Disclosure - LEASES - Amounts reported in the consolidated statements of financial condition (Details) link:presentationLink link:calculationLink link:definitionLink 99941304 - Disclosure - LEASES - Other supplemental information (Details) link:presentationLink link:calculationLink link:definitionLink 99941602 - Disclosure - WARRANTS (Details) link:presentationLink link:calculationLink link:definitionLink 99941705 - Disclosure - INCOME TAXES - Unrecognized Tax Benefits (Details) link:presentationLink link:calculationLink link:definitionLink 99941801 - Disclosure - NET 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 99941802 - Disclosure - NET 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 99942501 - Disclosure - SEGMENT INFORMATION (Details) link:presentationLink link:calculationLink link:definitionLink 99900 - Disclosure - Standard And Custom Axis Domain Defaults link:presentationLink link:calculationLink link:definitionLink