GAIN Capital 10-Q 9 May 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	May. 04, 2016
Document Documentand Entity Information [Abstract]
Entity Registrant Name	GAIN Capital Holdings, Inc.
Trading Symbol	GCAP
Entity Central Index Key	1,444,363
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		48,450,924

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
ASSETS:
Cash and cash equivalents	$ 189,729	$ 171,888
Cash and securities held for customers	875,962	920,621
Receivables from brokers, of which ($11,128) and ($12,568), respectively, are open contracts at fair value	119,952	121,153
Prepaid assets	6,122	7,835
Property and equipment, net of accumulated depreciation of ($48,104) and ($44,750), respectively	32,275	30,367
Intangible assets, net of accumulated amortization of ($51,598) and ($47,906), respectively	86,007	91,512
Goodwill	33,718	34,017
Other assets, net of allowance for doubtful accounts of ($7,646) and ($6,832), respectively	53,142	47,166
Total assets	1,396,907	1,424,559
Liabilities
Payables to customers, of which ($145,115) and ($143,918) respectively, are open contracts at fair value	875,962	920,621
Accrued compensation and benefits	8,904	12,362
Accrued expenses and other liabilities	66,241	51,638
Income tax payable	5,819	1,068
Convertible senior notes	121,189	121,740
Total liabilities	$ 1,078,115	$ 1,107,429
Commitments and contingent liabilities
Redeemable non-controlling interests	$ 11,296	$ 11,046
Shareholders’ equity
Common stock ($0.00001 par value; 120 million shares authorized, 52,529,627 shares issued and 48,718,428 shares outstanding as of March 31, 2016; 120 million shares authorized, 52,072,884 shares issued and 48,771,015 shares outstanding as of December 31, 2015)	0	0
Accumulated other comprehensive loss	(8,610)	(5,865)
Additional paid-in capital	214,696	212,981
Treasury stock, at cost (3,811,199 shares at March 31, 2016 and 3,301,869 at December 31, 2015)	(25,409)	(21,808)
Retained earnings	126,819	120,776
Total shareholders’ equity	307,496	306,084
Total liabilities and shareholders’ equity	$ 1,396,907	$ 1,424,559

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Receivables from brokers, open contracts at fair value	$ (11,128)	$ (12,568)
Property and equipment, accumulated depreciation	(48,104)	(44,750)
Intangible assets, accumulated amortization	(51,598)	(47,906)
Other assets, allowance for doubtful accounts	(7,646)	(6,832)
Payables to customers, open contracts at fair value	$ (145,115)	$ (143,918)
Common stock, par value (usd per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	52,529,627	52,072,884
Common stock, shares outstanding	48,718,428	48,771,015
Treasury stock, shares	3,811,199	3,301,869

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income and Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
REVENUE:
Retail revenue	$ 95,042	$ 72,942
Institutional revenue	6,707	9,871
Futures revenue	12,018	11,520
Other revenue	1,573	(1,366)
Total non-interest revenue	115,340	92,967
Interest revenue	318	337
Interest expense	104	318
Total net interest revenue	214	19
Net revenue	115,554	92,986
OPERATING EXPENSES:
Employee compensation and benefits	26,393	22,139
Selling and marketing	6,439	4,558
Referral fees	20,663	26,578
Trading expenses	8,433	6,975
General and administrative	16,038	9,371
Depreciation and amortization	3,153	1,975
Purchased intangible amortization	3,922	2,151
Communications and technology	5,279	2,758
Bad debt provision	572	3,324
Acquisition expenses	0	37
Restructuring	781	0
Integration expenses	813	64
Legal settlement	9,412	0
Total operating expense	101,898	79,930
OPERATING PROFIT	13,656	13,056
Interest expense on long term borrowings	2,592	1,502
INCOME BEFORE INCOME TAX EXPENSE	11,064	11,554
Income tax expense	2,347	5,745
Equity in net loss of affiliate	(16)	0
NET INCOME	8,701	5,809
Net income attributable to non-controlling interest	349	344
NET INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC.	8,352	5,465
Other comprehensive (loss)/income, net of tax:
Foreign currency translation adjustment	(2,745)	(2,248)
NET COMPREHENSIVE INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC.	$ 5,607	$ 3,217
Earnings per common share:
Basic (usd per share)	$ 0.17	$ 0.11
Diluted (usd per share)	$ 0.17	$ 0.11
Weighted average common shares outstanding used in computing earnings per common share:
Basic (shares)	48,622,816	43,206,628
Diluted (shares)	48,983,880	44,150,505

Condensed Consolidated Stateme5

Condensed Consolidated Statement of Changes in Shareholders' Equity - 3 months ended Mar. 31, 2016 - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss)
BEGINNING BALANCE (in shares) at Dec. 31, 2015		48,771,015
BEGINNING BALANCE at Dec. 31, 2015	$ 306,084		$ (21,808)	$ 212,981	$ 120,776	$ (5,865)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of options (in shares)		150,566
Exercise of options	577			577
Conversion of restricted stock into common stock (in shares)		306,177
Conversion of restricted stock into common stock	0
Repurchase of shares (in shares)		(509,330)
Repurchase of shares	(3,601)		(3,601)
Stock compensation expense	1,067			1,067
Tax benefit of stock options exercises	176			176
Convertible note buyback	(105)			(105)
Adjustment to the redemption value of put options related to non-controlling interests	99				99
Dividend declared ($0.05 quarterly dividend per share)	(2,408)				(2,408)
Foreign currency translation adjustment	(2,745)					(2,745)
Net income applicable to Gain Capital Holdings, Inc.	8,352				8,352
ENDING BALANCE (in shares) at Mar. 31, 2016		48,718,428
ENDING BALANCE at Mar. 31, 2016	$ 307,496		$ (25,409)	$ 214,696	$ 126,819	$ (8,610)

Condensed Consolidated Stateme6

Condensed Consolidated Statement of Changes in Shareholders' Equity (Parenthetical)	3 Months Ended
	Mar. 31, 2016$ / shares
Statement of Stockholders' Equity [Abstract]
Dividend payment (usd per share)	$ 0.05

Condensed Consolidated Stateme7

Condensed Consolidated Statement of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 8,701	$ 5,809
Adjustments to reconcile net income to cash provided by operating activities
Loss on foreign currency exchange rates	162	2,028
Depreciation and amortization	7,075	4,126
Non-cash integration costs	173	0
Deferred taxes	(169)	201
Amortization of deferred financing costs	110	89
Bad debt provision	572	3,324
Convertible senior notes discount amortization	1,057	566
Stock compensation expense	1,067	1,204
Gain on extinguishment of debt	(89)	0
Loss of equity method investment	16	0
Changes in operating assets and liabilities:
Cash and securities held for customers	45,873	(78,066)
Receivables from brokers	4,159	(44,916)
Prepaid assets	1,640	(495)
Other assets	(6,416)	2,265
Payables to customers	(45,873)	78,066
Accrued compensation and benefits	(3,373)	(11,096)
Accrued expenses and other liabilities	15,071	(1)
Income tax payable	4,353	814
Cash provided by/(used for) operating activities	34,109	(36,082)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(5,922)	(1,214)
Funding of acquisitions, net of cash acquired	0	(89)
Cash used for investing activities	(5,922)	(1,303)
CASH FLOWS FROM FINANCING ACTIVITIES:
Contractual payments for acquisitions	0	(9,800)
Proceeds from exercise of stock options	577	1,584
Purchase of treasury stock	(3,601)	0
Tax benefit from employee stock option exercises	238	704
Dividend payment	(2,408)	(2,170)
Distributions to non-controlling interest holders	0	(410)
Repurchase of convertible notes	(1,735)	0
Cash used for financing activities	(6,929)	(10,092)
Effect of exchange rate changes on cash and cash equivalents	(3,417)	(1,815)
INCREASE/(DECREASE) IN CASH AND CASH EQUIVALENTS	17,841	(49,292)
CASH AND CASH EQUIVALENTS-Beginning of period	171,888	139,351
CASH AND CASH EQUIVALENTS-End of period	189,729	90,059
Cash (paid)/received during the year for:
Interest	(104)	(34)
Taxes	688	(1,923)
Non-cash investing activities:
Adjustment to the redemption value of put options	$ 99	$ (524)

DESCRIPTION OF BUSINESS AND BAS

DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION	DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION Description of Business GAIN Capital Holdings, Inc. (together with its subsidiaries, the “Company”) is a Delaware corporation formed and incorporated on March 24, 2006. GAIN Holdings, LLC is a wholly-owned subsidiary of GAIN Capital Holdings, Inc., and it owns all outstanding membership units of GAIN Capital Group, LLC (“Group, LLC”), the Company's primary regulated entity in the United States. City Index (Holdings) Ltd (“City Index”) is the holding company of the Company's primary regulated entity outside of the United States. Group, LLC is a retail foreign exchange dealer (“RFED”) and a Futures Commission Merchant (“FCM”) registered with the Commodity Futures Trading Commission (the “CFTC”). As such, it is subject to the regulations of the CFTC, an agency of the U.S. government, and the rules of the National Futures Association (“NFA”), an industry self-regulatory organization. GAIN Capital-Forex.com U.K. Ltd. (“GCUK1”) and GAIN Capital UK Limited ("GCUK2") are each registered in the United Kingdom ("U.K.") and regulated by the Financial Conduct Authority (“FCA”) as full scope €730k IFPRU Investment Firms. The following list includes each of the Company’s significant U.S. and international regulated subsidiaries as of March 31, 2016 : GAIN Capital Group, LLC GAIN Capital Forex.com U.K., Ltd. GAIN Capital Japan Co., Ltd. GAIN Capital Forex.com Australia Pty. Ltd. GAIN GTX, LLC Global Assets Advisors, LLC Top Third Ag Marketing LLC Galvan Research and Trading, Ltd. GAIN Capital UK Limited GAIN Capital Australia Pty. Ltd. GAIN Capital Singapore Pte. Ltd. In April 2015, the Company acquired all of the outstanding share capital of City Index from City Index Group Limited. GCUK2, GAIN Capital Australia Pty. Ltd. (“GCAU2”) , and GAIN Capital Singapore Pte. Ltd. ("GCS") are each subsidiaries that were acquired as part of the City Index acquisition. Each of these entities is regulated locally by the relevant regulators, including the FCA. See Note 10 for further details related to the Company's acquisitions. Basis of Presentation and Principles of Consolidation The accompanying unaudited condensed consolidated financial statements reflect all adjustments that, in the opinion of management, are necessary for a fair presentation of the financial statements for the interim periods. The financial statements are presented in accordance with accounting principles generally accepted in the United States of America. The unaudited condensed consolidated financial statements have been prepared in accordance with the Securities and Exchange Commission's ("SEC") regulations for interim financial statements, and, in accordance with SEC rules, omit or condense certain information and footnote disclosures. Results for the interim periods are not necessarily indicative of results to be expected for any other interim period or for the full year. These financial statements should be read in conjunction with the consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K as of and for the year ended December 31, 2015, as amended on May 2, 2016. The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, after the elimination of inter-company transactions and balances. In April 2015, the Financial Accounting Standards Board ("FASB") issued new guidance regarding the accounting for debt issuance costs. The guidance requires a company to present any deferred financing costs from debt issuance as a reduction of debt. The Company has adopted this guidance in the first quarter of 2016. The table below shows the impact of this adoption on the Company's reported consolidated balance sheet. As of December 31, 2015 (As Reported) Adjustment As of December 31, 2015 (Adjusted) Assets: Other assets 47,422 (256 ) 47,166 Liabilities: Convertible senior notes 121,996 (256 ) 121,740

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	3 Months Ended
	Mar. 31, 2016
Accounting Changes and Error Corrections [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	RECENT ACCOUNTING PRONOUNCEMENTS In September 2015, the FASB issued new guidance regarding the accounting for provisional adjustments of business combinations. The guidance states that if changes are required to be made to provisional amounts included in previously issued financial statements, such changes should be included in the period in which they are identified. These changes include adjustments to goodwill, as well as the cumulative impact of adjustments for depreciation, amortization or other income. The guidance is effective for annual periods beginning after December 15, 2015, including interim periods within that reporting period. The Company adopted this guidance in the first quarter of 2016; however, the accounting for all acquisitions was finalized prior to January 1, 2016 and, therefore, there was no impact on the Company following adoption of this new guidance. In March 2016, FASB issued new guidance regarding the accounting for investments - equity method and joint ventures. The FASB issued this update to eliminate the requirement to retroactively adopt the equity method of accounting. The guidance is effective for fiscal years and interim periods within those fiscal years, beginning after December 15, 2016. The Company is currently assessing the impact of adopting this guidance on its financial statements. In March 2016, the FASB issued new guidance regarding the accounting for stock compensation. The FASB issued this update to simplify several aspects of the accounting for share-based payment transactions, including income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows, forfeitures, minimum statutory tax withholding requirements, classification of employee taxes paid on the Statement of Cash Flows when an employer withholds shares for tax-withholding purposes, expected term, intrinsic value, and eliminating the indefinite deferral. The guidance is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. The Company is currently assessing the impact of adopting this guidance on its financial statements. In March and April 2016, the FASB issued new guidance regarding the accounting for revenue from contracts with customers. The FASB issued this update to improve the operability and understandability of the implementation guidance on principal versus agent considerations, and to provide clarification on identifying performance obligations and the licensing implementation guidance, while retaining the related principles for those areas. The guidance affects the revenue recognition guidance issued in May 2014, which is not yet effective. The effective date and transition requirements for the amendments in this update are the same as the effective date and transition requirements of the revenue recognition guidance issued in May 2014. The Company is currently assessing the impact of adopting this guidance on its financial statements. In February 2016, the FASB issued new guidance regarding the accounting for leases. The FASB issued this update to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. The Company is currently assessing the impact on its consolidated financial statements of adopting this guidance. In May 2014, the FASB issued new revenue recognition guidance that supersedes the existing revenue recognition guidance and most industry-specific guidance applicable to revenue recognition. The guidance requires a company to recognize revenue when it transfers promised goods or services to customers. Recognition should be in an amount that reflects the consideration to which the company expects to be entitled in exchange for those services. The guidance requires enhanced disclosures to help users of financial statements better understand the nature, amount, timing, and uncertainty of revenues recognized. The guidance is effective for annual periods beginning after December 15, 2016. On April 1, 2015, the FASB voted to propose a deferral of the effective date of this accounting guidance by a year to annual periods beginning after December 15, 2017. As part of the proposal, early application would be permitted in annual periods beginning after December 15, 2016, including interim periods within that reporting period. The Company is currently assessing the impact of adopting this guidance on its financial statements.

FAIR VALUE INFORMATION

FAIR VALUE INFORMATION	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
FAIR VALUE INFORMATION	FAIR VALUE INFORMATION Accounting guidance defines fair value as the price that would be received in exchange for an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The guidance establishes a three level hierarchy that ranks the quality and reliability of information used in developing fair value estimates for financial instruments. The hierarchy gives the highest priority to quoted prices in active markets and the lowest priority to unobservable data. In cases where two or more levels of inputs are used to determine fair value, a financial instrument's level is determined based on the lowest level input that is considered significant to the fair value measurement in its entirety. The three levels of fair value hierarchy are summarized below: Level 1 - Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2 - Quoted prices in markets that are not considered to be active or financial instruments for which all significant inputs are observable, either directly or indirectly; and Level 3 - Valuations that require inputs that are both unobservable to a market participant and significant to the fair value measurement. For assets and liabilities that are transferred between levels during the period, fair values are ascribed as if the assets or liabilities had been transferred as of the beginning of the period. The following table presents the Company’s assets and liabilities that were measured at fair value on a recurring basis during the reporting period and the related hierarchy levels (amounts in thousands): Fair Value Measurements on a Recurring Basis Level 1 Level 2 Level 3 Total Financial Assets/(Liabilities): Customer derivative positions $ — $ 145,115 $ — $ 145,115 Broker derivative contracts — (11,128 ) — (11,128 ) Money market accounts 26,056 — — 26,056 Certificates of deposit 174 — — 174 Investment in gold 123 — — 123 Total $ 26,353 $ 133,987 $ — $ 160,340 Fair Value Measurements on a Recurring Basis as of December 31, 2015 Level 1 Level 2 Level 3 Total Financial Assets/(Liabilities): Customer derivative positions $ — $ 143,918 $ — $ 143,918 Broker derivative contracts — (12,568 ) — (12,568 ) Money market accounts 25,167 — — 25,167 Certificates of deposit 174 — — 174 Investment in gold 107 — — 107 Total $ 25,448 $ 131,350 $ — $ 156,798 The Company has not changed its valuation techniques for measuring the fair value of any financial assets and liabilities during the three months ended March 31, 2016, nor has there been any movement between levels during this period. Level 1 Financial Assets The Company has money market accounts, certificates of deposit and an investment in gold that are Level 1 financial instruments that are recorded based upon listed or quoted market rates. The money market accounts are recorded in Cash and cash equivalents and Cash and securities held for customers ; the certificates of deposit are recorded in Other Assets and the investment in gold is recorded in Other Assets . Level 2 Financial Assets and Liabilities The Company has customer derivative contracts that are Level 2 financial instruments recorded in Payables to customers . The Company has broker derivative contracts that are Level 2 financial instruments recorded in Receivables from brokers . The fair values of these Level 2 financial instruments are based upon directly observable values for underlying instruments. Level 3 Financial Liabilities The Company does not have any level 3 Financial Assets or Liabilities on March 31, 2016 or December 31, 2015. Financial Instruments Not Measured at Fair Value The table below presents the carrying value, fair value, and fair value hierarchy category of certain financial instruments that are not measured at fair value in the condensed consolidated balance sheet (amounts in thousands). Receivables from brokers comprise open trades, which are measured at fair value (disclosed above), and the Company's deposits, which are not measured at fair value but approximate fair value. These deposits approximate fair value because they are cash balances that the Company may withdraw at its discretion. Settlement would occur within a relatively short period of time once a withdrawal is initiated. Payables to customers comprise open trades, which are measured at fair value (disclosed above), and customer deposits that the Company holds for its role as clearing broker. These deposits are not measured at fair value, but approximate fair value, because they are cash balances that the Company or its customers can settle at either party's discretion. Such settlement would occur within a relatively short period of time once a withdrawal is initiated. The carrying value of Convertible senior notes represents the notes’ principal amounts net of unamortized discount (see Note 12). The Company assessed the notes' fair value as determined by current Company-specific and risk free interest rates as of the balance sheet date. As of March 31, 2016 Fair Value Measurements using: Carrying Value Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets: Receivables from brokers $ 131,080 $ 131,080 $ — $ 131,080 $ — Financial Liabilities: Payables to customers $ 1,021,077 $ 1,021,077 $ — $ 1,021,077 $ — Convertible senior notes $ 121,189 $ 118,470 $ — $ 118,470 $ — As of December 31, 2015 Fair Value Measurements using: Carrying Value Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets: Receivables from brokers $ 133,721 $ 133,721 $ — $ 133,721 $ — Financial Liabilities: Payables to customers $ 1,064,539 $ 1,064,539 $ — $ 1,064,539 $ — Convertible senior notes $ 121,740 $ 122,264 $ — $ 122,264 $ —

DERIVATIVES

DERIVATIVES	3 Months Ended
	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVES	DERIVATIVES The Company's contracts with its customers and its liquidity providers are deemed to be derivative instruments. The table below represents the fair values of the Company’s derivative instruments reported within Receivables from brokers and Payables to customers on the accompanying condensed Consolidated Balance Sheet (amounts in thousands): March 31, 2016 Gross amounts of Gross amount of Net amounts of Derivative Instruments: Foreign currency exchange contracts $ 133,525 $ (52,545 ) $ 80,980 CFD contracts 91,195 (46,248 ) 44,947 Metals contracts 12,227 (4,167 ) 8,060 Total $ 236,947 $ (102,960 ) $ 133,987 March 31, 2016 Cash Collateral Net amounts of Net amounts of Derivative Assets/Liabilities: Receivables from brokers $ 131,080 $ (11,128 ) $ 119,952 Payables to customers $ (1,021,077 ) $ 145,115 $ (875,962 ) December 31, 2015 Gross amounts of Gross amount of Net amounts of Derivative Instruments: Foreign currency exchange contracts $ 138,140 $ (59,468 ) $ 78,672 CFD contracts 111,844 (70,429 ) 41,415 Metals contracts 18,866 (7,603 ) 11,263 Total $ 268,850 $ (137,500 ) $ 131,350 December 31, 2015 Cash Collateral Net amounts of Net amounts of Derivative Assets/Liabilities: Receivables from brokers $ 133,721 $ (12,568 ) $ 121,153 Payables to customers $ (1,064,539 ) $ 143,918 $ (920,621 ) The Company’s derivatives include different underlyings, which vary in price. Foreign exchange contracts typically have prices less than two dollars, while certain metals contracts and CFDs can be considerably higher priced. The table below presents the number of contracts reported within Receivables from brokers and Payables to customers on the consolidated balance sheet (amounts in thousands): March 31, 2016 Total contracts in long positions Total contracts in short positions Derivative Instruments: Foreign currency exchange contracts 2,277,094 2,744,129 CFD contracts 132,514 236,429 Metals contracts 894 336 Total 2,410,502 2,980,894 December 31, 2015 Total contracts in long positions Total contracts in short positions Derivative Instruments: Foreign currency exchange contracts 3,106,885 2,931,109 CFD contracts 139,465 285,640 Metals contracts 1,278 308 Total 3,247,628 3,217,057 The Company did not designate any of its derivatives as hedging instruments at March 31, 2016 or December 31, 2015 . Net gains/(losses) with respect to derivative instruments reflected in Retail Revenue in the accompanying condensed consolidated statements of operations and comprehensive income for the three months ended March 31, 2016 and 2015 were as follows (amounts in thousands): Three Months Ended March 31, 2016 2015 Derivative Instruments: Foreign currency exchange contracts $ 54,297 $ 36,660 CFD contracts 35,222 29,064 Metals contracts 4,960 5,988 Total $ 94,479 $ 71,712

RECEIVABLES FROM BROKERS

RECEIVABLES FROM BROKERS	3 Months Ended
	Mar. 31, 2016
Brokers and Dealers [Abstract]
RECEIVABLES FROM BROKERS	RECEIVABLES FROM BROKERS Amounts receivable from brokers consisted of the following as of (amounts in thousands): March 31, 2016 December 31, 2015 Required collateral $ 127,326 $ 129,042 Excess from futures broker - Restricted 3,754 4,679 Open foreign exchange positions (11,128 ) (12,568 ) Total $ 119,952 $ 121,153 The Company has posted funds with brokers as collateral required by agreements for holding trading positions. These amounts are reflected as Receivables from brokers on the Condensed Consolidated Balance Sheet.

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	3 Months Ended
	Mar. 31, 2016
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	PROPERTY AND EQUIPMENT Property and equipment, including leasehold improvements and capitalized software development costs, consisted of the following as of (amounts in thousands): March 31, 2016 December 31, 2015 Software $ 47,736 $ 44,194 Computer equipment 16,061 14,300 Leasehold improvements 11,105 11,200 Telephone equipment 815 881 Office equipment 2,114 2,113 Furniture and fixtures 1,881 1,761 Web site development costs 667 668 Gross property and equipment 80,379 75,117 Less: Accumulated depreciation and amortization (48,104 ) (44,750 ) Property and equipment, net $ 32,275 $ 30,367 Depreciation and amortization expense for property and equipment was $3.2 million and $ 2.0 million for the three months ended March 31, 2016 and 2015 , respectively. The Company adjusted the depreciation and amortization period of certain property and equipment that experienced changes in estimated useful lives as a result of the City Index acquisition. This change in useful lives resulted in an additional charge of $0.2 million for the three months ended March 31, 2016 .

INTANGIBLE ASSETS

INTANGIBLE ASSETS	3 Months Ended
	Mar. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
INTANGIBLE ASSETS	INTANGIBLE ASSETS The Company's various finite-lived intangible assets consisted of the following as of (amounts in thousands): March 31, 2016 December 31, 2015 Intangibles Gross Accumulated Net Gross Accumulated Net Customer list $ 55,425 $ (16,054 ) $ 39,371 $ 56,388 $ (14,111 ) $ 42,277 Technology 73,714 (33,608 ) 40,106 74,378 (32,117 ) 42,261 Trademark 8,103 (1,936 ) 6,167 8,289 (1,678 ) 6,611 Total finite lived intangibles 137,242 (51,598 ) 85,644 139,055 (47,906 ) 91,149 Trademark not subject to amortization (1) 363 — 363 363 — 363 Total intangibles $ 137,605 $ (51,598 ) $ 86,007 $ 139,418 $ (47,906 ) $ 91,512 (1) These indefinite-life trademarks relate to the Forex.com and foreignexchange.com domain names where management determined there was no legal, regulatory or technological limitation on their useful lives. These trademarks are also supported annually in the Company's impairment test for intangible assets. The Company has the following identifiable intangible assets as of March 31, 2016: Intangible Asset Amount (in thousands) Weighted average amortization period Customer list $ 55,425 7.6 years Technology 73,714 8.9 years Trademark (1) 8,466 6.7 years $ 137,605 (1) Trademarks with indefinite lives, as described above, comprise $0.4 million of the $8.5 million total trademark value. Amortization expense for the purchased intangibles was $3.9 million and $2.2 million for the three months ended March 31, 2016 and 2015 , respectively. Goodwill Goodwill is calculated as the difference between the cost of acquisition of an acquired business and the fair value of the net identifiable assets of that business. As of March 31, 2016 and December 31, 2015 , the Company had recorded goodwill of approximately $33.7 million and $34.0 million , respectively. The decrease of $0.3 million was related to foreign currency translation adjustments. The following represents the carrying amount of goodwill by segment (amounts in thousands): Retail Institutional Futures Total Carrying amount of goodwill as of December 31, 2015 $ 26,722 $ 4,788 $ 2,507 $ 34,017 Foreign currency translation adjustments $ (235 ) $ (42 ) $ (22 ) $ (299 ) Carrying amount of goodwill as of March 31, 2016 $ 26,487 $ 4,746 $ 2,485 $ 33,718

OTHER ASSETS

OTHER ASSETS	3 Months Ended
	Mar. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
OTHER ASSETS	OTHER ASSETS Other assets consisted of the following as of (amounts in thousands): March 31, 2016 December 31, 2015 Vendor and security deposits $ 12,855 $ 11,486 Income tax receivable 11,073 9,482 Deferred tax assets, net 18,235 17,827 GTX trade receivables 5,036 4,881 Customer debit positions 7,995 7,340 Allowance on customer debit positions (7,646 ) (6,832 ) Miscellaneous receivables 4,749 2,160 Equity method investment 845 822 $ 53,142 $ 47,166

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	3 Months Ended
	Mar. 31, 2016
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS Certain officers and directors of the Company have personal funds on deposit in separate customer accounts with the Company. These accounts are recorded in Payables to customers on the condensed consolidated balance sheet. The aggregate amount of these funds was $0.3 million and $0.3 million at March 31, 2016 and December 31, 2015 , respectively. IPGL Limited, the majority selling shareholder in the acquisition of City Index, has a trading account with the Company, which is recorded in Payables to customers on the condensed consolidated balance sheet. The aggregate amount of these funds was $10.5 million and $21.7 million at March 31, 2016 and December 31, 2015, respectively.

ACQUISITIONS

ACQUISITIONS	3 Months Ended
	Mar. 31, 2016
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS City Index (Holdings) Limited On April 1, 2015, the Company acquired the entire issued and outstanding share capital of City Index. City Index is a global online trading firm specializing in offering CFDs, forex and spread betting for retail customers. This acquisition was made to strengthen and diversify the Company's existing global footprint in the retail business. The purchase price consisted of approximately $6.1 million in cash, inclusive of working capital adjustments and $1.0 million in cash to be held in escrow, 5,319,149 shares of the Company's common stock, inclusive of 4,787,234 shares to be held in escrow, and 4.125% unsecured Convertible Senior Notes with an aggregate principal amount of $60.0 million and fair value of $65.0 million , inclusive of an aggregate principal amount of $54.0 million to be held in escrow. In addition, the Company paid City Index approximately $22.4 million , which was used to settle certain inter-company liabilities between City Index and City Index Group Limited (its former parent company). The purchase price was derived as follows (amounts in thousands): Cash $ 6,103 Convertible senior notes 65,000 Common stock issued 45,100 Total purchase price $ 116,203 The purchase price of City Index was allocated to the fair value of various assets and liabilities as follows (amounts in thousands): Cash $ 10,546 Cash and securities held for customers 281,576 Receivable from brokers 35,974 Property and equipment 10,466 Prepaid assets 4,038 Other assets 5,119 Total tangible assets 347,719 Total liabilities assumed 299,000 Net assets acquired 48,719 Identifiable intangible assets: Customer list 34,277 Trade name 6,645 Technology 26,157 Intangible assets, net 67,079 Goodwill $ 405 Pro Forma Information: The following unaudited pro forma data is presented as if the acquisition of City Index had occurred on January 1, 2015. The unaudited pro forma data does not include the impact of forecasted operating expense synergies. The unaudited pro forma data is provided for informational purposes only and may not necessarily be indicative of future results of operations or what the results of operations would have been had the Company and City Index operated as a combined entity for the periods presented. Unaudited pro forma income statement line items for the three months ended March 31, 2015 were as follows (amounts in thousands): For the Three Months Ended December 31, 2015 REVENUE: Total non-interest revenue $ 129,820 Interest revenue 420 Interest expense 864 Total net interest revenue (444 ) Net revenue 129,376 EXPENSES: Depreciation and amortization 2,619 Purchased intangible amortization 3,319 Other expense items 109,423 Total operating expense 115,361 OPERATING PROFIT 14,015 Interest on long term borrowings 2,513 INCOME BEFORE INCOME TAX EXPENSE 11,502 Income tax expense 7,219 NET INCOME 4,283 Net income attributable to non-controlling interests 344 Net income applicable to Gain Capital Holdings, Inc. $ 3,939 Restructuring During the first quarter of 2016, the Company incurred restructuring expenses related to the global headcount reductions following the City Index acquisition. The Company incurred $0.8 million of restructuring expenses for the three months ended March 31, 2016. These expenses are recorded in Restructuring expenses in the condensed consolidated statements of operations and comprehensive income. The restructuring liabilities are recorded in Accrued compensation and benefits in the condensed consolidated balance sheet. For the Three Months Ended March 31, 2016 Restructuring liability as of January 1, 2016 $ 499 2016 restructuring expenses 781 Payments made in 2016 (567 ) Restructuring liability as of March 31, 2016 $ 713

NON-CONTROLLING INTEREST

NON-CONTROLLING INTEREST	3 Months Ended
	Mar. 31, 2016
Noncontrolling Interest [Abstract]
NON-CONTROLLING INTEREST	NON-CONTROLLING INTEREST Non-controlling interests In March 2014, the Company acquired controlling interests in GAA and Top Third. The Company purchased 55% of each entity, and the respective sellers maintained a 45% interest in each entity. The 45% interests are redeemable at prices determined by applying a contractually agreed upon formula to the respective acquired company's financial results. The Company owns immediately exercisable call options to purchase the remaining interests in each company. The minority owners hold put options, which become exercisable in 2017 or upon the occurrence of certain events, to compel the Company to purchase the remaining interests. The non-controlling interests are not classified as liabilities, because redemption is not mandatory or at fixed prices. They are not classified as equity, because their redemption is not exclusively in the Company's control. Therefore, the non-controlling interests are classified as temporary equity in the Condensed Consolidated Balance Sheet. The non-controlling interests' carrying value is determined by the Company's purchase prices and the non-controlling interests' share of the Company's subsequent net income. This value is benchmarked against the redemption value of the sellers' put options. The carrying value is adjusted to the latter, provided that it does not fall below the initial carrying values, as determined by the Company's purchase price allocation. The Company has made a policy election to reflect any changes caused by such an adjustment in retained earnings, rather than in current earnings. The Company recorded an adjustment of $(0.1) million for the three months ended March 31, 2016 . The table below reflects the non-controlling interests' effects on the Company's financial statements (amounts in thousands): Redeemable non-controlling interests January 1, 2016 $ 11,046 Adjustment to the redemption value of non-controlling interests (99 ) Net income attributable to non-controlling interests 349 Distributions to non-controlling interest holders — March 31, 2016 $ 11,296

CONVERTIBLE SENIOR NOTES

CONVERTIBLE SENIOR NOTES	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
CONVERTIBLE SENIOR NOTES	CONVERTIBLE SENIOR NOTES Convertible Senior Notes due 2020 On April 1, 2015, as part of the City Index acquisition consideration, the Company issued to the sellers $60.0 million aggregate principal amount of 4.125% Convertible Senior Notes maturing on April 1, 2020. These Convertible Senior Notes pay interest semi-annually on April 1 and October 1 at a rate of 4.125% per year, which commenced on October 1, 2015. Convertible Senior Notes due 2018 On November 27, 2013, the Company issued $80.0 million aggregate principal amount of 4.125% Convertible Senior Notes maturing on December 1, 2018. The Company received net proceeds of $77.9 million , after deducting the initial purchasers' discount. These Convertible Senior Notes pay interest semi-annually on June 1 and December 1 at a rate of 4.125% per year, commenced on June 1, 2014. During the quarter ending March 31, 2016, the Company repurchased $1.9 million in principal amount of the convertible senior notes due in 2018, for an aggregate purchase price of $1.7 million . Under accounting guidance, an entity must separately account for the liability and equity components of convertible debt instruments that may be settled entirely or partially in cash upon conversion. The separate accounting must reflect the issuer's economic interest cost. The balances of the liability and equity components of the Convertible Senior Notes as of March 31, 2016 , and December 31, 2015 were as follows (amounts in thousands): March 31, 2016 December 31, 2015 Liability component - principal $ 138,150 $ 140,000 Deferred bond discount 16,728 18,004 Deferred financing cost 233 256 Liability component - net carrying value $ 121,189 $ 121,740 Additional paid in capital $ 27,822 $ 27,920 Discount attributable to equity (419 ) (412 ) Equity component $ 27,403 $ 27,508 In April 2015, the FASB issued new guidance regarding the accounting for debt issuance costs. The guidance requires a company to present any deferred financing costs from debt issuance as a reduction of debt, which is a change from current presentation in assets. The Company has adopted this guidance in the first quarter of 2016. Interest expense related to the Convertible Senior Notes, included in Interest on long term borrowings in the condensed consolidated statements of operations and comprehensive income was as follows (amounts in thousands): Three Months Ended Three Months Ended March 31, 2016 March 31, 2015 Interest expense - stated coupon rate $ 1,444 $ 825 Interest expense - amortization of deferred bond discount and costs 1,079 588 Total interest expense - convertible senior notes $ 2,523 $ 1,413

EARNINGS PER COMMON SHARE

EARNINGS PER COMMON SHARE	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
EARNINGS PER COMMON SHARE	EARNINGS PER COMMON SHARE Basic and diluted earnings per common share are computed by dividing net income by the weighted average number of common shares outstanding during the period. Diluted earnings per share includes the determinants of basic net income per share and, in addition, gives effect to the potential dilution that would occur if securities or other contracts to issue common stock were exercised, vested or converted into common stock, unless they are anti-dilutive. Diluted weighted average common shares include vested and unvested stock options, vested restricted stock units and vested restricted stock awards which are to be delivered as soon as administratively practicable on or after December 31, 2016, unvested restricted stock units and unvested restricted stock awards. Approximately 0.4 million and 0.1 million stock options were excluded from the calculation of diluted earnings per share for the three months ended March 31, 2016 , and three months ended March 31, 2015 , respectively, as they were anti-dilutive. Diluted earnings per share excludes any shares of Company common stock potentially issuable under the Company's convertible senior notes, which are discussed in Note 12. Based upon an assumed trading price of $13 for each share of the Company's common stock, and if the relevant conditions under the indenture governing both 2018 and 2020 convertible senior notes were satisfied, there would be an additional 0.5 million and 1.5 million dilutive shares, for the 2018 and 2020 notes, respectively. The following table sets forth the computation of earnings per share (amounts in thousands except share and per share data): For the Three Months Ended March 31, 2016 2015 Net income applicable to GAIN Capital Holdings, Inc. $ 8,352 $ 5,465 Adjustment to the redemption value of non-controlling interests (1) 99 (524 ) Net income available to GAIN common shareholders $ 8,451 $ 4,941 Weighted average common shares outstanding: Basic weighted average common shares outstanding 48,622,816 43,206,628 Effect of dilutive securities: Stock options 172,193 581,086 RSUs/RSAs 188,871 362,791 Diluted weighted average common shares outstanding 48,983,880 44,150,505 Earnings per common share Basic $ 0.17 $ 0.11 Diluted $ 0.17 $ 0.11 (1) During the three months ended March 31, 2016 , the Company recorded an adjustment of $0.1 million to the carrying value of the put options related to the Company's redeemable non-controlling interests, which increased retained earnings and decreased non-controlling interests. During the three months ended March 31, 2015 , an adjustment of $(0.5) million was recorded to the carrying value of the put options related to the Company's redeemable non-controlling interests, which decreased retained earnings and increased non-controlling interests. The adjustment to the carrying value increased earnings available to the Company's shareholders for purposes of calculating basic and diluted earnings per common share for the three months ended March 31, 2016 and decreased earnings available to the Company's shareholders for purposes of calculating basic and diluted earnings per common share for the three months ended March 31, 2015

LEGAL

LEGAL	3 Months Ended
	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
LEGAL	LEGAL From time to time the Company becomes involved in legal proceedings and in each case the Company assesses the likely liability and/or the amount of damages as appropriate. Where available information indicates that it is probable a liability had been incurred at the date of the condensed consolidated financial statements and the Company can reasonably estimate the amount of that loss, the Company accrues the estimated loss by a charge to income. In many proceedings, however, it is inherently difficult to determine whether any loss is probable or even possible or to estimate the amount of any loss. In addition, even where loss is possible or an exposure to loss exists in excess of the liability already accrued with respect to a previously recognized loss contingency, it is often not possible to reasonably estimate the size of the possible loss or range of loss. For certain legal proceedings, the Company can estimate possible losses, additional losses, ranges of loss or ranges of additional loss in excess of amounts accrued. For certain other legal proceedings, the Company cannot reasonably estimate such losses, if any, since the Company cannot predict if, how or when such proceedings will be resolved or what the eventual settlement, fine, penalty or other relief, if any, may be, particularly for proceedings that are in their early stages of development or where plaintiffs seek substantial or indeterminate damages. Numerous issues must be developed, including the need to discover and determine important factual matters and the need to address novel or unsettled legal questions relevant to the proceedings in question, before a loss or additional loss or range of loss or additional loss can be reasonably estimated for any proceeding. Litigation On February 16, 2012, the Company received a Letter of Claim on behalf of certain individuals who had lost money in an investment scheme operated by a third-party money management firm, incorporated in the United Kingdom, which has since been closed down by the United Kingdom’s Financial Services Authority. The investment firm, Cameron Farley Ltd, had opened a corporate account with the Company and invested the individuals’ money, representing such funds as its own, while operating a fraudulent scheme. Though a complaint had been filed and served on the Company, the claimants requested, and the Company agreed, to follow the United Kingdom’s Pre-Action Protocol, a pre-litigation process intended to resolve matters without the need to engage in formal litigation. The Company submitted a Response to the Letter before Claim on July 4, 2012. On July 5, 2012 the Company received a substantially similar Letter of Claim on behalf of further individuals. Subsequently, the parties agreed to consolidate claims by those other similarly situated individuals with the pending Pre-Action Protocol process. The parties agreed it would be more appropriate for the proceedings to be dealt with in the Commercial Court and the matters were transferred pursuant to Consent Orders dated March 14, 2013. The Company subsequently filed an application for strike out and/or summary judgment in respect of all claims on March 15, 2013. The claimants filed an answer to the Company's motion on June 2, 2013 and subsequently the Company filed a response to this answer on July 15, 2013. A hearing was held on the Company's application for strike out and/or summary judgment on September 18 and 19, 2013. After the hearing, the judge asked the claimants to respond in writing to his additional questions from the hearing. The claimants had until October 11, 2013 to provide answers and the Company was given until November 1, 2013 to respond. On February 26, 2014, the judge denied the Company's motion for strike out and/or summary judgment. Case management conferences were held by the Court on October 17, 2014 and June 18, 2015. On August 3, 2015, the claimants filed an Amended Master Particulars of Claim, and on October 6, 2015, the Company filed an Amended Defense. The parties completed discovery and provided disclosure on October 30, 2015. On April 28, 2016, the parties entered into a Settlement Agreement in which the Company agreed to make a one-time settlement payment in exchange for a full and final settlement of all claims. The settlement amount, net of anticipated insurance recoveries, totaled approximately $9.4 million .

INCOME TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2016
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The Company’s provision for income taxes was approximately $2.3 million and $5.7 million for the three months ended March 31, 2016 and the three months ended March 31, 2015 , respectively. These amounts reflect effective tax rates of 21.2% and 49.7% for the three months ended March 31, 2016 and the three months ended March 31, 2015 , respectively, and reflect the Company's estimate of the annual effective tax rate adjusted for certain discrete items. Changes in the Company's effective rate arise primarily from changes in the geographic mix of revenues and expenses. Deferred income taxes reflect the net tax effects of temporary differences between the financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when such differences are expected to reverse. The Company’s net deferred tax assets are included in Other assets on the condensed consolidated balance sheet.

REGULATORY REQUIREMENTS

REGULATORY REQUIREMENTS	3 Months Ended
	Mar. 31, 2016
Banking and Thrift [Abstract]
REGULATORY REQUIREMENTS	REGULATORY REQUIREMENTS The following table illustrates the minimum regulatory capital our subsidiaries were required to maintain as of March 31, 2016 and the actual amounts of capital that were maintained (amounts in millions): Entity Name Minimum Capital Excess Percent of GAIN Capital Group, LLC $ 29.1 $ 44.5 $ 15.4 153 % GAIN Capital-Forex.com U.K., Ltd. 25.1 60.3 35.2 240 % GAIN Capital Japan Co., Ltd. 1.4 9.7 8.3 693 % GAIN Capital-Forex.com Hong Kong, Ltd. 1.9 3.6 1.7 189 % GAIN Capital Forex.com Australia, Pty. Ltd. 0.8 2.9 2.1 363 % Galvan Research and Trading, Ltd. 0.7 4.2 3.5 600 % GAIN Capital-Forex.com Canada Ltd. 0.2 1.4 1.2 700 % GAIN Capital Securities, Inc. 0.1 0.4 0.3 400 % GAIN Global Markets, Inc. 0.2 0.3 0.1 150 % Gain Capital UK, Ltd. 60.4 129.9 69.5 215 % Gain Capital Singapore Pte, Ltd. 0.6 7.8 7.2 1,300 % Gain Capital Australia Pty Ltd. 0.8 3.0 2.2 375 % Global Assets Advisors, LLC 0.1 1.6 1.5 1,600 % Total $ 121.4 $ 269.6 $ 148.2 222 %

SEGMENT INFORMATION

SEGMENT INFORMATION	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
SEGMENT INFORMATION	SEGMENT INFORMATION The Company's segment reporting structure includes three operating segments, retail, institutional and futures. These operating segments are discussed in more detail below. The Company also reports information relating to general corporate services in a fourth component, corporate and other. Information in these condensed consolidated financial statements reflects the information presented to the chief operating decision maker, and prior periods have been retrospectively adjusted to reflect the current segment structure. The chief operating decision maker does not review total assets by operating segment. Retail Segment Business in the retail segment is conducted primarily through the Company's FOREX.com and City Index brands. The Company provides its retail customers around the world with access to a diverse range of 12,500 global financial markets, including spot forex, precious metals and CFDs on commodities, indices, individual equities and interest rate products, as well as OTC options on forex. In the United Kingdom, the Company also offer spread bets, which are investment products similar to CFDs, but that offer more favorable tax treatment to residents of that country. Institutional Segment The institutional segment provides agency execution services and offers access to markets and self-directed trading in foreign exchange, commodities, equities, options and futures via an electronic communications network, or ECN, through the Company's GTX platform. The Company also offers high touch sales and trading aided by a team of sales employees. Futures Segment The futures segment offers execution and related services for exchange-traded futures and futures options on major U.S. and European exchanges. The Company offers futures services through its subsidiary, Group, LLC, under the GAIN Capital Futures brand. In addition, in 2014, the Company expanded its futures business by acquiring majority interests in GAA and TT. Corporate and other Corporate and other provides general corporate services to the Company's segments and also includes eliminations between operating segments which were $(0.4) million , $0.0 million for the three months ended March 31, 2016 and 2015. Corporate and other revenue primarily comprises foreign currency transaction gains and losses. Selected financial information by segment is presented in the following tables (amounts in thousands): Retail Three Months Ended March 31, 2016 2015 Net revenue $ 96,705 $ 73,342 Employee compensation and benefits 16,702 12,157 Selling and marketing 6,213 4,207 Referral fees 16,602 22,674 Other operating expenses 20,881 11,286 Segment profit $ 36,307 $ 23,018 Institutional Three Months Ended March 31, 2016 2015 Net revenue $ 7,119 $ 10,074 Employee compensation and benefits 3,202 3,960 Selling and marketing 6 71 Other operating expenses 2,440 2,512 Segment profit $ 1,471 $ 3,531 Futures Three Months Ended March 31, 2016 2015 Net revenue $ 12,204 11,536 Employee compensation and benefits 2,986 2,519 Selling and marketing 220 280 Referral fees 4,061 3,904 Other operating expenses 3,983 3,611 Segment profit $ 954 $ 1,222 Corporate and Other Three Months Ended March 31, 2016 2015 Other revenue $ (474 ) $ (1,966 ) Employee compensation and benefits 3,503 3,503 Other operating expenses 3,018 2,519 Loss $ (6,995 ) $ (7,988 ) Reconciliation of operating segment profit to Income before income tax expense Three Months Ended March 31, 2016 2015 Retail segment $ 36,307 $ 23,018 Institutional segment 1,471 3,531 Futures segment 954 1,222 Corporate and other (6,995 ) (7,988 ) SEGMENT PROFIT 31,737 19,783 Depreciation and amortization 3,153 1,975 Purchased intangible amortization 3,922 2,151 Acquisition expenses — 37 Restructuring expenses 781 — Integration expenses 813 64 Legal settlement 9,412 — SNB bad debt provision — 2,500 OPERATING PROFIT 13,656 13,056 Interest expense on long term borrowings 2,592 1,502 INCOME BEFORE INCOME TAX EXPENSE $ 11,064 $ 11,554

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	3 Months Ended
	Mar. 31, 2016
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS On April 28, 2016, the Company entered into a Settlement Agreement with the claimants in the Cameron Farley Ltd. matter discussed in Note 14. Pursuant to the terms of the Settlement Agreement, the Company agreed to make a one-time settlement payment in exchange for a full and final settlement of all claims. The settlement amount, net of anticipated insurance recoveries, totaled approximately $9.4 million . In May 2015, the Company announced the payment of a $0.05 dividend per share of Common Stock payable on June 20, 2016 to stockholders of record on June 13, 2016.

DESCRIPTION OF BUSINESS AND B26

DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (Policies)	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	The accompanying unaudited condensed consolidated financial statements reflect all adjustments that, in the opinion of management, are necessary for a fair presentation of the financial statements for the interim periods. The financial statements are presented in accordance with accounting principles generally accepted in the United States of America. The unaudited condensed consolidated financial statements have been prepared in accordance with the Securities and Exchange Commission's ("SEC") regulations for interim financial statements, and, in accordance with SEC rules, omit or condense certain information and footnote disclosures. Results for the interim periods are not necessarily indicative of results to be expected for any other interim period or for the full year. These financial statements should be read in conjunction with the consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K as of and for the year ended December 31, 2015, as amended on May 2, 2016. The unaudited condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, after the elimination of inter-company transactions and balances. In April 2015, the Financial Accounting Standards Board ("FASB") issued new guidance regarding the accounting for debt issuance costs. The guidance requires a company to present any deferred financing costs from debt issuance as a reduction of debt. The Company has adopted this guidance in the first quarter of 2016.
Recent Accounting Pronouncements	In March 2016, FASB issued new guidance regarding the accounting for investments - equity method and joint ventures. The FASB issued this update to eliminate the requirement to retroactively adopt the equity method of accounting. The guidance is effective for fiscal years and interim periods within those fiscal years, beginning after December 15, 2016. The Company is currently assessing the impact of adopting this guidance on its financial statements. In March 2016, the FASB issued new guidance regarding the accounting for stock compensation. The FASB issued this update to simplify several aspects of the accounting for share-based payment transactions, including income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows, forfeitures, minimum statutory tax withholding requirements, classification of employee taxes paid on the Statement of Cash Flows when an employer withholds shares for tax-withholding purposes, expected term, intrinsic value, and eliminating the indefinite deferral. The guidance is effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. The Company is currently assessing the impact of adopting this guidance on its financial statements. In March and April 2016, the FASB issued new guidance regarding the accounting for revenue from contracts with customers. The FASB issued this update to improve the operability and understandability of the implementation guidance on principal versus agent considerations, and to provide clarification on identifying performance obligations and the licensing implementation guidance, while retaining the related principles for those areas. The guidance affects the revenue recognition guidance issued in May 2014, which is not yet effective. The effective date and transition requirements for the amendments in this update are the same as the effective date and transition requirements of the revenue recognition guidance issued in May 2014. The Company is currently assessing the impact of adopting this guidance on its financial statements. In February 2016, the FASB issued new guidance regarding the accounting for leases. The FASB issued this update to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. The Company is currently assessing the impact on its consolidated financial statements of adopting this guidance. In May 2014, the FASB issued new revenue recognition guidance that supersedes the existing revenue recognition guidance and most industry-specific guidance applicable to revenue recognition. The guidance requires a company to recognize revenue when it transfers promised goods or services to customers. Recognition should be in an amount that reflects the consideration to which the company expects to be entitled in exchange for those services. The guidance requires enhanced disclosures to help users of financial statements better understand the nature, amount, timing, and uncertainty of revenues recognized. The guidance is effective for annual periods beginning after December 15, 2016. On April 1, 2015, the FASB voted to propose a deferral of the effective date of this accounting guidance by a year to annual periods beginning after December 15, 2017. As part of the proposal, early application would be permitted in annual periods beginning after December 15, 2016, including interim periods within that reporting period. The Company is currently assessing the impact of adopting this guidance on its financial statements.

DESCRIPTION OF BUSINESS AND B27

DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (Tables)	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
Schedule of Change in Debt Issuance Cost Due to New Accounting Pronouncement	The table below shows the impact of this adoption on the Company's reported consolidated balance sheet. As of December 31, 2015 (As Reported) Adjustment As of December 31, 2015 (Adjusted) Assets: Other assets 47,422 (256 ) 47,166 Liabilities: Convertible senior notes 121,996 (256 ) 121,740

FAIR VALUE INFORMATION (Tables)

FAIR VALUE INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table presents the Company’s assets and liabilities that were measured at fair value on a recurring basis during the reporting period and the related hierarchy levels (amounts in thousands): Fair Value Measurements on a Recurring Basis Level 1 Level 2 Level 3 Total Financial Assets/(Liabilities): Customer derivative positions $ — $ 145,115 $ — $ 145,115 Broker derivative contracts — (11,128 ) — (11,128 ) Money market accounts 26,056 — — 26,056 Certificates of deposit 174 — — 174 Investment in gold 123 — — 123 Total $ 26,353 $ 133,987 $ — $ 160,340 Fair Value Measurements on a Recurring Basis as of December 31, 2015 Level 1 Level 2 Level 3 Total Financial Assets/(Liabilities): Customer derivative positions $ — $ 143,918 $ — $ 143,918 Broker derivative contracts — (12,568 ) — (12,568 ) Money market accounts 25,167 — — 25,167 Certificates of deposit 174 — — 174 Investment in gold 107 — — 107 Total $ 25,448 $ 131,350 $ — $ 156,798
Carrying Value and Fair Value and Fair Value Hierarchy Category of Financial Instruments Not Measured at Fair Value in Condensed Consolidated Statements of Financial Condition	As of March 31, 2016 Fair Value Measurements using: Carrying Value Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets: Receivables from brokers $ 131,080 $ 131,080 $ — $ 131,080 $ — Financial Liabilities: Payables to customers $ 1,021,077 $ 1,021,077 $ — $ 1,021,077 $ — Convertible senior notes $ 121,189 $ 118,470 $ — $ 118,470 $ — As of December 31, 2015 Fair Value Measurements using: Carrying Value Fair Value Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Financial Assets: Receivables from brokers $ 133,721 $ 133,721 $ — $ 133,721 $ — Financial Liabilities: Payables to customers $ 1,064,539 $ 1,064,539 $ — $ 1,064,539 $ — Convertible senior notes $ 121,740 $ 122,264 $ — $ 122,264 $ —

DERIVATIVES (Tables)

DERIVATIVES (Tables)	3 Months Ended
	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Values of Derivative Instruments	The table below represents the fair values of the Company’s derivative instruments reported within Receivables from brokers and Payables to customers on the accompanying condensed Consolidated Balance Sheet (amounts in thousands): March 31, 2016 Gross amounts of Gross amount of Net amounts of Derivative Instruments: Foreign currency exchange contracts $ 133,525 $ (52,545 ) $ 80,980 CFD contracts 91,195 (46,248 ) 44,947 Metals contracts 12,227 (4,167 ) 8,060 Total $ 236,947 $ (102,960 ) $ 133,987 March 31, 2016 Cash Collateral Net amounts of Net amounts of Derivative Assets/Liabilities: Receivables from brokers $ 131,080 $ (11,128 ) $ 119,952 Payables to customers $ (1,021,077 ) $ 145,115 $ (875,962 ) December 31, 2015 Gross amounts of Gross amount of Net amounts of Derivative Instruments: Foreign currency exchange contracts $ 138,140 $ (59,468 ) $ 78,672 CFD contracts 111,844 (70,429 ) 41,415 Metals contracts 18,866 (7,603 ) 11,263 Total $ 268,850 $ (137,500 ) $ 131,350 December 31, 2015 Cash Collateral Net amounts of Net amounts of Derivative Assets/Liabilities: Receivables from brokers $ 133,721 $ (12,568 ) $ 121,153 Payables to customers $ (1,064,539 ) $ 143,918 $ (920,621 )
Notional Values of Derivative Instruments	The table below presents the number of contracts reported within Receivables from brokers and Payables to customers on the consolidated balance sheet (amounts in thousands): March 31, 2016 Total contracts in long positions Total contracts in short positions Derivative Instruments: Foreign currency exchange contracts 2,277,094 2,744,129 CFD contracts 132,514 236,429 Metals contracts 894 336 Total 2,410,502 2,980,894 December 31, 2015 Total contracts in long positions Total contracts in short positions Derivative Instruments: Foreign currency exchange contracts 3,106,885 2,931,109 CFD contracts 139,465 285,640 Metals contracts 1,278 308 Total 3,247,628 3,217,057
Net Gains (Losses) With Respect to Derivative Instruments Which are Reflected in Trading Revenue	Net gains/(losses) with respect to derivative instruments reflected in Retail Revenue in the accompanying condensed consolidated statements of operations and comprehensive income for the three months ended March 31, 2016 and 2015 were as follows (amounts in thousands): Three Months Ended March 31, 2016 2015 Derivative Instruments: Foreign currency exchange contracts $ 54,297 $ 36,660 CFD contracts 35,222 29,064 Metals contracts 4,960 5,988 Total $ 94,479 $ 71,712

RECEIVABLES FROM BROKERS (Table

RECEIVABLES FROM BROKERS (Tables)	3 Months Ended
	Mar. 31, 2016
Brokers and Dealers [Abstract]
Schedule of Receivable from Brokers	Amounts receivable from brokers consisted of the following as of (amounts in thousands): March 31, 2016 December 31, 2015 Required collateral $ 127,326 $ 129,042 Excess from futures broker - Restricted 3,754 4,679 Open foreign exchange positions (11,128 ) (12,568 ) Total $ 119,952 $ 121,153

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	3 Months Ended
	Mar. 31, 2016
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment, including leasehold improvements and capitalized software development costs, consisted of the following as of (amounts in thousands): March 31, 2016 December 31, 2015 Software $ 47,736 $ 44,194 Computer equipment 16,061 14,300 Leasehold improvements 11,105 11,200 Telephone equipment 815 881 Office equipment 2,114 2,113 Furniture and fixtures 1,881 1,761 Web site development costs 667 668 Gross property and equipment 80,379 75,117 Less: Accumulated depreciation and amortization (48,104 ) (44,750 ) Property and equipment, net $ 32,275 $ 30,367

INTANGIBLE ASSETS (Tables)

INTANGIBLE ASSETS (Tables)	3 Months Ended
	Mar. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The Company has the following identifiable intangible assets as of March 31, 2016: Intangible Asset Amount (in thousands) Weighted average amortization period Customer list $ 55,425 7.6 years Technology 73,714 8.9 years Trademark (1) 8,466 6.7 years $ 137,605 (1) Trademarks with indefinite lives, as described above, comprise $0.4 million of the $8.5 million total trademark value. The Company's various finite-lived intangible assets consisted of the following as of (amounts in thousands): March 31, 2016 December 31, 2015 Intangibles Gross Accumulated Net Gross Accumulated Net Customer list $ 55,425 $ (16,054 ) $ 39,371 $ 56,388 $ (14,111 ) $ 42,277 Technology 73,714 (33,608 ) 40,106 74,378 (32,117 ) 42,261 Trademark 8,103 (1,936 ) 6,167 8,289 (1,678 ) 6,611 Total finite lived intangibles 137,242 (51,598 ) 85,644 139,055 (47,906 ) 91,149 Trademark not subject to amortization (1) 363 — 363 363 — 363 Total intangibles $ 137,605 $ (51,598 ) $ 86,007 $ 139,418 $ (47,906 ) $ 91,512 (1) These indefinite-life trademarks relate to the Forex.com and foreignexchange.com domain names where management determined there was no legal, regulatory or technological limitation on their useful lives. These trademarks are also supported annually in the Company's impairment test for intangible assets.
Schedule of Goodwill	The following represents the carrying amount of goodwill by segment (amounts in thousands): Retail Institutional Futures Total Carrying amount of goodwill as of December 31, 2015 $ 26,722 $ 4,788 $ 2,507 $ 34,017 Foreign currency translation adjustments $ (235 ) $ (42 ) $ (22 ) $ (299 ) Carrying amount of goodwill as of March 31, 2016 $ 26,487 $ 4,746 $ 2,485 $ 33,718

OTHER ASSETS (Tables)

OTHER ASSETS (Tables)	3 Months Ended
	Mar. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Other Assets	Other assets consisted of the following as of (amounts in thousands): March 31, 2016 December 31, 2015 Vendor and security deposits $ 12,855 $ 11,486 Income tax receivable 11,073 9,482 Deferred tax assets, net 18,235 17,827 GTX trade receivables 5,036 4,881 Customer debit positions 7,995 7,340 Allowance on customer debit positions (7,646 ) (6,832 ) Miscellaneous receivables 4,749 2,160 Equity method investment 845 822 $ 53,142 $ 47,166

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	3 Months Ended
	Mar. 31, 2016
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Schedule of Restructuring Costs	For the Three Months Ended March 31, 2016 Restructuring liability as of January 1, 2016 $ 499 2016 restructuring expenses 781 Payments made in 2016 (567 ) Restructuring liability as of March 31, 2016 $ 713
City Index
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Preliminary Purchase Price	The purchase price was derived as follows (amounts in thousands): Cash $ 6,103 Convertible senior notes 65,000 Common stock issued 45,100 Total purchase price $ 116,203
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The purchase price of City Index was allocated to the fair value of various assets and liabilities as follows (amounts in thousands): Cash $ 10,546 Cash and securities held for customers 281,576 Receivable from brokers 35,974 Property and equipment 10,466 Prepaid assets 4,038 Other assets 5,119 Total tangible assets 347,719 Total liabilities assumed 299,000 Net assets acquired 48,719 Identifiable intangible assets: Customer list 34,277 Trade name 6,645 Technology 26,157 Intangible assets, net 67,079 Goodwill $ 405
Pro Forma Information	Unaudited pro forma income statement line items for the three months ended March 31, 2015 were as follows (amounts in thousands): For the Three Months Ended December 31, 2015 REVENUE: Total non-interest revenue $ 129,820 Interest revenue 420 Interest expense 864 Total net interest revenue (444 ) Net revenue 129,376 EXPENSES: Depreciation and amortization 2,619 Purchased intangible amortization 3,319 Other expense items 109,423 Total operating expense 115,361 OPERATING PROFIT 14,015 Interest on long term borrowings 2,513 INCOME BEFORE INCOME TAX EXPENSE 11,502 Income tax expense 7,219 NET INCOME 4,283 Net income attributable to non-controlling interests 344 Net income applicable to Gain Capital Holdings, Inc. $ 3,939

NON-CONTROLLING INTEREST (Table

NON-CONTROLLING INTEREST (Tables)	3 Months Ended
	Mar. 31, 2016
Noncontrolling Interest [Abstract]
Summary of redeemable noncontrolling interest treatment	The table below reflects the non-controlling interests' effects on the Company's financial statements (amounts in thousands): Redeemable non-controlling interests January 1, 2016 $ 11,046 Adjustment to the redemption value of non-controlling interests (99 ) Net income attributable to non-controlling interests 349 Distributions to non-controlling interest holders — March 31, 2016 $ 11,296

CONVERTIBLE SENIOR NOTES (Table

CONVERTIBLE SENIOR NOTES (Tables)	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
Schedule of Liability and Equity Components of Convertible Debt	The balances of the liability and equity components of the Convertible Senior Notes as of March 31, 2016 , and December 31, 2015 were as follows (amounts in thousands): March 31, 2016 December 31, 2015 Liability component - principal $ 138,150 $ 140,000 Deferred bond discount 16,728 18,004 Deferred financing cost 233 256 Liability component - net carrying value $ 121,189 $ 121,740 Additional paid in capital $ 27,822 $ 27,920 Discount attributable to equity (419 ) (412 ) Equity component $ 27,403 $ 27,508
Schedule of Interest Expense	Interest expense related to the Convertible Senior Notes, included in Interest on long term borrowings in the condensed consolidated statements of operations and comprehensive income was as follows (amounts in thousands): Three Months Ended Three Months Ended March 31, 2016 March 31, 2015 Interest expense - stated coupon rate $ 1,444 $ 825 Interest expense - amortization of deferred bond discount and costs 1,079 588 Total interest expense - convertible senior notes $ 2,523 $ 1,413

EARNINGS PER COMMON SHARE (Tabl

EARNINGS PER COMMON SHARE (Tables)	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Computation of Earnings Per Share	The following table sets forth the computation of earnings per share (amounts in thousands except share and per share data): For the Three Months Ended March 31, 2016 2015 Net income applicable to GAIN Capital Holdings, Inc. $ 8,352 $ 5,465 Adjustment to the redemption value of non-controlling interests (1) 99 (524 ) Net income available to GAIN common shareholders $ 8,451 $ 4,941 Weighted average common shares outstanding: Basic weighted average common shares outstanding 48,622,816 43,206,628 Effect of dilutive securities: Stock options 172,193 581,086 RSUs/RSAs 188,871 362,791 Diluted weighted average common shares outstanding 48,983,880 44,150,505 Earnings per common share Basic $ 0.17 $ 0.11 Diluted $ 0.17 $ 0.11 (1) During the three months ended March 31, 2016 , the Company recorded an adjustment of $0.1 million to the carrying value of the put options related to the Company's redeemable non-controlling interests, which increased retained earnings and decreased non-controlling interests. During the three months ended March 31, 2015 , an adjustment of $(0.5) million was recorded to the carrying value of the put options related to the Company's redeemable non-controlling interests, which decreased retained earnings and increased non-controlling interests. The adjustment to the carrying value increased earnings available to the Company's shareholders for purposes of calculating basic and diluted earnings per common share for the three months ended March 31, 2016 and decreased earnings available to the Company's shareholders for purposes of calculating basic and diluted earnings per common share for the three months ended March 31, 2015

REGULATORY REQUIREMENTS (Tables

REGULATORY REQUIREMENTS (Tables)	3 Months Ended
	Mar. 31, 2016
Banking and Thrift [Abstract]
Minimum Regulatory Capital Subsidiaries Required to Maintain	The following table illustrates the minimum regulatory capital our subsidiaries were required to maintain as of March 31, 2016 and the actual amounts of capital that were maintained (amounts in millions): Entity Name Minimum Capital Excess Percent of GAIN Capital Group, LLC $ 29.1 $ 44.5 $ 15.4 153 % GAIN Capital-Forex.com U.K., Ltd. 25.1 60.3 35.2 240 % GAIN Capital Japan Co., Ltd. 1.4 9.7 8.3 693 % GAIN Capital-Forex.com Hong Kong, Ltd. 1.9 3.6 1.7 189 % GAIN Capital Forex.com Australia, Pty. Ltd. 0.8 2.9 2.1 363 % Galvan Research and Trading, Ltd. 0.7 4.2 3.5 600 % GAIN Capital-Forex.com Canada Ltd. 0.2 1.4 1.2 700 % GAIN Capital Securities, Inc. 0.1 0.4 0.3 400 % GAIN Global Markets, Inc. 0.2 0.3 0.1 150 % Gain Capital UK, Ltd. 60.4 129.9 69.5 215 % Gain Capital Singapore Pte, Ltd. 0.6 7.8 7.2 1,300 % Gain Capital Australia Pty Ltd. 0.8 3.0 2.2 375 % Global Assets Advisors, LLC 0.1 1.6 1.5 1,600 % Total $ 121.4 $ 269.6 $ 148.2 222 %

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
Selected Financial Information by Segment	Selected financial information by segment is presented in the following tables (amounts in thousands): Retail Three Months Ended March 31, 2016 2015 Net revenue $ 96,705 $ 73,342 Employee compensation and benefits 16,702 12,157 Selling and marketing 6,213 4,207 Referral fees 16,602 22,674 Other operating expenses 20,881 11,286 Segment profit $ 36,307 $ 23,018 Institutional Three Months Ended March 31, 2016 2015 Net revenue $ 7,119 $ 10,074 Employee compensation and benefits 3,202 3,960 Selling and marketing 6 71 Other operating expenses 2,440 2,512 Segment profit $ 1,471 $ 3,531 Futures Three Months Ended March 31, 2016 2015 Net revenue $ 12,204 11,536 Employee compensation and benefits 2,986 2,519 Selling and marketing 220 280 Referral fees 4,061 3,904 Other operating expenses 3,983 3,611 Segment profit $ 954 $ 1,222 Corporate and Other Three Months Ended March 31, 2016 2015 Other revenue $ (474 ) $ (1,966 ) Employee compensation and benefits 3,503 3,503 Other operating expenses 3,018 2,519 Loss $ (6,995 ) $ (7,988 )
Reconciliation of Operating Segment Profit to Income Before Income Tax Expense	Three Months Ended March 31, 2016 2015 Retail segment $ 36,307 $ 23,018 Institutional segment 1,471 3,531 Futures segment 954 1,222 Corporate and other (6,995 ) (7,988 ) SEGMENT PROFIT 31,737 19,783 Depreciation and amortization 3,153 1,975 Purchased intangible amortization 3,922 2,151 Acquisition expenses — 37 Restructuring expenses 781 — Integration expenses 813 64 Legal settlement 9,412 — SNB bad debt provision — 2,500 OPERATING PROFIT 13,656 13,056 Interest expense on long term borrowings 2,592 1,502 INCOME BEFORE INCOME TAX EXPENSE $ 11,064 $ 11,554

DESCRIPTION OF BUSINESS AND B40

DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION - Change in Debt Issuance Cost (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets	$ 53,142	$ 47,166
Convertible senior notes	$ 121,189	121,740
As Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets		47,422
Convertible senior notes		121,996
Accounting Standards Update 2015-03 | Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets		(256)
Convertible senior notes		$ (256)

FAIR VALUE INFORMATION - Assets

FAIR VALUE INFORMATION - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets (liabilities)	$ 160,340	$ 156,798
Customer derivative positions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	145,115	143,918
Broker derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	(11,128)	(12,568)
Money market accounts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	26,056	25,167
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	174	174
Investment in gold
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	123	107
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets (liabilities)	26,353	25,448
Level 1 | Customer derivative positions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 1 | Broker derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0	0
Level 1 | Money market accounts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	26,056	25,167
Level 1 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	174	174
Level 1 | Investment in gold
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	123	107
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets (liabilities)	133,987	131,350
Level 2 | Customer derivative positions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	145,115	143,918
Level 2 | Broker derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	(11,128)	(12,568)
Level 2 | Money market accounts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 2 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 2 | Investment in gold
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets (liabilities)	0	0
Level 3 | Customer derivative positions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 3 | Broker derivative contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0	0
Level 3 | Money market accounts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 3 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 3 | Investment in gold
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	$ 0	$ 0

FAIR VALUE INFORMATION - Carryi

FAIR VALUE INFORMATION - Carrying Value and Fair Value of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financial Assets:
Receivables from brokers	$ 119,952	$ 121,153
Financial Liabilities:
Convertible senior notes	121,189	121,740
Derivative Assets | Level 1
Financial Assets:
Receivables from brokers	0	0
Derivative Assets | Level 2
Financial Assets:
Receivables from brokers	131,080	133,721
Derivative Assets | Level 3
Financial Assets:
Receivables from brokers	0	0
Derivative Assets | Carrying Value
Financial Assets:
Receivables from brokers	131,080	133,721
Derivative Assets | Fair Value
Financial Assets:
Receivables from brokers	131,080	133,721
Derivative Liabilities
Financial Liabilities:
Payables to customers	1,021,077	1,064,539
Derivative Liabilities | Level 1
Financial Liabilities:
Payables to customers	0	0
Convertible senior notes	0	0
Derivative Liabilities | Level 2
Financial Liabilities:
Payables to customers	1,021,077	1,064,539
Convertible senior notes	118,470	122,264
Derivative Liabilities | Level 3
Financial Liabilities:
Payables to customers	0	0
Convertible senior notes	0	0
Derivative Liabilities | Carrying Value
Financial Liabilities:
Payables to customers	1,021,077	1,064,539
Convertible senior notes	121,189	121,740
Derivative Liabilities | Fair Value
Financial Liabilities:
Payables to customers	1,021,077	1,064,539
Convertible senior notes	$ 118,470	$ 122,264

DERIVATIVES - Fair Value of Der

DERIVATIVES - Fair Value of Derivative Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Gross amounts of assets for derivative open positions at fair value	$ 236,947	$ 268,850
Gross amounts of liability for derivative open positions at fair value	(102,960)	(137,500)
Net amounts of assets/liabilities for derivative open positions at fair value	133,987	131,350
Receivables from brokers	119,952	121,153
Payables to customers	(875,962)	(920,621)
Derivative Assets
Derivatives, Fair Value [Line Items]
Cash Collateral	131,080	133,721
Net amounts of assets/liabilities for derivative open positions at fair value	(11,128)	(12,568)
Derivative Liabilities
Derivatives, Fair Value [Line Items]
Cash Collateral	(1,021,077)	(1,064,539)
Net amounts of assets/liabilities for derivative open positions at fair value	145,115	143,918
Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Gross amounts of assets for derivative open positions at fair value	133,525	138,140
Gross amounts of liability for derivative open positions at fair value	(52,545)	(59,468)
Net amounts of assets/liabilities for derivative open positions at fair value	80,980	78,672
CFD contracts
Derivatives, Fair Value [Line Items]
Gross amounts of assets for derivative open positions at fair value	91,195	111,844
Gross amounts of liability for derivative open positions at fair value	(46,248)	(70,429)
Net amounts of assets/liabilities for derivative open positions at fair value	44,947	41,415
Metal contracts
Derivatives, Fair Value [Line Items]
Gross amounts of assets for derivative open positions at fair value	12,227	18,866
Gross amounts of liability for derivative open positions at fair value	(4,167)	(7,603)
Net amounts of assets/liabilities for derivative open positions at fair value	8,060	11,263
Level 2 | Derivative Assets
Derivatives, Fair Value [Line Items]
Receivables from brokers	131,080	133,721
Level 2 | Derivative Liabilities
Derivatives, Fair Value [Line Items]
Cash Collateral	(1,021,077)	(1,064,539)
Carrying Value | Derivative Assets
Derivatives, Fair Value [Line Items]
Receivables from brokers	131,080	133,721
Carrying Value | Derivative Liabilities
Derivatives, Fair Value [Line Items]
Cash Collateral	$ (1,021,077)	$ (1,064,539)

DERIVATIVES - Notional Values o

DERIVATIVES - Notional Values of Derivative Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Total contracts in long positions
Derivative [Line Items]
Notional amounts of derivative	$ 2,410,502	$ 3,247,628
Total contracts in long positions | Foreign currency exchange contracts
Derivative [Line Items]
Notional amounts of derivative	2,277,094	3,106,885
Total contracts in long positions | CFD contracts
Derivative [Line Items]
Notional amounts of derivative	132,514	139,465
Total contracts in long positions | Metal contracts
Derivative [Line Items]
Notional amounts of derivative	894	1,278
Total contracts in short positions
Derivative [Line Items]
Notional amounts of derivative	2,980,894	3,217,057
Total contracts in short positions | Foreign currency exchange contracts
Derivative [Line Items]
Notional amounts of derivative	2,744,129	2,931,109
Total contracts in short positions | CFD contracts
Derivative [Line Items]
Notional amounts of derivative	236,429	285,640
Total contracts in short positions | Metal contracts
Derivative [Line Items]
Notional amounts of derivative	$ 336	$ 308

DERIVATIVES - Net Gains (Losses

DERIVATIVES - Net Gains (Losses) on Derivatives (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative [Line Items]
Net gains (losses) on derivative instruments, total	$ 94,479	$ 71,712
Foreign currency exchange contracts
Derivative [Line Items]
Net gains (losses) on derivative instruments	54,297	36,660
CFD contracts
Derivative [Line Items]
Net gains (losses) on derivative instruments	35,222	29,064
Metal contracts
Derivative [Line Items]
Net gains (losses) on derivative instruments	$ 4,960	$ 5,988

RECEIVABLES FROM BROKERS - Sche

RECEIVABLES FROM BROKERS - Schedule of Receivables from Brokers (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Receivables from Brokerage Clients [Line Items]
Receivables from brokers	$ 119,952	$ 121,153
Required collateral
Receivables from Brokerage Clients [Line Items]
Receivables from brokers	127,326	129,042
Excess from futures broker - Restricted
Receivables from Brokerage Clients [Line Items]
Receivables from brokers	3,754	4,679
Open foreign exchange positions
Receivables from Brokerage Clients [Line Items]
Receivables from brokers	$ (11,128)	$ (12,568)

PROPERTY AND EQUIPMENT - Additi

PROPERTY AND EQUIPMENT - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 3,153	$ 1,975
Additional depreciation charge due to change in useful life	$ 200

PROPERTY AND EQUIPMENT - Schedu

PROPERTY AND EQUIPMENT - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property and equipment	$ 80,379	$ 75,117
Less: Accumulated depreciation and amortization	(48,104)	(44,750)
Property and equipment, net	32,275	30,367
Software
Property, Plant and Equipment [Line Items]
Property and equipment	47,736	44,194
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment	16,061	14,300
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	11,105	11,200
Telephone equipment
Property, Plant and Equipment [Line Items]
Property and equipment	815	881
Office equipment
Property, Plant and Equipment [Line Items]
Property and equipment	2,114	2,113
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	1,881	1,761
Website development costs
Property, Plant and Equipment [Line Items]
Property and equipment	$ 667	$ 668

INTANGIBLE ASSETS - Intangible

INTANGIBLE ASSETS - Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, gross	$ 137,242		$ 139,055
Accumulated Amortization	(51,598)		(47,906)
Finite-lived intangible assets, net	85,644		91,149
Total intangibles, gross	137,605		139,418
Intangible assets, net	86,007		91,512
Amortization of Intangible Assets	3,922	$ 2,151
Trademark
Intangible Assets by Major Class [Line Items]
Indefinite-lived intangible assets	363		363
Intangible assets, net	400
Customer list
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, gross	55,425		56,388
Accumulated Amortization	(16,054)		(14,111)
Finite-lived intangible assets, net	39,371		42,277
Total intangibles, gross	$ 55,425
Weighted average amortization period	7 years 7 months 6 days
Technology
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, gross	$ 73,714		74,378
Accumulated Amortization	(33,608)		(32,117)
Finite-lived intangible assets, net	40,106		42,261
Total intangibles, gross	$ 73,714
Weighted average amortization period	8 years 10 months 24 days
Trademark
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, gross	$ 8,103		8,289
Accumulated Amortization	(1,936)		(1,678)
Finite-lived intangible assets, net	6,167		$ 6,611
Total intangibles, gross	8,466
Intangible assets, net	$ 8,500
Weighted average amortization period	6 years 8 months 12 days

INTANGIBLE ASSETS - Goodwill (D

INTANGIBLE ASSETS - Goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016USD ($)
Goodwill [Line Items]
Decrease in goodwill	$ 300
Goodwill [Roll Forward]
Goodwill. beginning balance	34,017
Foreign currency translation adjustments	(299)
Goodwill. ending balance	33,718
Operating Segments | Retail
Goodwill [Roll Forward]
Goodwill. beginning balance	26,722
Foreign currency translation adjustments	(235)
Goodwill. ending balance	26,487
Operating Segments | Institutional
Goodwill [Roll Forward]
Goodwill. beginning balance	4,788
Foreign currency translation adjustments	(42)
Goodwill. ending balance	4,746
Operating Segments | Futures
Goodwill [Roll Forward]
Goodwill. beginning balance	2,507
Foreign currency translation adjustments	(22)
Goodwill. ending balance	$ 2,485

OTHER ASSETS - Schedule of Othe

OTHER ASSETS - Schedule of Other Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Vendor and security deposits	$ 12,855	$ 11,486
Income tax receivable	11,073	9,482
Deferred tax assets, net	18,235	17,827
GTX trade receivables	5,036	4,881
Customer debit positions	7,995	7,340
Allowance on customer debit positions	(7,646)	(6,832)
Miscellaneous receivables	4,749	2,160
Equity method investment	845	822
Other assets, net	$ 53,142	$ 47,166

RELATED PARTY TRANSACTIONS - Ad

RELATED PARTY TRANSACTIONS - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Payables to customers	$ 875,962	$ 920,621
Management
Related Party Transaction [Line Items]
Payables to customers	300	300
IPGL Limited
Related Party Transaction [Line Items]
Payables to customers	$ 10,500	$ 21,700

ACQUISITIONS - Additional Infor

ACQUISITIONS - Additional Information (Details) - USD ($)	Apr. 01, 2015	Mar. 31, 2016	Mar. 31, 2015
Business Acquisition [Line Items]
Restructuring expenses		$ 781,000	$ 0
City Index
Business Acquisition [Line Items]
Total purchase price	$ 116,203,000
Amount of cash to be held in escrow	1,000,000
Cash used to settle certain inter-company liabilities	22,400,000
Cash payment	$ 6,103,000
Number of shares issued due to acquisitions	5,319,149
Number of shares issued due to acquisitions, held in escrow	4,787,234
Convertible senior notes	$ 65,000,000
Convertible notes to be held in escrow	$ 54,000,000
Restructuring expenses		$ 781,000
Convertible Notes Due 2020 | Convertible Debt
Business Acquisition [Line Items]
Stated interest rate	4.125%
Principal amount	$ 60,000,000
Convertible Notes Due 2020 | City Index | Convertible Debt
Business Acquisition [Line Items]
Stated interest rate	4.125%
Principal amount	$ 60,000,000

ACQUISITIONS - Schedule of Purc

ACQUISITIONS - Schedule of Purchase Price (Detail) - City Index $ in Thousands	Apr. 01, 2015USD ($)
Business Acquisition [Line Items]
Cash	$ 6,103
Convertible senior notes	65,000
Common stock issued	45,100
Total purchase price	$ 116,203

ACQUISITIONS - Allocation of Pu

ACQUISITIONS - Allocation of Purchase Price to Fair Value of Assets and Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Apr. 01, 2015
Business Acquisition [Line Items]
Goodwill	$ 33,718	$ 34,017
City Index
Business Acquisition [Line Items]
Cash			$ 10,546
Cash and securities held for customers			281,576
Receivable from brokers			35,974
Property and equipment			10,466
Prepaid assets			4,038
Other assets			5,119
Total tangible assets			347,719
Total liabilities assumed			299,000
Net assets			48,719
Identifiable intangible assets			67,079
Goodwill			405
City Index | Customer list
Business Acquisition [Line Items]
Identifiable intangible assets			34,277
City Index | Trade name
Business Acquisition [Line Items]
Identifiable intangible assets			6,645
City Index | Technology
Business Acquisition [Line Items]
Identifiable intangible assets			$ 26,157

ACQUISITIONS - Pro Forma Revenu

ACQUISITIONS - Pro Forma Revenue and Net Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Total non-interest revenue	$ 115,340	$ 92,967
Interest revenue	318	337
Interest expense	104	318
Total net interest revenue	214	19
Depreciation and amortization	3,153	1,975
Purchased intangible amortization	3,922	2,151
Total operating expense	101,898	79,930
OPERATING PROFIT	13,656	13,056
INCOME BEFORE INCOME TAX EXPENSE	11,064	11,554
Income tax expense	2,347	5,745
Net income attributable to non-controlling interest	349	344
NET INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC.	$ 8,352	5,465
Pro Forma | City Index
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Total non-interest revenue		129,820
Interest revenue		420
Interest expense		864
Total net interest revenue		(444)
Net revenue		129,376
Depreciation and amortization		2,619
Purchased intangible amortization		3,319
Other expense items		109,423
Total operating expense		115,361
OPERATING PROFIT		14,015
Interest on long term borrowings		2,513
INCOME BEFORE INCOME TAX EXPENSE		11,502
Income tax expense		7,219
NET INCOME		4,283
Net income attributable to non-controlling interest		344
NET INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC.		$ 3,939

ACQUISITIONS - Restructuring (D

ACQUISITIONS - Restructuring (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Restructuring Reserve [Roll Forward]
Restructuring expenses	$ 781	$ 0
City Index
Restructuring Reserve [Roll Forward]
Restructuring liability as of January 1, 2016	499
Restructuring expenses	781
Payments made in 2016	(567)
Restructuring liability as of March 31, 2016	$ 713

NON-CONTROLLING INTEREST (Detai

NON-CONTROLLING INTEREST (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Increase (Decrease) in Temporary Equity [Roll Forward]
Redeemable noncontrolling interest, beginning balance	$ 11,046
Adjustment to the redemption value of non-controlling interests	(99)	$ 524
Net income attributable to non-controlling interest	349	$ 344
Distributions to non-controlling interest holders	0
Redeemable noncontrolling interest, ending balance	$ 11,296
Top Third Ag Marketing, LLC
Redeemable Noncontrolling Interest [Line Items]
Percentage of company acquired			55.00%
Redeemable noncontrolling interest retained by noncontrolling owners			45.00%
Global Assets Advisors, LLC
Redeemable Noncontrolling Interest [Line Items]
Percentage of company acquired			55.00%
Redeemable noncontrolling interest retained by noncontrolling owners			45.00%

CONVERTIBLE SENIOR NOTES - Addi

CONVERTIBLE SENIOR NOTES - Additional Information (Details) - USD ($)	Nov. 27, 2013	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Apr. 01, 2015
Debt Instrument [Line Items]
Repurchase of convertible notes		$ 1,735,000	$ 0
Convertible Debt
Debt Instrument [Line Items]
Debt fair value		121,189,000		$ 121,740,000
Convertible Notes Due 2020 | Convertible Debt
Debt Instrument [Line Items]
Principal amount					$ 60,000,000
Stated interest rate					4.125%
Convertible Notes Due 2018 | Convertible Debt
Debt Instrument [Line Items]
Principal amount	$ 80,000,000	1,900,000
Stated interest rate	4.125%
Proceeds from Convertible Debt	$ 77,900,000
Repurchase of convertible notes		$ (1,700,000)

CONVERTIBLE SENIOR NOTES - Sche

CONVERTIBLE SENIOR NOTES - Schedule of Liability and Equity Components (Details) - Convertible Debt - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Liability component - principal	$ 138,150	$ 140,000
Deferred bond discount	16,728	18,004
Deferred financing cost	233	256
Liability component - net carrying value	121,189	121,740
Additional paid in capital	27,822	27,920
Discount attributable to equity	(419)	(412)
Equity component	$ 27,403	$ 27,508

CONVERTIBLE SENIOR NOTES - Sc61

CONVERTIBLE SENIOR NOTES - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Debt Instrument [Line Items]
Interest expense - amortization of deferred bond discount and costs	$ 110	$ 89
Convertible Debt
Debt Instrument [Line Items]
Interest expense - stated coupon rate	1,444	825
Interest expense - amortization of deferred bond discount and costs	1,079	588
Total interest expense - convertible senior notes	$ 2,523	$ 1,413

EARNINGS PER COMMON SHARE - Add

EARNINGS PER COMMON SHARE - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive stock options excluded from calculation of diluted earnings per share	0.4	0.1
Common stock threshold for additional dilutive shares (in dollars per share)	$ 13
Adjustment to the redemption value of put options related to non-controlling interests	$ 99	$ (524)
Convertible Notes Due 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Additional dilutive shares if indenture conditions were met	1.5
Convertible Notes Due 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Additional dilutive shares if indenture conditions were met	0.5

EARNINGS PER COMMON SHARE - Com

EARNINGS PER COMMON SHARE - Computation of Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Net income applicable to Gain Capital Holdings, Inc.	$ 8,352	$ 5,465
Adjustment	99	(524)
Net income applicable to GAIN common shareholders	$ 8,451	$ 4,941
Weighted average common shares outstanding:
Basic weighted average common shares outstanding	48,622,816	43,206,628
Effect of dilutive securities:
Stock options (in shares)	172,193	581,086
RSUs/RSAs (in shares)	188,871	362,791
Diluted weighted average common shares outstanding	48,983,880	44,150,505
Earnings per common share
Basic (usd per share)	$ 0.17	$ 0.11
Diluted (usd per share)	$ 0.17	$ 0.11

LEGAL - Additional Information

LEGAL - Additional Information (Detail) $ in Millions	Apr. 28, 2016USD ($)
Subsequent Event | Cameron Farley Ltd
Long-term Purchase Commitment [Line Items]
Payments for legal settlements	$ 9.4

INCOME TAXES - Additional Infor

INCOME TAXES - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Provision for income taxes expense (benefit)	$ 2,347	$ 5,745
Effective income tax rates	21.20%	49.70%

REGULATORY REQUIREMENTS - Minim

REGULATORY REQUIREMENTS - Minimum Regulatory Capital Subsidiaries Required to Maintain (Detail) $ in Millions	Mar. 31, 2016USD ($)
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 121.4
Capital Levels Maintained	269.6
Excess Net Capital	$ 148.2
Percent of Requirement Maintained	222.00%
GAIN Capital Group, LLC
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 29.1
Capital Levels Maintained	44.5
Excess Net Capital	$ 15.4
Percent of Requirement Maintained	153.00%
GAIN Capital-Forex.com U.K., Ltd.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 25.1
Capital Levels Maintained	60.3
Excess Net Capital	$ 35.2
Percent of Requirement Maintained	240.00%
GAIN Capital Japan Co., Ltd.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 1.4
Capital Levels Maintained	9.7
Excess Net Capital	$ 8.3
Percent of Requirement Maintained	693.00%
GAIN Capital-Forex.com Hong Kong, Ltd.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 1.9
Capital Levels Maintained	3.6
Excess Net Capital	$ 1.7
Percent of Requirement Maintained	189.00%
GAIN Capital Forex.com Australia, Pty. Ltd.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 0.8
Capital Levels Maintained	2.9
Excess Net Capital	$ 2.1
Percent of Requirement Maintained	363.00%
Galvan Research and Trading, Ltd.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 0.7
Capital Levels Maintained	4.2
Excess Net Capital	$ 3.5
Percent of Requirement Maintained	600.00%
GAIN Capital-Forex.com Canada Ltd.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 0.2
Capital Levels Maintained	1.4
Excess Net Capital	$ 1.2
Percent of Requirement Maintained	700.00%
GAIN Capital Securities, Inc.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 0.1
Capital Levels Maintained	0.4
Excess Net Capital	$ 0.3
Percent of Requirement Maintained	400.00%
GAIN Global Markets, Inc.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 0.2
Capital Levels Maintained	0.3
Excess Net Capital	$ 0.1
Percent of Requirement Maintained	150.00%
Gain Capital UK, Ltd. [Member]
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 60.4
Capital Levels Maintained	129.9
Excess Net Capital	$ 69.5
Percent of Requirement Maintained	215.00%
Gain Capital Singapore Pte. Ltd. [Member]
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 0.6
Capital Levels Maintained	7.8
Excess Net Capital	$ 7.2
Percent of Requirement Maintained	1300.00%
Gain Capital Australia Pty Ltd. [Member]
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 0.8
Capital Levels Maintained	3
Excess Net Capital	$ 2.2
Percent of Requirement Maintained	375.00%
Global Assets Advisors, LLC
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 0.1
Capital Levels Maintained	1.6
Excess Net Capital	$ 1.5
Percent of Requirement Maintained	1600.00%

SEGMENT INFORMATION - Additiona

SEGMENT INFORMATION - Additional Information (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)marketSegment	Mar. 31, 2015USD ($)
Segment Reporting [Abstract]
Number of operating segments | Segment	3
Number of accessible global financial markets | market	12,500
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net revenue | $	$ 0.4	$ 0

SEGMENT INFORMATION - Selected

SEGMENT INFORMATION - Selected Financial Information by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Employee compensation and benefits	$ 26,393	$ 22,139
Selling and marketing	6,439	4,558
Referral fees	20,663	26,578
Segment profit	31,737	19,783
Operating Segments | Retail
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net revenue	96,705	73,342
Employee compensation and benefits	16,702	12,157
Selling and marketing	6,213	4,207
Referral fees	16,602	22,674
Other operating expenses	20,881	11,286
Segment profit	36,307	23,018
Operating Segments | Institutional
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net revenue	7,119	10,074
Employee compensation and benefits	3,202	3,960
Selling and marketing	6	71
Referral fees	2,440	2,512
Other operating expenses	1,471	3,531
Segment profit	1,471	3,531
Operating Segments | Futures
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net revenue	12,204	11,536
Employee compensation and benefits	2,986	2,519
Selling and marketing	220	280
Referral fees	4,061	3,904
Other operating expenses	3,983	3,611
Segment profit	954	1,222
Corporate and Other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net revenue	(474)	(1,966)
Employee compensation and benefits	3,503	3,503
Other operating expenses	3,018	2,519
Segment profit	$ (6,995)	$ (7,988)

SEGMENT INFORMATION - Reconcili

SEGMENT INFORMATION - Reconciliation of Operating Segment Profit to Income Before Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment profit	$ 31,737	$ 19,783
Depreciation and amortization	3,153	1,975
Purchased intangible amortization	3,922	2,151
Acquisition expenses	0	37
Restructuring	781	0
Integration expenses	813	64
Legal settlement	9,412	0
SNB bad debt provision	0	2,500
OPERATING PROFIT	13,656	13,056
Interest expense on long term borrowings	2,592	1,502
INCOME BEFORE INCOME TAX EXPENSE	11,064	11,554
Operating Segments | Retail
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment profit	36,307	23,018
Operating Segments | Institutional
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment profit	1,471	3,531
Operating Segments | Futures
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment profit	954	1,222
Corporate and Other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment profit	$ (6,995)	$ (7,988)

SUBSEQUENT EVENTS - Additional

SUBSEQUENT EVENTS - Additional Information (Detail) - Subsequent Event - USD ($) $ / shares in Units, $ in Millions	Apr. 28, 2016	May. 31, 2016
Subsequent Event [Line Items]
Common stock dividend declared (usd per share)		$ 0.05
Cameron Farley Ltd
Subsequent Event [Line Items]
Payments for legal settlements	$ 9.4