GAIN Capital 10-Q/A 3 May 16 2015 Q2 Quarterly report (amended) Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Apr. 29, 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/A
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
Amendment Flag	true
Amendment Description	Amend the previously issued unaudited condensed consolidated financial statements for the quarters ended June 30, 2015 and June 30, 2014 to correct errors in accounting for income taxes during those periods.
Entity Common Stock, Shares Outstanding		48,483,199

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
ASSETS:
Cash and cash equivalents	$ 135,022	$ 139,351
Cash and securities held for customers	1,109,406	759,559
Short term investments, at fair value	255	174
Receivables from brokers, of which ($28,358) and $717, respectively, are open contracts at fair value	157,024	134,908
Prepaid assets	8,402	2,537
Property and equipment, net of accumulated depreciation of ($38,943) and ($31,544), respectively	27,813	18,796
Intangible assets, net of accumulated amortization of ($25,135) and ($12,670), respectively	111,528	60,806
Goodwill	44,728	33,579
Other assets, net of allowance for doubtful accounts of ($5,602) and ($4,555), respectively	38,226	33,591
Total assets	1,632,404	1,183,301
Liabilities
Payables to customers, of which ($153,408) and ($102,722), respectively, are open contracts at fair value	1,109,406	759,559
Accrued compensation and benefits	8,665	16,912
Accrued expenses and other liabilities	62,440	76,195
Income tax payable	5,248	1,010
Convertible senior notes	119,762	68,367
Total liabilities	$ 1,305,521	$ 922,043
Commitments and contingent liabilities
Redeemable noncontrolling interests	$ 12,783	$ 11,338
GAIN Capital Holdings, Inc. Shareholders' equity
Common stock ($0.00001 par value; 120 million shares authorized; 51,802,494 shares issued and 49,164,386 shares outstanding as of June 30, 2015; 45,582,066 shares issued and 42,934,559 shares outstanding as of December 31, 2014)	0	0
Accumulated other comprehensive income/(loss)	5,778	(1,513)
Additional paid-in capital	213,444	148,378
Treasury stock, at cost (2,638,108 shares at June 30, 2015 and 2,647,507 shares at December 31, 2014)	(17,120)	(16,720)
Retained earnings	111,998	119,775
Total GAIN Capital Holdings, Inc. Shareholders' equity	314,100	249,920
Total liabilities and shareholders' equity	$ 1,632,404	$ 1,183,301

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2015	Sep. 30, 2013
Statement of Financial Position [Abstract]
Receivables from brokers, Fair Value	$ (28,358)	$ 717
Property and equipment, accumulated depreciation	(38,943)
Intangible assets, accumulated amortization	(25,135)
Other assets, allowance for doubtful accounts	(5,602)
Payables to customers, at fair value	$ (153,408)	$ (102,722)
Common Stock, par value	$ 0.00001	$ 0.00001
Common Stock, shares authorized	120,000,000	120,000,000
Common Stock, Shares, Issued	51,802,494	45,582,066
Common Stock, shares outstanding	49,164,386	42,934,559
Treasury stock, shares	2,638,108	2,647,507

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
REVENUE:
Retail revenue	$ 97,228	$ 60,781	$ 181,502	$ 132,592
Institutional revenue	8,383	8,586	18,442	17,104
Other revenue	5,841	638	4,474	721
Total non-interest revenue	111,452	70,005	204,418	150,417
Interest revenue	314	401	651	764
Interest expense	309	142	627	222
Total net interest revenue	5	259	24	542
Net revenue	111,457	70,264	204,442	150,959
EXPENSES:
Employee compensation and benefits	30,676	24,093	52,815	45,683
Selling and marketing	8,415	5,199	12,973	11,315
Referral fees	29,539	20,537	56,117	41,105
Trading expenses	8,119	7,169	15,094	14,057
General and administrative	14,143	9,924	23,514	19,365
Depreciation and amortization	2,738	1,798	4,713	3,493
Purchased intangible amortization	4,257	1,409	6,408	2,613
Communications and technology	5,835	3,829	8,593	7,823
Bad debt provision	1,236	582	4,560	1,162
Acquisition expenses	2,442	202	2,479	628
Restructuring	1,935	212	1,935	1,690
Integration expenses	12,309	269	12,373	1,719
Total operating expense	121,644	75,223	201,574	150,653
OPERATING (LOSS)/PROFIT	(10,187)	(4,959)	2,868	306
Interest on long term borrowings	2,554	1,462	4,056	2,894
INCOME BEFORE INCOME TAX EXPENSE	(12,741)	(6,421)	(1,188)	(2,588)
Income tax (benefit)/expense	(6,039)	(1,926)	(294)	861
NET (LOSS)/INCOME	(6,702)	(4,495)	(894)	(3,449)
Net income attributable to non-controlling interests	416	164	760	202
NET LOSS APPLICABLE TO GAIN CAPITAL HOLDINGS, INC.	(7,118)	(4,659)	(1,654)	(3,651)
Other comprehensive income:
Foreign currency translation adjustment	9,540	1,417	7,291	2,719
NET COMPREHENSIVE INCOME/(LOSS) APPLICABLE TO GAIN CAPITAL HOLDINGS, INC.	$ 2,422	$ (3,242)	$ 5,637	$ (932)
Earnings per common share:
Basic (usd per share)	$ (0.16)	$ (0.12)	$ (0.07)	$ (0.10)
Diluted (usd per share)	$ (0.16)	$ (0.12)	$ (0.07)	$ (0.10)
Weighted average common shares outstanding used in computing earnings per common share:
Basic (shares)	49,070,387	40,135,820	46,154,717	39,839,012
Diluted (shares)	49,070,387	40,135,820	46,154,717	39,839,012

Condensed Consolidated Stateme5

Condensed Consolidated Statement of Changes in Shareholders' Equity - 6 months ended Jun. 30, 2015 - USD ($)		Total	Common Stock	Treasury Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss)
BEGINNING BALANCE at Dec. 31, 2014		$ 249,920,000	$ 0	$ (16,720,000)	$ 148,378,000	$ 119,775,000	$ (1,513,000)
BEGINNING BALANCE (in shares) at Dec. 31, 2014	[1]		42,934,559
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of options		1,987,000			1,987,000
Exercise of options (in shares)	[1]		492,969
Conversion of restricted stock into common stock		0
Conversion of restricted stock into common stock (in shares)	[1]		415,536
Issuance of common stock		48,280,000			48,280,000
Employee stock purchase plan		394,000			394,000
Employee stock purchase plan, shares	[1]		44,106
Issuance of common stock, shares	[1]		5,319,149
Repurchase of shares		(400,000)		(400,000)
Repurchase of shares, shares	[1]		(41,933)
Convertible note issuance		15,348,000			15,348,000
Tax effect of convertible senior note		(3,827,000)			(3,827,000)
Other		(55,000)				(55,000)
Stock compensation expense		2,019,000			2,019,000
Foreign currency translation adjustment		7,291,000					7,291,000
Tax benefit of stock options exercises		865,000			865,000
Dividends declared ($0.05 quarterly dividend per share)		(4,627,000)				(4,627,000)
Net loss applicable to Gain Capital Holdings, Inc.		(1,654,000)
Adjustment to the redemption value of non-controlling interests		(1,441,000)				(1,441,000)
ENDING BALANCE at Jun. 30, 2015		$ 314,100,000	$ 0	$ (17,120,000)	$ 213,444,000	$ 111,998,000	$ 5,778,000
ENDING BALANCE (in shares) at Jun. 30, 2015	[1]		49,164,386
[1]	The Company has 15,000,000 shares of authorized preferred stock, of which none are issued or outstanding.

Condensed Consolidated Stateme6

Condensed Consolidated Statement of Changes in Shareholders' Equity (Parenthetical) - $ / shares	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Statement of Stockholders' Equity [Abstract]
Dividend payment (usd per share)	$ 0.05
Preferred stock, authorized (in shares)	15,000,000	15,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income/(loss)	$ (894)	$ (3,449)
Adjustments to reconcile net income/(loss) to cash provided by/(used for) operating activities
Loss/(gain) on foreign currency exchange rates	3,103	(441)
Depreciation and amortization	11,121	6,106
Non-cash integration costs	10,249	0
Deferred taxes	(2,460)	(3,379)
Amortization of deferred financing costs	177	177
Bad debt provision	4,560	1,162
Convertible senior notes discount amortization	1,567	1,054
Stock compensation expense	2,019	1,837
Adjustment to fair value of contingent consideration	(4,043)	0
Changes in operating assets and liabilities:
Cash and securities held for customers	(103,483)	(103,732)
Receivables from brokers	12,382	(4,834)
Prepaid assets	(1,988)	153
Other assets	2,815	(5,166)
Payables to customers	103,483	103,632
Accrued compensation and benefits	(11,212)	(4,970)
Accrued expenses and other liabilities	(12,463)	(8,252)
Income tax payable	(220)	2,742
Cash provided by/(used for) operating activities	14,713	(17,360)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(8,517)	(4,311)
Sale of treasury bills	(4)	(2)
Funding of acquisitions, net of cash acquired	(3,258)	(6,501)
Cash used for investing activities	(11,779)	(10,814)
CASH FLOWS FROM FINANCING ACTIVITIES:
Contractual payments for acquisitions	(9,842)	0
Proceeds from exercise of stock options	1,987	1,113
Tax benefit from employee stock option exercises	394	461
Dividend payment	(400)	(793)
Tax benefit from employee stock option exercises	865	1,213
Dividend payment	(4,627)	(3,993)
Distributions to non-controlling interest holders	(756)	0
Cash used for financing activities	(12,379)	(1,999)
Effect of exchange rate changes on cash and cash equivalents	5,116	3,181
DECREASE IN CASH AND CASH EQUIVALENTS	(4,329)	(26,992)
CASH AND CASH EQUIVALENTS-Beginning of period	139,351	39,871
CASH AND CASH EQUIVALENTS-End of period	135,022	12,879
Cash paid during the year for:
Interest	(2,472)	(1,687)
Taxes	(1,677)	(5,179)
Non-cash investing activities:
Common stock issued as consideration for asset and business acquisitions	(48,280)	1,241
Convertible senior notes issued as consideration for business acquisitions	(65,000)	0
Deferred taxes related to convertible senior notes	(3,827)
Adjustment to the redemption value of put options	$ (1,441)	$ (197)

DESCRIPTION OF BUSINESS AND BAS

DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION	6 Months Ended
	Jun. 30, 2015
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 of America. Group, LLC is a retail foreign exchange dealer (“RFED”) and a Futures Commission Merchant (“FCM”) registered with the Commodity Futures Trading Commission (“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. (“GCUK”) and GAIN Capital UK Ltd. are registered in the United Kingdom ("U.K.") and regulated by the Financial Conduct Authority (“FCA”) as full scope €730k BIPRU Investment Firms. The following list includes each of the Company’s significant U.S. and international regulated subsidiaries as of June 30, 2015 : GAIN Capital Group, LLC GAIN Capital-Forex.com U.K., Ltd. Forex.com 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 Ltd. 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 (Holdings) Limited ("City Index") from City Index Group Limited. GAIN Capital UK Ltd., GAIN Capital Australia Pty. Ltd., and GAIN Capital Singapore Pte. Ltd. are each subsidiaries of City Index that were acquired as part of the City Index acquisition. Each of these entities is regulated locally by the relevant regulators, including the FCA. In July 2014, the Company acquired all of the outstanding share capital of Galvan Research and Trading, Ltd. ("Galvan"), a U.K. based corporation, and its subsidiaries, Faraday Research LLP and Galvan LLP. Galvan is regulated by the FCA. In March 2014, the Company acquired controlling interests in Global Asset Advisors, LLC ("GAA") and Top Third Ag Marketing LLC ("Top Third"). See Note 5 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, 2014 filed with the SEC on March 16, 2015 and amended on April 30, 2015 (the “2014 Form 10-K”). There have been no changes in the significant accounting policies from those included in the 2014 Form 10-K. The unaudited condensed consolidated financial statements include the accounts of the Gain Capital Holdings, Inc. and its wholly owned subsidiaries after the elimination of inter-company transactions and balances. For the three and six months ended June 30, 2015, the Company revised its revenue captions to "Retail revenue" , "Institutional revenue" , and "Other revenue" . Previously, certain business lines now presented in "Retail revenue" were presented in "Commission revenue" . Following the City Index acquisition, organizing the Company's revenues in this fashion allows for the most useful presentation of the Company's major customer types and revenue streams, given changes to the relative current and expected magnitude of those streams. Revenues for the three and six months ended June 30, 2014 have been reclassified to align with this revised presentation. There are no changes to net revenue or net income in any period due to this reclassification. For the period ended June 30, 2015, the Company revised certain captions shown in its condensed consolidated balance sheets. "Receivables from banks and brokers" has been renamed, "Receivables from brokers" , and "Payables to customers, brokers, dealers, FCMs and other regulated entities" has been renamed "Payables to customers" . The Company believes that these captions more succinctly represent the nature of the transactions and balances contained within each line item. The composition and the amounts reported in the line items have not changed.

RESTATEMENT

RESTATEMENT	6 Months Ended
	Jun. 30, 2015
Accounting Changes and Error Corrections [Abstract]
RESTATEMENT	RESTATEMENT Subsequent to the date of the Original Filing, the Company has determined that there were errors in the manner in which the Company accounted for income taxes as of and for the quarters ended June 30, 2015 and 2014 under ASC 740, Income Taxes (ASC 740). These errors related primarily to the manner in which certain intercompany payables and receivables among domestic and overseas subsidiaries of the Company were treated for accounting and tax purposes during the impacted periods. The condensed consolidated financial statements of the Company as of and for the quarters ended June 30, 2015 and June 30, 2014, included in this report have been restated to reflect the correction of these errors. In addition, certain other adjustments, previously determined to be immaterial individually and in the aggregate, have also been corrected in the restated financial statements. These immaterial adjustments include the correction of an out of period adjustment related to the calculation of the redemption value of the noncontrolling interests previously recorded in the six month period ended June 30, 2015. This previous out of period adjustment of $1.3 million reduced retained earnings and increased non-controlling interests. The adjustment has now been reflected in the appropriate periods. The following tables reflect the financial statement line items impacted by the restatement. The column headed "Tax Adjustment" reflects the impact of the tax matters discussed above, while the "All Other Adjustments" column reflects the impact of the other previously identified immaterial adjustments in the Unaudited Interim Condensed Consolidated Balance Sheet and Unaudited Interim Condensed Consolidated Statements of Income and Comprehensive Income. The column headed "Adjustments" reflects the impact of the tax matters discussed above as well as the impact of the other previously identified immaterial adjustments in the Condensed Consolidated Statement of Cash Flows. For the avoidance of doubt, the following tables include only those line items impacted by the restatement. Condensed Consolidated Balance Sheet As of June 30, 2015 As Reported Tax Adjustment Other Adjustments As Restated ASSETS: Goodwill 48,006 (3,278 ) — 44,728 Other assets, net of allowance for doubtful accounts 43,521 (318 ) (4,977 ) 38,226 Total assets $ 1,640,977 $ (3,596 ) $ (4,977 ) $ 1,632,404 LIABILITIES AND SHAREHOLDERS’ EQUITY: Liabilities Accrued compensation and benefits 8,462 — 203 8,665 Accrued expenses and other liabilities 53,933 13,484 (4,977 ) 62,440 Income tax payable 3,645 1,603 — 5,248 Total liabilities $ 1,295,208 $ 15,087 $ (4,774 ) $ 1,305,521 Shareholders’ equity Accumulated other comprehensive loss 5,237 541 — 5,778 Additional paid-in capital 221,577 (8,133 ) — 213,444 Retained earnings 123,292 (11,091 ) (203 ) 111,998 Total shareholders’ equity 332,986 (18,683 ) (203 ) 314,100 Total liabilities and shareholders’ equity $ 1,640,977 $ (3,596 ) $ (4,977 ) $ 1,632,404 As of December 31, 2014 As Reported Tax Adjustment Other Adjustments As Restated ASSETS: Cash and cash equivalents $ 139,403 $ — $ (52 ) $ 139,351 Goodwill 34,567 (988 ) — 33,579 Other assets, net of allowance for doubtful accounts 35,137 917 (2,463 ) 33,591 Total assets $ 1,185,887 $ (71 ) $ (2,515 ) $ 1,183,301 LIABILITIES AND SHAREHOLDERS’ EQUITY: Liabilities Accrued expenses and other liabilities 64,476 12,170 (451 ) 76,195 Income tax payable 1,470 1,603 (2,063 ) 1,010 Total liabilities $ 910,784 $ 13,773 $ (2,514 ) $ 922,043 Redeemable non-controlling interests 10,209 — 1,129 11,338 Shareholders’ equity Accumulated other comprehensive loss (2,054 ) 541 — (1,513 ) Additional paid-in capital 152,684 (4,306 ) — 148,378 Retained earnings 130,984 (10,079 ) (1,130 ) 119,775 Total shareholders’ equity 264,894 (13,844 ) (1,130 ) 249,920 Total liabilities and shareholders’ equity $ 1,185,887 $ (71 ) $ (2,515 ) $ 1,183,301 Condensed Consolidated Statements of Income and Comprehensive Income Three Months Ended June 30, 2015 As Reported Tax Adjustment Other Adjustments As Restated REVENUE: Retail revenue $ 97,335 $ — $ (107 ) $ 97,228 Total non-interest revenue 111,559 — (107 ) 111,452 Net revenue $ 111,564 $ — $ (107 ) $ 111,457 EXPENSES: Employee compensation and benefits $ 30,473 $ — $ 203 $ 30,676 Trading expenses 8,226 — (107 ) 8,119 Total operating expense 121,548 — 96 121,644 OPERATING LOSS (9,984 ) — (203 ) (10,187 ) LOSS BEFORE INCOME TAX EXPENSE (12,538 ) — (203 ) (12,741 ) Income tax (benefit)/expense (4,124 ) (1,915 ) — (6,039 ) NET LOSS (8,414 ) 1,915 (203 ) (6,702 ) NET LOSS APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. (8,830 ) 1,915 (203 ) (7,118 ) NET COMPREHENSIVE INCOME/(LOSS) APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. $ 710 $ 1,915 $ (203 ) $ 2,422 Loss per common share: Basic $ (0.23 ) $ (0.16 ) Diluted $ (0.23 ) $ (0.16 ) Weighted average common shares outstanding used in computing earnings per common share: Basic 49,070,783 49,070,387 Diluted 49,070,783 49,070,387 Six Months Ended June 30, 2015 As Reported Tax Adjustment Other Adjustments As Restated REVENUE: Retail revenue $ 181,575 $ — $ (73 ) $ 181,502 Total non-interest revenue 204,491 — (73 ) 204,418 Net revenue $ 204,515 $ — $ (73 ) $ 204,442 EXPENSES: Employee compensation and benefits $ 52,612 $ — $ 203 $ 52,815 Trading expenses 15,274 — (180 ) 15,094 General and administrative 23,463 — 51 23,514 Total operating expense 201,500 — 74 201,574 OPERATING PROFIT 3,015 — (147 ) 2,868 LOSS BEFORE INCOME TAX EXPENSE (1,041 ) — (147 ) (1,188 ) Income tax (benefit)/expense (1,306 ) 1,012 — (294 ) NET INCOME/(LOSS) 265 (1,012 ) (147 ) (894 ) NET LOSS APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. (495 ) (1,012 ) (147 ) (1,654 ) NET COMPREHENSIVE INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. $ 6,796 $ (1,012 ) $ (147 ) $ 5,637 Loss per common share: Basic $ (0.07 ) $ — $ — $ (0.07 ) Diluted $ (0.07 ) $ — $ — $ (0.07 ) Weighted average common shares outstanding used in computing earnings per common share: Basic 46,154,905 46,154,717 Diluted 46,154,905 46,154,717 Three Months Ended June 30, 2014 As Reported Tax Adjustment Other Adjustments As Restated REVENUE: Retail revenue $ 60,280 $ — $ 501 $ 60,781 Total non-interest revenue 69,504 — 501 70,005 Net revenue $ 69,763 $ — $ 501 $ 70,264 EXPENSES: — General and administrative 9,850 — 74 9,924 Purchased intangible amortization 1,574 — (165 ) 1,409 Total operating expense 75,314 — (91 ) 75,223 OPERATING (LOSS)/PROFIT (5,551 ) — 592 (4,959 ) (LOSS)/INCOME BEFORE INCOME TAX EXPENSE (7,013 ) — 592 (6,421 ) Income tax (benefit)/expense (2,021 ) 95 — (1,926 ) NET INCOME (4,992 ) (95 ) 592 (4,495 ) NET (LOSS)/INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. (5,156 ) (95 ) 592 (4,659 ) NET COMPREHENSIVE (LOSS)/INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. $ (3,739 ) $ (95 ) $ 592 $ (3,242 ) Loss per common share: Basic $ (0.13 ) $ — $ — $ (0.12 ) Diluted $ (0.13 ) $ — $ — $ (0.12 ) Six Months Ended June 30, 2014 As Reported Tax Adjustment Other Adjustments As Restated REVENUE: Retail revenue $ 132,766 $ — $ (174 ) $ 132,592 Total non-interest revenue 150,591 — (174 ) 150,417 Net revenue $ 151,133 $ — $ (174 ) $ 150,959 EXPENSES: Employee compensation and benefits $ 45,935 $ — $ (252 ) $ 45,683 Referral fees 41,225 — (120 ) 41,105 General and administrative 19,057 — 308 19,365 Depreciation and amortization 4,008 — (515 ) 3,493 Restructuring expenses 571 — 1,119 1,690 Total operating expense 150,113 — 540 150,653 OPERATING PROFIT/(LOSS) 1,020 — (714 ) 306 LOSS BEFORE INCOME TAX EXPENSE (1,874 ) — (714 ) (2,588 ) Income tax (benefit)/expense (745 ) 1,606 — 861 NET LOSS (1,129 ) (1,606 ) (714 ) (3,449 ) NET LOSS APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. (1,331 ) (1,606 ) (714 ) (3,651 ) NET COMPREHENSIVE INCOME/(LOSS) APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. $ 1,388 $ (1,606 ) $ (714 ) $ (932 ) Loss per common share: Basic $ (0.04 ) $ — $ — $ (0.10 ) Diluted $ (0.04 ) $ — $ — $ (0.10 ) Condensed Statement of Changes in Shareholders' Equity Additional Paid in Capital Retained Earnings Accumulated Other Comprehensive Income/(Loss) Total As Reported As Restated As Reported As Restated As Reported As Restated As Reported As Restated BALANCE—December 31, 2014 $ 152,684 $ 148,378 $ 130,984 $ 119,775 $ (2,054 ) $ (1,513 ) $ 264,894 $ 249,920 BALANCE—June 30, 2015 $ 221,577 $ 213,444 $ 123,292 $ 111,998 $ 5,237 $ 5,778 $ 332,986 $ 314,100 Condensed Statement of Cash Flows Six Months Ended June 30, 2015 As Reported Adjustments As Restated CASH FLOWS FROM OPERATING ACTIVITIES: Net income $ 265 (1,159 ) $ (894 ) Adjustments to reconcile net income to cash provided by / (used for) operating activities — Deferred taxes (1,563 ) (897 ) (2,460 ) Changes in operating assets and liabilities: — Cash and securities held for customers (102,746 ) (737 ) (103,483 ) Receivables from brokers 12,486 (104 ) 12,382 Other assets (2,504 ) 5,319 2,815 Payables to customers 102,746 737 103,483 Accrued compensation and benefits (11,424 ) 212 (11,212 ) Accrued expenses and other liabilities (9,387 ) (3,076 ) (12,463 ) Income tax payable 2,223 (2,443 ) (220 ) Cash provided by / (used for) operating activities 16,861 (2,148 ) 14,713 Effect of exchange rate changes on cash and cash equivalents 2,916 2,200 5,116 INCREASE/ (DECREASE) IN CASH AND CASH EQUIVALENTS (4,381 ) 52 (4,329 ) CASH AND CASH EQUIVALENTS-Beginning of period 139,403 (52 ) 139,351 SUPPLEMENTARY DISCLOSURES OF CASH FLOW INFORMATION: Deferred taxes related to convertible senior notes $ — $ (3,827 ) $ (3,827 ) Adjustment to redemption value of non-controlling interests $ (2,570 ) $ 1,129 $ (1,441 ) Six Months Ended June 30, 2014 As Reported Adjustments As Restated CASH FLOWS FROM OPERATING ACTIVITIES: Net income $ (1,129 ) $ (2,320 ) $ (3,449 ) Adjustments to reconcile net income to cash provided by / (used for) operating activities Depreciation and amortization 6,621 (515 ) 6,106 Changes in operating assets and liabilities: Receivables from brokers (5,187 ) $ 353 (4,834 ) Other assets (5,034 ) $ (132 ) (5,166 ) Payables to customers 103,732 $ (100 ) 103,632 Accrued compensation and benefits (5,802 ) $ 832 (4,970 ) Accrued expenses and other liabilities (8,962 ) $ 710 (8,252 ) Income tax payable 1,624 $ 1,118 2,742 Cash provided by / (used for) operating activities (17,306 ) (54 ) (17,360 ) DECREASE IN CASH AND CASH EQUIVALENTS (26,938 ) (54 ) (26,992 ) CASH AND CASH EQUIVALENTS—End of period $ 12,933 $ (54 ) $ 12,879 SUPPLEMENTARY DISCLOSURES OF CASH FLOW INFORMATION: Adjustment to redemption value of non-controlling interests $ (173 ) $ (24 ) $ (197 )

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	6 Months Ended
	Jun. 30, 2015
Accounting Changes and Error Corrections [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	RECENT ACCOUNTING PRONOUNCEMENTS In April 2015, the Financial Accounting Standards Board ("FASB") issued new guidance regarding the accounting for debt issuance costs. The guidance requires presenting any deferred financing costs from debt issuance as a reduction of debt, a change from current presentation, in which such costs are classified in assets. The guidance is effective for annual periods beginning after December 15, 2015, including interim periods within that reporting period. Early adoption is permitted for financial statements that have not been previously issued. The Company does not expect this guidance to have a material impact on its financial statements. 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 financial statement users better understand the nature, amount, timing, and uncertainty of revenues recognized. The guidance is effective for annual periods beginning after December 15, 2017, which is a one year deferral from the original guidance, approved by the FASB in July 2015. Early application is 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.

ADDITIONAL FINANCIAL INFORMATIO

ADDITIONAL FINANCIAL INFORMATION	6 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ADDITIONAL FINANCIAL INFORMATION	ADDITIONAL FINANCIAL INFORMATION Fair Value Measurement 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 hierarchy that categorizes financial instruments into the following three levels based on valuation technique inputs (highest to lowest): 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 are 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 open contracts and other positions $ — $ 153,408 $ — $ 153,408 Broker open contracts and other positions — (28,358 ) — (28,358 ) Money market accounts 20,152 — — 20,152 Certificates of deposit 255 — — 255 Investment in gold 116 — 116 Contingent consideration — (6,031 ) (6,031 ) Total $ 20,523 $ 125,050 $ (6,031 ) $ 139,542 Fair Value Measurements on a Recurring Basis as of December 31, 2014 Level 1 Level 2 Level 3 Total Financial Assets/(Liabilities): Customer open contracts and other positions $ — $ 102,722 $ — $ 102,722 Broker open contracts and other positions — 717 — 717 Money market accounts 20,537 — — 20,537 Certificates of deposit 174 — — 174 Investment in gold 118 — — 118 Contingent consideration — — (9,974 ) (9,974 ) Total $ 20,829 $ 103,439 $ (9,974 ) $ 114,294 The Company has not changed its valuation techniques for measuring the fair value of any financial assets or liabilities during the six months ended June 30, 2015 , 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 Short term investments and the investment in gold is recorded in Other assets. Level 2 Financial Assets and Liabilities The Company has customer open contracts and other positions that are Level 2 financial instruments recorded in Payables to customers. The Company has broker open contracts and other positions that are Level 2 financial instruments recorded in Receivables from brokers. The fair value of these Level 2 financial instruments are based upon directly observable values for underlying instruments. Level 3 Financial Liabilities Under the agreements governing the Company's acquisition of Galvan, the Company is obligated to make contingent payments that are Level 3 financial liabilities. These contingent payments are recorded under Accrued expenses and other liabilities on the Company's condensed consolidated balance sheets. The fair value of these payments is determined using prevailing interest rates as of the balance sheet date and probability-weighted forecasts of the acquired company's performance and client accounts, the estimation of which does not have any basis in quoted or observable markets. Significant changes in any of the forecast inputs in isolation or in interest rates would result in significant fair value measurement changes. The following is a rollforward of the Level 3 liabilities from January 1, 2015 to June 30, 2015 (amounts in thousands): Liabilities Contingent Consideration Balance at January 1, 2015 $ 9,974 Gains included in earnings - adjustment to fair value of contingent consideration (4,466 ) Gains included in earnings - currency revaluation 100 Losses included in earnings - discount amortization 423 Balance at June 30, 2015 $ 6,031 Gains included in earnings - adjustment to fair value of contingent consideration and Gains included in earnings - currency revaluation for Level 3 liabilities are reported in Other revenue , while losses included in earnings attributable to discount amortization are reported in Interest expense . 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 sheets (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. Such 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 parties' 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 7). The Company assessed the notes' fair value as determined by current Company-specific and risk free interest rates as of the balance sheet date. The carrying value of Accrued expenses and other liabilities includes $1.4 million as of June 30, 2015 , referred to as the Holdback Amount, which is an amount relating to our acquisition of Global Futures & Forex, Ltd. ("GFT"). These liabilities were $20.0 million as of December 31, 2014 . The carrying values of Accrued expense and other liabilities not measured at fair value approximate fair value because of the relatively short period of time between their origination and expected settlement date. As of June 30, 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 $ 185,382 $ 185,382 $ — $ 185,382 $ — Financial Liabilities: Payables to customers 1,262,814 1,262,814 — 1,262,814 — Convertible senior notes 119,762 120,187 — 120,187 — Accrued expenses and other liabilities 1,366 1,366 — 1,366 — As of December 31, 2014 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 $ 134,191 $ 134,191 $ — $ 134,191 $ — Financial Liabilities: Payables to customers 862,281 862,281 — 862,281 — Convertible senior notes 68,367 66,440 — 66,440 — Accrued expenses and other liabilities 20,000 20,000 — 20,000 — Receivables from Brokers Amounts receivable from brokers consisted of the following as of (amounts in thousands): June 30, 2015 December 31, 2014 Required collateral $ 162,513 $ 95,599 Futures brokers - Restricted 22,869 38,592 Open positions (28,358 ) 717 $ 157,024 $ 134,908 Derivatives The Company's open 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 condensed consolidated balance sheets (amounts in thousands): June 30, 2015 Derivative open positions at fair value Gross assets Gross liabilities Net assets Derivative Instruments: Foreign currency exchange contracts $ 136,209 $ 59,614 $ 76,595 CFD contracts 144,817 107,178 37,639 Metals contracts 15,721 4,905 10,816 Total $ 296,747 $ 171,697 $ 125,050 June 30, 2015 Net assets/liabilities at fair value Cash Collateral Derivative open positions Presented in the balance sheet Derivative Assets/Liabilities: Receivables from brokers $ 185,382 $ (28,358 ) $ 157,024 Payables to customers $ 1,262,814 $ 153,408 $ 1,109,406 December 31, 2014 Derivative open positions at fair value Gross Gross Net assets Derivative Instruments: Foreign currency exchange contracts $ 168,034 $ 93,057 $ 74,977 CFD contracts 44,329 24,420 19,909 Metals contracts 16,146 7,593 8,553 Total $ 228,509 $ 125,070 $ 103,439 December 31, 2014 Net assets/liabilities at fair value Cash Collateral Derivative Derivative Assets/Liabilities: Receivables from brokers $ 134,191 $ 717 $ 134,908 Payables to customers $ 862,281 $ 102,722 $ 759,559 The Company’s derivatives have many different underlyings, which vary in price. Foreign exchange contracts typically have prices less than two dollars, while certain metals contracts and contracts for difference ("CFD") can have considerably higher prices. The table below represents the number of contracts underlying amounts reported within Receivables from brokers and Payables to customers on the condensed consolidated balance sheets (amounts in thousands): June 30, 2015 Total contracts in long positions Total contracts in short positions Derivative Instruments: Foreign currency exchange contracts 2,824,897 3,073,585 CFD contracts 478,704 106,087 Metals contracts 3,505 2,572 Total 3,307,106 3,182,244 December 31, 2014 Total contracts in long positions Total contracts in short positions Derivative Instruments: Foreign currency exchange contracts 3,147,518 2,679,041 CFD contracts 873,070 10,753 Metals contracts 835 335 Total 4,021,423 2,690,129 The Company did not designate any of its derivatives as hedging instruments at June 30, 2015 or December 31, 2014 . 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 and six months ended June 30, 2015 and 2014 were as follows (amounts in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Derivative Instruments: Foreign currency exchange contracts $ 61,587 $ 15,974 $ 97,659 $ 56,798 CFD contracts 13,523 13,289 37,864 17,493 Metals contracts 5,721 7,680 11,527 13,181 Total $ 80,831 $ 36,943 $ 147,050 $ 87,472 Property and Equipment Property and equipment consisted of the following as of (amounts in thousands): June 30, 2015 December 31, 2014 Software $ 28,938 $ 30,351 Computer equipment 13,691 8,516 Leasehold improvements 10,375 6,719 Telephone equipment 717 719 Office equipment 2,209 2,345 Furniture and fixtures 1,572 1,044 Web site development costs 9,254 646 66,756 50,340 Less: Accumulated depreciation and amortization (38,943 ) (31,544 ) Property and equipment, net $ 27,813 $ 18,796 As mentioned in Note 1 above, the Company purchased all of the outstanding share capital of City Index in April 2015, Galvan in July 2014 and controlling interests in GAA and Top Third in March 2014. The preliminary purchase price allocation for City Index and the final purchase price allocations for Galvan, GAA and Top Third to property and equipment are detailed below in Note 5, “Acquisitions”. Depreciation and amortization expense for property and equipment was $2.7 million and $ 1.8 million for the three months ended June 30, 2015 and 2014 , respectively, and $4.7 million and $3.5 million for the six months ended June 30, 2015 and 2014 , respectively. The Company adjusted the amortization period of certain property and equipment that experienced changes in useful lives as a result of the City Index acquisition. This change in useful lives resulted in an additional charge of $3.7 million during the three months ended June 30, 2015 . The additional charge is recorded in integration expenses. Intangible Assets The Company's various intangible assets consisted of the following as of (amounts in thousands): June 30, 2015 December 31, 2014 Intangibles Gross Accumulated Net Gross Accumulated Net Customer lists $ 53,432 $ (9,396 ) $ 44,036 $ 22,945 $ (7,152 ) $ 15,793 Technology 74,424 (14,623 ) 59,801 48,376 (4,671 ) 43,705 Trademarks 8,445 (1,116 ) 7,329 1,793 (847 ) 946 Total finite lived intangibles 136,301 (25,135 ) 111,166 73,114 (12,670 ) 60,444 Trademark not subject to amortization (1) 362 — 362 362 — 362 Total intangibles (2) $ 136,663 $ (25,135 ) $ 111,528 $ 73,476 $ (12,670 ) $ 60,806 (1) These indefinite-life trademarks relate to the Forex.com and foreignexchange.com domain names. Management determined there was no legal, regulatory or technological limitation on the domains' useful lives. The trademarks' values are evaluated annually in the Company's impairment test for intangible assets. (2) The increase in total intangibles for the six months ended June 30, 2015 is primarily due to the customer lists, technology and trademarks acquired as part of the City Index acquisition. See Note 5 for details of the intangibles acquired from the Company's City Index, GAA, Top Third and Galvan acquisitions. The technology acquired from the asset purchase agreements with Valaquenta Intellectual Property Limited ("Valaquenta") and Forexster Limited ("Forexster") is described in further detail below. The Company has the following gross identifiable intangible assets as of June 30, 2015: Intangible Assets Amount (in thousands) Weighted average amortization period Customer lists $ 53,432 8.1 years Technology 74,424 8.9 years Trademarks (1) 8,807 6.7 years $ 136,663 (1) Trademarks with an indefinite-life, as described above, comprise $0.4 million of the $8.8 million of trademarks. The preliminary purchase price allocations to intangible assets for the acquisition of City Index are detailed below in Note 5, “Acquisitions”, along with the final purchase price allocations for Galvan, GAA and Top Third. On July 10, 2014, the Company entered into asset purchase agreements with Valaquenta and Forexster, pursuant to which one of the Company's subsidiaries, GTX Bermuda, Ltd. ("GTX Bermuda"), agreed to purchase from Valaquenta and Forexster the software and other intellectual property assets utilized to operate the electronic trading platform offered to customers in the Company's GTX business. The purchase was made with a combination of $12.4 million in cash and $5.3 million in unregistered shares of the Company's common stock. Prior to the closing of the acquisitions, which took place on July 10, 2014, the Company had agreements with Valaquenta and Forexster granting it the exclusive right to use the intellectual property in the field of forex trading and non-exclusive rights to use the intellectual property for the trading of financial products in the fields of precious metals and hydrocarbons. Following the closing of the acquisition, GTX Bermuda has full rights and title over the intellectual property for trading of currencies, commodities and any other financial instruments of any kind whatsoever. This purchase added $21.4 million to the Company's intangible assets, $3.7 million of which were previously held as a prepayment made to Forexster under the aforementioned exclusive rights agreement. The Company has assigned a 10 year useful life to this asset. Amortization expense for the purchased intangibles was $4.3 million and $1.4 million for the three months ended June 30, 2015 and 2014 , respectively, and $6.4 million and $2.6 million for the six months ended June 30, 2015 and 2014 , respectively. The Company adjusted the amortization periods of certain intangible assets that experienced a change of estimated useful lives as a result of the City Index acquisition. This change resulted in an additional charge of $6.5 million during the three months ended June 30, 2015 . The additional charge is recorded in integration expenses. Future annual estimated purchased intangible amortization expense is as follows (amounts in thousands): Years Ended December 31: 2015 $ 21,700 2016 14,501 2017 13,189 2018 12,073 2019 11,489 Thereafter 38,214 Total $ 111,166 Of the total future estimated amortization expense above, $13.0 million is expected to be recorded as integration expense for the acceleration of the amortization of technology platforms that are being discontinued as a result of the City Index acquisition, primarily in the second half of 2015. Goodwill Goodwill is calculated as the difference between the cost of an acquired business and the fair value of the net identifiable assets of that business. As of June 30, 2015 and December 31, 2014 , the Company had recorded goodwill of approximately $44.7 million and $33.6 million , respectively. The increase of $11.1 million was primarily related to the City Index acquisition. Other Assets Other assets consisted of the following as of (amounts in thousands): June 30, 2015 December 31, 2014 Vendor and security deposits $ 4,944 $ 3,373 Current tax receivable 8,883 5,163 Deferred tax assets 10,517 6,308 Indemnification asset — 8,792 GTX trade receivables 4,347 4,190 Customer debit positions 7,311 6,594 Allowance for doubtful customer debit positions (5,602 ) (4,555 ) Acquisition related receivable 7,065 — Miscellaneous receivables and other assets 761 3,726 $ 38,226 $ 33,591 Under the terms of the GFT acquisition, an initial amount of $20.0 million , referred to as the Holdback Amount, was deferred, to be paid following the settlement of certain liabilities of GFT after the closing date of the acquisition. The selling stockholder of GFT agreed to indemnify the Company for these liabilities. At December 31, 2014, based on the Company's best estimate of the amounts necessary to settle such liabilities, the Company recorded an indemnification asset of $8.8 million . During the six months ended June 30, 2015, the Company made a payment of $9.9 million to the selling shareholder of GFT, as required by the stock purchase agreement providing for the acquisition of GFT, which reduced the liability associated with the Holdback Amount. At the time of such payment, the Company felt it was appropriate to offset the remaining liability with the indemnification asset based on its contractual rights. As a result, at June 30, 2015 , the Company has recorded a net liability of $1.4 million in Accrued expenses and other liabilities. In connection with the City Index acquisition, the Company has recorded an acquisition related receivable reflecting the Company's preliminary estimate of the working capital adjustment payable to the Company under the terms of the acquisition agreement. See note 5.

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	6 Months Ended
	Jun. 30, 2015
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, which are recorded in Payables to customers on the condensed consolidated balance sheets. The aggregate amount of these funds was $4.9 million and $3.6 million at June 30, 2015 and December 31, 2014 , 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 $10.0 million at June 30, 2015.

ACQUISITIONS

ACQUISITIONS	6 Months Ended
	Jun. 30, 2015
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. The preliminary purchase price consisted of approximately $6.7 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; and 4.125% unsecured Convertible Senior Notes with an aggregate principal amount of $60.0 million and fair value of $ 65.0 million . In addition the Company paid approximately $22.4 million to settle certain inter-company liabilities between City Index and City Index Group Limited (its former parent company). The preliminary purchase price was derived as follows (amounts in thousands): Cash $ 6,650 Convertible senior notes 65,000 Common stock issued (based on the April 1, 2015 quoted price of $9.77) 48,280 Total purchase price $ 119,930 The preliminary purchase price of City Index was allocated to the fair value of various assets and liabilities as follows (amounts in thousands): Cash and cash equivalents $ 32,991 Cash and securities held for customers 265,012 Receivable from brokers 35,974 Property and equipment 10,411 Prepaid assets 3,972 Other current assets 893 Total tangible assets 349,253 Total liabilities assumed 302,283 Net assets acquired 46,970 Identifiable intangible assets: Customer list 29,143 Trade name 6,339 Technology 24,583 Intangible assets, net 60,065 Goodwill $ 12,895 The foregoing purchase price allocation is preliminary. The final allocation will be based on final analyses of identifiable intangible assets and income taxes. It will be finalized after the data necessary to complete the analyses of fair value of assets and liabilities is obtained and analyzed. For the period from acquisition to June 30, 2015, revenues generated by City Index were $24.3 million and expenses were $30.7 million , generating losses before taxes of $6.4 million . The weighted average lives of City Index intangible assets are 9.0 years for customer lists, 7.0 years for trade names, and 6.9 years for technology. Galvan Research and Trading, Ltd. In July 2014, the Company acquired all the share capital of Galvan and its subsidiaries, Faraday Research LLP and Galvan LLP. The purchase price was $20.3 million . This acquisition was made to add an advisory capability to complement the Company's retail business. The purchase price was $9.7 million in cash and a contingent payment of $10.5 million payable over a three year period. The contingent payment is subject to a fair value assessment over the three year period. The contingent payment amount is subject to achieving specific financial and customer account targets. For the three months ended June 30, 2015, the Company adjusted the contingent payment's value (See Note 3). The purchase price was derived as follows (amounts in thousands): Cash $ 9,732 Contingent payment 10,540 Total purchase price $ 20,272 The purchase price of Galvan was allocated to the fair value of various assets and liabilities as follows (amounts in thousands): Cash and cash equivalents $ 2,193 Receivable from brokers 745 Property and equipment 12 Prepaid assets 94 Other current assets 64 Total tangible assets 3,108 Total liabilities assumed 1,931 Net assets acquired 1,177 Identifiable intangible assets: Customer list 4,203 Trade name 784 Intangible assets, net 4,987 Goodwill $ 14,108 Global Assets Advisors, LLC In March 2014, the Company acquired a 55% interest in GAA. The purchase price was $5.6 million . This acquisition was made to strengthen the Company's futures business. The purchase price was derived as follows (amounts in thousands): Cash $ 4,365 Common stock issued 1,241 Total purchase price $ 5,606 The purchase price of GAA was allocated to the fair value of various assets and liabilities as follows (amounts in thousands): Non-controlling interest $ 4,509 Cash and cash equivalents $ 360 Receivable from brokers 438 Property and equipment 148 Prepaid assets 153 Other current assets 3 Total tangible assets 1,102 Total liabilities assumed 515 Net assets acquired 587 Identifiable intangible assets: Customer list 3,100 Trade name 270 Intangible assets, net 3,370 Goodwill $ 6,158 Top Third Ag Marketing LLC In March 2014, the Company acquired a 55% interest in Top Third. The purchase price was a $3.5 million cash payment. This acquisition was made as part of the Company's strategy to diversify its revenue base. The purchase price of Top Third was allocated to the fair value of various assets and liabilities as follows (amounts in thousands): Non-controlling interest $ 3,885 Cash and cash equivalents $ 73 Receivable from brokers 663 Total tangible assets 736 Total liabilities assumed 1,103 Net assets acquired (367 ) Identifiable intangible assets: Customer list 3,900 Trade name 90 Intangible assets, net 3,990 Goodwill $ 3,806 Pro Forma Information: The following unaudited pro forma operating data is presented as if the acquisition of GAA, Top Third and Galvan had occurred on January 1, 2014. 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 the acquired companies operated as a combined entity for the periods presented. Unaudited pro forma income statement line items for the three and six months ended June 30, 2014 were as follows (amounts in thousands): For the Three Months Ended June 30, For the Six Months Ended June 30, 2014 2014 REVENUE: Total non-interest revenue $ 72,362 $ 158,008 Interest revenue 401 771 Interest expense 367 670 Total net interest revenue 34 101 Net revenue 72,396 158,109 EXPENSES: Depreciation and amortization 1,800 3,510 Purchased intangible amortization 1,674 3,193 Other expense items 73,594 151,285 Total operating expense 77,068 157,988 OPERATING (LOSS)/PROFIT (4,672 ) 121 Interest on long term borrowings 1,462 2,894 LOSS BEFORE INCOME TAX BENEFIT (6,134 ) (2,773 ) Income tax (benefit) / expense (2,427 ) 833 NET LOSS (3,707 ) (3,606 ) Net income attributable to non-controlling interests 164 196 Net loss applicable to Gain Capital Holdings, Inc. $ (3,871 ) $ (3,802 ) The following unaudited pro forma operating data is presented as if the acquisition of City Index had occurred on January 1, 2014, and includes actual results for GAA and Top Third for periods after its acquisition in March 2014, but does not reflect actual results for Galvan, which was acquired on July 1, 2014, or any other proforma adjustments for the GAA, Top Third or Galvan acquisitions. 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 six months ended June 30, 2015 and three and six months ended June 30, 2014 were as follows (amounts in thousands): For the Six Months Ended June 30, For the Three Months Ended June 30, For the Six Months Ended June 30, 2015 2014 2014 REVENUE: Total non-interest revenue $ 241,461 $ 94,674 $ 190,913 Interest revenue 734 614 855 Interest expense 627 142 222 Total net interest revenue 107 472 633 Net revenue 241,568 95,146 191,546 EXPENSES: Depreciation and amortization 5,360 3,249 2,378 Purchased intangible amortization 8,492 3,712 7,178 Other expense items 224,885 101,515 182,184 Total operating expense 238,737 108,476 191,740 OPERATING PROFIT/(LOSS) 2,831 (13,330 ) (194 ) Interest on long term borrowings 5,101 2,507 3,939 LOSS BEFORE INCOME TAX BENEFIT (2,270 ) (15,837 ) (4,133 ) Income tax benefit 215 (6,066 ) 324 NET LOSS (2,485 ) (9,771 ) (4,457 ) Net income attributable to non-controlling interests 760 164 202 Net loss applicable to Gain Capital Holdings, Inc. $ (3,245 ) $ (9,935 ) $ (4,659 ) Restructuring During the second quarter of 2015, the Company incurred restructuring expenses, which reflected the cost of reducing global headcount following the City Index acquisition. The Company previously incurred restructuring expenses in connection with headcount reductions in the third quarter of 2014 that were designed to meet challenging market conditions in the first half of 2014 and to achieve greater cost efficiency in general. The Company incurred $1.2 million of restructuring expenses for the twelve months ended December 31, 2014 . These expenses are recorded in Restructuring expenses in the condensed consolidated statements of operations and comprehensive income. For the Six Months Ended June 30, 2015 Restructuring liability as of January 1, 2015 $ 374 2015 restructuring expenses 1,935 Payments made in 2015 (1,608 ) Restructuring liability as of June 30, 2015 $ 701

NON-CONTROLLING INTERESTS (Note

NON-CONTROLLING INTERESTS (Notes)	6 Months Ended
	Jun. 30, 2015
Noncontrolling Interest [Abstract]
Non-Controlling Interests	NON-CONTROLLING INTERESTS 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 vested call options to purchase the remaining interests in each company. The minority owners hold put options, which vest 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 sheets. The non-controlling interests' carrying value is determined by the initial purchase prices for the acquired interests, the non-controlling interests' share of the acquired companies' subsequent net income, the non-controlling interests' share of the acquired companies' current net assets, and distributions to non-controlling interest holders. This value is benchmarked against the redemption value of the sellers' put options. The carrying values are adjusted to the latter, provided that they do 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 table below reflects the non-controlling interests' effects on the Company's financial statements (amounts in thousands): Redeemable non-controlling interests January 1, 2015 $ 11,338 Adjustment to the redemption value of non-controlling interests 1,441 Net income attributable to non-controlling interests 760 Distributions to non-controlling interest holders (756 ) June 30, 2015 $ 12,783

CONVERTIBLE SENIOR NOTES Conver

CONVERTIBLE SENIOR NOTES Convertible Senior Notes	6 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
CONVERTIBLE SENIOR NOTES	CONVERTIBLE SENIOR NOTES Convertible Senior Notes 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 will commence on October 1, 2015. 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, which commenced on June 1, 2014. 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 as of June 30, 2015 and December 31, 2014 were as follows (amounts in thousands): June 30, 2015 December 31, 2014 Liability component - principal $ 140,000 $ 80,000 Deferred bond discount (20,238 ) (11,633 ) Liability component - net carrying value $ 119,762 $ 68,367 Additional paid in capital $ 27,920 $ 12,572 Discount attributable to equity (425 ) (425 ) Equity component $ 27,495 $ 12,147 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): For the Three Months Ended June 30, For the Six Months Ended June 30, 2015 2014 2015 2014 Interest expense - stated coupon rate $ 1,443 $ 825 $ 2,268 $ 1,650 Interest expense - amortization of deferred bond discount and costs 1,023 531 1,611 1,054 Total interest expense - convertible senior notes $ 2,466 $ 1,356 $ 3,879 $ 2,704

EARNINGS PER COMMON SHARE

EARNINGS PER COMMON SHARE	6 Months Ended
	Jun. 30, 2015
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. Because of the loss for the three and six months ended June 30, 2015 and 2014, no shares were 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 7. The convertible senior notes due in 2018 and 2020 are not dilutive under present market conditions. Based upon an assumed trading price of $13 for each share of the Company's common stock, and if the relevant conditions under the indentures 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. For the convertible senior notes due in 2018 and in 2020, based on the Company's closing stock price as of June 30, 2015, there were no dilutive shares for the three and six months ended June 30, 2015 and 2014. 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 June 30, For the Six Months Ended June 30, 2015 2014 2015 2014 Net loss applicable to GAIN Capital Holdings, Inc. $ (7,118 ) $ (4,659 ) $ (1,654 ) $ (3,651 ) Adjustment to the redemption value of non-controlling interests (1) (917 ) (94 ) (1,441 ) (197 ) Loss available to common shareholders $ (8,035 ) $ (4,753 ) $ (3,095 ) $ (3,848 ) Weighted average common shares outstanding: Basic weighted average common shares outstanding 49,070,387 40,135,820 46,154,717 39,839,012 Effect of dilutive securities: Stock options — RSUs/RSAs — Diluted weighted average common shares outstanding 49,070,387 40,135,820 46,154,717 39,839,012 Net loss per common share: Basic $ (0.16 ) $ (0.12 ) $ (0.07 ) $ (0.10 ) Diluted $ (0.16 ) $ (0.12 ) $ (0.07 ) $ (0.10 ) (1) During the three and six months ended June 30, 2015 and 2014, the Company concluded that the value of the put options related to the Company's redeemable non-controlling interests in GAA and Top Third was less than redemption value. The adjustment to increase the carrying value reduces earnings available to the Company's shareholders for purposes of calculating basic and diluted net loss per common share.

LEGAL

LEGAL	6 Months Ended
	Jun. 30, 2015
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. 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 has 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. The parties are still in discovery. The Company can provide no assurances that this matter will be successfully resolved. This matter is currently pending. As of the date of this report, a potential loss or a potential range of loss cannot be reasonably estimated. Through the Company's acquisition of Open E Cry ("OEC"), the Company became the subject of a patent infringement lawsuit originally filed against OEC on February 9, 2010 in the U.S. District Court for the Northern District of Illinois by Trading Technologies International, Inc. ("Trading Technologies") seeking injunctive relief and unspecified damages. As reflected in a Second Amended Complaint filed on June 15, 2011, plaintiff alleged infringement of 12 patents relating to real-time display of price quotes and market depth on OEC's electronic trading interfaces. The case was consolidated with 11 related cases in February 2011, and the parties have exchanged infringement, non-infringement and invalidity contentions for several of the disputed patents. On May 6, 2015, the Company entered into a settlement and license agreement with Trading Technologies pursuant to which the Company made a one-time royalty payment to Trading Technologies in exchange for a volume-based license for the disputed patents. The Company was fully indemnified for the amount of the royalty payment by the former owner of OEC and therefore the Company incurred no net expense. The lawsuit was dismissed on May 6, 2015.

INCOME TAXES

INCOME TAXES	6 Months Ended
	Jun. 30, 2015
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The Company's benefit for income taxes was approximately $6.0 million and $0.3 million for the three and six months ended June 30, 2015, respectively. The Company’s benefit for income taxes was approximately $1.9 million and $0.9 million for the three and six months ended June 30, 2014, respectively. These amounts reflect effective tax rates of 47.4% and 30.0% , adjusted for certain discrete items, for the three months ended June 30, 2015 and 2014, respectively. The Company's effective tax rates of 24.7% and (33.3)% for the six months ended June 30, 2015 and 2014, respectively, 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 bases 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 sheets.

REGULATORY REQUIREMENTS

REGULATORY REQUIREMENTS	6 Months Ended
	Jun. 30, 2015
Banking and Thrift [Abstract]
REGULATORY REQUIREMENTS	REGULATORY REQUIREMENTS The following table illustrates the minimum regulatory capital our subsidiaries were required to maintain as of June 30, 2015 and the actual amounts of capital that were maintained (amounts in millions): Entity Name Minimum Capital Excess Percent of GAIN Capital Group, LLC $ 25.1 $ 32.6 $ 7.5 130 % GAIN Capital-Forex.com U.K., Ltd. 32.1 64.0 31.9 199 % Forex.com Japan Co., Ltd. 3.6 8.5 4.9 236 % GAIN Capital-Forex.com Hong Kong, Ltd. 1.9 2.7 0.8 142 % GFT Global Markets Asia Pte., Ltd. 0.7 3.1 2.4 443 % GAIN Capital Forex.com Australia, Pty. Ltd. 0.8 2.6 1.8 325 % Galvan Research and Trading, Ltd. 0.8 4.5 3.7 563 % GAIN Capital-Forex.com Canada Ltd. 0.2 1.5 1.3 750 % GAIN Capital Securities, Inc. 0.1 0.4 0.3 400 % GAIN Global Markets, Inc. 0.1 0.2 0.1 200 % GAIN Capital UK, Ltd. 1 41.6 94.1 52.5 226 % GAIN Capital Singapore Pte. Ltd. 1 0.7 3.2 2.5 457 % GAIN Capital Australia Pty Ltd. 1 0.8 1.8 1.0 225 % Global Assets Advisors, LLC 0.1 0.9 0.8 900 % Total $ 108.6 $ 220.1 $ 111.5 203 % (1) Entity acquired as part of the City Index acquisition.

SEGMENT INFORMATION

SEGMENT INFORMATION	6 Months Ended
	Jun. 30, 2015
Segment Reporting [Abstract]
SEGMENT INFORMATION	SEGMENT INFORMATION ASC 280, Disclosures about Segments of an Enterprise and Related Information , establishes standards for reporting information about operating segments. Operating segments are defined as components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision-maker, or decision making group, in deciding how to allocate resources and in assessing performance. Reportable segments are defined as an operating segment that either (a) exceeds 10% of revenue, (b) reported profit or loss in absolute amount exceeds 10% of profit of all operating segments that did not report a loss or (c) exceeds 10% of the combined assets of all operating segments. The Company’s operations relate to global trading services and solutions. Based on the Company’s management strategies, and common production, marketing, development and client coverage teams, the Company has concluded that it operates in a single operating segment.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	6 Months Ended
	Jun. 30, 2015
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS In August 2015, the Company announced the payment of a $ 0.05 dividend per share of Common Stock payable on September 23, 2015 to stockholders of record on September 14, 2015.

RESTATEMENT (Tables)

RESTATEMENT (Tables)	6 Months Ended
	Jun. 30, 2015
Accounting Changes and Error Corrections [Abstract]
Schedule of Prior Period Adjustments	Condensed Consolidated Balance Sheet As of June 30, 2015 As Reported Tax Adjustment Other Adjustments As Restated ASSETS: Goodwill 48,006 (3,278 ) — 44,728 Other assets, net of allowance for doubtful accounts 43,521 (318 ) (4,977 ) 38,226 Total assets $ 1,640,977 $ (3,596 ) $ (4,977 ) $ 1,632,404 LIABILITIES AND SHAREHOLDERS’ EQUITY: Liabilities Accrued compensation and benefits 8,462 — 203 8,665 Accrued expenses and other liabilities 53,933 13,484 (4,977 ) 62,440 Income tax payable 3,645 1,603 — 5,248 Total liabilities $ 1,295,208 $ 15,087 $ (4,774 ) $ 1,305,521 Shareholders’ equity Accumulated other comprehensive loss 5,237 541 — 5,778 Additional paid-in capital 221,577 (8,133 ) — 213,444 Retained earnings 123,292 (11,091 ) (203 ) 111,998 Total shareholders’ equity 332,986 (18,683 ) (203 ) 314,100 Total liabilities and shareholders’ equity $ 1,640,977 $ (3,596 ) $ (4,977 ) $ 1,632,404 As of December 31, 2014 As Reported Tax Adjustment Other Adjustments As Restated ASSETS: Cash and cash equivalents $ 139,403 $ — $ (52 ) $ 139,351 Goodwill 34,567 (988 ) — 33,579 Other assets, net of allowance for doubtful accounts 35,137 917 (2,463 ) 33,591 Total assets $ 1,185,887 $ (71 ) $ (2,515 ) $ 1,183,301 LIABILITIES AND SHAREHOLDERS’ EQUITY: Liabilities Accrued expenses and other liabilities 64,476 12,170 (451 ) 76,195 Income tax payable 1,470 1,603 (2,063 ) 1,010 Total liabilities $ 910,784 $ 13,773 $ (2,514 ) $ 922,043 Redeemable non-controlling interests 10,209 — 1,129 11,338 Shareholders’ equity Accumulated other comprehensive loss (2,054 ) 541 — (1,513 ) Additional paid-in capital 152,684 (4,306 ) — 148,378 Retained earnings 130,984 (10,079 ) (1,130 ) 119,775 Total shareholders’ equity 264,894 (13,844 ) (1,130 ) 249,920 Total liabilities and shareholders’ equity $ 1,185,887 $ (71 ) $ (2,515 ) $ 1,183,301 Condensed Consolidated Statements of Income and Comprehensive Income Three Months Ended June 30, 2015 As Reported Tax Adjustment Other Adjustments As Restated REVENUE: Retail revenue $ 97,335 $ — $ (107 ) $ 97,228 Total non-interest revenue 111,559 — (107 ) 111,452 Net revenue $ 111,564 $ — $ (107 ) $ 111,457 EXPENSES: Employee compensation and benefits $ 30,473 $ — $ 203 $ 30,676 Trading expenses 8,226 — (107 ) 8,119 Total operating expense 121,548 — 96 121,644 OPERATING LOSS (9,984 ) — (203 ) (10,187 ) LOSS BEFORE INCOME TAX EXPENSE (12,538 ) — (203 ) (12,741 ) Income tax (benefit)/expense (4,124 ) (1,915 ) — (6,039 ) NET LOSS (8,414 ) 1,915 (203 ) (6,702 ) NET LOSS APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. (8,830 ) 1,915 (203 ) (7,118 ) NET COMPREHENSIVE INCOME/(LOSS) APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. $ 710 $ 1,915 $ (203 ) $ 2,422 Loss per common share: Basic $ (0.23 ) $ (0.16 ) Diluted $ (0.23 ) $ (0.16 ) Weighted average common shares outstanding used in computing earnings per common share: Basic 49,070,783 49,070,387 Diluted 49,070,783 49,070,387 Six Months Ended June 30, 2015 As Reported Tax Adjustment Other Adjustments As Restated REVENUE: Retail revenue $ 181,575 $ — $ (73 ) $ 181,502 Total non-interest revenue 204,491 — (73 ) 204,418 Net revenue $ 204,515 $ — $ (73 ) $ 204,442 EXPENSES: Employee compensation and benefits $ 52,612 $ — $ 203 $ 52,815 Trading expenses 15,274 — (180 ) 15,094 General and administrative 23,463 — 51 23,514 Total operating expense 201,500 — 74 201,574 OPERATING PROFIT 3,015 — (147 ) 2,868 LOSS BEFORE INCOME TAX EXPENSE (1,041 ) — (147 ) (1,188 ) Income tax (benefit)/expense (1,306 ) 1,012 — (294 ) NET INCOME/(LOSS) 265 (1,012 ) (147 ) (894 ) NET LOSS APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. (495 ) (1,012 ) (147 ) (1,654 ) NET COMPREHENSIVE INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. $ 6,796 $ (1,012 ) $ (147 ) $ 5,637 Loss per common share: Basic $ (0.07 ) $ — $ — $ (0.07 ) Diluted $ (0.07 ) $ — $ — $ (0.07 ) Weighted average common shares outstanding used in computing earnings per common share: Basic 46,154,905 46,154,717 Diluted 46,154,905 46,154,717 Three Months Ended June 30, 2014 As Reported Tax Adjustment Other Adjustments As Restated REVENUE: Retail revenue $ 60,280 $ — $ 501 $ 60,781 Total non-interest revenue 69,504 — 501 70,005 Net revenue $ 69,763 $ — $ 501 $ 70,264 EXPENSES: — General and administrative 9,850 — 74 9,924 Purchased intangible amortization 1,574 — (165 ) 1,409 Total operating expense 75,314 — (91 ) 75,223 OPERATING (LOSS)/PROFIT (5,551 ) — 592 (4,959 ) (LOSS)/INCOME BEFORE INCOME TAX EXPENSE (7,013 ) — 592 (6,421 ) Income tax (benefit)/expense (2,021 ) 95 — (1,926 ) NET INCOME (4,992 ) (95 ) 592 (4,495 ) NET (LOSS)/INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. (5,156 ) (95 ) 592 (4,659 ) NET COMPREHENSIVE (LOSS)/INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. $ (3,739 ) $ (95 ) $ 592 $ (3,242 ) Loss per common share: Basic $ (0.13 ) $ — $ — $ (0.12 ) Diluted $ (0.13 ) $ — $ — $ (0.12 ) Six Months Ended June 30, 2014 As Reported Tax Adjustment Other Adjustments As Restated REVENUE: Retail revenue $ 132,766 $ — $ (174 ) $ 132,592 Total non-interest revenue 150,591 — (174 ) 150,417 Net revenue $ 151,133 $ — $ (174 ) $ 150,959 EXPENSES: Employee compensation and benefits $ 45,935 $ — $ (252 ) $ 45,683 Referral fees 41,225 — (120 ) 41,105 General and administrative 19,057 — 308 19,365 Depreciation and amortization 4,008 — (515 ) 3,493 Restructuring expenses 571 — 1,119 1,690 Total operating expense 150,113 — 540 150,653 OPERATING PROFIT/(LOSS) 1,020 — (714 ) 306 LOSS BEFORE INCOME TAX EXPENSE (1,874 ) — (714 ) (2,588 ) Income tax (benefit)/expense (745 ) 1,606 — 861 NET LOSS (1,129 ) (1,606 ) (714 ) (3,449 ) NET LOSS APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. (1,331 ) (1,606 ) (714 ) (3,651 ) NET COMPREHENSIVE INCOME/(LOSS) APPLICABLE TO GAIN CAPITAL HOLDINGS, INC. $ 1,388 $ (1,606 ) $ (714 ) $ (932 ) Loss per common share: Basic $ (0.04 ) $ — $ — $ (0.10 ) Diluted $ (0.04 ) $ — $ — $ (0.10 ) Condensed Statement of Changes in Shareholders' Equity Additional Paid in Capital Retained Earnings Accumulated Other Comprehensive Income/(Loss) Total As Reported As Restated As Reported As Restated As Reported As Restated As Reported As Restated BALANCE—December 31, 2014 $ 152,684 $ 148,378 $ 130,984 $ 119,775 $ (2,054 ) $ (1,513 ) $ 264,894 $ 249,920 BALANCE—June 30, 2015 $ 221,577 $ 213,444 $ 123,292 $ 111,998 $ 5,237 $ 5,778 $ 332,986 $ 314,100 Condensed Statement of Cash Flows Six Months Ended June 30, 2015 As Reported Adjustments As Restated CASH FLOWS FROM OPERATING ACTIVITIES: Net income $ 265 (1,159 ) $ (894 ) Adjustments to reconcile net income to cash provided by / (used for) operating activities — Deferred taxes (1,563 ) (897 ) (2,460 ) Changes in operating assets and liabilities: — Cash and securities held for customers (102,746 ) (737 ) (103,483 ) Receivables from brokers 12,486 (104 ) 12,382 Other assets (2,504 ) 5,319 2,815 Payables to customers 102,746 737 103,483 Accrued compensation and benefits (11,424 ) 212 (11,212 ) Accrued expenses and other liabilities (9,387 ) (3,076 ) (12,463 ) Income tax payable 2,223 (2,443 ) (220 ) Cash provided by / (used for) operating activities 16,861 (2,148 ) 14,713 Effect of exchange rate changes on cash and cash equivalents 2,916 2,200 5,116 INCREASE/ (DECREASE) IN CASH AND CASH EQUIVALENTS (4,381 ) 52 (4,329 ) CASH AND CASH EQUIVALENTS-Beginning of period 139,403 (52 ) 139,351 SUPPLEMENTARY DISCLOSURES OF CASH FLOW INFORMATION: Deferred taxes related to convertible senior notes $ — $ (3,827 ) $ (3,827 ) Adjustment to redemption value of non-controlling interests $ (2,570 ) $ 1,129 $ (1,441 ) Six Months Ended June 30, 2014 As Reported Adjustments As Restated CASH FLOWS FROM OPERATING ACTIVITIES: Net income $ (1,129 ) $ (2,320 ) $ (3,449 ) Adjustments to reconcile net income to cash provided by / (used for) operating activities Depreciation and amortization 6,621 (515 ) 6,106 Changes in operating assets and liabilities: Receivables from brokers (5,187 ) $ 353 (4,834 ) Other assets (5,034 ) $ (132 ) (5,166 ) Payables to customers 103,732 $ (100 ) 103,632 Accrued compensation and benefits (5,802 ) $ 832 (4,970 ) Accrued expenses and other liabilities (8,962 ) $ 710 (8,252 ) Income tax payable 1,624 $ 1,118 2,742 Cash provided by / (used for) operating activities (17,306 ) (54 ) (17,360 ) DECREASE IN CASH AND CASH EQUIVALENTS (26,938 ) (54 ) (26,992 ) CASH AND CASH EQUIVALENTS—End of period $ 12,933 $ (54 ) $ 12,879 SUPPLEMENTARY DISCLOSURES OF CASH FLOW INFORMATION: Adjustment to redemption value of non-controlling interests $ (173 ) $ (24 ) $ (197 )

ADDITIONAL FINANCIAL INFORMAT23

ADDITIONAL FINANCIAL INFORMATION (Tables)	6 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table presents the Company’s assets and liabilities that are 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 open contracts and other positions $ — $ 153,408 $ — $ 153,408 Broker open contracts and other positions — (28,358 ) — (28,358 ) Money market accounts 20,152 — — 20,152 Certificates of deposit 255 — — 255 Investment in gold 116 — 116 Contingent consideration — (6,031 ) (6,031 ) Total $ 20,523 $ 125,050 $ (6,031 ) $ 139,542 Fair Value Measurements on a Recurring Basis as of December 31, 2014 Level 1 Level 2 Level 3 Total Financial Assets/(Liabilities): Customer open contracts and other positions $ — $ 102,722 $ — $ 102,722 Broker open contracts and other positions — 717 — 717 Money market accounts 20,537 — — 20,537 Certificates of deposit 174 — — 174 Investment in gold 118 — — 118 Contingent consideration — — (9,974 ) (9,974 ) Total $ 20,829 $ 103,439 $ (9,974 ) $ 114,294
Rollforward of Level 3 Liabilities	The following is a rollforward of the Level 3 liabilities from January 1, 2015 to June 30, 2015 (amounts in thousands): Liabilities Contingent Consideration Balance at January 1, 2015 $ 9,974 Gains included in earnings - adjustment to fair value of contingent consideration (4,466 ) Gains included in earnings - currency revaluation 100 Losses included in earnings - discount amortization 423 Balance at June 30, 2015 $ 6,031
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 June 30, 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 $ 185,382 $ 185,382 $ — $ 185,382 $ — Financial Liabilities: Payables to customers 1,262,814 1,262,814 — 1,262,814 — Convertible senior notes 119,762 120,187 — 120,187 — Accrued expenses and other liabilities 1,366 1,366 — 1,366 — As of December 31, 2014 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 $ 134,191 $ 134,191 $ — $ 134,191 $ — Financial Liabilities: Payables to customers 862,281 862,281 — 862,281 — Convertible senior notes 68,367 66,440 — 66,440 — Accrued expenses and other liabilities 20,000 20,000 — 20,000 —
Receivable from Brokers	Amounts receivable from brokers consisted of the following as of (amounts in thousands): June 30, 2015 December 31, 2014 Required collateral $ 162,513 $ 95,599 Futures brokers - Restricted 22,869 38,592 Open positions (28,358 ) 717 $ 157,024 $ 134,908
Fair Values of Derivative Instruments	June 30, 2015 Derivative open positions at fair value Gross assets Gross liabilities Net assets Derivative Instruments: Foreign currency exchange contracts $ 136,209 $ 59,614 $ 76,595 CFD contracts 144,817 107,178 37,639 Metals contracts 15,721 4,905 10,816 Total $ 296,747 $ 171,697 $ 125,050 June 30, 2015 Net assets/liabilities at fair value Cash Collateral Derivative open positions Presented in the balance sheet Derivative Assets/Liabilities: Receivables from brokers $ 185,382 $ (28,358 ) $ 157,024 Payables to customers $ 1,262,814 $ 153,408 $ 1,109,406 December 31, 2014 Derivative open positions at fair value Gross Gross Net assets Derivative Instruments: Foreign currency exchange contracts $ 168,034 $ 93,057 $ 74,977 CFD contracts 44,329 24,420 19,909 Metals contracts 16,146 7,593 8,553 Total $ 228,509 $ 125,070 $ 103,439 December 31, 2014 Net assets/liabilities at fair value Cash Collateral Derivative Derivative Assets/Liabilities: Receivables from brokers $ 134,191 $ 717 $ 134,908 Payables to customers $ 862,281 $ 102,722 $ 759,559
Notional Values of Derivative Instruments	The table below represents the number of contracts underlying amounts reported within Receivables from brokers and Payables to customers on the condensed consolidated balance sheets (amounts in thousands): June 30, 2015 Total contracts in long positions Total contracts in short positions Derivative Instruments: Foreign currency exchange contracts 2,824,897 3,073,585 CFD contracts 478,704 106,087 Metals contracts 3,505 2,572 Total 3,307,106 3,182,244 December 31, 2014 Total contracts in long positions Total contracts in short positions Derivative Instruments: Foreign currency exchange contracts 3,147,518 2,679,041 CFD contracts 873,070 10,753 Metals contracts 835 335 Total 4,021,423 2,690,129
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 and six months ended June 30, 2015 and 2014 were as follows (amounts in thousands): Three Months Ended June 30, Six Months Ended June 30, 2015 2014 2015 2014 Derivative Instruments: Foreign currency exchange contracts $ 61,587 $ 15,974 $ 97,659 $ 56,798 CFD contracts 13,523 13,289 37,864 17,493 Metals contracts 5,721 7,680 11,527 13,181 Total $ 80,831 $ 36,943 $ 147,050 $ 87,472
Property and Equipment Including Leasehold Improvements and Capitalized Software Development Costs	Property and equipment consisted of the following as of (amounts in thousands): June 30, 2015 December 31, 2014 Software $ 28,938 $ 30,351 Computer equipment 13,691 8,516 Leasehold improvements 10,375 6,719 Telephone equipment 717 719 Office equipment 2,209 2,345 Furniture and fixtures 1,572 1,044 Web site development costs 9,254 646 66,756 50,340 Less: Accumulated depreciation and amortization (38,943 ) (31,544 ) Property and equipment, net $ 27,813 $ 18,796
Intangible Assets	The Company's various intangible assets consisted of the following as of (amounts in thousands): June 30, 2015 December 31, 2014 Intangibles Gross Accumulated Net Gross Accumulated Net Customer lists $ 53,432 $ (9,396 ) $ 44,036 $ 22,945 $ (7,152 ) $ 15,793 Technology 74,424 (14,623 ) 59,801 48,376 (4,671 ) 43,705 Trademarks 8,445 (1,116 ) 7,329 1,793 (847 ) 946 Total finite lived intangibles 136,301 (25,135 ) 111,166 73,114 (12,670 ) 60,444 Trademark not subject to amortization (1) 362 — 362 362 — 362 Total intangibles (2) $ 136,663 $ (25,135 ) $ 111,528 $ 73,476 $ (12,670 ) $ 60,806 (1) These indefinite-life trademarks relate to the Forex.com and foreignexchange.com domain names. Management determined there was no legal, regulatory or technological limitation on the domains' useful lives. The trademarks' values are evaluated annually in the Company's impairment test for intangible assets. (2) The increase in total intangibles for the six months ended June 30, 2015 is primarily due to the customer lists, technology and trademarks acquired as part of the City Index acquisition. See Note 5 for details of the intangibles acquired from the Company's City Index, GAA, Top Third and Galvan acquisitions. The technology acquired from the asset purchase agreements with Valaquenta Intellectual Property Limited ("Valaquenta") and Forexster Limited ("Forexster") is described in further detail below. The Company has the following gross identifiable intangible assets as of June 30, 2015: Intangible Assets Amount (in thousands) Weighted average amortization period Customer lists $ 53,432 8.1 years Technology 74,424 8.9 years Trademarks (1) 8,807 6.7 years $ 136,663 (1) Trademarks with an indefinite-life, as described above, comprise $0.4 million of the $8.8 million of trademarks.
Future Annual Estimated Purchased Intangible Amortization Expense	Future annual estimated purchased intangible amortization expense is as follows (amounts in thousands): Years Ended December 31: 2015 $ 21,700 2016 14,501 2017 13,189 2018 12,073 2019 11,489 Thereafter 38,214 Total $ 111,166
Other Assets	Other assets consisted of the following as of (amounts in thousands): June 30, 2015 December 31, 2014 Vendor and security deposits $ 4,944 $ 3,373 Current tax receivable 8,883 5,163 Deferred tax assets 10,517 6,308 Indemnification asset — 8,792 GTX trade receivables 4,347 4,190 Customer debit positions 7,311 6,594 Allowance for doubtful customer debit positions (5,602 ) (4,555 ) Acquisition related receivable 7,065 — Miscellaneous receivables and other assets 761 3,726 $ 38,226 $ 33,591

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	6 Months Ended
	Jun. 30, 2015
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Schedule of Restructuring Costs	For the Six Months Ended June 30, 2015 Restructuring liability as of January 1, 2015 $ 374 2015 restructuring expenses 1,935 Payments made in 2015 (1,608 ) Restructuring liability as of June 30, 2015 $ 701
City Index
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Preliminary Purchase Price	The preliminary purchase price was derived as follows (amounts in thousands): Cash $ 6,650 Convertible senior notes 65,000 Common stock issued (based on the April 1, 2015 quoted price of $9.77) 48,280 Total purchase price $ 119,930
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The preliminary purchase price of City Index was allocated to the fair value of various assets and liabilities as follows (amounts in thousands): Cash and cash equivalents $ 32,991 Cash and securities held for customers 265,012 Receivable from brokers 35,974 Property and equipment 10,411 Prepaid assets 3,972 Other current assets 893 Total tangible assets 349,253 Total liabilities assumed 302,283 Net assets acquired 46,970 Identifiable intangible assets: Customer list 29,143 Trade name 6,339 Technology 24,583 Intangible assets, net 60,065 Goodwill $ 12,895
Pro Forma Information	Unaudited pro forma income statement line items for the six months ended June 30, 2015 and three and six months ended June 30, 2014 were as follows (amounts in thousands): For the Six Months Ended June 30, For the Three Months Ended June 30, For the Six Months Ended June 30, 2015 2014 2014 REVENUE: Total non-interest revenue $ 241,461 $ 94,674 $ 190,913 Interest revenue 734 614 855 Interest expense 627 142 222 Total net interest revenue 107 472 633 Net revenue 241,568 95,146 191,546 EXPENSES: Depreciation and amortization 5,360 3,249 2,378 Purchased intangible amortization 8,492 3,712 7,178 Other expense items 224,885 101,515 182,184 Total operating expense 238,737 108,476 191,740 OPERATING PROFIT/(LOSS) 2,831 (13,330 ) (194 ) Interest on long term borrowings 5,101 2,507 3,939 LOSS BEFORE INCOME TAX BENEFIT (2,270 ) (15,837 ) (4,133 ) Income tax benefit 215 (6,066 ) 324 NET LOSS (2,485 ) (9,771 ) (4,457 ) Net income attributable to non-controlling interests 760 164 202 Net loss applicable to Gain Capital Holdings, Inc. $ (3,245 ) $ (9,935 ) $ (4,659 )
Galvan Research and Trading, Ltd.
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Preliminary Purchase Price	The purchase price was derived as follows (amounts in thousands): Cash $ 9,732 Contingent payment 10,540 Total purchase price $ 20,272
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The purchase price of Galvan was allocated to the fair value of various assets and liabilities as follows (amounts in thousands): Cash and cash equivalents $ 2,193 Receivable from brokers 745 Property and equipment 12 Prepaid assets 94 Other current assets 64 Total tangible assets 3,108 Total liabilities assumed 1,931 Net assets acquired 1,177 Identifiable intangible assets: Customer list 4,203 Trade name 784 Intangible assets, net 4,987 Goodwill $ 14,108
Global Assets Advisors, LLC
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Preliminary Purchase Price	The purchase price was derived as follows (amounts in thousands): Cash $ 4,365 Common stock issued 1,241 Total purchase price $ 5,606
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The purchase price of GAA was allocated to the fair value of various assets and liabilities as follows (amounts in thousands): Non-controlling interest $ 4,509 Cash and cash equivalents $ 360 Receivable from brokers 438 Property and equipment 148 Prepaid assets 153 Other current assets 3 Total tangible assets 1,102 Total liabilities assumed 515 Net assets acquired 587 Identifiable intangible assets: Customer list 3,100 Trade name 270 Intangible assets, net 3,370 Goodwill $ 6,158
Top Third Ag Marketing, LLC
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The purchase price of Top Third was allocated to the fair value of various assets and liabilities as follows (amounts in thousands): Non-controlling interest $ 3,885 Cash and cash equivalents $ 73 Receivable from brokers 663 Total tangible assets 736 Total liabilities assumed 1,103 Net assets acquired (367 ) Identifiable intangible assets: Customer list 3,900 Trade name 90 Intangible assets, net 3,990 Goodwill $ 3,806
Top Third Ag Marketing, LLC, Global Assets Advisors, LLC, and Galvan Research and Trading, Ltd [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Pro Forma Information	Unaudited pro forma income statement line items for the three and six months ended June 30, 2014 were as follows (amounts in thousands): For the Three Months Ended June 30, For the Six Months Ended June 30, 2014 2014 REVENUE: Total non-interest revenue $ 72,362 $ 158,008 Interest revenue 401 771 Interest expense 367 670 Total net interest revenue 34 101 Net revenue 72,396 158,109 EXPENSES: Depreciation and amortization 1,800 3,510 Purchased intangible amortization 1,674 3,193 Other expense items 73,594 151,285 Total operating expense 77,068 157,988 OPERATING (LOSS)/PROFIT (4,672 ) 121 Interest on long term borrowings 1,462 2,894 LOSS BEFORE INCOME TAX BENEFIT (6,134 ) (2,773 ) Income tax (benefit) / expense (2,427 ) 833 NET LOSS (3,707 ) (3,606 ) Net income attributable to non-controlling interests 164 196 Net loss applicable to Gain Capital Holdings, Inc. $ (3,871 ) $ (3,802 )

NON-CONTROLLING INTERESTS (Tabl

NON-CONTROLLING INTERESTS (Tables)	6 Months Ended
	Jun. 30, 2015
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, 2015 $ 11,338 Adjustment to the redemption value of non-controlling interests 1,441 Net income attributable to non-controlling interests 760 Distributions to non-controlling interest holders (756 ) June 30, 2015 $ 12,783

CONVERTIBLE SENIOR NOTES Conv26

CONVERTIBLE SENIOR NOTES Convertible Senior Notes (Tables)	6 Months Ended
	Jun. 30, 2015
Debt Disclosure [Abstract]
Schedule of Liability and Equity Components of Convertible Debt	The balances of the liability and equity components as of June 30, 2015 and December 31, 2014 were as follows (amounts in thousands): June 30, 2015 December 31, 2014 Liability component - principal $ 140,000 $ 80,000 Deferred bond discount (20,238 ) (11,633 ) Liability component - net carrying value $ 119,762 $ 68,367 Additional paid in capital $ 27,920 $ 12,572 Discount attributable to equity (425 ) (425 ) Equity component $ 27,495 $ 12,147
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): For the Three Months Ended June 30, For the Six Months Ended June 30, 2015 2014 2015 2014 Interest expense - stated coupon rate $ 1,443 $ 825 $ 2,268 $ 1,650 Interest expense - amortization of deferred bond discount and costs 1,023 531 1,611 1,054 Total interest expense - convertible senior notes $ 2,466 $ 1,356 $ 3,879 $ 2,704

EARNINGS PER COMMON SHARE (Tabl

EARNINGS PER COMMON SHARE (Tables)	6 Months Ended
	Jun. 30, 2015
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 June 30, For the Six Months Ended June 30, 2015 2014 2015 2014 Net loss applicable to GAIN Capital Holdings, Inc. $ (7,118 ) $ (4,659 ) $ (1,654 ) $ (3,651 ) Adjustment to the redemption value of non-controlling interests (1) (917 ) (94 ) (1,441 ) (197 ) Loss available to common shareholders $ (8,035 ) $ (4,753 ) $ (3,095 ) $ (3,848 ) Weighted average common shares outstanding: Basic weighted average common shares outstanding 49,070,387 40,135,820 46,154,717 39,839,012 Effect of dilutive securities: Stock options — RSUs/RSAs — Diluted weighted average common shares outstanding 49,070,387 40,135,820 46,154,717 39,839,012 Net loss per common share: Basic $ (0.16 ) $ (0.12 ) $ (0.07 ) $ (0.10 ) Diluted $ (0.16 ) $ (0.12 ) $ (0.07 ) $ (0.10 ) (1) During the three and six months ended June 30, 2015 and 2014, the Company concluded that the value of the put options related to the Company's redeemable non-controlling interests in GAA and Top Third was less than redemption value. The adjustment to increase the carrying value reduces earnings available to the Company's shareholders for purposes of calculating basic and diluted net loss per common share.

REGULATORY REQUIREMENTS (Tables

REGULATORY REQUIREMENTS (Tables)	6 Months Ended
	Jun. 30, 2015
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 June 30, 2015 and the actual amounts of capital that were maintained (amounts in millions): Entity Name Minimum Capital Excess Percent of GAIN Capital Group, LLC $ 25.1 $ 32.6 $ 7.5 130 % GAIN Capital-Forex.com U.K., Ltd. 32.1 64.0 31.9 199 % Forex.com Japan Co., Ltd. 3.6 8.5 4.9 236 % GAIN Capital-Forex.com Hong Kong, Ltd. 1.9 2.7 0.8 142 % GFT Global Markets Asia Pte., Ltd. 0.7 3.1 2.4 443 % GAIN Capital Forex.com Australia, Pty. Ltd. 0.8 2.6 1.8 325 % Galvan Research and Trading, Ltd. 0.8 4.5 3.7 563 % GAIN Capital-Forex.com Canada Ltd. 0.2 1.5 1.3 750 % GAIN Capital Securities, Inc. 0.1 0.4 0.3 400 % GAIN Global Markets, Inc. 0.1 0.2 0.1 200 % GAIN Capital UK, Ltd. 1 41.6 94.1 52.5 226 % GAIN Capital Singapore Pte. Ltd. 1 0.7 3.2 2.5 457 % GAIN Capital Australia Pty Ltd. 1 0.8 1.8 1.0 225 % Global Assets Advisors, LLC 0.1 0.9 0.8 900 % Total $ 108.6 $ 220.1 $ 111.5 203 % (1) Entity acquired as part of the City Index acquisition.

RESTATEMENT - Additional Inform

RESTATEMENT - Additional Information (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings	$ (111,998)	$ (119,775)
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings	(123,292)	$ (130,984)
Out of Period Adjustment | As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings	1,300
Out of Period Adjustment | Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Adjustment to redemption value of noncontrolling interest	$ 1,300

RESTATEMENT - Condensed Consoli

RESTATEMENT - Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cash and cash equivalents	$ 135,022	$ 139,351	$ 12,879	$ 39,871
Goodwill	44,728	33,579
Other assets, net of allowance for doubtful accounts	38,226	33,591
Total assets	1,632,404	1,183,301
Accrued compensation and benefits	8,665	16,912
Accrued expenses and other liabilities	62,440	76,195
Income tax payable	5,248	1,010
Total liabilities	1,305,521	922,043
Redeemable noncontrolling interests	12,783	11,338
Accumulated other comprehensive income/(loss)	5,778	(1,513)
Additional paid-in capital	213,444	148,378
Retained earnings	111,998	119,775
Total shareholders’ equity	314,100	249,920
Total liabilities and shareholders’ equity	1,632,404	1,183,301
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cash and cash equivalents		139,403	12,933
Goodwill	48,006	34,567
Other assets, net of allowance for doubtful accounts	43,521	35,137
Total assets	1,640,977	1,185,887
Accrued compensation and benefits	8,462
Accrued expenses and other liabilities	53,933	64,476
Income tax payable	3,645	1,470
Total liabilities	1,295,208	910,784
Redeemable noncontrolling interests		10,209
Accumulated other comprehensive income/(loss)	5,237	(2,054)
Additional paid-in capital	221,577	152,684
Retained earnings	123,292	130,984
Total shareholders’ equity	332,986	264,894
Total liabilities and shareholders’ equity	1,640,977	1,185,887
Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cash and cash equivalents		(52)	$ (54)
Tax Adjustment | Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cash and cash equivalents		0
Goodwill	(3,278)	(988)
Other assets, net of allowance for doubtful accounts	(318)	917
Total assets	(3,596)	(71)
Accrued compensation and benefits	0
Accrued expenses and other liabilities	13,484	12,170
Income tax payable	1,603	1,603
Total liabilities	15,087	13,773
Redeemable noncontrolling interests		0
Accumulated other comprehensive income/(loss)	541	541
Additional paid-in capital	(8,133)	(4,306)
Retained earnings	(11,091)	(10,079)
Total shareholders’ equity	(18,683)	(13,844)
Total liabilities and shareholders’ equity	(3,596)	(71)
Other Adjustments | Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cash and cash equivalents		(52)
Goodwill	0	0
Other assets, net of allowance for doubtful accounts	(4,977)	(2,463)
Total assets	(4,977)	(2,515)
Accrued compensation and benefits	203
Accrued expenses and other liabilities	(4,977)	(451)
Income tax payable	0	(2,063)
Total liabilities	(4,774)	(2,514)
Redeemable noncontrolling interests		1,129
Accumulated other comprehensive income/(loss)	0	0
Additional paid-in capital	0	0
Retained earnings	(203)	(1,130)
Total shareholders’ equity	(203)	(1,130)
Total liabilities and shareholders’ equity	$ (4,977)	$ (2,515)

RESTATEMENT - Condensed Conso31

RESTATEMENT - Condensed Consolidated Statements of Income and Comprehensive Income (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retail revenue	$ 97,228	$ 60,781	$ 181,502	$ 132,592
Total non-interest revenue	111,452	70,005	204,418	150,417
Net revenue	111,457	70,264	204,442	150,959
Employee compensation and benefits	30,676	24,093	52,815	45,683
Referral fees	29,539	20,537	56,117	41,105
Trading expenses	8,119	7,169	15,094	14,057
General and administrative	14,143	9,924	23,514	19,365
Depreciation and amortization	2,738	1,798	4,713	3,493
Purchased intangible amortization	4,257	1,409	6,408	2,613
Restructuring	1,935	212	1,935	1,690	$ 1,200
Total operating expense	121,644	75,223	201,574	150,653
OPERATING PROFIT	(10,187)	(4,959)	2,868	306
LOSS BEFORE INCOME TAX EXPENSE	(12,741)	(6,421)	(1,188)	(2,588)
Income tax (benefit)/expense	(6,039)	(1,926)	(294)	861
NET INCOME/(LOSS)	(6,702)	(4,495)	(894)	(3,449)
Net loss applicable to Gain Capital Holdings, Inc.	(7,118)	(4,659)	(1,654)	(3,651)
NET COMPREHENSIVE INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC.	$ 2,422	$ (3,242)	$ 5,637	$ (932)
Basic (usd per share)	$ (0.16)	$ (0.12)	$ (0.07)	$ (0.10)
Diluted (usd per share)	$ (0.16)	$ (0.12)	$ (0.07)	$ (0.10)
Basic (shares)	49,070,387	40,135,820	46,154,717	39,839,012
Diluted (shares)	49,070,387	40,135,820	46,154,717	39,839,012
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retail revenue	$ 97,335	$ 60,280	$ 181,575	$ 132,766
Total non-interest revenue	111,559	69,504	204,491	150,591
Net revenue	111,564	69,763	204,515	151,133
Employee compensation and benefits	30,473		52,612	45,935
Referral fees				41,225
Trading expenses	8,226		15,274
General and administrative		9,850	23,463	19,057
Depreciation and amortization				4,008
Purchased intangible amortization		1,574
Restructuring				571
Total operating expense	121,548	75,314	201,500	150,113
OPERATING PROFIT	(9,984)	(5,551)	3,015	1,020
LOSS BEFORE INCOME TAX EXPENSE	(12,538)	(7,013)	(1,041)	(1,874)
Income tax (benefit)/expense	(4,124)	(2,021)	(1,306)	(745)
NET INCOME/(LOSS)	(8,414)	(4,992)	265	(1,129)
Net loss applicable to Gain Capital Holdings, Inc.	(8,830)	(5,156)	(495)	(1,331)
NET COMPREHENSIVE INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC.	$ 710	$ (3,739)	$ 6,796	$ 1,388
Basic (usd per share)	$ (0.23)	$ (0.13)	$ (0.07)	$ (0.04)
Diluted (usd per share)	$ (0.23)	$ (0.13)	$ (0.07)	$ (0.04)
Basic (shares)	49,070,783		46,154,905
Diluted (shares)	49,070,783		46,154,905
Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
NET INCOME/(LOSS)			$ (1,159)	$ (2,320)
Tax Adjustment | Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retail revenue	$ 0	$ 0	0	0
Total non-interest revenue	0	0	0	0
Net revenue	0	0	0	0
Employee compensation and benefits	0		0	0
Referral fees				0
Trading expenses	0		0
General and administrative		0	0	0
Depreciation and amortization				0
Purchased intangible amortization		0
Restructuring				0
Total operating expense	0	0	0	0
OPERATING PROFIT	0	0	0	0
LOSS BEFORE INCOME TAX EXPENSE	0	0	0	0
Income tax (benefit)/expense	(1,915)	95	1,012	1,606
NET INCOME/(LOSS)	1,915	(95)	(1,012)	(1,606)
Net loss applicable to Gain Capital Holdings, Inc.	1,915	(95)	(1,012)	(1,606)
NET COMPREHENSIVE INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC.	1,915	$ (95)	$ (1,012)	$ (1,606)
Basic (usd per share)		$ 0	$ 0	$ 0
Diluted (usd per share)		$ 0	$ 0	$ 0
Other Adjustments | Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retail revenue	(107)	$ 501	$ (73)	$ (174)
Total non-interest revenue	(107)	501	(73)	(174)
Net revenue	(107)	501	(73)	(174)
Employee compensation and benefits	203		203	(252)
Referral fees				(120)
Trading expenses	(107)		(180)
General and administrative		74	51	308
Depreciation and amortization				(515)
Purchased intangible amortization		(165)
Restructuring				1,119
Total operating expense	96	(91)	74	540
OPERATING PROFIT	(203)	592	(147)	(714)
LOSS BEFORE INCOME TAX EXPENSE	(203)	592	(147)	(714)
Income tax (benefit)/expense	0	0	0	0
NET INCOME/(LOSS)	(203)	592	(147)	(714)
Net loss applicable to Gain Capital Holdings, Inc.	(203)	592	(147)	(714)
NET COMPREHENSIVE INCOME APPLICABLE TO GAIN CAPITAL HOLDINGS, INC.	$ (203)	$ 592	$ (147)	$ (714)
Basic (usd per share)		$ 0	$ 0	$ 0
Diluted (usd per share)		$ 0	$ 0	$ 0

RESTATEMENT - Condensed Stateme

RESTATEMENT - Condensed Statement of Changes in Shareholders' Equity (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Shareholders' equity	$ 314,100	$ 249,920
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Shareholders' equity	332,986	264,894
Additional Paid in Capital
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Shareholders' equity	213,444	148,378
Additional Paid in Capital | As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Shareholders' equity	221,577	152,684
Retained Earnings
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Shareholders' equity	111,998	119,775
Retained Earnings | As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Shareholders' equity	123,292	130,984
Accumulated Other Comprehensive (Loss)
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Shareholders' equity	5,778	(1,513)
Accumulated Other Comprehensive (Loss) | As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Shareholders' equity	$ 5,237	$ (2,054)

RESTATEMENT - Condensed State33

RESTATEMENT - Condensed Statement of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income/(loss)	$ (6,702)	$ (4,495)	$ (894)	$ (3,449)
Depreciation and amortization			11,121	6,106
Deferred taxes			(2,460)	(3,379)
Cash and securities held for customers			(103,483)	(103,732)
Receivables from brokers			12,382	(4,834)
Other assets			2,815	(5,166)
Payables to customers			103,483	103,632
Accrued compensation and benefits			(11,212)	(4,970)
Accrued expenses and other liabilities			(12,463)	(8,252)
Income tax payable			(220)	2,742
Cash provided by / (used for) operating activities			14,713	(17,360)
Effect of exchange rate changes on cash and cash equivalents			5,116	3,181
INCREASE/ (DECREASE) IN CASH AND CASH EQUIVALENTS			(4,329)	(26,992)
Deferred taxes related to convertible senior notes			(3,827)
CASH AND CASH EQUIVALENTS—End of period	135,022	12,879	135,022	12,879	$ 139,351	$ 39,871
Adjustment to the redemption value of non-controlling interests			(1,441)	(197)
As Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income/(loss)	$ (8,414)	(4,992)	265	(1,129)
Depreciation and amortization				6,621
Deferred taxes			(1,563)
Cash and securities held for customers			(102,746)
Receivables from brokers			12,486	(5,187)
Other assets			(2,504)	(5,034)
Payables to customers			102,746	103,732
Accrued compensation and benefits			(11,424)	(5,802)
Accrued expenses and other liabilities			(9,387)	(8,962)
Income tax payable			2,223	1,624
Cash provided by / (used for) operating activities			16,861	(17,306)
Effect of exchange rate changes on cash and cash equivalents			2,916
INCREASE/ (DECREASE) IN CASH AND CASH EQUIVALENTS			(4,381)	(26,938)
Deferred taxes related to convertible senior notes			0
CASH AND CASH EQUIVALENTS—End of period		12,933		12,933	139,403
Adjustment to the redemption value of non-controlling interests			(2,570)	(173)
Adjustments
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income/(loss)			(1,159)	(2,320)
Depreciation and amortization				(515)
Deferred taxes			(897)
Cash and securities held for customers			(737)
Receivables from brokers			(104)	353
Other assets			5,319	(132)
Payables to customers			737	(100)
Accrued compensation and benefits			212	832
Accrued expenses and other liabilities			(3,076)	710
Income tax payable			(2,443)	1,118
Cash provided by / (used for) operating activities			(2,148)	(54)
Effect of exchange rate changes on cash and cash equivalents			2,200
INCREASE/ (DECREASE) IN CASH AND CASH EQUIVALENTS			52	(54)
Deferred taxes related to convertible senior notes			(3,827)
CASH AND CASH EQUIVALENTS—End of period		$ (54)		(54)	$ (52)
Adjustment to the redemption value of non-controlling interests			$ 1,129	$ (24)

ADDITIONAL FINANCIAL INFORMAT34

ADDITIONAL FINANCIAL INFORMATION - Additional Information (Detail) - USD ($) $ in Thousands	Apr. 01, 2015	Jul. 10, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Business Acquisition [Line Items]
Depreciation and amortization expense			$ 2,738	$ 1,798	$ 4,713	$ 3,493
Integration costs related to property and equipment			3,700		3,700
Common stock issued as consideration for asset and business acquisitions					(48,280)	1,241
Purchased intangible amortization			4,257	1,409	6,408	2,613
Integration costs related to intangible assets			6,500		6,500
Future amortization expense expected to be recorded as integration expense			13,000		13,000
Goodwill			44,728		44,728		$ 33,579
Increase in goodwill					11,100
Payment against Holdback liability					9,900
Accrued Expenses and Other Liabilities
Business Acquisition [Line Items]
Holdback liability, net of indemnification asset			1,400		1,400
Global Futures & Forex Ltd
Business Acquisition [Line Items]
Contingent consideration liability			1,400		1,400		20,000
Holdback amount			$ 20,000		20,000
Indemnification Asset							$ 8,800
City Index
Business Acquisition [Line Items]
Depreciation and amortization expense				3,249	5,360	2,378
Cash payment	$ 6,650
Common stock issued as consideration for asset and business acquisitions	48,280
Purchased intangible amortization				$ 3,712	$ 8,492	$ 7,178
Goodwill	$ 12,895
Forexster Limited Asset Acquisition [Member]
Business Acquisition [Line Items]
Cash payment		$ 12,400
Common stock issued as consideration for asset and business acquisitions		5,300
Intangible assets acquired		21,400
Intangible assets previously held as a prepayment		$ 3,700
Useful life of asset		10 years

ADDITIONAL FINANCIAL INFORMAT35

ADDITIONAL FINANCIAL INFORMATION - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets (liabilities)	$ 139,542	$ 114,294
Customer open contracts and other positions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	153,408	102,722
Broker open contracts and other positions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		717
Liabilities	(28,358)
Money market accounts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	20,152	20,537
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	255	174
Investment in gold
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	116	118
Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	(6,031)	(9,974)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets (liabilities)	20,523	20,829
Level 1 | Customer open contracts and other positions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 1 | Broker open contracts and other positions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		0
Liabilities	0
Level 1 | Money market accounts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	20,152	20,537
Level 1 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	255	174
Level 1 | Investment in gold
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	116	118
Level 1 | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets (liabilities)	125,050	103,439
Level 2 | Customer open contracts and other positions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	153,408	102,722
Level 2 | Broker open contracts and other positions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		717
Liabilities	(28,358)
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 2 | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities		0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets (liabilities)	$ (6,031)	(9,974)
Level 3 | Customer open contracts and other positions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets	0	0
Level 3 | Broker open contracts and other positions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets		0
Liabilities	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
Level 3 | Contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liabilities	$ (6,031)	$ (9,974)

ADDITIONAL FINANCIAL INFORMAT36

ADDITIONAL FINANCIAL INFORMATION - Reconciliation of Unobservable Level 3 Inputs (Details) - Contingent Payments [Member] $ in Thousands	6 Months Ended
	Jun. 30, 2015USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 9,974
Gains included in earnings - adjustment to fair value of contingent consideration	(4,466)
Gains included in earnings - currency revaluation	100
Losses included in earnings - discount amortization	423
Ending balance	$ 6,031

ADDITIONAL FINANCIAL INFORMAT37

ADDITIONAL FINANCIAL INFORMATION - 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 (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Financial Assets:
Receivable from banks and brokers	$ 157,024	$ 134,908
Financial Liabilities:
Convertible senior notes	119,762	68,367
Derivative Assets
Financial Assets:
Receivable from banks and brokers		134,908
Derivative Assets | Level 2
Financial Assets:
Receivable from banks and brokers	185,382	134,191
Derivative Assets | Carrying Value
Financial Assets:
Receivable from banks and brokers	185,382	134,191
Derivative Assets | Fair Value
Financial Assets:
Receivable from banks and brokers	185,382	134,191
Derivative Liabilities
Financial Liabilities:
Derivative, Collateral, Obligation to Return Cash		862,281
Derivative Liabilities | Level 2
Financial Liabilities:
Derivative, Collateral, Obligation to Return Cash	1,262,814	862,281
Convertible senior notes	120,187	66,440
Accrued Liabilities, Current	1,366	20,000
Derivative Liabilities | Carrying Value
Financial Liabilities:
Derivative, Collateral, Obligation to Return Cash	1,262,814	862,281
Convertible senior notes	119,762	68,367
Accrued Liabilities, Current	1,366	20,000
Derivative Liabilities | Fair Value
Financial Liabilities:
Derivative, Collateral, Obligation to Return Cash	1,262,814	862,281
Convertible senior notes	120,187	66,440
Accrued Liabilities, Current	$ 1,366	$ 20,000

ADDITIONAL FINANCIAL INFORMAT38

ADDITIONAL FINANCIAL INFORMATION - Receivable from Brokers (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Receivables from Brokerage Clients [Line Items]
Receivable from banks and brokers	$ 157,024	$ 134,908
Required collateral
Receivables from Brokerage Clients [Line Items]
Receivable from banks and brokers	162,513	95,599
Excess From Futures Broker - Restricted [Member]
Receivables from Brokerage Clients [Line Items]
Receivable from banks and brokers	22,869	38,592
Open Position
Receivables from Brokerage Clients [Line Items]
Receivable from banks and brokers	$ (28,358)	$ 717

ADDITIONAL FINANCIAL INFORMAT39

ADDITIONAL FINANCIAL INFORMATION - Fair Values of Derivative Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Gross amounts of assets for derivative open positions at fair value	$ 296,747	$ 228,509
Gross amounts of liability for derivative open positions at fair value	171,697	125,070
Net amounts of assets/liabilities for derivative open positions at fair value	125,050	103,439
Receivable from banks and brokers	157,024	134,908
Net amounts of assets/liabilities presented in the balance sheet		759,559
Payables to customers	1,109,406	759,559
Derivative Assets
Derivatives, Fair Value [Line Items]
Cash Collateral		134,191
Net amounts of assets/liabilities for derivative open positions at fair value	(28,358)	717
Receivable from banks and brokers		134,908
Derivative Liabilities
Derivatives, Fair Value [Line Items]
Cash Collateral		862,281
Net amounts of assets/liabilities for derivative open positions at fair value	153,408	102,722
Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Gross amounts of assets for derivative open positions at fair value	136,209	168,034
Gross amounts of liability for derivative open positions at fair value	59,614	93,057
Net amounts of assets/liabilities for derivative open positions at fair value	76,595	74,977
CFD contracts
Derivatives, Fair Value [Line Items]
Gross amounts of assets for derivative open positions at fair value	144,817	44,329
Gross amounts of liability for derivative open positions at fair value	107,178	24,420
Net amounts of assets/liabilities for derivative open positions at fair value	37,639	19,909
Metal contracts
Derivatives, Fair Value [Line Items]
Gross amounts of assets for derivative open positions at fair value	15,721	16,146
Gross amounts of liability for derivative open positions at fair value	4,905	7,593
Net amounts of assets/liabilities for derivative open positions at fair value	10,816	8,553
Level 2 | Derivative Assets
Derivatives, Fair Value [Line Items]
Cash Collateral	185,382
Receivable from banks and brokers	185,382	134,191
Level 2 | Derivative Liabilities
Derivatives, Fair Value [Line Items]
Cash Collateral	1,262,814	862,281
Carrying Value | Derivative Assets
Derivatives, Fair Value [Line Items]
Receivable from banks and brokers	185,382	134,191
Carrying Value | Derivative Liabilities
Derivatives, Fair Value [Line Items]
Cash Collateral	$ 1,262,814	$ 862,281

ADDITIONAL FINANCIAL INFORMAT40

ADDITIONAL FINANCIAL INFORMATION - Notional Values of Derivative Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Notional amounts of derivative open long positions
Derivative [Line Items]
Notional amounts of derivative open long positions	$ 3,307,106	$ 4,021,423
Notional amounts of derivative open long positions | Foreign currency exchange contracts
Derivative [Line Items]
Notional amounts of derivative open long positions	2,824,897	3,147,518
Notional amounts of derivative open long positions | CFD contracts
Derivative [Line Items]
Notional amounts of derivative open long positions	478,704	873,070
Notional amounts of derivative open long positions | Metal contracts
Derivative [Line Items]
Notional amounts of derivative open long positions	3,505	835
Notional amounts of derivative open short positions
Derivative [Line Items]
Notional amounts of derivative open long positions	3,182,244	2,690,129
Notional amounts of derivative open short positions | Foreign currency exchange contracts
Derivative [Line Items]
Notional amounts of derivative open long positions	3,073,585	2,679,041
Notional amounts of derivative open short positions | CFD contracts
Derivative [Line Items]
Notional amounts of derivative open long positions	106,087	10,753
Notional amounts of derivative open short positions | Metal contracts
Derivative [Line Items]
Notional amounts of derivative open long positions	$ 2,572	$ 335

ADDITIONAL FINANCIAL INFORMAT41

ADDITIONAL FINANCIAL INFORMATION - Net Gains (Losses) with Respect to Derivative Instruments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Derivative [Line Items]
Net gains (losses) on derivative instruments, total	$ 80,831	$ 36,943	$ 147,050	$ 87,472
Foreign currency exchange contracts
Derivative [Line Items]
Net gains (losses) on derivative instruments	61,587	15,974	97,659	56,798
CFD contracts
Derivative [Line Items]
Net gains (losses) on derivative instruments	13,523	13,289	37,864	17,493
Metal contracts
Derivative [Line Items]
Net gains (losses) on derivative instruments	$ 5,721	$ 7,680	$ 11,527	$ 13,181

ADDITIONAL FINANCIAL INFORMAT42

ADDITIONAL FINANCIAL INFORMATION - Property and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and equipment	$ 66,756	$ 50,340
Less: Accumulated depreciation and amortization	(38,943)	(31,544)
Property and equipment, net	27,813	18,796
Software
Property, Plant and Equipment [Line Items]
Property and equipment	28,938	30,351
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment	13,691	8,516
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment	10,375	6,719
Telephone equipment
Property, Plant and Equipment [Line Items]
Property and equipment	717	719
Office equipment
Property, Plant and Equipment [Line Items]
Property and equipment	2,209	2,345
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment	1,572	1,044
Website development costs
Property, Plant and Equipment [Line Items]
Property and equipment	$ 9,254	$ 646

ADDITIONAL FINANCIAL INFORMAT43

ADDITIONAL FINANCIAL INFORMATION - Intangible Assets (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, gross	$ 136,301	$ 73,114
Accumulated Amortization	(25,135)	(12,670)
Finite-lived intangible assets, net	111,166	60,444
Total intangibles, gross	136,663	73,476
Intangible assets, net	111,528	60,806
Future Annual Estimated Purchased Intangible Amortization Expense
2,015	21,700
2,016	14,501
2,017	13,189
2,018	12,073
2,019	11,489
Thereafter	38,214
Trademark
Intangible Assets by Major Class [Line Items]
Indefinite-lived intangible assets	362	362
Customer list
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, gross	53,432	22,945
Accumulated Amortization	(9,396)	(7,152)
Finite-lived intangible assets, net	44,036	15,793
Total intangibles, gross	$ 53,432
Weighted average amortization period	8 years 1 month
Technology
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, gross	$ 74,424	48,376
Accumulated Amortization	(14,623)	(4,671)
Finite-lived intangible assets, net	59,801	43,705
Total intangibles, gross	$ 74,424
Weighted average amortization period	8 years 11 months
Trademark
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, gross	$ 8,445	1,793
Accumulated Amortization	(1,116)	(847)
Finite-lived intangible assets, net	7,329	$ 946
Total intangibles, gross	$ 8,807
Weighted average amortization period	6 years 8 months

ADDITIONAL FINANCIAL INFORMAT44

ADDITIONAL FINANCIAL INFORMATION - Other Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Vendor and security deposits	$ 4,944	$ 3,373
Current tax receivable	8,883	5,163
Deferred tax assets	10,517	6,308
Indemnification asset	0	8,792
GTX Trade Receivables	4,347	4,190
Customer debit positions	7,311	6,594
Allowance for uncollectible customer debit positions	(5,602)	(4,555)
Acquisition related receivable	7,065	0
Miscellaneous receivables	761	3,726
Other assets, net	$ 38,226	$ 33,591

RELATED PARTY TRANSACTIONS - Ad

RELATED PARTY TRANSACTIONS - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Payables to customers	$ 1,109,406	$ 759,559
Management
Related Party Transaction [Line Items]
Payables to customers	4,900	$ 3,600
IPGL Limited
Related Party Transaction [Line Items]
Payables to customers	$ 10,000

ACQUISITIONS - Additional Infor

ACQUISITIONS - Additional Information (Details) - USD ($)	Apr. 01, 2015	Jul. 31, 2014	Mar. 31, 2014	Jun. 30, 2015
Business Acquisition [Line Items]
Decrease in goodwill				$ (11,100,000)
Customer list
Business Acquisition [Line Items]
Weighted average amortization period				8 years 1 month
Convertible Debt [Member] | Convertible Notes Due 2020 [Member]
Business Acquisition [Line Items]
Stated interest rate	4.125%
Principal amount	$ 60,000,000
City Index
Business Acquisition [Line Items]
Cash payment	6,650,000
Cash to be held in escrow	$ 1,000,000
Number of shares issued due to acquisitions	5,319,149
Liabilities incurred	$ 65,000,000
Revenues since acquisition date				$ 24,300,000
Expenses since acquisition date				30,700,000
Losses before taxes since acquisition date				$ 6,400,000
Payments to settle inter-company liabilities	22,400,000
Total purchase price	$ 119,930,000
City Index | Customer list
Business Acquisition [Line Items]
Weighted average amortization period				9 years
City Index | Trade name
Business Acquisition [Line Items]
Weighted average amortization period				7 years
City Index | Technology
Business Acquisition [Line Items]
Weighted average amortization period				6 years 11 months
Galvan Research and Trading, Ltd.
Business Acquisition [Line Items]
Cash payment		$ 9,732,000
Liabilities incurred		$ 10,540,000
Contingent payment, payable period		3 years
Total purchase price		$ 20,272,000
Global Assets Advisors, LLC
Business Acquisition [Line Items]
Cash payment			$ 4,365,000
Percentage of company acquired			55.00%
Total purchase price			$ 5,606,000
Top Third Ag Marketing, LLC
Business Acquisition [Line Items]
Cash payment			$ 3,500,000
Percentage of company acquired			55.00%

ACQUISITIONS - Schedule of Purc

ACQUISITIONS - Schedule of Purchase Price (Detail) - USD ($) $ / shares in Units, $ in Thousands	Apr. 01, 2015	Jul. 31, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014
Business Acquisition [Line Items]
Common stock issued as consideration for asset and business acquisitions				$ (48,280)	$ 1,241
City Index
Business Acquisition [Line Items]
Cash	$ 6,650
Liabilities incurred	65,000
Common stock issued as consideration for asset and business acquisitions	48,280
Total purchase price	$ 119,930
Share price (in dollars per share)	$ 9.77
Galvan Research and Trading, Ltd.
Business Acquisition [Line Items]
Cash		$ 9,732
Liabilities incurred		10,540
Total purchase price		$ 20,272
Global Assets Advisors, LLC
Business Acquisition [Line Items]
Cash			$ 4,365
Common stock issued as consideration for asset and business acquisitions			1,241
Total purchase price			5,606
Top Third Ag Marketing, LLC
Business Acquisition [Line Items]
Cash			$ 3,500

ACQUISITIONS - Allocation of Pu

ACQUISITIONS - Allocation of Purchase Price to Fair Value of Assets and Liabilities (Detail) - USD ($) $ in Thousands	1 Months Ended
	Mar. 31, 2014	Jun. 30, 2015	Apr. 01, 2015	Dec. 31, 2014	Jul. 31, 2014	Jun. 30, 2014
Business Acquisition [Line Items]
Goodwill		$ 44,728		$ 33,579
City Index
Business Acquisition [Line Items]
Cash and cash equivalents acquired			$ 32,991
Cash and securities held for customers			265,012
Receivable from brokers			35,974
Property and equipment			10,411
Prepaid assets			3,972
Other current assets			893
Total tangible assets			349,253
Total liabilities assumed			302,283
Net assets			46,970
Identifiable intangible assets			60,065
Goodwill			12,895
City Index | Customer list
Business Acquisition [Line Items]
Identifiable intangible assets			29,143
City Index | Trade name
Business Acquisition [Line Items]
Identifiable intangible assets			6,339
City Index | Technology
Business Acquisition [Line Items]
Identifiable intangible assets			$ 24,583
Galvan Research and Trading, Ltd.
Business Acquisition [Line Items]
Cash and cash equivalents acquired					$ 2,193
Receivable from brokers					745
Property and equipment					12
Prepaid assets					94
Other current assets					64
Total tangible assets					3,108
Total liabilities assumed					1,931
Net assets					1,177
Identifiable intangible assets					4,987
Goodwill					14,108
Galvan Research and Trading, Ltd. | Customer list
Business Acquisition [Line Items]
Identifiable intangible assets					4,203
Galvan Research and Trading, Ltd. | Trade name
Business Acquisition [Line Items]
Identifiable intangible assets					$ 784
Global Assets Advisors, LLC
Business Acquisition [Line Items]
Non-controlling interest	$ 4,509
Cash and cash equivalents acquired						$ 360
Receivable from brokers						438
Property and equipment						148
Prepaid assets						153
Other current assets						3
Total tangible assets						1,102
Total liabilities assumed						515
Net assets						587
Identifiable intangible assets						3,370
Goodwill						6,158
Global Assets Advisors, LLC | Customer list
Business Acquisition [Line Items]
Identifiable intangible assets						3,100
Global Assets Advisors, LLC | Trade name
Business Acquisition [Line Items]
Identifiable intangible assets						$ 270
Top Third Ag Marketing, LLC
Business Acquisition [Line Items]
Non-controlling interest	3,885
Cash and cash equivalents acquired	73
Receivable from brokers	663
Total tangible assets	736
Total liabilities assumed	1,103
Net assets	(367)
Identifiable intangible assets	3,990
Goodwill	3,806
Top Third Ag Marketing, LLC | Customer list
Business Acquisition [Line Items]
Identifiable intangible assets	3,900
Top Third Ag Marketing, LLC | Trade name
Business Acquisition [Line Items]
Identifiable intangible assets	$ 90

ACQUISITIONS - Pro Forma Revenu

ACQUISITIONS - Pro Forma Revenue and Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Total non-interest revenue	$ 111,452	$ 70,005	$ 204,418	$ 150,417
Interest revenue	314	401	651	764
Interest expense	309	142	627	222
Total net interest revenue	5	259	24	542
Depreciation and amortization	2,738	1,798	4,713	3,493
Purchased intangible amortization	4,257	1,409	6,408	2,613
Total operating expense	121,644	75,223	201,574	150,653
OPERATING PROFIT/(LOSS)	(10,187)	(4,959)	2,868	306
Interest on long term borrowings	2,554	1,462	4,056	2,894
INCOME BEFORE INCOME TAX EXPENSE	(12,741)	(6,421)	(1,188)	(2,588)
Income tax (benefit)/expense	(6,039)	(1,926)	(294)	861
Net income attributable to non-controlling interests	416	164	760	202
NET LOSS APPLICABLE TO GAIN CAPITAL HOLDINGS, INC.	$ (7,118)	(4,659)	(1,654)	(3,651)
Top Third Ag Marketing, LLC, Global Assets Advisors, LLC, and Galvan Research and Trading, Ltd [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Total non-interest revenue		72,362		158,008
Interest revenue		401		771
Interest expense		367		670
Total net interest revenue		34		101
Net revenue		72,396		158,109
Depreciation and amortization		1,800		3,510
Purchased intangible amortization		1,674		3,193
Other expense items		73,594		151,285
Total operating expense		77,068		157,988
OPERATING PROFIT/(LOSS)		(4,672)		121
Interest on long term borrowings		1,462		2,894
INCOME BEFORE INCOME TAX EXPENSE		(6,134)		(2,773)
Income tax (benefit)/expense		(2,427)		833
NET LOSS		(3,707)		(3,606)
Net income attributable to non-controlling interests		164		196
NET LOSS APPLICABLE TO GAIN CAPITAL HOLDINGS, INC.		(3,871)		(3,802)
City Index
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Total non-interest revenue		94,674	241,461	190,913
Interest revenue		614	734	855
Interest expense		142	627	222
Total net interest revenue		472	107	633
Net revenue		95,146	241,568	191,546
Depreciation and amortization		3,249	5,360	2,378
Purchased intangible amortization		3,712	8,492	7,178
Other expense items		101,515	224,885	182,184
Total operating expense		108,476	238,737	191,740
OPERATING PROFIT/(LOSS)		(13,330)	2,831	(194)
Interest on long term borrowings		2,507	5,101	3,939
INCOME BEFORE INCOME TAX EXPENSE		(15,837)	(2,270)	(4,133)
Income tax (benefit)/expense		(6,066)	215	324
NET LOSS		(9,771)	(2,485)	(4,457)
Net income attributable to non-controlling interests		164	760	202
NET LOSS APPLICABLE TO GAIN CAPITAL HOLDINGS, INC.		$ (9,935)	$ (3,245)	$ (4,659)

ACQUISITIONS - Restructuring (D

ACQUISITIONS - Restructuring (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Restructuring Reserve [Roll Forward]
Restructuring liability as of January 1, 2015			$ 374
Restructuring expenses	$ 1,935	$ 212	1,935	$ 1,690	$ 1,200
Payments made in 2015			(1,608)
Restructuring liability as of June 30, 2015	$ 701		$ 701		$ 374

NON-CONTROLLING INTERESTS (Deta

NON-CONTROLLING INTERESTS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2014
Increase (Decrease) in Temporary Equity [Roll Forward]
Redeemable noncontrolling interest, beginning balance			$ 11,338
Adjustment to the redemption value of non-controlling interests			1,441	$ 197
Net income attributable to non-controlling interests	$ 416	$ 164	760	$ 202
Distributions to non-controlling interest holders			(756)
Redeemable noncontrolling interest, ending balance	$ 12,783		$ 12,783
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) - Convertible Debt [Member] - USD ($)	Nov. 27, 2013	Apr. 01, 2015
Convertible Notes Due 2018 [Member]
Debt Instrument [Line Items]
Principal amount	$ 80,000,000
Stated interest rate	4.125%
Proceeds from Convertible Debt	$ 77,900,000
Convertible Notes Due 2020 [Member]
Debt Instrument [Line Items]
Principal amount		$ 60,000,000
Stated interest rate		4.125%

CONVERTIBLE SENIOR NOTES - Sche

CONVERTIBLE SENIOR NOTES - Schedule of Liability and Equity Components (Details) - Convertible Debt [Member] - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Liability component - principal	$ 140,000	$ 80,000
Deferred bond discount	(20,238)	(11,633)
Liability component - net carrying value	119,762	68,367
Additional paid in capital	27,920	12,572
Discount attributable to equity	(425)	(425)
Equity component	$ 27,495	$ 12,147

CONVERTIBLE SENIOR NOTES - Sc54

CONVERTIBLE SENIOR NOTES - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Debt Instrument [Line Items]
Interest expense - amortization of deferred bond discount and costs			$ 1,567	$ 1,054
Total interest expense - convertible senior notes	$ 2,554	$ 1,462	4,056	2,894
Convertible Debt [Member]
Debt Instrument [Line Items]
Interest expense - stated coupon rate	1,443	825	2,268	1,650
Interest expense - amortization of deferred bond discount and costs	1,023	531	1,611	1,054
Total interest expense - convertible senior notes	$ 2,466	$ 1,356	$ 3,879	$ 2,704

EARNINGS PER COMMON SHARE - Add

EARNINGS PER COMMON SHARE - Additional Information (Detail) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from calculation of diluted earnings per share	0	0	0	0
Common stock threshold for additional dilutive shares (in dollars per share)			$ 13
Convertible Notes Due 2018 [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Additional dilutive shares if indenture conditions were met			500,000
Convertible Notes Due 2020 [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Additional dilutive shares if indenture conditions were met			1,500,000

EARNINGS PER COMMON SHARE - Com

EARNINGS PER COMMON SHARE - Computation of Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Earnings Per Share [Abstract]
Net loss applicable to Gain Capital Holdings, Inc.	$ (7,118)	$ (4,659)	$ (1,654)	$ (3,651)
Adjustment	(917)	(94)	(1,441)	(197)
Net income applicable to GAIN common shareholders	$ (8,035)	$ (4,753)	$ (3,095)	$ (3,848)
Weighted average common shares outstanding:
Basic weighted average common shares outstanding	49,070,387	40,135,820	46,154,717	39,839,012
Effect of dilutive securities:
Stock options (in shares)				0
RSUs/RSAs (in shares)				0
Diluted weighted average common shares outstanding	49,070,387	40,135,820	46,154,717	39,839,012
Earnings per common share
Basic (usd per share)	$ (0.16)	$ (0.12)	$ (0.07)	$ (0.10)
Diluted (usd per share)	$ (0.16)	$ (0.12)	$ (0.07)	$ (0.10)
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Redeemable noncontrolling interests	$ 12,783		$ 12,783		$ 11,338
Out of period adjustment, effect on diluted earnings per share (in dollars per share)			$ 0.03

LEGAL - Additional Information

LEGAL - Additional Information (Detail)	Jun. 15, 2011patents	Feb. 28, 2011cases
Long-term Purchase Commitment [Line Items]
Number of alleged patent infringement lawsuit against the company | cases		11
Open E Cry Limited Liability Company
Long-term Purchase Commitment [Line Items]
Number of alleged patent infringement lawsuit against the company | patents	12

INCOME TAXES - Additional Infor

INCOME TAXES - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Tax Disclosure [Abstract]
Provision for income taxes expense (benefit)	$ (6,039)	$ (1,926)	$ (294)	$ 861
Effective income tax rates	47.40%	30.00%	24.70%	(33.30%)

REGULATORY REQUIREMENTS - Minim

REGULATORY REQUIREMENTS - Minimum Regulatory Capital Subsidiaries Required to Maintain (Detail) $ in Millions	Jun. 30, 2015USD ($)
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 108.6
Capital Levels Maintained	220.1
Excess Net Capital	$ 111.5
Percent of Requirement Maintained	203.00%
GAIN Capital Group, LLC
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 25.1
Capital Levels Maintained	32.6
Excess Net Capital	$ 7.5
Percent of Requirement Maintained	130.00%
GAIN Capital-Forex.com U.K., Ltd.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 32.1
Capital Levels Maintained	64
Excess Net Capital	$ 31.9
Percent of Requirement Maintained	199.00%
Forex.com Japan Co., Ltd.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 3.6
Capital Levels Maintained	8.5
Excess Net Capital	$ 4.9
Percent of Requirement Maintained	236.00%
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	2.7
Excess Net Capital	$ 0.8
Percent of Requirement Maintained	142.00%
GFT Global Markets Asia Pte., Ltd.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 0.7
Capital Levels Maintained	3.1
Excess Net Capital	$ 2.4
Percent of Requirement Maintained	443.00%
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	2.6
Excess Net Capital	$ 1.8
Percent of Requirement Maintained	325.00%
Galvan Research and Trading, Ltd.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 0.8
Capital Levels Maintained	4.5
Excess Net Capital	$ 3.7
Percent of Requirement Maintained	563.00%
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	1.5
Excess Net Capital	$ 1.3
Percent of Requirement Maintained	750.00%
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	$ 0.1
Capital Levels Maintained	0.2
Excess Net Capital	$ 0.1
Percent of Requirement Maintained	200.00%
Gain Capital UK, Ltd.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 41.6
Capital Levels Maintained	94.1
Excess Net Capital	$ 52.5
Percent of Requirement Maintained	226.00%
Gain Capital Singapore Pte. Ltd.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 0.7
Capital Levels Maintained	3.2
Excess Net Capital	$ 2.5
Percent of Requirement Maintained	457.00%
Gain Capital Australia Pty Ltd.
Schedule Of Compliance With Regulatory Capital Requirements For Broker Dealer [Line Items]
Minimum Regulatory Capital Requirements	$ 0.8
Capital Levels Maintained	1.8
Excess Net Capital	$ 1
Percent of Requirement Maintained	225.00%
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	0.9
Excess Net Capital	$ 0.8
Percent of Requirement Maintained	900.00%

SEGMENT INFORMATION - Additiona

SEGMENT INFORMATION - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2015Segment
Segment Reporting [Abstract]
Number of operating segments	1

SUBSEQUENT EVENTS - Additional

SUBSEQUENT EVENTS - Additional Information (Detail)	Aug. 10, 2015$ / shares
Subsequent event
Subsequent Event [Line Items]
Common stock dividend declared per share (in dollars per share)	$ 0.05