SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): May 2, 2014 (May 1, 2014)

KCG HOLDINGS, INC.

(Exact name of registrant as specified in its charter)

545 Washington Boulevard, Jersey City, NJ 07310

(Address of principal executive offices) (Zip Code)

(201) 222-9400

(Registrant’s telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

KCG Holdings, Inc.

Current Report on Form 8-K

Item 2.02 Results of Operations and Financial Condition.

See Item 9.01

Item 7.01 Regulation FD Disclosure.

The following information is furnished under Item 2.02, “Results of Operations and Financial Condition”, Item 7.01, “Regulation FD Disclosure”, and Item 9.01 “Financial Statements and Exhibits.” This information, including Exhibit 99.1, shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

On May 2, 2014, KCG Holdings, Inc. (the “Company” of “KCG”) issued a press release announcing its earnings for the first quarter of 2014. The press release did not include certain financial statements, related footnotes and certain other financial information relating to the Company that will be filed with the Securities and Exchange Commission as part of the Company’s Quarterly Report on Form 10-Q. A copy of the press release is attached hereto as Exhibit 99.1 and incorporated by reference into this Current Report on Form 8-K.

Item 8.01 Other Events.

On May 1, 2014, KCG’s Board of Directors approved an initial program to repurchase up to a total of $150 million in shares of the Company’s outstanding Class A Common Stock (“Common Stock”) and warrants to purchase shares of Common Stock (“Warrants”), subject to compliance with the covenants contained in the Company’s debt indenture. Under the program, the Company may repurchase shares or Warrants from time to time in open market transactions, accelerated stock buyback programs, tender offers, privately-negotiated transactions or by other means. Repurchases of shares may also be made under a Rule 10b5-1 plan. The timing and amount of repurchase transactions will be based on market conditions, share price, legal requirements and other factors. The program has no expiration date and may be suspended, modified or discontinued at any time without prior notice. There are no assurances that any repurchases of shares of Common Stock or Warrants may actually occur. The Company currently has approximately 125.7 million shares of Common Stock outstanding (including restricted stock units convertible into Common Stock) and 24.3 million Warrants outstanding.

Item 9.01 Financial Statements and Exhibits.

Not Applicable

Not Applicable

Not Applicable

Exhibit 99.1 – Press Release of KCG Holdings, Inc. issued on May 2, 2014.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned’s duly authorized signatory.

EXHIBIT INDEX