UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 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): February 17, 2011

LaBRANCHE & CO INC.

(Exact name of registrant as specified in its charter)

33 Whitehall Street, New York, New York 10004

(Address of principal executive offices)

(212) 425-1144

(Registrant’s telephone number, including area code)

Not applicable

(Former Name or Former Address, if Changed Since Last Report)

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):

Item 2.02. Results of Operations and Financial Condition.

On February 17, 2011, LaBranche & Co Inc, a Delaware corporation (“LaBranche”) issued a press release announcing its results for the fourth quarter of 2010. A copy of this press release is furnished herewith as Exhibit 99.1.

The information in this Current Report, including the news release attached hereto, is being furnished pursuant to Item 2.02 of Form 8-K and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 or otherwise subject to liabilities of that Section.

Item 8.01 Other Events

On February 17, 2011, Cowen Group, Inc., a Delaware corporation (“Cowen”) issued a joint press release with LaBranche announcing that they had entered into an Agreement and Plan of Merger relating to the merger of Cowen and LaBranche and the other matters described therein. A copy of the press release is attached hereto as Exhibit 99.2 and is incorporated by reference into this Item 8.01.

Important Information For Investors And Stockholders

This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval. In connection with the proposed transaction, Cowen and LaBranche will file relevant materials with the SEC, including a registration statement on Form S-4 that will include a joint proxy statement of Cowen and LaBranche and that also constitutes a prospectus of Cowen. Cowen and LaBranche will each mail the final joint proxy statement/prospectus to its respective stockholders. Investors and security holders are urged to read these documents (if and when they become available) and any other relevant documents filed with the SEC, as well as any amendments or supplements to those documents, because they will contain important information about Cowen, LaBranche and the proposed transaction. Investors and security holders may obtain these documents (and any other documents filed by Cowen or LaBranche with the SEC) free of charge at the SEC’s website at www.sec.gov. In addition, the documents filed with the SEC by Cowen may be obtained free of charge by directing such request to: Investor Relations, 599 Lexington Avenue, New York, NY 10022 or from Cowen’s Investor Relations page on its corporate website at www.cowen.com and the documents filed with the SEC by LaBranche be obtained free of charge by directing such request to: Investor Relations, 33 Whitehall Street, New York, NY 10004 or from LaBranche’s Investor Relations page on its corporate website at www.labranche.com.

The directors, executive officers, and certain other members of management and employees of each of Cowen and LaBranche may be deemed to be participants in the solicitation of proxies in favor of the proposed transactions from the stockholders of Cowen and from the stockholders of LaBranche, respectively. Information about the executive officers and directors of Cowen is set forth in the proxy statement for Cowen’s 2010 Annual Meeting of Stockholders, which was filed with the SEC on April 30, 2010 and information about the executive officers and directors of LaBranche is set forth in the proxy statement for LaBranche’s 2010 Annual Meeting of Stockholders, which was filed with the SEC on April 8, 2010.

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Cautionary Notice Regarding Forward-Looking Statements

This communication may contain forward-looking statements including statements relating to the market opportunity and future business prospects of Cowen and LaBranche. Such statements are subject to certain risks and uncertainties that could cause actual results to differ materially from those expressed or implied in the forward-looking statements. Consequently, all forward-looking statements made during this communication are qualified by those risks, uncertainties and other factors.

These factors include, but are not limited to, (1) the occurrence of any event, change or other circumstances that could give rise to the termination of the Agreement and Plan of Merger among Cowen, LaBranche and Louisiana Merger Sub, Inc. (the “Merger Agreement”); (2) the outcome of any legal proceedings that may be instituted against Cowen, LaBranche or others following announcement of the Merger Agreement and transactions contemplated therein; (3) the inability to complete the transactions contemplated by the Merger Agreement due to the failure to obtain the required stockholder approvals, (4) the inability to obtain necessary regulatory approvals required to complete the transactions contemplated by the Merger Agreement; (5) the risk that the proposed transactions disrupt current plans and operations and the potential difficulties in employee retention as a result of the announcement and consummation of such transactions; (6) the ability to recognize the anticipated benefits of the combination of Cowen and LaBranche, including potential cost savings; and (7) the possibility that Cowen or LaBranche may be adversely affected by other economic, business, and/or competitive factors.

Actual results may differ materially and reported results should not be considered an indication of future performance. Please reference the SEC filings of Cowen and LaBranche, which are available on their respective web sites, for detailed descriptions of factors that could cause actual results to differ materially from those expressed or implied in such forward-looking statements.

Certain statements in this communication relate to future results that are forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995. Except for the ongoing obligations of Cowen and LaBranche to disclose material information under the federal securities laws, neither Cowen nor LaBranche undertakes any obligation to release any revisions to any forward-looking statements, to report events or to report the occurrence of unanticipated events unless required by law.

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Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

The following exhibits are furnished or filed, as applicable, with this Current Report on Form 8-K:

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SIGNATURES

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 thereunto duly authorized.

Dated: February 17, 2011

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EXHIBIT INDEX

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