Exhibit 10.1

Execution Version

VOTING AGREEMENT

This VOTING AGREEMENT (this “Agreement”), dated as of February 16, 2011, is
entered into by and among LaBranche & Co Inc., a Delaware corporation (the
“Company”), and RCG Holdings LLC, a Delaware limited liability company (the
“Stockholder”).

WHEREAS, the Stockholder owns (both beneficially and of record) in the aggregate
33,576,099 shares of the Class A common stock, par value $0.01 per share
(“Parent Common Stock”) and such shares of Parent Common Stock together with any
shares of Parent Common Stock acquired by the Stockholder after the date hereof
being collectively referred to herein as the “Shares”) of Cowen Group, Inc., a
Delaware corporation (“Parent”);

WHEREAS, the Company, Parent, and Louisiana Merger Sub, Inc., a Delaware
corporation and a direct wholly owned subsidiary of Parent (“Merger Sub”), have
entered into an Agreement and Plan of Merger, dated as of the date hereof (the
“Merger Agreement”); and

WHEREAS, the Stockholder has agreed to enter into this Agreement in order to
induce the Company to enter into the Merger Agreement and to consummate the
transactions contemplated thereby.

NOW, THEREFORE, in consideration of the Company’s entering into the Merger
Agreement and of the mutual covenants and agreements contained herein and other
good and valuable consideration, the adequacy of which is hereby acknowledged,
and intending to be legally bound hereby, the parties hereto agree as follows:

SECTION 1. Defined Terms. Capitalized terms used in this Agreement and not
otherwise defined herein shall have the meanings assigned to them in the Merger
Agreement.

SECTION 2. Representations and Warranties of Stockholder. The Stockholder hereby
represents and warrants to the Company as follows:

(a) Title to the Shares. The Stockholder is the record and beneficial owner of,
and has good and marketable title to, 33,576,099 shares of Parent Common Stock,
which as of the date hereof constitutes all of the shares of Parent Common
Stock, or any other securities convertible into or exercisable for any shares of
Parent Common Stock, (all collectively being “Parent Securities”) owned
beneficially and of record by the Stockholder. The Stockholder does not have any
rights of any nature to acquire any additional Parent Securities. Except for
(i) the Fourth Amended and Restated Limited Liability Company Agreement of the
Stockholder, dated as of November 2, 2009 (the “Stockholder LLC Agreement”),
(ii) proxies and restrictions in favor of the Company granted pursuant to this
Agreement and (iii) such transfer restrictions of general applicability as may
be provided under the Securities Act and the “blue sky” laws of the various
states of the United States, the Stockholder owns all of such shares of Parent
Common Stock free and clear of all security interests, liens, claims, pledges,
options, rights of first refusal, agreements, limitations on voting rights,
restrictions, charges, proxies and other encumbrances of any nature, and has not
appointed or granted any proxy, power of attorney or other authorization, which
appointment or grant is still effective, with respect to any of such shares of
Parent Common Stock owned by the Stockholder.

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(b) Organization. The Stockholder is duly organized, validly existing, and in
good standing under the laws of the State of Delaware.

(c) Authority Relative to this Agreement. The Stockholder has the limited
liability company power and authority to execute and deliver this Agreement, to
perform its obligations hereunder and to consummate the transactions
contemplated hereby. The execution and delivery of this Agreement by the
Stockholder and the consummation by the Stockholder of the transactions
contemplated hereby have been duly and validly authorized by all necessary
action on the part of the Stockholder. This Agreement has been duly and validly
executed and delivered by the Stockholder and, assuming the due authorization,
execution and delivery by the Company, constitutes a legal, valid and binding
obligation of the Stockholder, enforceable against the Stockholder in accordance
with its terms, subject to the Bankruptcy and Equity Exception.

(d) No Conflict. Except for any filings as may be required by applicable federal
securities laws, the execution and delivery of this Agreement by the Stockholder
does not, and the performance of this Agreement by the Stockholder will not,
(a) require any consent, approval, authorization or permit of, or filing with or
notification to, any Governmental Entity or any other Person by the Stockholder;
(b) conflict with, or result in any violation of, or default (with or without
notice or lapse of time or both) under any provision of, the Stockholder LLC
Agreement or any other agreement to which the Stockholder is a party, including
any voting agreement, stockholders agreement, voting trust, trust agreement,
pledge agreement, loan or credit agreement, note, bond, mortgage, indenture
lease or other agreement, instrument, permit, concession, franchise or license;
or (c) conflict with or violate any judgment, order, notice, decree, statute,
law, ordinance, rule or regulation applicable to the Stockholder or to the
Stockholder’s property or assets.

SECTION 3. Covenants of Stockholder.

(a) Restriction on Transfer. Except as may be required pursuant to the
Stockholder LLC Agreement or as set forth on Schedule A hereto, the Stockholder
hereby covenants and agrees that prior to the termination or expiration of this
Agreement, Stockholder shall not sell, transfer, tender, assign, hypothecate or
otherwise dispose of, grant any proxy to, deposit any Shares into a voting
trust, enter into a voting trust agreement or create or permit to exist any
additional security interest, lien, claim, pledge, option, right of first
refusal, limitation on voting rights, charge or other encumbrance of any nature
with respect to the Shares.

(b) Additional Shares. Prior to the termination of this Agreement, the
Stockholder will promptly notify the Company of the number of any new shares of
Parent Common Stock or any other Parent Securities acquired directly or
beneficially by the Stockholder, if any, after the date hereof. Any such shares
shall automatically become “Shares” within the meaning of this Agreement
immediately upon their acquisition by such Stockholder.

SECTION 4. Voting Agreement.

(a) Voting Agreement. The Stockholder hereby agrees that prior to the
termination of this Agreement, at any meeting of the stockholders of Parent,
however called, in

 

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any action by written consent of the stockholders of Parent, or in any other
circumstances upon which the Stockholder’s vote, consent or other approval is
sought, the Stockholder shall vote the Shares owned beneficially or of record by
the Stockholder as follows:

(i) in favor of the Parent Stock Issuance;

(ii) against any action or agreement that has or would be reasonably likely to
result in any conditions to Parent’s obligations under Article VIII of the
Merger Agreement not being satisfied;

(iii) against any Parent Acquisition Proposal;

(iv) against any amendments to the Parent Organizational Documents if such
amendment would reasonably be expected to prevent or delay the consummation of
the Closing; and

(v) against any other action or agreement that is intended, or would reasonably
be expected, to impede, interfere with, delay, or postpone the Merger or the
other transactions contemplated by the Merger Agreement or change in any manner
the voting rights of any class of stock of Parent.

(b) Grant of Proxy. The Stockholder hereby irrevocably grants to and appoints,
the Company and each of its designees (the “Authorized Parties” and each an
“Authorized Party”), and each of them individually as the Stockholder’s proxy
and attorney-in-fact (with full power of substitution) for and in the name,
place and stead of the Stockholder, to vote the Shares or execute one or more
written consents or approvals in respect of the Shares:

(i) in favor of the Parent Stock Issuance;

(ii) against any action or agreement that has or would be reasonably likely to
result in any conditions to Parent’s obligations under Article VIII of the
Merger Agreement not being satisfied;

(iii) against any Parent Acquisition Proposal;

(iv) against any amendments to the Parent Organizational Documents if such
amendment would reasonably be expected to prevent or delay the consummation of
the Closing; and

(v) against any other action or agreement that is intended, or would reasonably
be expected, to impede, interfere with, delay, or postpone the Merger or the
transactions contemplated by the Merger Agreement or change in any manner the
voting rights of any class of stock of Parent.

The Stockholder hereby ratifies and confirms that the irrevocable proxy set
forth in this Section 4.2(b) is given in connection with the execution of the
Merger Agreement and that such irrevocable proxy is given to secure the
performance of the Stockholder’s duties in accordance with this Agreement. The
Stockholder hereby further ratifies and confirms that the irrevocable

 

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proxy granted hereby is coupled with an interest and may under no circumstances
be revoked, except as otherwise provided in this Agreement. Such irrevocable
proxy shall be valid until termination of this Agreement. The power of attorney
granted by the Stockholder herein is a durable power of attorney and shall
survive the dissolution, bankruptcy, death or incapacity of the Stockholder.
Upon the execution of this Agreement, the Stockholder hereby revokes any and all
prior proxies or powers of attorney given by the Stockholder with respect to
voting of the Shares on the matters contemplated hereby and agrees not to grant
any subsequent proxies or powers of attorney with respect to the voting of the
Shares on the matters contemplated hereby until after the termination of this
Agreement. The Stockholder understands and acknowledges that the Company is
entering into the Merger Agreement in reliance upon the Stockholder’s execution
and delivery of this Agreement and the Stockholder’s granting of the proxy
contained in this Section 4(b). The Stockholder hereby affirms that the proxy
granted in this Section 4(b) is given in connection with the execution of the
Merger Agreement, and that such proxy is given to secure the performance of the
duties of the Stockholder under this Agreement. If for any reason the proxy
granted herein is found by a court of competent jurisdiction to not be valid,
then the Stockholder agrees to vote the Shares in accordance with Section 4(a).
For Shares as to which the Stockholder is the beneficial but not the record
owner, the Stockholder shall take all necessary actions to cause any record
owner of such Shares to irrevocably constitute and appoint the Company and its
designees as such record owner’s attorney and proxy an irrevocable proxy to the
same effect as that contained herein.

(c) Other Voting. The Stockholder shall vote on all issues other than those
specified in this Section 4 that may come before a meeting of the stockholders
of Parent in its sole discretion, provided that such vote does not contravene
the provisions of this Section 4. Nothing in this Agreement shall be deemed to
govern or relate to any actions, omissions to act, or votes taken or not taken
by any designee of the Stockholder serving on the Parent’s Board of Directors in
such designee’s capacity as a director of Parent and in accordance with the
Merger Agreement, and no such action taken by such designee in his capacity as a
director of Parent shall be deemed to violate any of the Stockholder’s duties
under this Agreement.

SECTION 5. Representations and Warranties of the Company. The Company hereby
represents and warrants to the Stockholder as follows:

5.1. Organization. The Company is duly organized, validly existing, and in good
standing under the laws of the state of Delaware.

5.2. Authority Relative to this Agreement. The Company has the corporate power
and authority to execute and deliver this Agreement, to perform its obligations
hereunder and to consummate the transactions contemplated hereby. The execution
and delivery of this Agreement by the Company and the consummation by the
Company of the transactions contemplated hereby have been duly and validly
authorized by all necessary action on the part of the Company. This Agreement
has been duly and validly executed and delivered by the Company and, assuming
the due authorization, execution and delivery by the Stockholder, constitutes a
legal, valid and binding obligation of the Company, enforceable against the
Company in accordance with its terms, subject to the Bankruptcy and Equity
Exception.

 

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5.3. No Conflict. The execution and delivery of this Agreement by the Company
does not, and the performance of this Agreement by the Company will not,
(a) require any consent, approval, authorization or permit of, or filing with or
notification to, any Governmental Entity or any other Person by the Company,
except for filings with the SEC of such reports under the Exchange Act as may be
required in connection with this Agreement and the transactions contemplated by
this Agreement; (b) conflict with, or result in any violation of, or default
(with or without notice or lapse of time or both) under any provision of, the
certificate of incorporation or by-laws of the Company or any other agreement to
which the Company is a party; or (c) conflict with or violate any judgment,
order, notice, decree, statute, law, ordinance, rule or regulation applicable to
the Company or to the Company’s property or assets.

SECTION 6. Further Assurances. The Stockholder shall, without further
consideration, from time to time, execute and deliver, or cause to be executed
and delivered, such additional or further consents, documents and other
instruments as the Company may request for the purpose of effectuating the
matters covered by this Agreement.

SECTION 7. Stop Transfer Order. In furtherance of this Agreement, concurrently
herewith the Stockholder shall and hereby does authorize the Company to notify
Parent’s transfer agent that there is a stop transfer order with respect to all
Shares (and that this Agreement places limits on the voting and transfer of the
Shares). The Stockholder further agrees to cause Parent not to register the
transfer of any certificate representing any of the Shares unless such transfer
is made in accordance with the terms of this Agreement.

SECTION 8. Certain Events. The Stockholder agrees that this Agreement and the
obligations hereunder shall attach to the Shares and shall be binding on any
Person to which legal or beneficial ownership of such Shares shall pass, whether
by operation of law or otherwise. In the event of any stock split, stock
dividend, merger, consolidation, reorganization, recapitalization or other
change in the capital structure of Parent affecting the Parent Common Stock or
other voting securities of Parent, the number of Shares shall be deemed adjusted
appropriately and this Agreement and the obligations hereunder shall attach to
any additional shares of Parent Common Stock or other Parent Securities issued
to or acquired by the Stockholder.

SECTION 9. Termination. This Agreement and the proxy granted pursuant to
Section 4(b) shall automatically terminate without further action of the parties
on the first to occur of (a) the Effective Time, (b) a Parent Adverse
Recommendation Change in accordance with the Merger Agreement or (c) the
termination of the Merger Agreement, provided that the provisions of Section 10
hereof shall survive any such termination.

SECTION 10. Miscellaneous.

(a) Expenses. All costs and expenses incurred in connection with the
transactions contemplated by this Agreement shall be paid by the party incurring
such costs and expenses.

 

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(b) Specific Performance. The parties hereto agree that, in the event any
provision of this Agreement is not performed in accordance with the terms
hereof, (i) the non-breaching party will sustain irreparable damages for which
there is not an adequate remedy at law for money damages and (ii) the parties
shall be entitled to specific performance of the terms hereof, in addition to
any other remedy at law or in equity.

(c) Entire Agreement. This Agreement constitutes the entire agreement among the
parties hereto with respect to the subject matter hereof and supersedes all
prior agreements and understandings, both written and oral, among such parties
with respect to the subject matter hereof.

(d) Assignment. Without the prior written consent of the other party to this
Agreement, no party may assign any rights or delegate any obligations under this
Agreement. Any such purported assignment or delegation made without prior
consent of the other party hereto shall be null and void.

(e) Parties in Interest. This Agreement shall be binding upon, inure solely to
the benefit of, and be enforceable by, the parties hereto and their successors
and permitted assigns. Nothing in this Agreement, express or implied, is
intended to or shall confer upon any other person not a party hereto any right,
benefit or remedy of any nature whatsoever under or by reason of this Agreement.

(f) Amendment. This Agreement may not be amended except by an instrument in
writing signed by the parties hereto.

(g) Severability. If any term or other provision of this Agreement is invalid,
illegal or incapable of being enforced by any rule of law, or public policy, all
other conditions and provisions of this Agreement shall nevertheless remain in
full force and effect so long as the economic or legal substance of this
Agreement is not affected in any manner materially adverse to any party. Upon
such determination that any term or other provision is invalid, illegal or
incapable of being enforced, the parties hereto shall negotiate in good faith to
modify this Agreement so as to effect the original intent of the parties as
closely as possible in a mutually acceptable manner in order that the terms of
this Agreement remain as originally contemplated to the fullest extent possible.

(h) Notices. Except as otherwise provided herein, all notices and other
communications hereunder shall be in writing and shall be deemed duly given
(i) on the date of delivery if delivered personally, or by facsimile, upon
confirmation of receipt, (ii) on the first Business Day following the date of
dispatch if delivered by a recognized next-day courier service, or (iii) on the
fifth Business Day following the date of mailing if delivered by registered or
certified mail, return receipt requested, postage prepaid. All notices hereunder
shall be delivered as set forth below, or pursuant to such other instructions as
may be designated in writing by the party to receive such notice (or at such
other address for a party as shall be specified in a notice given in accordance
with this Section 10(h):

 

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if to the Stockholder:

 

RCG Holdings LLC

c/o C4S & Co., L.L.C.

599 Lexington Avenue

New York, NY 10022

Attention:    Peter A. Cohen    Owen S. Littman Facsimile:    (212) 845-7995

with a copy to:

Willkie Farr & Gallagher LLP

787 Seventh Avenue

New York, NY 10019

Attention:    David K. Boston    Laura L. Delanoy, Esq. Facsimile:    (212)
728-8111

if to the Company:

LaBranche & Co Inc.

33 Whitehall Street

New York, NY 10004

Attention:    Stephen H. Gray    General Counsel Facsimile:    (212) 952-9280

with a copy to:

Weil, Gotshal & Manges LLP

767 Fifth Avenue

New York, NY 10153

Attention:    Michael J. Aiello Facsimile:    (212) 310-8007

(or at such other address for a party as shall be specified by like notice).

(i) Governing Law. This Agreement shall be governed by and construed, performed
and enforced in accordance with the internal laws of the State of Delaware
applicable to contracts made and wholly-performed within such state, without
regard to any applicable conflicts of law principles.

(j) Exclusive Jurisdiction. The parties hereto agree that any suit, action or
proceeding brought by either party to enforce any provision of, or based on any
matter arising out of or in connection with, this Agreement or the transactions
contemplated hereby shall be brought in any federal or state court located in
the State of Delaware. Each of the parties hereto

 

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submits to the jurisdiction of any such court in any suit, action or proceeding
seeking to enforce any provision of, or based on any matter arising out of, or
in connection with, this Agreement or the transactions contemplated hereby and
hereby irrevocably waives the benefit of jurisdiction derived from present or
future domicile or otherwise in such action or proceeding. Each party hereto
irrevocably waives, to the fullest extent permitted by Law, any objection that
it may now or hereafter have to the laying of the venue of any such suit, action
or proceeding in any such court or that any such suit, action or proceeding
brought in any such court has been brought in an inconvenient forum.

(k) WAIVER OF JURY TRIAL. EACH OF THE PARTIES HEREBY WAIVES TRIAL BY JURY IN ANY
JUDICIAL PROCEEDING INVOLVING, DIRECTLY, IN ANY MATTERS (WHETHER SOUNDING IN
TORT, CONTRACT OR OTHERWISE) IN ANY WAY ARISING OUT OF, RELATED TO, OR CONNECTED
WITH THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY.

(l) Headings. The descriptive headings contained in this Agreement are included
for convenience of reference only and shall not affect in any way the meaning or
interpretation of this Agreement.

(m) Counterparts. This Agreement may be executed and delivered (including by
facsimile transmission) in one or more counterparts, and by the different
parties hereto in separate counterparts, each of which when so executed and
delivered shall be deemed to be an original but all of which taken together
shall constitute one and the same agreement.

[Rest of page intentionally blank.]

 

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IN WITNESS WHEREOF, each of the parties hereto has caused this Agreement to be
duly executed and delivered as of the date first written above.

 

LABRANCHE & CO INC. By:  

/s/ George M.L. LaBranche, IV

  Name: George M.L. LaBranche, IV   Title: Chief Executive Officer RCG HOLDINGS
LLC By:  

/s/ Peter A. Cohen

  Name: Peter A. Cohen   Title: Authorized Signatory

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Schedule A

 

1. The Stockholder intends to distribute no more than 975,000 shares of Parent
Common Stock no later than March 31, 2011 to certain of its members in
accordance with the terms of the Stockholder LLC Agreement.