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                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934
                                (Amendment No. )*

                     Flagstone Reinsurance Holdings Limited
--------------------------------------------------------------------------------
                                (Name of Issuer)

                     Common Stock, Par Value $0.01 Per Share
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    G3529T105
                                    ---------
                                 (CUSIP Number)

                                December 31, 2009
                                -----------------
                      (Date of Event which Requires Filing
                               of this Statement)



Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

                  [X]      Rule 13d-1(b)
                  [ ]      Rule 13d-1(c)
                  [ ]      Rule 13d-1(d)



*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).





-------------------                                            -----------------
CUSIP No. G3529T105                    13G                     Page 2 of 9 Pages
-------------------                                            -----------------

---------- ---------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           Neuberger Berman Group LLC
---------- ---------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                                      (a) [ ]
                                                                      (b) [X]
---------- ---------------------------------------------------------------------
        3  SEC USE ONLY

---------- ---------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------- ----- ----------------------------------------------------
                         5  SOLE VOTING POWER

                            0
NUMBER OF             ----- ----------------------------------------------------
SHARES                   6  SHARED VOTING POWER
BENEFICIALLY
OWNED                       5,657,818 (see Item 4)
BY                    ----- ----------------------------------------------------
EACH                     7  SOLE DISPOSITIVE POWER
REPORTING
PERSON                      0
WITH:                 ----- ----------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            5,657,818 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           5,657,818 (see Item 4)
---------- ---------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           [ ]
---------- ---------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           6.8 % (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           HC
---------- ---------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT





-------------------                                            -----------------
CUSIP No. G3529T105                    13G                     Page 3 of 9 Pages
-------------------                                            -----------------

---------- ---------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           NB Alternatives Advisers LLC
---------- ---------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                                      (a) [ ]
                                                                      (b) [X]
---------- ---------------------------------------------------------------------
        3  SEC USE ONLY

---------- ---------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------- ----- ----------------------------------------------------
                         5  SOLE VOTING POWER

                            0
NUMBER OF             ----- ----------------------------------------------------
SHARES                   6  SHARED VOTING POWER
BENEFICIALLY
OWNED                       5,657,818 (see Item 4)
BY                    ----- ----------------------------------------------------
EACH                     7  SOLE DISPOSITIVE POWER
REPORTING
PERSON                      0
WITH:                 ----- ----------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            5,657,818 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           5,657,818 (see Item 4)
---------- ---------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           [ ]
---------- ---------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           6.8 % (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           IA
---------- ---------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT





-------------------                                            -----------------
CUSIP No. G3529T105                    13G                     Page 4 of 9 Pages
-------------------                                            -----------------

---------- ---------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           NB C-Investment Partners LP
---------- ---------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                                      (a) [ ]
                                                                      (b) [X]
---------- ---------------------------------------------------------------------
        3  SEC USE ONLY

---------- ---------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------- ----- ----------------------------------------------------
                         5  SOLE VOTING POWER

                            0
NUMBER OF             ----- ----------------------------------------------------
SHARES                   6  SHARED VOTING POWER
BENEFICIALLY
OWNED                       4,705,737 (see Item 4)
BY                    ----- ----------------------------------------------------
EACH                     7  SOLE DISPOSITIVE POWER
REPORTING
PERSON                      0
WITH:                 ----- ----------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            4,705,737 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           4,705,737 (see Item 4)
---------- ---------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           [ ]
---------- ---------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           5.7 % (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           PN
---------- ---------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT





-------------------                                            -----------------
CUSIP No. G3529T105                    13G                     Page 5 of 9 Pages
-------------------                                            -----------------

---------- ---------------------------------------------------------------------
        1  NAME OF REPORTING PERSON
           I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

           NB Co-Investment Associates LP
---------- ---------------------------------------------------------------------
        2  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*

                                                                      (a) [ ]
                                                                      (b) [X]
---------- ---------------------------------------------------------------------
        3  SEC USE ONLY

---------- ---------------------------------------------------------------------
        4  CITIZENSHIP OR PLACE OF ORGANIZATION

           Delaware
--------------------- ----- ----------------------------------------------------
                         5  SOLE VOTING POWER

                            0
NUMBER OF             ----- ----------------------------------------------------
SHARES                   6  SHARED VOTING POWER
BENEFICIALLY
OWNED                       4,705,737 (see Item 4)
BY                    ----- ----------------------------------------------------
EACH                     7  SOLE DISPOSITIVE POWER
REPORTING
PERSON                      0
WITH:                 ----- ----------------------------------------------------
                         8  SHARED DISPOSITIVE POWER

                            4,705,737 (see Item 4)
---------- ---------------------------------------------------------------------
        9  AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

           4,705,737 (see Item 4)
---------- ---------------------------------------------------------------------
       10  CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES

           [ ]
---------- ---------------------------------------------------------------------
       11  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

           5.7 % (see Item 4)
---------- ---------------------------------------------------------------------
       12  TYPE OF REPORTING PERSON*

           PN
---------- ---------------------------------------------------------------------
                       *SEE INSTRUCTION BEFORE FILLING OUT





Item 1(a)           Name of Issuer:
                    --------------

                    Flagstone Reinsurance Holdings Limited

Item 1(b)           Address of Issuer's Principal Executive Offices:
                    -----------------------------------------------

                    Crawford House
                    23 Church Street
                    Hamilton HM 11, Bermuda

Item 2(a)           Name of Person Filing:
                    ---------------------

                    This statement is filed by: (i) Neuberger Berman Group LLC
                    ("NBG") with respect to shares of Common Stock, Par Value
                    $0.01 Per Share (the "Shares") of the Issuer beneficially
                    owned by NB Co-Investment Partners LP ("NB Partners") and
                    certain affiliated investment funds of NBG, (ii) NB
                    Alternatives Advisers LLC ("NB Alternatives") with respect
                    to Shares owned by NB Partners and certain affiliated
                    investment funds of NBG, (iii) NB Partners with respect to
                    Shares owned by it, and (iv) NB Co-Investment Associates LP
                    ("NB Associates") with respect to Shares owned by NB
                    Partners.

                    NB Partners (f/k/a Lehman Brothers Co-Investment Partners
                    L.P.), NB Associates (f/k/a Lehman Brothers Co-Investment
                    Associates L.P.) and certain other reporting persons, filed
                    a Schedule 13D with the Securities and Exchange Commission
                    on February 14, 2008 with respect to the Shares. On May 4,
                    2009, NBG acquired from Lehman Brothers Holdings Inc.
                    various assets and businesses, including NB Alternatives and
                    NB Associates.

                    NBG, NB Alternatives, NB Partners and NB Associates have
                    entered into a Joint Filing Agreement, a copy of which is
                    filed with this Schedule 13G as Exhibit 99.1, pursuant to
                    which they have agreed to file this Schedule 13G jointly in
                    accordance with the provisions of Rule 13d-1(k) of the
                    Securities Exchange Act of 1934, as amended.

Item 2(b)           Address or Principal Business Office:
                    ------------------------------------

                    The address of the principal business office of each
                    reporting person is 605 Third Avenue New York, New York
                    10158.

Item 2(c)           Citizenship:
                    -----------

                    Each of NBG and NB Alternatives is a Delaware limited
                    liability company. Each of NB Partners and NB Associates is
                    a Delaware limited partnership.

Item 2(d)           Title of Class of Securities:
                    ----------------------------

                    Common Stock, Par Value $0.01 Per Share


                                  Page 6 of 9





Item 2(e)           CUSIP Number:
                    ------------

                    G3529T105

Item 3              This statement is filed pursuant to Rules 13d-1(b), or
                    13d-2(b) or (c), the person filing is a (j) "Group," in
                    accordance with Rule 13d-1(b)(1)(ii)(J).

Item 4              Ownership:
                    ---------

                    The percentages used herein are calculated based upon the
                    82,864,844 Shares issued and outstanding as of November 2,
                    2009, as reported on the Issuer's quarterly report filed on
                    Form 10-Q filed with the Securities and Exchange Commission
                    by the Issuer for the quarter ended September 30, 2009.

                    As of the close of business on December 31, 2009:

                    1. NBG
                    (a) Amount beneficially owned: 5,657,818
                    (b) Percent of class: 6.8 %
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii) Shared power to vote or direct the vote: 5,657,818
                    (iii) Sole power to dispose or direct the disposition: -0-
                    (iv) Shared power to dispose or direct the disposition:
                    5,657,818

                    2. NB Alternatives
                    (a) Amount beneficially owned: 5,657,818
                    (b) Percent of class: 6.8 %
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii) Shared power to vote or direct the vote: 5,657,818
                    (iii) Sole power to dispose or direct the disposition: -0-
                    (iv) Shared power to dispose or direct the disposition:
                    5,657,818

                    3. NB Partners
                    (a) Amount beneficially owned: 4,705,737
                    (b) Percent of class: 5.7 %
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii) Shared power to vote or direct the vote: 4,705,737
                    (iii) Sole power to dispose or direct the disposition: -0-
                    (iv) Shared power to dispose or direct the disposition:
                    4,705,737

                    4. NB Associates
                    (a) Amount beneficially owned: 4,705,737
                    (b) Percent of class: 5.7 %
                    (c)(i) Sole power to vote or direct the vote: -0-
                    (ii) Shared power to vote or direct the vote: 4,705,737
                    (iii) Sole power to dispose or direct the disposition: -0-
                    (iv) Shared power to dispose or direct the disposition:
                    4,705,737

                    NBG, NB Alternatives and NB Associates own directly no
                    Shares. Pursuant to investment management agreements, NB
                    Alternatives maintains investment and voting power with
                    respect to the securities held


                                  Page 7 of 9





                    by NB Partners and certain affiliated investment funds. NB
                    Associates is the general partner of NB Partners and may be
                    deemed to have beneficial ownership of the securities held
                    by NB Partners. NBG controls each of NB Alternatives and NB
                    Associates. By reason of the provisions of Rule 13d-3 of the
                    Securities Exchange Act of 1934, as amended, each of NBG and
                    NB Alternatives may be deemed to beneficially own 5,657,818
                    Shares (constituting approximately 6.8 % of the Shares
                    outstanding). Each of NBG and NB Alternatives disclaims
                    beneficial ownership of any of the securities covered by
                    this statement.

Item 5              Ownership of Five Percent or Less of a Class:
                    --------------------------------------------

                    If this statement is being filed to report the fact that as
                    of the date hereof the reporting person has ceased to be the
                    beneficial owner of more than five percent of the class of
                    securities, check the following. [ ]

Item 6              Ownership of More than Five Percent on Behalf of Another
                    --------------------------------------------------------
                    Person:
                    ------

                    Not Applicable

Item 7              Identification and Classification of the Subsidiary Which
                    ---------------------------------------------------------
                    Acquired the Security Being Reported on By the Parent
                    -----------------------------------------------------
                    Holding Company:
                    ---------------

                    Not Applicable

Item 8              Identification and Classification of Members of the Group:
                    ---------------------------------------------------------

                    Not Applicable

Item 9              Notice of Dissolution of Group:
                    ------------------------------

                    Not Applicable

Item 10             Certification:

     By signing below the signatory certifies that, to the best of his knowledge
and belief, the securities referred to above were not acquired and are not held
for the purpose of or with the effect of changing or influencing the control of
the issuer of the securities and were not acquired and are not held in
connection with or as a participant in any transaction having that purpose or
effect.


                                  Page 8 of 9





                                    SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

Dated:  February 16, 2010

Neuberger Berman Group LLC


By: /s/ Kevin Handwerker
   -----------------------------------------
Name:   Kevin Handwerker
Title:  General Counsel

NB Alternatives Advisers LLC


By: /s/ Kevin Handwerker
   -----------------------------------------
Name:   Kevin Handwerker
Title:  General Counsel

NB Co-Investment Partners LP


By: /s/ Sean Ward
   -----------------------------------------
Name:   Sean Ward
Title:  Vice President

NB Co-Investment Associates LP


By: /s/ Sean Ward
   -----------------------------------------
Name:   Sean Ward
Title:  Vice President


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