Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
Slade Brenton
  2. Issuer Name and Ticker or Trading Symbol
Flagstone Reinsurance Holdings, S.A. [FSR]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
Director of Marketing
(Last)
(First)
(Middle)
FLAGSTONE REINSURANCE HOLDINGS SA, 37, VAL ST ANDRE
3. Date of Earliest Transaction (Month/Day/Year)
03/10/2011
(Street)

LUXEMBOURG, N4 L-1128
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Shares 03/10/2011   M   43,957 A $ 0 (1) 43,957 D  
Common Shares 03/10/2011   F   1,902 D $ 11.33 42,055 D  

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Performance Share Units $ 0 (1) 03/10/2011   M     29,305 01/01/2011(2) 04/01/2011(2) Common Shares 43,957 (3) $ 0 (1) 119,305 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
Slade Brenton
FLAGSTONE REINSURANCE HOLDINGS SA
37, VAL ST ANDRE
LUXEMBOURG, N4 L-1128
      Director of Marketing  

Signatures

 /s/ William F. Fawcett, by power of attorney   03/10/2011
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) Vesting of Performance Share Units ("PSUs") is contingent on the reporting person's continued employment with Flagstone Reinsurance Holdings SA (the "Company") and the Company meeting certain fully diluted return-on-equity ("FDROE") goals. Upon vesting, the PSU holder is entitled to receive a number of common shares of the Company (or the cash equivalent, at the election of the Company) equal to the product of the number of PSUs granted multiplied by a factor based on the Company's FDROE during the vesting period. The factor ranges between 0.5 and 1.5, depending on the FDROE achieved during the vesting period.
(2) The PSUs vested on January 1, 2011; however, settlement of any shares took place following the calculation of the factor described in footnote (1). The factor used to determine the number of common shares awarded was determined following the filing of the Company's annual report on Form 10-K on March 2, 2011. The expiration date assumes that the Company would settle these PSUs within three months of the vesting date.
(3) Based on the FDROE achieved during the relevant period, the number of common shares awarded was determined by multiplying the number of PSUs by a factor of 1.5.

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