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
OMB APPROVAL
OMB Number: 3235-0287
Expires: January 31, 2005
Estimated average burden hours per response... 0.5

(Print or Type Responses)
1. Name and Address of Reporting Person *
BYRNE MARK JAMES
  2. Issuer Name and Ticker or Trading Symbol
Flagstone Reinsurance Holdings Ltd [FSR]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director __X__ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
Executive Chairman
(Last)
(First)
(Middle)
FLAGSTONE REINSURANCE HOLDINGS LTD., CRAWFORD HOUSE, 23 CHURCH STREET
3. Date of Earliest Transaction (Month/Day/Year)
12/15/2009
(Street)

HAMILTON, D0 HM11
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 12/15/2009   J(1)   24,000 A $ 10.8986 9,862,795 (2) I See Footnote (1)
Common Shares 12/16/2009   J(1)   24,000 A $ 10.8446 9,886,795 (2) I See Footnote (1)
Common Shares 12/17/2009   J(1)   22,000 A $ 10.7197 9,908,795 (2) I See Footnote (1)
Common Shares 12/18/2009   J(1)   20,000 A $ 10.7939 9,928,795 (2) I See Footnote (1)
Common Shares 12/21/2009   J(1)   1,700 A $ 10.9095 9,930,495 (2) I See Footnote (1)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number. SEC 1474 (9-02)

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

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
BYRNE MARK JAMES
FLAGSTONE REINSURANCE HOLDINGS LTD.
CRAWFORD HOUSE, 23 CHURCH STREET
HAMILTON, D0 HM11
  X   X   Executive Chairman  

Signatures

 /s/ Mark James Byrne   12/29/2009
**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) Between December 15, 2009 and December 21, 2009, Haverford (Bermuda) Ltd ("Haverford"), an affiliate of Flagstone Reinsurance Holdings Limited (the "Company") purchased 91,700 common shares of the Company. [2,718,604] of these common shares represent the indirect proportionate interest of the reporting person in 2,934,109 common shares of the Company held by Haverford, based on the proportionate interest of the reporting person in Haverford. The reporting person may be deemed to have investment or voting control over Haverford. These shares are held through a trust for the benefit of others and the reporting person therefore disclaims beneficial ownership of these shares.
(2) 7,155,156 of these common shares represent shares held by IAL FSR Limited which are held for the benefit of a company owned by a trust for which the reporting person serves as settlor. The reporting person disclaims beneficial ownership of these shares. 50,000 of these common shares represent shares purchased in connection with the initial public offering of the Company and are owned by Rebecca Byrne, the wife of the reporting person. The reporting person disclaims beneficial ownership of the common shares held by his wife.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.