Sec Form 4 Filing - Bell David @ Allied World Assurance Co Holdings, AG - 2012-02-28

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 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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1. Name and Address of Reporting Person Bell David 2. Issuer Name and Ticker or Trading Symbol Allied World Assurance Co Holdings, AG [ AWH] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) COO (Last) (First) (Middle) ALLIED WORLD ASSURANCE CO. HOLDINGS, AG, LINDENSTRASSE 8 3. Date of Earliest Transaction (MM/DD/YY) 02/28/2012 (Street) BAAR/ZUG, V8CH-6340 4. If Amendment, Date Original Filed (MM/DD/YY) 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 (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 02/28/2012 M 3,333 A $ 29.52 57,050 D Common Shares 02/28/2012 M 3,333 A $ 32.7 60,383 D Common Shares 02/28/2012 M 1,222 A $ 61.51 61,605 D Common Shares 02/28/2012 S 8,261 D $ 66.4307 ( 1 ) 53,344 D Common Shares 02/29/2012 S 8,627 D $ 66.4345 ( 2 ) 44,717 D

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 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 Employee Stock Options (right to buy) $ 29.52 02/28/2012 M 3,333 12/31/2004( 3 ) 12/31/2013 Common Shares 3,333 $ 0 0 D Employee Stock Options (right to buy) $ 32.7 02/28/2012 M 3,333 01/03/2006( 3 ) 01/03/2015 Common Shares 3,333 $ 0 0 D Employee Stock Options (right to buy) $ 61.51 02/28/2012 M 1,222 02/22/2012( 3 ) 02/22/2021 Common Shares 1,222 $ 0 3,668 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Bell David ALLIED WORLD ASSURANCE CO. HOLDINGS, AG LINDENSTRASSE 8 BAAR/ZUG, V8CH-6340 COO Signatures /s/ Wesley D. Dupont, by Power of Attorney 03/01/2012 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents a weighted average sale price: the sales prices range from $66.40 to $66.52. Upon request, the full sale information regarding the number of shares sold at each price increment will be provided to the U.S. Securities and Exchange Commission, the issuer or a security holder of the issuer. ( 2 )Represents a weighted average sale price: the sales prices range from $66.40 to $66.60. Upon request, the full sale information regarding the number of shares sold at each price increment will be provided to the U.S. Securities Exchange Commission, the issuer or a security holder of the issuer. ( 3 )These securities vest in four equal annual installments with the first installment vesting on the date shown.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* 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).

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