SEC FORM 4

SEC Form 4

FORM 4

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
or Section 30(h) of the Investment Company Act of 1940

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person^*

Mullan Adam

(Last)

(First)

(Middle)

C/O ALTERRA CAPITAL HOLDINGS LIMITED

ALTERRA HOUSE, 2 FRONT STREET

(Street)

HAMILTON, BERMUDA

HM 11

(City)

(State)

(Zip)

2. Issuer Name and Ticker or Trading Symbol
ALTERRA CAPITAL HOLDINGS Ltd [ ALTE ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	10% Owner
X	Officer (give title below)	Other (specify below)
	CEO, Reinsurance and Lloyd's

3. Date of Earliest Transaction (Month/Day/Year)
05/01/2013

4. If Amendment, Date of 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

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Shares	05/01/2013		D		11,784	D	⁽¹⁾	59,456	D
Common Shares	05/01/2013		D		59,456	D	⁽²⁾	0	D
Restricted Stock Units	05/01/2013		D		26,801	D	⁽³⁾	0	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 (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 Securities Underlying Derivative Security (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: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

Explanation of Responses:

1. Disposed of pursuant to the Agreement and Plan of Merger, dated as of December 18, 2012 (the "Merger Agreement") between Alterra Capital Holdings Ltd. (the "Issuer"), Markel Corporation ("Markel") and Commonwealth Merger Subsidiary Limited in exchange on a per share basis for (i) the amount of shares of Markel common stock equal to the number of shares of Issuer common stock multiplied by 0.04315 plus (ii) $10.00 in cash, without interest, together with any cash paid in lieu of fractional shares relating to each award and form of ownership.

2. Restricted stock of the Issuer that did not automatically vest upon the closing of the transactions contemplated by the Merger Agreement (the "Closing") disposed of pursuant to the Merger Agreement in exchange on a per share basis for the amount of shares of Markel restricted stock equal to the number of shares of Issuer restricted stock multiplied by the Incentive Exchange Ratio, together with any cash paid in lieu of fractional shares. The Incentive Exchange Ratio is (i) 0.04315 plus (ii) (a) $10.00 divided by (b) the volume weighted average share price per share of Markel common stock for the five consecutive trading days immediately preceding the second trading day before the closing date.

3. Restricted stock units of the Issuer that did not automatically vest upon the Closing disposed of pursuant to the Merger Agreement in exchange on a per unit basis for (i) the amount of Markel restricted stock units equal to the number of Issuer restricted stock units multiplied by the Incentive Exchange Ratio, together with any cash paid in lieu of fractional shares.

Remarks:

	H. Matthew Crusey, Attorney-in-Fact	05/03/2013
	** Signature of Reporting Person	Date
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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