Migausky George V Form 4 Dimension Therapeutics / GEORGE V MIGAUSKY ownership change

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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X

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^*

MIGAUSKY GEORGE V

(Last) (First) (Middle)

C/O DIMENSION THERAPEUTICS, INC.

840 MEMORIAL DRIVE, 4TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Dimension Therapeutics, Inc. [ DMTX ]

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

X	Director	10% Owner
	Officer (give title below)	Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
11/07/2017

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)
			Code	V	Amount	(A) or (D)	Price

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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (Right to Buy)	$4.09	11/07/2017		D			55,772	(1)	06/02/2025	Common Stock	55,772	(1)	0	D
Stock Option (Right to Buy)	$7.08	11/07/2017		D			32,069	(2)	05/18/2026	Common Stock	32,069	(2)	0	D
Stock Option (Right to Buy)	$1.15	11/07/2017		D			17,000	(3)	05/24/2027	Common Stock	17,000	(3)	0	D

Explanation of Responses:

1. This stock option, which vests in equal monthly installments over 48 months beginning June 3, 2015, was assumed by Ultragenyx Pharmaceutical Inc. ("Ultragenyx"), and converted in accordance with the exchange ratio as set forth in the Agreement and Plan of Merger dated October 2, 2017 between the Issuer, Ultragenyx and Mystic River Merger Sub Inc., a direct, wholly-owned subsidiary of Ultragenyx.

2. These options were assumed by Ultragenyx and converted in accordance with the exchange ratio as set forth in the Merger Agreement.

3. These options, which vest in full on the earlier of May 25, 2018 or the Issuer's next annual meeting of stockholders, subject to the director's continued service on the Board, were assumed by Ultragenyx and converted in accordance with the exchange ratio as set forth in the Merger Agreement.

Remarks:

	/s/ Mary Thistle, as Attorney-in-Fact for George V. Migausky	11/07/2017
	** Signature of Reporting Person	Date
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