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^*

MCGUIRE TERRANCE

(Last)

(First)

(Middle)

C/O POLARIS VENTURE PARTNERS

1000 WINTER STREET SUITE 3350

(Street)

WALTHAM

02451

(City)

(State)

(Zip)

2. Issuer Name and Ticker or Trading Symbol
ACCELERON PHARMA INC [ XLRN ]

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)
09/24/2013

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 Stock	09/24/2013		C		1,706,532	A	⁽⁵⁾	1,718,602	I	See Footnotes⁽¹⁾⁽²⁾⁽³⁾⁽⁴⁾
Common Stock	09/24/2013		C		629,499	A	⁽⁵⁾	2,348,101	I	See Footnotes⁽¹⁾⁽²⁾⁽³⁾⁽⁴⁾
Common Stock	09/24/2013		C		363,495	A	⁽⁵⁾	2,711,596	I	See Footnotes⁽¹⁾⁽²⁾⁽³⁾⁽⁴⁾
Common Stock	09/24/2013		C		48,577	A	⁽⁵⁾	2,760,173	I	See Footnotes⁽¹⁾⁽²⁾⁽³⁾⁽⁴⁾
Common Stock	09/24/2013		J		277,520	A	⁽⁶⁾	3,037,693	I	See Footnotes⁽¹⁾⁽²⁾⁽³⁾⁽⁴⁾
Common Stock	09/24/2013		C		95,541	A	⁽⁵⁾	3,133,234	I	See Footnotes⁽¹⁾⁽²⁾⁽³⁾⁽⁴⁾

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)
Series A Convertible Preferred Stock	⁽⁵⁾	09/24/2013		C			1,706,532	⁽⁵⁾	⁽⁵⁾	Common Stock	1,706,532	$0	0	I	See Footnotes⁽¹⁾⁽²⁾⁽³⁾⁽⁴⁾
Series B Convertible Preferred Stock	⁽⁵⁾	09/24/2013		C			629,499	⁽⁵⁾	⁽⁵⁾	Common Stock	629,499	$0	0	I	See Footnotes⁽¹⁾⁽²⁾⁽³⁾⁽⁴⁾
Series C Convertible Preferred Stock	⁽⁵⁾	09/24/2013		C			363,495	⁽⁵⁾	⁽⁵⁾	Common Stock	363,495	$0	0	I	See Footnotes⁽¹⁾⁽²⁾⁽³⁾⁽⁴⁾
Series D Convertible Preferred Stock	⁽⁵⁾	09/24/2013		C			48,577	⁽⁵⁾	⁽⁵⁾	Common Stock	48,577	$0	0	I	See Footnotes⁽¹⁾⁽²⁾⁽³⁾⁽⁴⁾
Series E Convertible Preferred Stock	⁽⁶⁾	09/24/2013		J			172,188	⁽⁶⁾	⁽⁶⁾	Common Stock	277,520	$0	0	I	See Footnotes⁽¹⁾⁽²⁾⁽³⁾⁽⁴⁾
Series F Convertible Preferred Stock	⁽⁵⁾	09/24/2013		C			95,541	⁽⁵⁾	⁽⁵⁾	Common Stock	95,541	$0	0	I	See Footnotes⁽¹⁾⁽²⁾⁽³⁾⁽⁴⁾

Explanation of Responses:

1. 222 shares of common stock, 29,594 shares of Series A Convertible Preferred Stock, 11,584 shares of Series B Convertible Preferred Stock, 6,689 shares of Series C Convertible Preferred Stock, 894 shares of Series D Convertible Preferred Stock, 3,168 shares of Series E Convertible Preferred Stock and 1,758 shares of Series F Convertible Preferred Stock of the registrant were owned directly by Polaris Venture Partners Entrepreneurs Fund IV, L.P. (PVPE IV). After the conversions listed herein PVPE IV owns 55,846 shares of common stock.

2. Polaris Venture Management Co. IV, L.L.C. (PVM IV) is the general partner of PVPE IV. PVM IV disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM IV is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Jonathan A. Flint, Terrance G. McGuire and Alan G. Spoon are the managing members of PVM IV. Each of Messrs. Flint, McGuire and Spoon disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their pecuniary interest therein.

3. 11,848 shares of common stock, 1,676,938 shares of Series A Convertible Preferred Stock, 617,915 shares of Series B Convertible Preferred Stock, 356,806 shares of Series C Convertible Preferred Stock, 47,683 shares of Series D Convertible Preferred Stock, 169,020 shares of Series E Convertible Preferred Stock and 93,783 shares of Series F Convertible Preferred Stock of the registrant were owned directly by Polaris Venture Partners IV, L.P. (PVP IV). After the conversions listed herein PVP IV owns 3,077,388 shares of common stock.

4. PVM IV is the general partner of PVP IV. PVM IV disclaims beneficial ownership of these securities and this report shall not be deemed an admission that PVM IV is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of its pecuniary interest therein. Each of Messrs. Flint, McGuire and Spoon are the managing members of PVM IV. Each of Messrs. Flint, McGuire and Spoon disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their pecuniary interest therein.

5. Upon closing of the Issuers initial public offering, each share of Series A, B, C, D and F Convertible Preferred Stock automatically converted into one share of Common Stock without payment of further consideration. The shares had no expiration date.

6. Upon closing of the Issuers initial public offering, each share of Series E Preferred Stock automatically converted at a ratio of 1-for-1.61174 into the number of shares of Common Stock shown in column 7 without payment of further consideration. The shares had no expiration date.

	/s/ Kevin F. McLaughlin, attorney in fact for Terrance G. McGuire	09/26/2013
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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