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
                                                                                  
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OMB Number: 3235-0287
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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940
                      

1. Name and Address of Reporting Person *

MCGUIRE TERRANCE 		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)
(Last)          (First)          (Middle)

ONE MARINA PARK DRIVE, SUITE 1100 		3. Date of Earliest Transaction (MM/DD/YYYY)

12/7/2016
(Street)

BOSTON, MA 02210
(City)        (State)        (Zip)
4. If Amendment, Date Original Filed (MM/DD/YYYY)

 
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. Trans. Date 2A. Deemed Execution Date, if any 3. Trans. 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 Stock   12/7/2016     X    180518   A $5.88   778671   (1) I   See Footnote   (2)
Common Stock   12/8/2016     S (3)    34285   D $30.96   744386   (4) I   See Footnote   (2)
Common Stock   12/7/2016     X    3384   A $5.88   747770   (5) I   See Footnote   (2)
Common Stock   12/8/2016     S (6)    643   D $30.96   747127   (7) I   See Footnote   (2)
Common Stock                  1624   D    

Table II - Derivative Securities Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security
(Instr. 3) 		2. Conversion or Exercise Price of Derivative Security 3. Trans. Date 3A. Deemed Execution Date, if any 4. Trans. 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 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 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
Warrant (Right to Buy)   $5.88   12/7/2016     X         180518    6/10/2010   6/10/2020   Common Stock   180518   $0.00   0   I   See Footnote   (2)
Warrant (Right to Buy)   $5.88   12/7/2016     X         3384    6/10/2010   6/10/2020   Common Stock   3384   $0.00   0   I   See Footnote   (2)

Explanation of Responses:
( 1)  Represents 766,574 shares, 10,102 shares, and 1,995 shares directly owned by Polaris Venture Partners IV, L.P. ("PVP IV"), Polaris Venture Partners Entrepreneurs' Fund IV, L.P. ("PVPE IV") and Polaris Venture Management IV, L.L.C. ("PVM IV"), respectively.
( 2)  The Reporting Person is a managing member of PVM IV, the general partner of each of PVP IV and PVPE IV. The Reporting Person disclaims beneficial ownership of the Funds' and PVM IV's 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, if any, therein.
( 3)  On December 7, 2016, the PVP IV exercised a warrant to purchase 180,518 share of the Issuer's Common Stock for $5.88 per share. PVP IV paid the exercise price on a cashless basis, resulting in the Issuer withholding 34,285 shares of the Issuer's shares of common stock subject to the warrant to pay the exercise price and issuing PVP IV the remaining 146,233 shares of the Issuer's common stock. The Issuer also paid $17.76 to PVP IV in lieu of a fractional share.
( 4)  Represents 732,289 shares, 10,102 shares, and 1,995 shares directly owned by PVP IV, PVPE IV and PVM IV, respectively.
( 5)  Represents 732,289 shares, 13,486 shares, and 1,995 shares directly owned by PVP IV, PVPE IV and PVM IV, respectively.
( 6)  On December 7, 2016, the PVPE IV exercised a warrant to purchase 3,384 share of the Issuer's Common Stock for $5.88 per share. PVPE IV paid the exercise price on a cashless basis, resulting in the Issuer withholding 643 shares of the Issuer's shares of common stock subject to the warrant to pay the exercise price and issuing PVPE IV the remaining 2,741 shares of the Issuer's common stock. The Issuer also paid $9.36 to PVPE IV in lieu of a fractional share.
( 7)  Represents 732,289 shares, 12,843 shares, and 1,995 shares directly owned by PVP IV, PVPE IV and PVM IV, respectively.

Reporting Owners
Reporting Owner Name / Address
Relationships
Director 10% Owner Officer Other
MCGUIRE TERRANCE
ONE MARINA PARK DRIVE, SUITE 1100
BOSTON, MA 02210 		X



Signatures
/s/ Mary Blair, Attorney in-Fact for Terrance McGuire 12/9/2016
** 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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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.
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