SCHEDULE 13G
Amendment No. 3
ACCELERON PHARMA INC
COMMON STOCK
Cusip #00434H108
Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:
[x] Rule 13d-1(b)
[ ] Rule 13d-1(c)
[ ] Rule 13d-1(d)
Cusip #00434H108
Item 1: Reporting Person - FMR LLC
Item 2: (a) [ ]
(b) [ ]
Item 4: Delaware
Item 5: 4,857
Item 6: 0
Item 7: 4,987,985
Item 8: 0
Item 9: 4,987,985
Item 11: 14.999%
Item 12: HC
Cusip #00434H108
Item 1: Reporting Person - Abigail P. Johnson
Item 2: (a) [ ]
(b) [ ]
Item 4: United States of America
Item 5: 0
Item 6: 0
Item 7: 4,987,985
Item 8: 0
Item 9: 4,987,985
Item 11: 14.999%
Item 12: IN
Cusip #00434H108
Item 1: Reporting Person - Select Biotechnology Portfolio
Item 2: (a) [ ]
(b) [ ]
Item 4: Massachusetts
Item 5: 3,246,194
Item 6: 0
Item 7: 0
Item 8: 0
Item 9: 3,246,194
Item 11: 9.762%
Item 12: IV
Item 1(a). Name of Issuer:
ACCELERON PHARMA INC
Item 1(b). Address of Issuer's Principal Executive Offices:
128 SYDNEY STREET
Cambridge, MA 02139MA
USA
Item 2(a). Name of Person Filing:
FMR LLC
Item 2(b). Address or Principal Business Office or, if None,
Residence:
245 Summer Street, Boston, Massachusetts 02210
Item 2(c). Citizenship:
Not applicable
Item 2(d). Title of Class of Securities:
COMMON STOCK
Item 2(e). CUSIP Number:
00434H108
Item 3. This statement is filed pursuant to Rule 13d-1(b) or 13d-2(b)
or (c) and the
person filing, FMR LLC, is a parent holding company in accordance with
Section 240.13d-1(b)(1)(ii)(G). (Note: See Exhibit A).
Item 4. Ownership
(a) Amount Beneficially Owned: 4,987,985
(b) Percent of Class: 14.999%
(c) Number of shares as to which such person has:
(i) sole power to vote or to direct the vote: 4,857
(ii) shared power to vote or to direct the vote: 0
(iii) sole power to dispose or to direct the
disposition of: 4,987,985
(iv) shared power to dispose or to direct the
disposition of: 0
Item 5. Ownership of Five Percent or Less of a Class.
Not applicable.
Item 6. Ownership of More than Five Percent on Behalf of Another
Person.
Various persons have the right to receive or the power to direct the
receipt of dividends from, or the proceeds from the sale of, the COMMON
STOCK of ACCELERON PHARMA INC. No one other person's interest in the COMMON
STOCK of ACCELERON PHARMA INC is more than five percent of the total
outstanding COMMON STOCK.
Item 7. Identification and Classification of the Subsidiary Which
Acquired the Security Being Reported on By the Parent Holding Company.
See attached Exhibit A.
Item 8. Identification and Classification of Members of the Group.
Not applicable.
Item 9. Notice of Dissolution of Group.
Not applicable.
Item 10. Certifications.
By signing below I certify that, to the best of my knowledge and belief,
the securities referred to above were acquired and are held in the ordinary
course of business and were not acquired and are not held for the purpose
of or with the effect of changing or influencing the control of the issuer
of the securities and were not acquired and are not held in connection with
or as a participant in any transaction having that purpose or effect.
Signature
After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete
and correct.
February 12, 2016
Date
/s/ Marc R. Bryant
Signature
Marc R. Bryant
Duly authorized under Power of Attorney effective as of September 23,
2015, by and on behalf of FMR LLC and its direct and indirect subsidiaries*
* This power of attorney is incorporated herein by reference to Exhibit 24
to the Form 4 filed by FMR LLC on November 25, 2015, accession number:
0000315066-15-003312
Exhibit A
Pursuant to the instructions in Item 7 of Schedule 13G,
the following table lists the identity and Item 3 classification, if
applicable, of each relevant entity that beneficially owns shares of the
security class being reported on this Schedule 13G.
Entity ITEM 3 Classification
FMR CO., INC * IA
* Entity beneficially owns 5% or greater of the outstanding shares of the
security class being reported on this Schedule 13G.
Abigail P. Johnson is a Director, the Vice Chairman, the
Chief Executive Officer and the President of FMR LLC.
Members of the Johnson family, including Abigail P.
Johnson, are the predominant owners, directly or through trusts, of Series
B voting common shares of FMR LLC, representing 49% of the voting power of
FMR LLC. The Johnson family group and all other Series B shareholders have
entered into a shareholders' voting agreement under which all Series B
voting common shares will be voted in accordance with the majority vote of
Series B voting common shares. Accordingly, through their ownership of
voting common shares and the execution of the shareholders' voting
agreement, members of the Johnson family may be deemed, under the
Investment Company Act of 1940, to form a controlling group with respect to
FMR LLC.
Neither FMR LLC nor Abigail P. Johnson has the sole power
to vote or direct the voting of the shares owned directly by the various
investment companies registered under the Investment Company Act ("Fidelity
Funds") advised by Fidelity Management & Research Company ("FMR Co"), a
wholly owned subsidiary of FMR LLC, which power resides with the Fidelity
Funds' Boards of Trustees. Fidelity Management & Research Company carries
out the voting of the shares under written guidelines established by the
Fidelity Funds' Boards of Trustees.
This filing reflects the securities beneficially owned, or
that may be deemed to be beneficially owned, by FMR LLC, certain of its
subsidiaries and affiliates, and other companies (collectively, the "FMR
Reporters"). This filing does not reflect securities, if any, beneficially
owned by certain other companies whose beneficial ownership of securities
is disaggregated from that of the FMR Reporters in accordance with
Securities and Exchange Commission Release No. 34-39538 (January 12, 1998).
RULE 13d-1(k)(1) AGREEMENT
The undersigned persons, on February 12, 2016, agree and
consent to the joint filing on their behalf of this Schedule 13G in
connection with their beneficial ownership of the COMMON STOCK of ACCELERON
PHARMA INC at December 31, 2015.
FMR LLC
By /s/ Marc R. Bryant
Marc R. Bryant
Duly authorized under Power of Attorney effective as of September 23,
2015, by and on behalf of FMR LLC and its direct and indirect subsidiaries*
Abigail P. Johnson
By /s/ Marc R. Bryant
Marc R. Bryant
Duly authorized under Power of Attorney effective as of October 12,
2015, by and on behalf of Abigail P. Johnson*
Select Biotechnology Portfolio
By /s/ Marc R. Bryant
Marc R. Bryant
Secretary
* This power of attorney is incorporated herein by reference to Exhibit 24
to the Form 4 filed by FMR LLC on November 25, 2015, accession number:
0000315066-15-003312