Ownership Submission
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

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
Polaris Venture Partners V, L.P.
  2. Issuer Name and Ticker or Trading Symbol
T2 Biosystems, Inc. [TTOO]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)
1000 WINTER STREET, SUITE 3350
3. Date of Earliest Transaction (Month/Day/Year)
07/08/2015
(Street)

WALTHAM, MA 02451
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
___ Form filed by One Reporting Person
_X_ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
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
Common Stock 07/08/2015   S(1)   282 D $ 15.9949 (6) 41,273 I See Footnotes (2) (7) (8)
Common Stock 07/08/2015   S(1)   99 D $ 15.9949 (6) 59,164 I See Footnotes (3) (7) (8)
Common Stock 07/08/2015   S(1)   144 D $ 15.9949 (6) 81,536 I See Footnotes (4) (7) (8)
Common Stock 07/08/2015   S(1)   14,474 D $ 15.9949 (6) 2,200,883 I See Footnotes (5) (7) (8)
Common Stock 07/09/2015   S(1)   282 D $ 16.1239 (9) 40,991 I See Footnotes (2) (7) (8)
Common Stock 07/09/2015   S(1)   99 D $ 16.1239 (9) 59,065 I See Footnotes (3) (7) (8)
Common Stock 07/09/2015   S(1)   144 D $ 16.1239 (9) 81,392 I See Footnotes (4) (7) (8)
Common Stock 07/09/2015   S(1)   14,474 D $ 16.1239 (9) 2,186,409 I See Footnotes (5) (7) (8)
Common Stock 07/10/2015   S(1)   282 D $ 16.6255 (10) 40,709 I See Footnotes (2) (7) (8)
Common Stock 07/10/2015   S(1)   99 D $ 16.6255 (10) 58,966 I See Footnotes (3) (7) (8)
Common Stock 07/10/2015   S(1)   144 D $ 16.6255 (10) 81,248 I See Footnotes (4) (7) (8)
Common Stock 07/10/2015   S(1)   14,474 D $ 16.6255 (10) 2,171,935 I See Footnotes (5) (7) (8)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 Underlying Securities
(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

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
Polaris Venture Partners V, L.P.
1000 WINTER STREET, SUITE 3350
WALTHAM, MA 02451
    X    
Polaris Venture Partners Special Founders' Fund V, L.P.
1000 WINTER STREET, SUITE 3350
WALTHAM, MA 02451
    X    
Polaris Venture Partners Founders' Fund V, L.P.
1000 WINTER STREET, SUITE 3350
WALTHAM, MA 02451
    X    
Polaris Venture Partners Entrepreneurs' Fund V, L.P.
1000 WINTER STREET, SUITE 3350
WALTHAM, MA 02451
    X    
Polaris Venture Management Co. V, L.L.C.
1000 WINTER STREET, SUITE 3350
WALTHAM, MA 02451
    X    

Signatures

 POLARIS VENTURE PARTNERS V, L.P. By: /s/ John J. Gannon, Attorney-in-fact   07/10/2015
**Signature of Reporting Person Date

 POLARIS VENTURE PARTNERS SPECIAL FOUNDERS' FUND V, L.P. By: /s/ John J. Gannon, Attorney-in-fact   07/10/2015
**Signature of Reporting Person Date

 POLARIS VENTURE PARTNERS FOUNDERS' FUND V, L.P. By: /s/ John J. Gannon, Attorney-in-fact   07/10/2015
**Signature of Reporting Person Date

 POLARIS VENTURE PARTNERS ENTREPRENEURS' FUND V, L.P. By: /s/ John J. Gannon, Attorney-in-fact   07/10/2015
**Signature of Reporting Person Date

 POLARIS VENTURE MANAGEMENT CO. V, LLC By: /s/ John J. Gannon, Attorney-in-fact   07/10/2015
**Signature of Reporting Person Date

Explanation of Responses:

* 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).
(1) The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting persons on May 22, 2015.
(2) By Polaris Venture Partners Entrepreneurs' Fund V, L.P.
(3) By Polaris Venture Partners Founders' Fund V, L.P.
(4) By Polaris Venture Partners Special Founders' Fund V, L.P.
(5) By Polaris Venture Partners V, L.P.
(6) The price reported is a weighted average price. These shares were sold in multiple transactions at per share prices ranging from $15.76 to $16.33. The reporting persons undertake to provide upon request to the SEC staff, the Issuer, or any stockholder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
(7) Each of Polaris Venture Partners V, L.P., Polaris Venture Partners Special Founder's Fund V, L.P., Polaris Venture Partners Founders' Fund V, L.P. and Polaris Venture Partners Entrepreneurs' Fund V, L.P. (collectively, the "Funds") has the sole voting and investment power with respect to the shares directly held by it. The general partner of each of the Funds is Polaris Venture Management Co. V, LLC, or Polaris Management. Polaris Management may be deemed to have sole voting and investment power with respect to the shares held by the Funds and disclaims beneficial ownership of all the shares held by the Funds except to the extent of its proportionate pecuniary interest therein.
(8) The members of North Star Venture Management 2000, LLC, Terrence McGuire and Jonathan Flint, collectively the Management Members, are also members of Polaris Management, and as members of the general partner, they may be deemed to share voting and investment power over the shares held by the Funds. The Management Members disclaim beneficial ownership of such shares, except to the extent of their proportionate pecuniary interest therein.
(9) The price reported is a weighted average price. These shares were sold in multiple transactions at per share prices ranging from $15.75 to $16.31. The reporting persons undertake to provide upon request to the SEC staff, the Issuer, or any stockholder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
(10) The price reported is a weighted average price. These shares were sold in multiple transactions at per share prices ranging from $15.90 to $17.27. The reporting persons undertake to provide upon request to the SEC staff, the Issuer, or any stockholder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

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