Sec Form 4 Filing - Third Rock Ventures II, L.P. @ Global Blood Therapeutics, Inc. - 2015-08-17

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 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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1. Name and Address of Reporting Person Third Rock Ventures II, L.P. 2. Issuer Name and Ticker or Trading Symbol Global Blood Therapeutics, Inc. [ GBT] 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) C/O THIRD ROCK VENTURES, LLC, 29 NEWBURY STREET, 3RD FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 08/17/2015 (Street) BOSTON, MA02116 4. If Amendment, Date Original Filed (MM/DD/YY) 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 (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 08/17/2015 C 11,903,763 A 12,475,191 ( 2 ) D ( 3 )

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 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 Series A Preferred Stock ( 1 ) 08/17/2015 C 41,663,168 ( 1 ) ( 1 ) Common Stock 11,903,763 ( 2 ) $ 0 0 D ( 3 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Third Rock Ventures II, L.P. C/O THIRD ROCK VENTURES, LLC 29 NEWBURY STREET, 3RD FLOOR BOSTON, MA02116 X Third Rock Ventures GP II, L.P. 29 NEWBURY STREET, 3RD FLOOR BOSTON, MA02116 X TRV GP II, LLC 29 NEWBURY STREET, 3RD FLOOR BOSTON, MA02116 X LEVIN MARK J 29 NEWBURY STREET, 3RD FLOOR BOSTON, MA02116 X TEPPER ROBERT I 29 NEWBURY STREET, 3RD FLOOR BOSTON, MA02116 X Signatures /s/ Third Rock Ventures II, L.P. by Third Rock Ventures GP II, L.P. its general partner by TRV GP II, LLC its general partner 08/19/2015 Signature of Reporting Person Date /s/ Third Rock Ventures GP II, L.P. by TRV GP II, LLC its general partner 08/19/2015 Signature of Reporting Person Date /s/ TRV GP II, LLC 08/19/2015 Signature of Reporting Person Date /s/ Kevin Gillis by power of attorney for Mark Levin 08/19/2015 Signature of Reporting Person Date /s/ Kevin Gillis by power of attorney for Dr. Robert Tepper 08/19/2015 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The aggregate number of shares of Issuer's Preferred Stock held by the Reporting Person converted into Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. These shares converted into Common Stock on a 3.5-for-1 basis. ( 2 )Reflects the conversion of the Issuer's Preferred Stock into Common Stock on a 3.5-for-1 basis, which became effective immediately prior to the closing of the Issuer's initial public offering. ( 3 )The shares are directly held by Third Rock Ventures II, L.P. ("TRV"). The general partner of TRV is Third Rock Ventures GP II, L.P. ("TRV GP"). The general partner of TRV GP is TRV GP II, LLC ("TRV GP LLC"). The individual managers of TRV GP LLC are Mark Levin ("Levin"), Kevin Starr ("Starr") and Dr. Robert Tepper ("Tepper") and, as such, each of TRV GP, TRV GP LLC, Levin, Starr and Tepper exercises shared voting and investment power over the shares held of record by TRV. Each of the Reporting Persons disclaims beneficial ownership of the shares except to the extent of their pecuniary interest therein, if any.

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).

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