Sec Form 4 Filing - Third Rock Ventures IV, L.P. @ Magenta Therapeutics, Inc. - 2018-06-25

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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 IV, L.P.
2. Issuer Name and Ticker or Trading Symbol
Magenta Therapeutics, Inc. [ MGTA]
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)
06/25/2018
(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 06/25/2018 C 7,911,455 A 8,008,204 D ( 2 )
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 ) 06/25/2018 C 20,102,478 ( 1 ) ( 1 ) Common Stock 7,779,656 ( 1 ) 0 D ( 2 )
Series B Preferred Stock ( 1 ) 06/25/2018 C 340,566 ( 1 ) ( 1 ) Common Stock 131,799 ( 1 ) 0 D ( 2 )
Reporting Owners
Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
Third Rock Ventures IV, L.P.
C/O THIRD ROCK VENTURES, LLC
29 NEWBURY STREET, 3RD FLOOR
BOSTON, MA02116
X
Third Rock Ventures GP IV, L.P.
29 NEWBURY STREET, 3RD FLOOR
BOSTON, MA02116
X
TRV GP IV, LLC
29 NEWBURY STREET, 3RD FLOOR
BOSTON, MA02116
X
Signatures
/s/ Kevin Gillis, Chief Financial Officer of TRV GP IV, LLC, general partner of Third Rock Ventures GP IV, L.P., general partner of Third Rock Ventures IV, L.P. 06/27/2018
Signature of Reporting Person Date
/s/ Kevin Gillis, Chief Financial Officer of TRV GP IV, LLC, general partner of Third Rock Ventures GP IV, L.P. 06/27/2018
Signature of Reporting Person Date
/s/ Kevin Gillis, Chief Financial Officer of TRV GP IV, LLC 06/27/2018
Signature of Reporting Person Date
Explanation of Responses:
( 1 )The Series A Preferred Stock and Series B Preferred Stock (collectively, the "Preferred Stock") converted into Common Stock on a 2.58398:1 basis upon the closing of the Issuer's initial public offering on June 25, 2018. The Preferred Stock had no expiration date.
( 2 )The shares are directly held by Third Rock Ventures IV, L.P. ("TRV IV"). The general partner of TRV IV is Third Rock Ventures GP IV, L.P. ("TRV GP IV"). The general partner of TRV GP IV is TRV GP IV, LLC ("TRV GP IV LLC"). Each of TRV GP IV and TRV GP IV LLC disclaims beneficial ownership of these shares except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that it is the beneficial owner of such shares.

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* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
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