SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 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. (Last) (First) (Middle) C/O THIRD ROCK VENTURES, LLC, 29 NEWBURY STREET, 3RD FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip)	2. Date of Event Requiring Statement (Month/Day/Year) 08/10/2021	3. Issuer Name and Ticker or Trading Symbol Tango Therapeutics, Inc. [ TNGX ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)	5. If Amendment, Date of 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

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	19,363,975(1)	D(2)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person* Third Rock Ventures IV, L.P. (Last) (First) (Middle) C/O THIRD ROCK VENTURES, LLC, 29 NEWBURY STREET, 3RD FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip)

1. Name and Address of Reporting Person* Third Rock Ventures GP IV, L.P. (Last) (First) (Middle) 29 NEWBURY STREET, 3RD FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip)

1. Name and Address of Reporting Person* TRV GP IV, LLC (Last) (First) (Middle) 29 NEWBURY STREET, 3RD FLOOR (Street) BOSTON MA 02116 (City) (State) (Zip)

Explanation of Responses:

1. On August 10, 2021, Tango Therapeutics, Inc. (f/k/a BCTG Acquisition Corp., the "Issuer") consummated a business combination (the "Business Combination") pursuant to which BCTG Merger Sub Corp., a wholly-owned subsidiary of the Issuer merged with and into Tango Therapeutics, Inc. ("Tango"). At the effective time of the Business Combination, each share of Tango outstanding as of immediately prior to the effective time was exchanged for shares of Common Stock of the Issuer based on an exchange ratio of approximately 0.34. As a result, the Reporting Persons received 19,363,975 shares of the Issuer's Common Stock in consideration for the equity securities of Tango held by the Reporting Persons prior to the Business Combination.

2. These shares are directly held by 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.

Remarks:

	/s/ Kevin Gillis, Chief Operating 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.	08/12/2021
	/s/ Kevin Gillis, Chief Operating Officer of TRV GP IV, LLC, general partner of Third Rock Ventures GP IV, L.P.	08/12/2021
	/s/ Kevin Gillis, Chief Operating Officer of TRV GP IV, LLC	08/12/2021
	** Signature of Reporting Person	Date
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