SEC Form 4

FORM 4		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 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* Omega Fund V, L.P. (Last) (First) (Middle) 888 BOYLSTON STREET, SUITE 1111 (Street) BOSTON MA 02199 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol Gossamer Bio, Inc. [ GOSS ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 09/16/2019
	4. 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 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	09/16/2019		S		13,213	D	$21.519(1)	6,806,023	D(4)
Common Stock	09/17/2019		S		23,400	D	$21.615(2)	6,782,623	D(4)
Common Stock	09/18/2019		S		45,600	D	$21.878(3)	6,737,023	D(4)

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 Securities Underlying Derivative Security (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: 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

1. Name and Address of Reporting Person* Omega Fund V, L.P. (Last) (First) (Middle) 888 BOYLSTON STREET, SUITE 1111 (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Omega Fund V GP, L.P. (Last) (First) (Middle) 888 BOYLSTON STREET, SUITE 1111 (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Omega Fund V GP Manager, Ltd. (Last) (First) (Middle) 888 BOYLSTON STREET, SUITE 1111 (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Stampacchia Otello (Last) (First) (Middle) 888 BOYLSTON STREET, SUITE 1111 (Street) BOSTON MA 02199 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) X Other (specify below) Former director.

Explanation of Responses:

1. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $21.50 to $21.56 per share, inclusive.

2. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $21.50 to $22.24 per share, inclusive.

3. The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $21.50 to $22.35 per share, inclusive.

4. The reported securities are held directly by Omega Fund V, L.P. ("Omega V"). The reported securities may be deemed to be beneficially owned by each of Omega Fund V GP, L.P. ("Omega V GP"), as the general partner of Omega V, and Omega Fund V GP Manager, Ltd. ("Omega V GP Manager"), as the general partner of Omega V GP. Otello Stampacchia, Richard Lim, Anne-Mari Paster and Claudio Nessi (the "Omega Directors") are all the shareholders and directors of Omega V GP Manager and have shared voting and investment power over the shares held by Omega V. Each of Omega V GP, Omega Fund V GP Manager and the Omega Directors disclaims beneficial ownership of the securities reported herein, except to the extent of its or their pecuniary interest therein, if any. Effective as of September 12, 2019, Otello Stampacchia is no longer a member of the issuer's board of directors.

Remarks:

	/s/ Anne-Mari Paster, as an authorized signatory of each Reporting Person	09/18/2019
	** Signature of Reporting Person	Date
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).
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