$GOSS

$9.77 +$0.62 (6.78%) Close

$GOSS Overview Financial Statements SEC Filings Executives News Red Flags Capital Raising Ownership Insider Transactions Congressional Trades

Ownership

13F as of Q2 2026 · 6.1M shares outstanding

Who owns GOSS?

By type of holder

Institutions 100.0% Insiders 0.0% Everyone else 0.0%

Concentration Top 10 holders own 3833.3%

D. E. Shaw & Co., Inc. 669.3% · 683 Capital Management, LLC 640.5%

Institutional ownership

100.0%

0 pts vs last qtr

Institutional holders

169

-16 vs last qtr

Net shares bought

+203.2M

by institutions in Q2 2026

New / sold out

28 / 44

positions opened vs closed

How is ownership changing?

Institutions, last 8 quarters

Biggest buyers in Q2 2026

D. E. Shaw & Co., Inc. +40.6M
DeepCurrents Investment Group LLC NEW +37.7M

Biggest sellers in Q2 2026

BlackRock, Inc. −9.2M
Balyasny Asset Management L.P. −5.8M

Who is planning to sell?

No insider has filed a notice of proposed sale (Form 144) for Gossamer Bio, Inc. in the last 12 months.

Is your stake being diluted?

Diluted share count, FY2019–FY2025

+317.5%

+26.89% a year

Each share's claim on the business

−76.0%

shrank without buying or selling a share

Spent on buybacks vs paid in stock

— vs $194M

over 7 fiscal years

Diluted shares, split-adjusted

Buybacks Stock-based comp

How patient are the owners?

Institutional shares by how long they've been held

5+ years14% 3–5 years5% 1–3 years39% Under 1 year42%

Quarterly turnover

84.8%

of institutional shares changed hands

Top 10 managers, median time held

3 quarters

Super Investors

Investment managers reporting GOSS on Form 13F

Holder	Shares	% of company	Change vs last qtr	Held since	% of their book
DE D. E. Shaw & Co., Inc.	41.0M	669.27%	+40.6M (+10417.7%)	2025	0.0%
Shares held by quarter Peak holding41.0M (Q2'26) Change over 8 quarters+41.0M Share of the company669.270% D. E. Shaw & Co., Inc.'s full portfolio →
6C 683 Capital Management, LLC	39.2M	640.50%	+34.2M (+684.0%)	2023	0.3%
Shares held by quarter Peak holding39.2M (Q2'26) Change over 8 quarters+33.4M Share of the company640.500% 683 Capital Management, LLC's full portfolio →

D. E. Shaw & Co., Inc.

41.0M

% of company

669.27%

Change vs last qtr

+40.6M (+10417.7%)

Held since

2025

683 Capital Management, LLC

39.2M

% of company

640.50%

Change vs last qtr

+34.2M (+684.0%)

Held since

2023

28 more super investors behind a free account

See every manager holding Gossamer Bio, Inc., how their position has changed, and how long they've held it.

Institutional Funds

Mutual funds and ETFs reporting GOSS on Form N-PORT; together they hold 542.1% of the company

Fund	Position value	Shares	% of company	% of the fund	As of
IR iShares Russell 2000 ETF iShares Trust	$1.59M	4.8M	79.11%	0.00%	March 31, 2026
VT Vanguard Total Stock Market Index Fund Vanguard Index Funds	$1.14M	6.9M	112.92%	0.00%	June 30, 2026

iShares Russell 2000 ETF

iShares Trust

Position value

$1.59M

% of company

79.11%

% of the fund

0.00%

As of

March 31, 2026

Vanguard Total Stock Market Index Fund

Vanguard Index Funds

Position value

$1.14M

% of company

112.92%

% of the fund

0.00%

As of

June 30, 2026

23 more funds behind a free account

See every fund holding Gossamer Bio, Inc. and how much of the fund the position is.

Insiders and 5%+ holders

From Forms 3/4/5 and Schedules 13D/G

Holder	Shares	% of company	Change vs last qtr	8 quarters	Held since	% of their book
CC Carmen Chang 5%+ holder 13D · 1.7%	4.1M	66.42%	—	—	—	—
This holder reports through Schedule 13D/G, not a quarterly 13F. Share of the company66.420% Disclosed stake13D · 1.7% View the 13D/G filing →
AB Ali Behbahani 5%+ holder 13D · 1.7%	4.1M	66.42%	—	—	—	—
This holder reports through Schedule 13D/G, not a quarterly 13F. Share of the company66.420% Disclosed stake13D · 1.7% View the 13D/G filing →

Carmen Chang

5%+ holder13D · 1.7%

4.1M

% of company

66.42%

Change vs last qtr

—

Held since

—

Ali Behbahani

5%+ holder13D · 1.7%

4.1M

% of company

66.42%

Change vs last qtr

—

Held since

—

20 more holders behind a free account

See every insider and 5%+ holder of Gossamer Bio, Inc..

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