$UPB

$2.79 +$0.04 (1.45%) Close

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

Ownership

13F as of Q2 2026 · 54.8M shares outstanding

Who owns UPB?

By type of holder

Institutions 92.3% Insiders 0.3% Everyone else 7.4%

Concentration Top 10 holders own 57.8%

FMR LLC 14.9% · Orbimed Advisors LLC 10.4%

Institutional ownership

92.3%

+10.4 pts vs last qtr

Institutional holders

148

+8 vs last qtr

Net shares bought

+5.7M

by institutions in Q2 2026

New / sold out

37 / 29

positions opened vs closed

How is ownership changing?

Institutions, last 8 quarters

Biggest buyers in Q2 2026

Norges Bank NEW +3.8M
Jpmorgan Chase & Co +549.0K

Biggest sellers in Q2 2026

Federated Hermes, Inc. SOLD OUT −979.8K
Pictet Asset Management Holding SA SOLD OUT −733.4K

Who is planning to sell?

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

Is your stake being diluted?

Diluted share count, FY2023–FY2025

+1723.2%

+326.99% a year

Each share's claim on the business

−94.5%

shrank without buying or selling a share

Spent on buybacks vs paid in stock

— vs $19.7M

over 3 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+ years0% 3–5 years0% 1–3 years71% Under 1 year29%

Quarterly turnover

17.9%

of institutional shares changed hands

Top 10 managers, median time held

1.5 years

Super Investors

Investment managers reporting UPB on Form 13F

Holder	Shares	% of company	Change vs last qtr	Held since	% of their book
F FMR LLC	8.2M	14.90%	+61.3K (+0.8%)	2024	0.0%
Shares held by quarter Peak holding8.2M (Q2'26) Change over 8 quarters+8.2M Share of the company14.900% FMR LLC's full portfolio →
OA Orbimed Advisors LLC	5.7M	10.40%	Unchanged	2024	0.7%
Shares held by quarter Peak holding5.7M (Q4'24) Change over 8 quarters+5.7M Share of the company10.400% Orbimed Advisors LLC's full portfolio →

FMR LLC

8.2M

% of company

14.90%

Change vs last qtr

+61.3K (+0.8%)

Held since

2024

Orbimed Advisors LLC

5.7M

% of company

10.40%

Change vs last qtr

Unchanged

Held since

2024

28 more super investors behind a free account

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

Institutional Funds

Mutual funds and ETFs reporting UPB on Form N-PORT; together they hold 28.8% of the company

Fund	Position value	Shares	% of company	% of the fund	As of
VT Vanguard Total Stock Market Index Fund Vanguard Index Funds	$9.99M	1.4M	2.63%	0.00%	June 30, 2026
FS Fidelity Small Cap Growth Fund Fidelity Securities Fund	$8.65M	1.4M	2.50%	0.10%	July 31, 2026

Vanguard Total Stock Market Index Fund

Vanguard Index Funds

Position value

$9.99M

% of company

2.63%

% of the fund

0.00%

As of

June 30, 2026

Fidelity Small Cap Growth Fund

Fidelity Securities Fund

Position value

$8.65M

% of company

2.50%

% of the fund

0.10%

As of

July 31, 2026

23 more funds behind a free account

See every fund holding Upstream 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
SE Sutherland Everett Rand Insider	68.7K	0.13%	—	—	—	—
Insider holdings come from Form 3/4/5 filings, which are not quarterly. Share of the company0.130% Sutherland Everett Rand's insider activity →
DA Deykin Aaron Insider	32.3K	0.06%	—	—	—	—
Insider holdings come from Form 3/4/5 filings, which are not quarterly. Share of the company0.060% Deykin Aaron's insider activity →

Sutherland Everett Rand

Insider

68.7K

% of company

0.13%

Change vs last qtr

—

Held since

—

Deykin Aaron

Insider

32.3K

% of company

0.06%

Change vs last qtr

—

Held since

—

3 more holders behind a free account

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

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