Upstream Bio, Inc.

UPB

Exchange: Nasdaq
Industry: Pharmaceutical Preparations
SEC CIK: 0002022626

SEC filings (opens in a new tab)

In the last 90 days, Upstream Bio, Inc. insiders filed 0 open-market purchases and 5 sales; 148 institutions reported holding it in 13F filings for Q2 2026, worth $350.1M in total; no superinvestor holds it.

Q3 2025 vs. Q2 2025

How the institutions holding Upstream Bio, Inc. changed between Q2 2025 and Q3 2025.

All holders in Q3 2025 All holders in Q2 2025

13F holders of UPB: Q2 2025 compared with Q3 2025
Measure	Q2 2025	Of which not filed for Q3 2025	Q3 2025	Change
Holders	83	1	95	+13
Shares	48.4M	969.9K	44.5M	−2.92M (−6.2%)
Value	$530.9M	$10.6M	$836.3M	+$316.1M (+60.7%)

1 institution that held it in Q2 2025 haven't filed for Q3 2025 yet. Not filing isn't selling, so the changes leave them out.

New holders (22)

Institutions that held Upstream Bio, Inc. at the end of Q3 2025 but not at the end of Q2 2025.

Institutions new to UPB in Q3 2025
Institution	Shares	Value	% of portfolio
Integral Health Asset Management, LLC	575,000	$10.8M	0.79%
Goldman Sachs Group Inc	223,214	$4.20M	0.00%
Ikarian Capital, LLC	161,113	$3.03M	0.69%
SummitTX Capital, L.P.	112,404	$2.11M	0.09%
Balyasny Asset Management LLC	73,131	$1.38M	0.00%
Boothbay Fund Management, LLC	61,299	$1.15M	0.03%
Exome Asset Management LLC	51,960	$977.4K	0.65%
Millennium Management LLC	40,113	$754.5K	0.00%
Rafferty Asset Management, LLC	34,521	$649.3K	0.00%
Nomura Holdings Inc	28,290	$532.1K	0.00%
Caption Management, LLC	18,196	$342.3K	0.02%
Prelude Capital Management, LLC	15,735	$296.0K	0.02%
Mariner, LLC	10,933	$205.7K	0.00%
Two Sigma Investments, LP	10,500	$197.5K	0.00%
Group One Trading, L.P.	1,305	$24.5K	0.00%
Aster Capital Management (DIFC) Ltd	1,141	$21.5K	0.01%
Global Retirement Partners, LLC	332	$6.25K	0.00%
SRS Capital Advisors, Inc.	149	$2.80K	0.00%
The PNC Financial Services Group, Inc.	130	$2.45K	0.00%
J.Safra Asset Management Corp	128	$2.41K	0.00%
N.E.W. Advisory Services LLC	60	$1.13K	0.00%
Sunbelt Securities, Inc.	19	$357	0.00%

Sold out (9)

Institutions that held Upstream Bio, Inc. at the end of Q2 2025 and filed for Q3 2025 without it.

Institutions that sold out of UPB in Q3 2025
Institution	Shares, Q2 2025	Value, Q2 2025
Deep Track Capital, LP	1,442,767	$15.8M
Lynx1 Capital Management LP	219,247	$2.41M
Velan Capital Investment Management LP	107,000	$1.17M
Alyeska Investment Group, L.P.	85,000	$933.3K
Susquehanna International Group, LLP	42,263	$464.0K
STRS Ohio	1,800	$19.8K
Caitong International Asset Management Co., Ltd	224	$2.46K
True Wealth Design, LLC	31	$341
Advisor Group Holdings, Inc.	42	$257

Not filed for Q3 2025 yet (1)

Institutions that held Upstream Bio, Inc. at the end of Q2 2025 and haven't filed a 13F for Q3 2025. Not filing isn't selling, so they aren't counted as sold out.

Institutions holding UPB in Q2 2025 that haven't filed for Q3 2025
Institution	Shares, Q2 2025	Value, Q2 2025
Norges Bank	969,916	$10.6M