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.

Q1 2025 vs. Q4 2024

How the institutions holding Upstream Bio, Inc. changed between Q4 2024 and Q1 2025.

All holders in Q1 2025 All holders in Q4 2024

13F holders of UPB: Q4 2024 compared with Q1 2025
Measure	Q4 2024	Of which not filed for Q1 2025	Q1 2025	Change
Holders	70	1	79	+10
Shares	42.1M	22.6K	46.3M	+4.23M (+10.1%)
Value	$690.1M	$371.3K	$266.9M	−$422.8M (−61.3%)

1 institution that held it in Q4 2024 haven't filed for Q1 2025 yet. Not filing isn't selling, so the changes leave them out.

New holders (24)

Institutions that held Upstream Bio, Inc. at the end of Q1 2025 but not at the end of Q4 2024.

Institutions new to UPB in Q1 2025
Institution	Shares	Value	% of portfolio
Altshuler Shaham Ltd	3,235,293	$3.52M	0.09%
Parkman Healthcare Partners LLC	233,563	$1.43M	0.17%
Schonfeld Strategic Advisors LLC	177,984	$1.09M	0.01%
Velan Capital Investment Management LP	107,000	$654.8K	0.67%
Millennium Management LLC	61,796	$378.2K	0.00%
Nuveen, LLC	22,586	$138.2K	0.00%
Two Sigma Investments, LP	21,789	$133.3K	0.00%
Susquehanna International Group, LLP	21,264	$130.1K	0.00%
AQR Capital Management LLC	18,822	$115.2K	0.00%
Intech Investment Management LLC	15,285	$93.5K	0.00%
Quantinno Capital Management LP	15,225	$93.2K	0.00%
ADAR1 Capital Management, LLC	15,000	$91.8K	0.02%
XTX Topco Ltd	12,731	$77.9K	0.00%
New York State Common Retirement Fund	4,700	$28.8K	0.00%
Police & Firemen's Retirement System of New Jersey	3,350	$20.5K	0.00%
CWM, LLC	1,596	$10.0K	0.00%
Versant Capital Management, Inc	615	$3.76K	0.00%
GAMMA Investing LLC	593	$3.63K	0.00%
Allworth Financial LP	185	$1.66K	0.00%
Nisa Investment Advisors, LLC	136	$832	0.00%
EverSource Wealth Advisors, LLC	135	$826	0.00%
Signaturefd, LLC	90	$551	0.00%
UMA Financial Services, Inc.	69	$423	0.00%
True Wealth Design, LLC	16	$98	0.00%

Sold out (14)

Institutions that held Upstream Bio, Inc. at the end of Q4 2024 and filed for Q1 2025 without it.

Institutions that sold out of UPB in Q1 2025
Institution	Shares, Q4 2024	Value, Q4 2024
Balyasny Asset Management LLC	301,152	$4.95M
Citadel Advisors LLC	180,000	$2.96M
Moody Aldrich Partners LLC	74,773	$1.23M
Soros Fund Management LLCSuperinvestorSoros Fund Management	46,350	$762.0K
Jane Street Group, LLC	45,549	$748.8K
Verition Fund Management LLC	37,379	$614.5K
Davidson Kempner Capital Management LP	12,500	$205.3K
Sandia Investment Management LP	10,000	$164.4K
SG Americas Securities, LLC	7,590	$125.0K
R Squared Ltd	160	$2.63K
Aster Capital Management (DIFC) Ltd	134	$2.20K
Caitong International Asset Management Co., Ltd	44	$723
Advisor Group Holdings, Inc.	17	$279
National Bank of Canada	7	$115

Not filed for Q1 2025 yet (1)

Institutions that held Upstream Bio, Inc. at the end of Q4 2024 and haven't filed a 13F for Q1 2025. Not filing isn't selling, so they aren't counted as sold out.

Institutions holding UPB in Q4 2024 that haven't filed for Q1 2025
Institution	Shares, Q4 2024	Value, Q4 2024
Nuveen Asset Management, LLC	22,586	$371.3K