Who owns Upstream Bio (UPB)
Which tracked institutional funds hold UPB, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See UPB company fundamentals →
Ownership as of the 2026-Q2 13F filings (latest filed 2026-09-22). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
How the tape is positioned
19 tracked funds added or opened UPB while 40 trimmed or exited it between 2026-Q1 and 2026-Q2 — the tape is split. When large holders disagree on a name, the funds moving first are sometimes ahead of the story.
A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.
Conviction spread
UPB’s largest tracked holder by dollar value, FMR LLC, sizes it at 0.0% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 0.0pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in UPB divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.
Institutional & insider positioning
Between 2026-Q1 and 2026-Q2, across 145 tracked filers holding UPB, 98 increased or opened the position and 59 reduced or closed it; over the same quarter, open-market insider Form 4s were net sales.
This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.
New buyers & exits
Funds opening or closing a position in UPB between the 2026-Q1 and 2026-Q2 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.
New buyers 4
- Walleye Capital LLC$3M
- Voleon Capital Management LP$2M
- JACOBS LEVY EQUITY MANAGEMENT, INC$2M
- ALGERT GLOBAL LLC$821K
Full exits 7
- FEDERATED HERMES, INC.$9M
- Pictet Asset Management Holding SA$7M
- Nantahala Capital Management, LLC$4M
- Alyeska Investment Group, L.P.$3M
- Prosight Management, LP$2M
- TCG Crossover Management, LLC$2M
Largest adds
- NORGES BANK$20M
- AQR CAPITAL MANAGEMENT LLC$3M
- JPMORGAN CHASE & CO$3M
- BNP PARIBAS FINANCIAL MARKETS$2M
- BANK OF AMERICA CORP /DE/$2M
- DIMENSIONAL FUND ADVISORS LP$2M
Largest trims
- ORBIMED ADVISORS LLC$12M
- FMR LLC$8M
- HSBC HOLDINGS PLC$6M
- Decheng Capital LLC$6M
- ENAVATE SCIENCES GP, LLC$5M
- BlackRock, Inc.$4M
Institutional holders
One row per tracked fund, most shares held first (every row is from one quarter; reported value breaks ties). “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding.
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| FMR LLC added | 8,162,897 | $56M | 16.3% | 2026-Q2 |
| ORBIMED ADVISORS LLC | 5,693,589 | $39M | 11.4% | 2026-Q2 |
| NORGES BANK added | 3,768,619 | $26M | 7.5% | 2026-Q2 |
| BlackRock, Inc. added | 3,753,358 | $26M | 7.5% | 2026-Q2 |
| Decheng Capital LLC | 2,724,868 | $19M | 5.4% | 2026-Q2 |
| ENAVATE SCIENCES GP, LLC | 2,459,703 | $17M | 4.9% | 2026-Q2 |
| VANGUARD CAPITAL MANAGEMENT LLC added | 1,876,734 | $13M | 3.8% | 2026-Q2 |
| MILLENNIUM MANAGEMENT LLC added | 1,143,775 | $8M | 2.3% | 2026-Q2 |
| D. E. Shaw & Co., Inc. added | 1,036,044 | $7M | 2.1% | 2026-Q2 |
| JPMORGAN CHASE & CO added | 1,012,044 | $7M | 2.0% | 2026-Q2 |
| Qube Research & Technologies Ltd added | 978,500 | $7M | 2.0% | 2026-Q2 |
| Parkman Healthcare Partners LLC added | 935,247 | $6M | 1.9% | 2026-Q2 |
| GEODE CAPITAL MANAGEMENT, LLC trimmed | 931,261 | $6M | 1.9% | 2026-Q2 |
| SEB Asset Management AB | 878,473 | $6M | 1.8% | 2026-Q2 |
| Woodline Partners LP | 831,481 | $6M | 1.7% | 2026-Q2 |
| STATE STREET CORP added | 766,323 | $5M | 1.5% | 2026-Q2 |
| VANGUARD PORTFOLIO MANAGEMENT LLC trimmed | 712,667 | $5M | 1.4% | 2026-Q2 |
| Y-Intercept (Hong Kong) Ltd trimmed | 693,555 | $5M | 1.4% | 2026-Q2 |
| Bain Capital Life Sciences Investors, LLC trimmed | 600,949 | $4M | 1.2% | 2026-Q2 |
| AQR CAPITAL MANAGEMENT LLC added | 544,869 | $4M | 1.1% | 2026-Q2 |
| MORGAN STANLEY trimmed | 524,632 | $4M | 1.0% | 2026-Q2 |
| BNP PARIBAS FINANCIAL MARKETS added | 511,546 | $4M | 1.0% | 2026-Q2 |
| Walleye Capital LLC added | 498,490 | $3M | 1.0% | 2026-Q2 |
| Trexquant Investment LP added | 466,430 | $3M | 0.9% | 2026-Q2 |
| Point72 Asset Management, L.P. added | 453,011 | $3M | 0.9% | 2026-Q2 |
| BANK OF AMERICA CORP /DE/ added | 391,762 | $3M | 0.8% | 2026-Q2 |
| DIMENSIONAL FUND ADVISORS LP added | 381,613 | $3M | 0.8% | 2026-Q2 |
| Altshuler Shaham Ltd | 380,061 | $3M | 0.8% | 2026-Q2 |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP added | 357,756 | $2M | 0.7% | 2026-Q2 |
| SAMSARA BIOCAPITAL, LLC trimmed | 353,717 | $2M | 0.7% | 2026-Q2 |
| Propel Bio Management, LLC added | 350,389 | $2M | 0.7% | 2026-Q2 |
| WELLINGTON MANAGEMENT GROUP LLP | 342,353 | $2M | 0.7% | 2026-Q2 |
| NORTHERN TRUST CORP added | 297,346 | $2M | 0.6% | 2026-Q2 |
| Squarepoint Ops LLC added | 290,904 | $2M | 0.6% | 2026-Q2 |
| Voleon Capital Management LP new | 285,234 | $2M | 0.6% | 2026-Q2 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC added | 262,456 | $2M | 0.5% | 2026-Q2 |
| JACOBS LEVY EQUITY MANAGEMENT, INC new | 253,092 | $2M | 0.5% | 2026-Q2 |
| GOLDMAN SACHS GROUP INC trimmed | 246,917 | $2M | 0.5% | 2026-Q2 |
| XTX Topco Ltd added | 242,346 | $2M | 0.5% | 2026-Q2 |
| DEUTSCHE BANK AG\ added | 241,447 | $2M | 0.5% | 2026-Q2 |
| VANGUARD FIDUCIARY TRUST CO added | 239,616 | $2M | 0.5% | 2026-Q2 |
| UBS Group AG added | 234,714 | $2M | 0.5% | 2026-Q2 |
| Schonfeld Strategic Advisors LLC added | 225,760 | $2M | 0.5% | 2026-Q2 |
| Jump Financial, LLC trimmed | 223,223 | $2M | 0.4% | 2026-Q2 |
| SPHERA FUNDS MANAGEMENT LTD. trimmed | 219,700 | $2M | 0.4% | 2026-Q2 |
| Boxer Capital Management, LLC | 150,000 | $1M | 0.3% | 2026-Q2 |
| RENAISSANCE TECHNOLOGIES LLC added | 131,300 | $909K | 0.3% | 2026-Q2 |
| EntryPoint Capital, LLC added | 129,446 | $896K | 0.3% | 2026-Q2 |
| ALGERT GLOBAL LLC new | 118,630 | $821K | 0.2% | 2026-Q2 |
| Bank of New York Mellon Corp added | 85,747 | $593K | 0.2% | 2026-Q2 |
| Nuveen, LLC added | 84,770 | $587K | 0.2% | 2026-Q2 |
| AMERICAN CENTURY COMPANIES INC trimmed | 78,194 | $541K | 0.2% | 2026-Q2 |
| Man Group plc added | 73,823 | $511K | 0.1% | 2026-Q2 |
| Simplify Asset Management Inc. trimmed | 62,113 | $430K | 0.1% | 2026-Q2 |
| ALPS ADVISORS INC added | 55,228 | $382K | 0.1% | 2026-Q2 |
| Quantinno Capital Management LP added | 54,838 | $379K | 0.1% | 2026-Q2 |
| Virtus Investment Advisers, LLC added | 53,638 | $371K | 0.1% | 2026-Q2 |
| Invesco Ltd. added | 53,397 | $370K | 0.1% | 2026-Q2 |
| ALLIANCEBERNSTEIN L.P. added | 51,680 | $465K | 0.1% | 2026-Q2 |
| Brevan Howard Capital Management LP new | 50,369 | $349K | 0.1% | 2026-Q2 |
| Swiss National Bank | 48,100 | $333K | 0.1% | 2026-Q2 |
| Russell Investments Group, Ltd. added | 47,543 | $329K | 0.1% | 2026-Q2 |
| Allspring Global Investments Holdings, LLC new | 43,182 | $299K | 0.1% | 2026-Q2 |
| RHUMBLINE ADVISERS added | 42,384 | $293K | 0.1% | 2026-Q2 |
| TWO SIGMA INVESTMENTS, LP added | 42,325 | $293K | 0.1% | 2026-Q2 |
| ExodusPoint Capital Management, LP trimmed | 41,045 | $284K | 0.1% | 2026-Q2 |
| CITIGROUP INC added | 40,339 | $279K | 0.1% | 2026-Q2 |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM trimmed | 38,634 | $267K | 0.1% | 2026-Q2 |
| Stonepine Capital Management, LLC trimmed | 33,432 | $231K | 0.1% | 2026-Q2 |
| Mariner, LLC added | 33,141 | $229K | 0.1% | 2026-Q2 |
| WELLS FARGO & COMPANY/MN added | 29,497 | $204K | 0.1% | 2026-Q2 |
| BARCLAYS PLC added | 29,208 | $202K | 0.1% | 2026-Q2 |
| Creative Planning added | 28,483 | $197K | 0.1% | 2026-Q2 |
| Quantbot Technologies LP added | 28,178 | $195K | 0.1% | 2026-Q2 |
| PRICE T ROWE ASSOCIATES INC /MD/ added | 28,058 | $195K | 0.1% | 2026-Q2 |
| AXQ CAPITAL, LP trimmed | 27,068 | $187K | 0.1% | 2026-Q2 |
| nVerses Capital, LLC new | 24,029 | $166K | 0.0% | 2026-Q2 |
| DNB Asset Management AS added | 23,600 | $163K | 0.0% | 2026-Q2 |
| VANGUARD ASSET MANAGEMENT, Ltd added | 22,724 | $157K | 0.0% | 2026-Q2 |
| Graham Capital Management, L.P. added | 22,508 | $156K | 0.0% | 2026-Q2 |
| LOS ANGELES CAPITAL MANAGEMENT LLC new | 22,385 | $155K | 0.0% | 2026-Q2 |
| Verdad Advisers, LP new | 21,810 | $151K | 0.0% | 2026-Q2 |
| MetLife Investment Management, LLC added | 20,852 | $144K | 0.0% | 2026-Q2 |
| SEI INVESTMENTS CO added | 20,026 | $139K | 0.0% | 2026-Q2 |
| WINTON GROUP Ltd new | 19,800 | $137K | 0.0% | 2026-Q2 |
| IEQ CAPITAL, LLC new | 19,535 | $135K | 0.0% | 2026-Q2 |
| DIADEMA PARTNERS LP trimmed | 19,093 | $132K | 0.0% | 2026-Q2 |
| Shay Capital LLC added | 18,000 | $125K | 0.0% | 2026-Q2 |
| Quadrature Capital Ltd new | 17,988 | $124K | 0.0% | 2026-Q2 |
| Entropy Technologies, LP trimmed | 17,542 | $121K | 0.0% | 2026-Q2 |
| STATE OF WISCONSIN INVESTMENT BOARD trimmed | 17,065 | $118K | 0.0% | 2026-Q2 |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. added | 16,217 | $112K | 0.0% | 2026-Q2 |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE added | 15,735 | $109K | 0.0% | 2026-Q2 |
| JANE STREET GROUP, LLC trimmed | 15,594 | $108K | 0.0% | 2026-Q2 |
| MERCER GLOBAL ADVISORS INC /ADV new | 13,352 | $92K | 0.0% | 2026-Q2 |
| Vanguard Global Advisers, LLC | 13,059 | $90K | 0.0% | 2026-Q2 |
| Legal & General Group Plc added | 12,561 | $87K | 0.0% | 2026-Q2 |
| Engineers Gate Manager LP new | 12,491 | $86K | 0.0% | 2026-Q2 |
| STRS OHIO added | 12,000 | $83K | 0.0% | 2026-Q2 |
| CANADA PENSION PLAN INVESTMENT BOARD new | 11,500 | $80K | 0.0% | 2026-Q2 |
Ownership over time
Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.
Reading this table
Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.
About 13F filings
A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.