Latest Period
Q1 2026
Security Snapshot
Upstream Bio, Inc. - Common Stock, par value $0.001 per share (UPB) Institutional Ownership
CUSIP: 91678A107
13F Institutional Holders and Ownership History from Q4 2024 to Q1 2026
Institutions Reporting
138
Shares (Excl. Options)
44,855,500
Price
$9.00
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- Security type / class
- Equity / Common Stock, par value $0.001 per share
- Symbol
- UPB on Nasdaq
- All holders as of 31 Mar 2026
- Q1 2026
- Total 13F shares
- 44,855,500
- Total 13F value
- $403,623,162
- Portfolio coverage rank
- 0%
- Share change
- -7,752,396
- Value change
- -$257,351,863
- Number of holders
- 138
- Shares outstanding
- 54,497,360
- SEC-reported price per share
- $9.36
Latest holder snapshot
5 signals
Issuer context
Names, identifiers, and filing context for this profile.
2 identity fields
13F Shares, Excluding Options vs Price
13F Value, Excluding Options
Total Investors
Key facts
- UPB - Upstream Bio, Inc. - Common Stock, par value $0.001 per share is tracked under CUSIP 91678A107.
- 138 institutions reported positions in Q1 2026.
- 5 significant owners is listed from Schedule 13D/13G reporting.
Change
- Holder count moved from 133 to 138 between Q4 2025 and Q1 2026.
- SEC-reported value moved from $1,389,381,175 to $403,623,162.
Research use
- You can quickly see who holds this security, then open quarter and manager detail pages for full evidence.
- 13F and Schedule 13D/13G sections are kept together so you can cross-check institutional and beneficial ownership context.
Evidence
Source: SEC Form 13F
Open SEC evidence
Latest holder context comes from 138 institutions filings for Q1 2026.
Security key
91678A107
Latest holder period
Q1 2026
13F holders
138
13D/G owners
5
CIK / CUSIP context first
Open Q1 2026 holders
UPB full holder history
Upstream Bio, Inc. SEC filings
Upstream Bio, Inc. company facts
Upstream Bio, Inc. insider transactions
Broader feeds
Recent Quarterly Holder Reports
Open recent reporting periods for CUSIP 91678A107:
13D/G owners
Significant owners
Large-stake holder rows connected to Schedule 13D/G evidence.
Rows
5
Security
UPB
| Filer | Ownership | Change % | Holdings Value | Net Change | Nb Shares | Change % | Reporting Name | Report Period |
|---|---|---|---|---|---|---|---|---|
| FMR LLC | 15% | +11% | $93,972,663 | +$9,006,605 | 7,936,880 | +11% | FMR LLC | 30 Jun 2025 |
| NORGES BANK | 5.3% | $54,226,626 | 2,882,647 | Norges Bank | 30 Sep 2025 | |||
| Decheng Capital Global Life Sciences Fund IV, L.P. | 5% | -18% | $25,886,246 | -$5,324,038 | 2,724,868 | -17% | Decheng Capital Global Life Sciences Fund IV, L.P. | 31 Mar 2026 |
| HBM Healthcare Investments (Cayman) Ltd. | 4.1% | -20% | $41,290,257 | -$9,780,217 | 2,195,111 | -19% | HBM Healthcare Investments (Cayman) Ltd. | 30 Sep 2025 |
| TCG Crossover GP I, LLC | 3.9% | -26% | $39,822,919 | -$12,878,523 | 2,117,103 | -24% | TCG Crossover GP I, LLC | 30 Sep 2025 |
As of 31 Mar 2026, 138 institutional investors reported holding 44,855,500 shares of Upstream Bio, Inc. - Common Stock, par value $0.001 per share (UPB). This represents 82% of the company’s total 54,497,360 outstanding shares.
13F concentration
Top 25 institutional shareholders
Largest 13F positions for this security by reported shares and value.
Top holder share
70%
| Institution | Ownership % | Shares Held | Share Change % | Portfolio % | Holdings Value |
|---|---|---|---|---|---|
| FMR LLC | 15% | 8,101,563 | +7.8% | 0% | $72,914,070 |
| ORBIMED ADVISORS LLC | 10% | 5,693,589 | 0% | 1.2% | $51,242,301 |
| BlackRock, Inc. | 6.2% | 3,370,689 | +0.78% | 0% | $30,336,201 |
| Decheng Capital LLC | 5% | 2,724,868 | -13% | 3.7% | $24,523,812 |
| ENAVATE SCIENCES GP, LLC | 4.5% | 2,459,703 | 0% | 6.3% | $22,137,327 |
| VANGUARD CAPITAL MANAGEMENT LLC | 3.4% | 1,873,574 | 0% | 0% | $16,862,166 |
| Y-Intercept (Hong Kong) Ltd | 1.8% | 1,000,631 | +2049% | 0.17% | $9,005,679 |
| FEDERATED HERMES, INC. | 1.8% | 979,758 | +203169% | 0.01% | $8,817,822 |
| GEODE CAPITAL MANAGEMENT, LLC | 1.7% | 950,617 | +12% | 0% | $8,557,453 |
| MILLENNIUM MANAGEMENT LLC | 1.7% | 937,323 | +81% | 0.01% | $8,435,907 |
| SEB Asset Management AB | 1.6% | 878,473 | 0% | 0.03% | $7,906,247 |
| Bain Capital Life Sciences Investors, LLC | 1.6% | 867,211 | -35% | 0.7% | $7,804,899 |
| Woodline Partners LP | 1.5% | 831,481 | +9.4% | 0.03% | $7,483,329 |
| D. E. Shaw & Co., Inc. | 1.5% | 820,480 | +2929% | 0.01% | $7,384,320 |
| Parkman Healthcare Partners LLC | 1.4% | 786,783 | -5.7% | 0.73% | $7,081,047 |
| SAMSARA BIOCAPITAL, LLC | 1.4% | 736,047 | 0% | 0.64% | $6,624,423 |
| Pictet Asset Management Holding SA | 1.3% | 733,431 | -5.1% | 0.01% | $6,600,879 |
| VANGUARD PORTFOLIO MANAGEMENT LLC | 1.3% | 727,711 | 0% | 0% | $6,549,399 |
| STATE STREET CORP | 1.3% | 705,350 | -47% | 0% | $6,348,150 |
| HSBC HOLDINGS PLC | 1.2% | 640,326 | 0% | $5,762,934 | |
| Qube Research & Technologies Ltd | 1.1% | 619,321 | 0.01% | $5,573,889 | |
| MORGAN STANLEY | 1% | 552,609 | +353% | 0% | $4,973,481 |
| JPMORGAN CHASE & CO | 0.85% | 463,001 | +320% | 0% | $4,065,149 |
| Nantahala Capital Management, LLC | 0.73% | 400,000 | -19% | 0.22% | $3,600,000 |
| Altshuler Shaham Ltd | 0.7% | 380,061 | -72% | 0.06% | $3,420,549 |
Quarter history
Institutional holders across reporting periods
Holder count, reported shares/value, and median price by quarter.
Periods
6
Latest
Q1 2026
Rows shown
1-6 of 6
| Period | 13F Shares, Excl. Options | Value, Excl. Options | Value Change | Price (Median) | Investors |
|---|---|---|---|---|---|
| 2026 Q1 | 44,855,500 | $403,623,162 | -$257,351,863 | $9.00 | 138 |
| 2025 Q4 | 51,176,304 | $1,389,381,175 | +$178,186,919 | $27.15 | 133 |
| 2025 Q3 | 44,461,719 | $836,327,467 | -$50,813,162 | $18.81 | 94 |
| 2025 Q2 | 48,353,677 | $530,923,062 | +$32,738,813 | $10.98 | 82 |
| 2025 Q1 | 42,073,968 | $257,482,324 | -$17,702,490 | $6.12 | 76 |
| 2024 Q4 | 42,074,592 | $690,108,943 | +$649,643,232 | $16.44 | 70 |