UPB
Upstream Bio, Inc. · Healthcare · Biotechnology
Momentum inputs (comparable managers):
holder breadth +14.3% ·
share flow -8.5% ·
net new positions +12.5%
· formula
Ownership fragmentation: more holders, smaller aggregate stake
All ownership figures: tracked 13F managers only, common-stock positions, reporting period Q1 2025
| # | Manager | Shares | Δ shares | Value | Their weight | Held | ||
|---|---|---|---|---|---|---|---|---|
| 1 | Wellington Management ✦ | 1.31M | -17.0% | $8.03M | 0.0% | ▼ Trim | 2 | SEC ↗ ×3 |
| 2 | Norges Bank ✦ (passive) | 969.92K | -3.0% | $5.94M | 0.0% | ▼ Trim | 2 | SEC ↗ |
| 3 | Geode Capital Management ✦ (passive) | 410.68K | +13.1% | $2.51M | 0.0% | ▲ Add | 2 | SEC ↗ ×2 |
| 4 | Marshall Wace ✦ | 304.96K | +4.9% | $1.87M | 0.0% | ▲ Add | 2 | SEC ↗ ×2 |
| 5 | State Street Global Advisors ✦ (passive) | 295.59K | +19.6% | $1.81M | 0.0% | ▲ Add | 2 | SEC ↗ |
| 6 | Millennium Management ✦ | 61.80K | New | $378,192 | 0.0% | New | 1 | SEC ↗ |
| 7 | Two Sigma Investments ✦ | 21.79K | New | $133,349 | 0.0% | New | 1 | SEC ↗ |
| 8 | AQR Capital Management ✦ | 18.82K | New | $115,190 | 0.0% | New | 1 | SEC ↗ ×5 |
“Their weight” = the position's share of that manager's reported 13F equity value: the conviction measure. ✦ = curated manager.
New buyers
| Millennium Management | $378,192 | 0.0% |
| Two Sigma Investments | $133,349 | 0.0% |
| AQR Capital Management | $115,190 | 0.0% |
Exited
| Citadel Advisors | $2.96M | was 0.0% |
| Soros Fund Management | $761,994 | was 0.0% |
Full-market context: across ALL 13F filers (SEC structured data, Q1 2026): 140 holders, 44.42M shares, $399.81M reported. This is a different, older period than the tracked-universe figures above and the two are never mixed.
What else this security's tracked holders most often hold: shared-ownership counts, not fundamental relationships.
Open-market purchases (P)
No open-market insider purchases in our coverage window.
Open-market sales (S)
Officer · 485 sh · $2,663
Officer · 895 sh · $4,914
Officer · 853 sh · $4,683
Officer · 700 sh · $3,843
Awards, exercises and tax withholding are never counted as buys or sales here. Methodology