UPB in the 13F filings
Upstream Bio Inc · CUSIP 91678A107
New listing in Q4 2024· first held by a tracked manager this quarter, so its new positions are allocations rather than a turn towards it
- Quarter end
- 31 Dec 2024
- the date the book describes
- Filed
- 14 Feb 2025
- latest of these filings; the earliest 14 Feb 2025
- Managers listing it
- 3
- at least, of 95 tracked, among listed positions
- Comparable managers
- 94
- filed both Q3 2024 and Q4 2024; 0 listed it in both
- Shares listed
- 585,361
- combined, among listed positions
- Reported value
- $9.6m
- combined, at the quarter end
Among the 94 comparable managers: 3 buyers (opened or added shares) and 0 sellers (trimmed or exited), at least, among listed positions. Their net change in shares was +585,361.
Managers listing UPB in Q4 2024
3 of 3 holders
| Action | Filing | |||||
|---|---|---|---|---|---|---|
| Woodline Partners LP | 526,511 | $8.7m | 0.06% | New | new | 14 Feb 2025 (the filing on sec.gov) |
| Soros Fund Management LLC | 46,350 | $762k | under 0.1% | New | new | 14 Feb 2025 (the filing on sec.gov) |
| Davidson Kempner Capital Management LP | 12,500 | $205k | under 0.1% | New | new | 14 Feb 2025 (the filing on sec.gov) |
Largest increases and reductions, by shares
Increases
- Woodline Partners LPnew position · 526,511 shares now+526,511
- Soros Fund Management LLCnew position · 46,350 shares now+46,350
- Davidson Kempner Capital Management LPnew position · 12,500 shares now+12,500
Reductions
No reduction among listed positions.
New positions and exits
New (3)
Exited (0)
No exit shown by a manager’s own filing.
Ownership over time
Tracked managers listing it, at least.
| Quarter | Holders | Reported value | Buyers | Sellers |
|---|---|---|---|---|
| Q4 2024 | 3 | $9.6m | 3 | 0 |
| Q3 2025 | 1 | $11m | 1 | 0 |
| Q4 2025 | 2 | $62m | 12 | 6 |
Compare with…
Holders over time, buyers and sellers, and the managers holding both, side by side for up to four stocks.
UPB and LLY →UPB and JNJ →UPB and VRTX →Choose a stock to compare with UPB →
How much of the picture this is
A 13F is a manager’s long US-listed equity book at a quarter end, filed up to 45 days later. It shows no shorts, cash, bonds or performance, and it is never today’s portfolio. Large books are listed to their largest positions, so a manager missing from this table may still hold a small position below that line. These are 95 tracked managers, not the institutional market.
Which funds own UPB, latest filings →Back to the 13F Explorer →