Alyeska Investment Group
UPB

Alyeska Investment Group’s Upstream Bio Inc UPB Stock Holding History

Alyeska Investment Group’s Portfolio UPB Stock Details UPB Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q1 		$2.68M Hold
298,329
– – 0.01% 535
2025
Q4 		$8.1M Buy
+298,329
New +$7.43M 0.02% 416
2025
Q3 		– Sell
-85,000
Closed -$933K – 744
2025
Q2 		$933K Hold
85,000
– – ﹤0.01% 509
2025
Q1 		$520K Hold
85,000
– – ﹤0.01% 466
2024
Q4 		$1.4M Buy
+85,000
New +$1.9M 0.01% 480

Other funds holding UPB

Fidelity Investments
Fidelity Investments Boston, Massachusetts $1.9T AUM 41.92% 1-Year Est. Return
O
OrbiMed New York $5.05B AUM 125.28% 1-Year Est. Return
BlackRock
BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return
DC
Decheng Capital Menlo Park, California $661M AUM 299.97% 1-Year Est. Return
ES
Enavate Sciences Menlo Park, California $352M AUM 220.14% 1-Year Est. Return
VCM
Vanguard Capital Management Malvern, Pennsylvania $4.04T AUM
YIH
Y-Intercept (HK) Hong Kong $5.05B AUM 17.89% 1-Year Est. Return
Federated Hermes
Federated Hermes Pittsburgh, Pennsylvania $61.5B AUM 30.7% 1-Year Est. Return
Geode Capital Management
Geode Capital Management Boston, Massachusetts $1.61T AUM 30.72% 1-Year Est. Return
Millennium Management
Millennium Management New York $240B AUM 35.51% 1-Year Est. Return

Alyeska Investment Group's UPB Position: Q1 2026 in Review

Alyeska Investment Group held its Upstream Bio Inc (UPB) position steady in Q1 2026 at 298,329 shares worth $2.68M. The position accounts for 0.01% of the portfolio, ranked #535.

Alyeska Investment Group first reported a position in UPB in Q4 2024 and has held it in 5 quarters since. The position peaked at $8.1M in Q4 2025. 140 funds tracked by Wall St. Rank hold UPB as of Q1 2026.

  • Alyeska Investment Group held 298,329 shares of Upstream Bio Inc worth $2.68M as of Q1 2026.
  • Alyeska Investment Group left its Upstream Bio Inc share count unchanged in Q1 2026.
  • Upstream Bio Inc made up 0.01% of Alyeska Investment Group's portfolio in Q1 2026, its #535 holding.
  • Alyeska Investment Group first reported a position in Upstream Bio Inc in Q4 2024 and has held it in 5 quarters since.
  • Alyeska Investment Group's Upstream Bio Inc position peaked at $8.1M in Q4 2025.
  • 140 funds tracked by Wall St. Rank held Upstream Bio Inc as of Q1 2026.

Based on Alyeska Investment Group's 13F filing for Q1 2026, filed 15 May 2026.