Millennium Management
UPB

Millennium Management’s Upstream Bio Inc UPB Stock Holding History

Millennium Management’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 		$8.44M Buy
937,323
+420,059
+81% +$7.56M ﹤0.01% 2345
2025
Q4 		$14M Buy
517,264
+477,151
+1,190% +$11.9M 0.01% 1910
2025
Q3 		$755K Buy
+40,113
New +$623K ﹤0.01% 4826
2025
Q2 		– Sell
-61,796
Closed -$378K – 6445
2025
Q1 		$378K Buy
+61,796
New +$590K ﹤0.01% 4973

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
SAM
SEB Asset Management Stockholm $23.4B AUM

Millennium Management's UPB Position: Q1 2026 in Review

Millennium Management increased its Upstream Bio Inc (UPB) stake by 81% in Q1 2026, buying an estimated $7.56M and bringing the position to 937,323 shares worth $8.44M. The position accounts for ﹤0.01% of the portfolio, ranked #2345.

Millennium Management first reported a position in UPB in Q1 2025 and has held it in 4 quarters since. The position peaked at $14M in Q4 2025. 140 funds tracked by Wall St. Rank hold UPB as of Q1 2026.

  • Millennium Management held 937,323 shares of Upstream Bio Inc worth $8.44M as of Q1 2026.
  • Millennium Management bought 420,059 Upstream Bio Inc shares in Q1 2026, an estimated $7.56M.
  • Upstream Bio Inc made up ﹤0.01% of Millennium Management's portfolio in Q1 2026, its #2345 holding.
  • Millennium Management first reported a position in Upstream Bio Inc in Q1 2025 and has held it in 4 quarters since.
  • Millennium Management's Upstream Bio Inc position peaked at $14M in Q4 2025.
  • 140 funds tracked by Wall St. Rank held Upstream Bio Inc as of Q1 2026.

Based on Millennium Management's 13F filing for Q1 2026, filed 15 May 2026.