JY
UPB

Jeff Yass’s Upstream Bio Inc UPB Stock Holding History

Jeff Yass’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
Q2 		– Sell
-15,961
Closed -$134K – 14795
2026
Q1 		$144K Sell
15,961
-39,880
-71% -$717K ﹤0.01% 12058
2025
Q4 		$1.52M Buy
+55,841
New +$1.39M ﹤0.01% 6218
2025
Q3 		– Sell
-42,263
Closed -$464K – 14233
2025
Q2 		$464K Buy
42,263
+20,999
+99% +$194K ﹤0.01% 9344
2025
Q1 		$130K Buy
+21,264
New +$203K ﹤0.01% 11337

Other funds holding UPB

Fidelity Investments
Fidelity Investments Boston, Massachusetts $2.3T AUM 54.33% 1-Year Est. Return
O
OrbiMed New York $5.4B AUM 163.13% 1-Year Est. Return
Norges Bank
Norges Bank Oslo, Norway $1T AUM
BlackRock
BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return
DC
Decheng Capital Menlo Park, California $732M AUM 275.56% 1-Year Est. Return
ES
Enavate Sciences Menlo Park, California $345M AUM 134.64% 1-Year Est. Return
Vanguard Capital Management
Vanguard Capital Management Malvern, Pennsylvania $4.68T AUM
Millennium Management
Millennium Management New York $276B AUM 44.8% 1-Year Est. Return
D.E. Shaw & Co
D.E. Shaw & Co New York $210B AUM 57.28% 1-Year Est. Return
JP Morgan Chase
JP Morgan Chase New York $1.81T AUM 41.13% 1-Year Est. Return

Jeff Yass's UPB Position: Q2 2026 in Review

Jeff Yass sold out of Upstream Bio Inc (UPB) in Q2 2026, closing a stake of 15,961 shares — an estimated $134K sold.

Jeff Yass first reported a position in UPB in Q1 2025 and held it in 4 quarters. The position peaked at $1.52M in Q4 2025. 149 funds tracked by Wall St. Rank hold UPB as of Q2 2026.

  • Jeff Yass reported no remaining Upstream Bio Inc position as of Q2 2026 after selling out during the quarter.
  • Jeff Yass sold 15,961 Upstream Bio Inc shares in Q2 2026, an estimated $134K.
  • Jeff Yass first reported a position in Upstream Bio Inc in Q1 2025 and held it in 4 quarters.
  • Jeff Yass's Upstream Bio Inc position peaked at $1.52M in Q4 2025.
  • 149 funds tracked by Wall St. Rank held Upstream Bio Inc as of Q2 2026.

Based on Susquehanna International Group's 13F filing for Q2 2026, filed 14 Aug 2026.