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	-12,100	Closed	-$109K	–	14796
2026 Q1	$109K	Sell	12,100 -4,400	-27%	-$79.2K	﹤0.01%	12281
2025 Q4	$448K	Buy	+16,500	New	+$411K	﹤0.01%	9055

Other funds holding UPB

Fidelity Investments Boston, Massachusetts $2.3T AUM 54.33% 1-Year Est. Return

OrbiMed New York $5.4B AUM 163.13% 1-Year Est. Return

Norges Bank Oslo, Norway $1T AUM

BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return

Decheng Capital Menlo Park, California $732M AUM 275.56% 1-Year Est. Return

Enavate Sciences Menlo Park, California $345M AUM 134.64% 1-Year Est. Return

Vanguard Capital Management Malvern, Pennsylvania $4.68T AUM

Millennium Management New York $276B AUM 44.8% 1-Year Est. Return

D.E. Shaw & Co New York $210B AUM 57.28% 1-Year Est. Return

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.