Jim Simons’s Upstream Bio Inc UPB Stock Holding History

Jim Simons’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	$909K	Buy	131,300 +69,200	+111%	+$580K	﹤0.01%	2351
2026 Q1	$559K	Buy	62,100 +45,700	+279%	+$822K	﹤0.01%	2558
2025 Q4	$445K	Buy	+16,400	New	+$408K	﹤0.01%	2620

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

Jim Simons's UPB Position: Q2 2026 in Review

Jim Simons increased its Upstream Bio Inc (UPB) stake by 111% in Q2 2026, buying an estimated $580K and bringing the position to 131,300 shares worth $909K. The position accounts for ﹤0.01% of the portfolio, ranked #2351.

Jim Simons first reported a position in UPB in Q4 2025 and has held it in 3 quarters since. 148 funds tracked by Wall St. Rank hold UPB as of Q2 2026.

Jim Simons held 131,300 shares of Upstream Bio Inc worth $909K as of Q2 2026.
Jim Simons bought 69,200 Upstream Bio Inc shares in Q2 2026, an estimated $580K.
Upstream Bio Inc made up ﹤0.01% of Jim Simons's portfolio in Q2 2026, its #2351 holding.
Jim Simons first reported a position in Upstream Bio Inc in Q4 2025 and has held it in 3 quarters since.
148 funds tracked by Wall St. Rank held Upstream Bio Inc as of Q2 2026.

Based on Renaissance Technologies's 13F filing for Q2 2026, filed 13 Aug 2026.