NCM
UPB

Nantahala Capital Management’s Upstream Bio Inc UPB Stock Holding History

Nantahala Capital 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
Q2 		– Sell
-400,000
Closed -$3.6M – 177
2026
Q1 		$3.6M Sell
400,000
-94,971
-19% -$1.71M 0.13% 111
2025
Q4 		$13.4M Sell
494,971
-100,000
-17% -$2.49M 0.44% 55
2025
Q3 		$11.2M Hold
594,971
– – 0.39% 59
2025
Q2 		$6.53M Hold
594,971
– – 0.26% 75
2025
Q1 		$3.64M Sell
594,971
-5,029
-0.8% -$48K 0.14% 87
2024
Q4 		$9.86M Buy
+600,000
New +$13.4M 0.42% 46

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

Nantahala Capital Management's UPB Position: Q2 2026 in Review

Nantahala Capital Management sold out of Upstream Bio Inc (UPB) in Q2 2026, closing a stake of 400,000 shares — an estimated $3.6M sold.

Nantahala Capital Management first reported a position in UPB in Q4 2024 and held it in 6 quarters. The position peaked at $13.4M in Q4 2025. 148 funds tracked by Wall St. Rank hold UPB as of Q2 2026.

  • Nantahala Capital Management reported no remaining Upstream Bio Inc position as of Q2 2026 after selling out during the quarter.
  • Nantahala Capital Management sold 400,000 Upstream Bio Inc shares in Q2 2026, an estimated $3.6M.
  • Nantahala Capital Management first reported a position in Upstream Bio Inc in Q4 2024 and held it in 6 quarters.
  • Nantahala Capital Management's Upstream Bio Inc position peaked at $13.4M in Q4 2025.
  • 148 funds tracked by Wall St. Rank held Upstream Bio Inc as of Q2 2026.

Based on Nantahala Capital Management's 13F filing for Q2 2026, filed 14 Aug 2026.