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
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 $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
Millennium Management
Millennium Management New York $240B AUM 35.51% 1-Year Est. Return

Nantahala Capital Management's UPB Position: Q1 2026 in Review

Nantahala Capital Management reduced its Upstream Bio Inc (UPB) stake by 19% in Q1 2026, selling an estimated $1.71M and leaving 400,000 shares worth $3.6M. The position accounts for 0.13% of the portfolio, ranked #111.

Nantahala Capital Management first reported a position in UPB in Q4 2024 and has held it in 6 quarters since. The position peaked at $13.4M in Q4 2025. 140 funds tracked by Wall St. Rank hold UPB as of Q1 2026.

  • Nantahala Capital Management held 400,000 shares of Upstream Bio Inc worth $3.6M as of Q1 2026.
  • Nantahala Capital Management sold 94,971 Upstream Bio Inc shares in Q1 2026, an estimated $1.71M.
  • Upstream Bio Inc made up 0.13% of Nantahala Capital Management's portfolio in Q1 2026, its #111 holding.
  • Nantahala Capital Management first reported a position in Upstream Bio Inc in Q4 2024 and has held it in 6 quarters since.
  • Nantahala Capital Management's Upstream Bio Inc position peaked at $13.4M in Q4 2025.
  • 140 funds tracked by Wall St. Rank held Upstream Bio Inc as of Q1 2026.

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