Mariner
UPB

Mariner’s Upstream Bio Inc UPB Stock Holding History

Mariner’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 		$246K Buy
27,314
+15,484
+131% +$279K ﹤0.01% 3036
2025
Q4 		$321K Buy
11,830
+897
+8% +$22.3K ﹤0.01% 2780
2025
Q3 		$206K Buy
+10,933
New +$170K ﹤0.01% 3159

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

Mariner's UPB Position: Q1 2026 in Review

Mariner increased its Upstream Bio Inc (UPB) stake by 131% in Q1 2026, buying an estimated $279K and bringing the position to 27,314 shares worth $246K. The position accounts for ﹤0.01% of the portfolio, ranked #3036.

Mariner first reported a position in UPB in Q3 2025 and has held it in 3 quarters since. The position peaked at $321K in Q4 2025. 140 funds tracked by Wall St. Rank hold UPB as of Q1 2026.

  • Mariner held 27,314 shares of Upstream Bio Inc worth $246K as of Q1 2026.
  • Mariner bought 15,484 Upstream Bio Inc shares in Q1 2026, an estimated $279K.
  • Upstream Bio Inc made up ﹤0.01% of Mariner's portfolio in Q1 2026, its #3036 holding.
  • Mariner first reported a position in Upstream Bio Inc in Q3 2025 and has held it in 3 quarters since.
  • Mariner's Upstream Bio Inc position peaked at $321K in Q4 2025.
  • 140 funds tracked by Wall St. Rank held Upstream Bio Inc as of Q1 2026.

Based on Mariner's 13F filing for Q1 2026, filed 13 May 2026.