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
Q2 		$229K Buy
33,141
+5,827
+21% +$48.8K ﹤0.01% 3044
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 $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

Mariner's UPB Position: Q2 2026 in Review

Mariner increased its Upstream Bio Inc (UPB) stake by 21% in Q2 2026, buying an estimated $48.8K and bringing the position to 33,141 shares worth $229K. The position accounts for ﹤0.01% of the portfolio, ranked #3044.

Mariner first reported a position in UPB in Q3 2025 and has held it in 4 quarters since. The position peaked at $321K in Q4 2025. 149 funds tracked by Wall St. Rank hold UPB as of Q2 2026.

  • Mariner held 33,141 shares of Upstream Bio Inc worth $229K as of Q2 2026.
  • Mariner bought 5,827 Upstream Bio Inc shares in Q2 2026, an estimated $48.8K.
  • Upstream Bio Inc made up ﹤0.01% of Mariner's portfolio in Q2 2026, its #3044 holding.
  • Mariner first reported a position in Upstream Bio Inc in Q3 2025 and has held it in 4 quarters since.
  • Mariner's Upstream Bio Inc position peaked at $321K in Q4 2025.
  • 149 funds tracked by Wall St. Rank held Upstream Bio Inc as of Q2 2026.

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