RSCM
MBX

Rock Springs Capital Management’s MBX Biosciences MBX Stock Holding History

Rock Springs Capital Management’s Portfolio MBX Stock Details MBX Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q1 		$8.6M Buy
287,967
+5,343
+2% +$182K 0.51% 52
2025
Q4 		$8.91M Hold
282,624
– – 0.46% 54
2025
Q3 		$4.95M Buy
+282,624
New +$3.78M 0.29% 65

Other funds holding MBX

FLSM
Frazier Life Sciences Management Palo Alto, California $3.89B AUM 201.1% 1-Year Est. Return
O
OrbiMed New York $5.05B AUM 125.28% 1-Year Est. Return
NMC
NEA Management Company Timonium, Maryland $1.76B AUM 223.33% 1-Year Est. Return
Wellington Management Group
Wellington Management Group Boston, Massachusetts $535B AUM 26.23% 1-Year Est. Return
BlackRock
BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return
Fidelity Investments
Fidelity Investments Boston, Massachusetts $1.9T AUM 41.92% 1-Year Est. Return
DTC
Deep Track Capital Greenwich, Connecticut $6.12B AUM 144% 1-Year Est. Return
NA
NVP Associates Menlo Park, California $176M AUM 208.78% 1-Year Est. Return
PCH
Polar Capital Holdings London, United Kingdom $28.2B AUM 115.26% 1-Year Est. Return
B
Braidwell Stamford, Connecticut $3B AUM 46.72% 1-Year Est. Return

Rock Springs Capital Management's MBX Position: Q1 2026 in Review

Rock Springs Capital Management increased its MBX Biosciences (MBX) stake by 1.9% in Q1 2026, buying an estimated $182K and bringing the position to 287,967 shares worth $8.6M. The position accounts for 0.51% of the portfolio, ranked #52.

Rock Springs Capital Management first reported a position in MBX in Q3 2025 and has held it in 3 quarters since. The position peaked at $8.91M in Q4 2025. 157 funds tracked by Wall St. Rank hold MBX as of Q1 2026.

  • Rock Springs Capital Management held 287,967 shares of MBX Biosciences worth $8.6M as of Q1 2026.
  • Rock Springs Capital Management bought 5,343 MBX Biosciences shares in Q1 2026, an estimated $182K.
  • MBX Biosciences made up 0.51% of Rock Springs Capital Management's portfolio in Q1 2026, its #52 holding.
  • Rock Springs Capital Management first reported a position in MBX Biosciences in Q3 2025 and has held it in 3 quarters since.
  • Rock Springs Capital Management's MBX Biosciences position peaked at $8.91M in Q4 2025.
  • 157 funds tracked by Wall St. Rank held MBX Biosciences as of Q1 2026.

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