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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
Q2 		$16.5M Buy
298,218
+10,251
+4% +$358K 0.8% 40
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

Frazier Life Sciences Management
Frazier Life Sciences Management Palo Alto, California $4.59B AUM 237.58% 1-Year Est. Return
Fidelity Investments
Fidelity Investments Boston, Massachusetts $2.3T AUM 54.33% 1-Year Est. Return
Wellington Management Group
Wellington Management Group Boston, Massachusetts $580B AUM 38.23% 1-Year Est. Return
NMC
NEA Management Company Timonium, Maryland $1.59B AUM 234.06% 1-Year Est. Return
OrbiMed
OrbiMed New York $5.4B AUM 163.13% 1-Year Est. Return
BlackRock
BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return
Paradigm Biocapital Advisors
Paradigm Biocapital Advisors New York $5.34B AUM 380.18% 1-Year Est. Return
NA
NVP Associates Menlo Park, California $328M AUM 166.51% 1-Year Est. Return
Deep Track Capital
Deep Track Capital Greenwich, Connecticut $6.87B AUM 205.24% 1-Year Est. Return
Polar Capital Holdings
Polar Capital Holdings London, United Kingdom $42.4B AUM 181.11% 1-Year Est. Return

Rock Springs Capital Management's MBX Position: Q2 2026 in Review

Rock Springs Capital Management increased its MBX Biosciences (MBX) stake by 3.6% in Q2 2026, buying an estimated $358K and bringing the position to 298,218 shares worth $16.5M. The position accounts for 0.8% of the portfolio, ranked #40.

Rock Springs Capital Management first reported a position in MBX in Q3 2025 and has held it in 4 quarters since. 172 funds tracked by Wall St. Rank hold MBX as of Q2 2026.

  • Rock Springs Capital Management held 298,218 shares of MBX Biosciences worth $16.5M as of Q2 2026.
  • Rock Springs Capital Management bought 10,251 MBX Biosciences shares in Q2 2026, an estimated $358K.
  • MBX Biosciences made up 0.8% of Rock Springs Capital Management's portfolio in Q2 2026, its #40 holding.
  • Rock Springs Capital Management first reported a position in MBX Biosciences in Q3 2025 and has held it in 4 quarters since.
  • 172 funds tracked by Wall St. Rank held MBX Biosciences as of Q2 2026.

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