EC
MBX

EcoR1 Capital’s MBX Biosciences MBX Stock Holding History

EcoR1 Capital’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 		$21.4M Sell
388,500
-388,500
-50% -$13.6M 1.04% 16
2026
Q1 		$23.2M Sell
777,000
-1,346,604
-63% -$45.8M 0.98% 15
2025
Q4 		$67M Hold
2,123,604
– – 3.04% 7
2025
Q3 		$37.2M Buy
2,123,604
+973,810
+85% +$13M 1.78% 14
2025
Q2 		$13.1M Sell
1,149,794
-109,479
-9% -$1.12M 0.78% 24
2025
Q1 		$9.29M Hold
1,259,273
– – 0.55% 24
2024
Q4 		$23.2M Buy
1,259,273
+83,464
+7% +$1.78M 0.88% 23
2024
Q3 		$30.5M Buy
+1,175,809
New +$26.9M 1.05% 24

Other funds holding MBX

FLSM
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
O
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
PBA
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
DTC
Deep Track Capital Greenwich, Connecticut $6.87B AUM 205.24% 1-Year Est. Return
PCH
Polar Capital Holdings London, United Kingdom $42.4B AUM 181.11% 1-Year Est. Return

EcoR1 Capital's MBX Position: Q2 2026 in Review

EcoR1 Capital reduced its MBX Biosciences (MBX) stake by 50% in Q2 2026, selling an estimated $13.6M and leaving 388,500 shares worth $21.4M. The position accounts for 1.04% of the portfolio, ranked #16.

EcoR1 Capital first reported a position in MBX in Q3 2024 and has held it in 8 quarters since. The position peaked at $67M in Q4 2025. 173 funds tracked by Wall St. Rank hold MBX as of Q2 2026.

  • EcoR1 Capital held 388,500 shares of MBX Biosciences worth $21.4M as of Q2 2026.
  • EcoR1 Capital sold 388,500 MBX Biosciences shares in Q2 2026, an estimated $13.6M.
  • MBX Biosciences made up 1.04% of EcoR1 Capital's portfolio in Q2 2026, its #16 holding.
  • EcoR1 Capital first reported a position in MBX Biosciences in Q3 2024 and has held it in 8 quarters since.
  • EcoR1 Capital's MBX Biosciences position peaked at $67M in Q4 2025.
  • 173 funds tracked by Wall St. Rank held MBX Biosciences as of Q2 2026.

Based on EcoR1 Capital's 13F filing for Q2 2026, filed 14 Aug 2026.