Bartram Richard plan to sell securities of MBX Biosciences, Inc. under Form 144

Bartram Richard filed Form 144 to notify SEC of plan to sell 15000 units of MBX Biosciences, Inc. securities around 2026-05-13, with aggregate market value of $554,295.75. The total outstanding units is 47597536.0. The amount planned to be sold represents 0.03% of total outstanding units; Recent transactions in past 3 months include: On 03/16/2026, sold 10000 units for $300471.00; On 03/25/2026, sold 1061 units for $30217.49; On 04/22/2026, sold 10423 units for $341377.72; On 05/01/2026, sold 5000 units for $159000.00; On 05/07/2026, sold 10000 units for $322050.00; On 05/08/2026, sold 10000 units for $379562.50; On 05/11/2026, sold 22500 units for $991901.00;