John W. Smither, Chief Financial Officer of MBX Biosciences, Inc. (NASDAQ: MBX), filed a Form 4 on August 4, 2026, disclosing the acquisition of restricted stock units and stock options granted on August 3, 2026.

Key Highlights

  • RSU Grant: Smither acquired 28,000 restricted stock units at a price of $0, held directly.
  • Stock Option Grant: Smither received options to purchase 130,000 shares of Common Stock at an exercise price of $64.41, expiring 08/03/2036.
  • RSU Vesting Schedule: 25% of RSUs vest annually on each of July 13, 2027, 2028, 2029, and 2030, subject to continued service.
  • Option Vesting Schedule: 25% of options vest on July 13, 2027, with the remainder vesting in 36 equal monthly installments thereafter, subject to continued service.
  • Post-Transaction Ownership: Following the grants, Smither directly holds 28,000 shares of Common Stock and 130,000 derivative securities (stock options).

MBX Biosciences CFO Equity Grant Details: RSUs and Options

According to the filing, John W. Smither, serving as Chief Financial Officer of MBX Biosciences, Inc., reported two equity awards granted on August 3, 2026. The first is a grant of 28,000 restricted stock units (RSUs) in Common Stock, acquired at $0, held directly. The filing notes that "25% of the shares subject to the RSU grant will vest annually over four years, on each July 13, 2027, 2028, 2029 and 2030, subject to continued service on each such vesting date."

The second award, also dated August 3, 2026, is a stock option granting the right to purchase 130,000 shares of Common Stock at an exercise price of $64.41 per share, with an expiration date of 08/03/2036. The filing states that "the options will vest and become exercisable with 25% of the shares subject to the award vesting on July 13, 2027 and the remainder vesting in 36 equal monthly installments thereafter, subject to continued service on each such vesting date." The price of the derivative security is listed as $0.

Both transactions are coded as acquisitions (Code A) in the filing. Following these grants, the filing reports Smither's direct beneficial ownership as 28,000 shares of Common Stock and 130,000 stock options. The Form 4 was filed by one reporting person and is not identified as an amendment. The filing references Exhibit 24, a Power of Attorney, and was signed by John W. Smither on August 4, 2026.

What Was Disclosed

MBX Biosciences CFO John W. Smither reported receiving a grant of 28,000 RSUs and options to purchase 130,000 shares at $64.41 each, both dated August 3, 2026, with multi-year vesting schedules tied to continued service.