DesRosier Thomas 4

What Happened

• Thomas DesRosier, EVP and Chief Legal Officer of Seres Therapeutics (MCRB), was granted a derivative award covering 22,500 shares on March 4, 2026. The filing reports an acquisition at $0.00 per share (award/option grant), so no cash was paid at grant and this is not an exercised option or sale.

Key Details

• Transaction date: 2026-03-04; Form 4 filed: 2026-03-06 (filed within the typical 2-business-day window).
• Transaction type/code: A (award/grant/acquisition of a derivative security).
• Shares/units granted: 22,500 (reported at $0.00 per share in the filing).
• Shares owned after transaction: Not disclosed in the provided excerpt of the filing.
• Footnote: The option vests 25% on March 2, 2027; the remaining 75% vests in 12 equal quarterly installments thereafter.

Context

• This was a grant of a derivative security (an option award), not an exercise or sale — meaning DesRosier did not sell shares or receive cash; the award vests over time before any shares become transferable.
• For retail investors, awards like this are routine executive compensation and are not an immediate market signal; they create potential future exposure depending on vesting and any eventual exercise.