Brun Scott C. 4

What Happened
Scott C. Brun, a director of Cabaletta Bio, was granted a derivative award covering 22,000 shares on June 9, 2026. The filing reports an acquisition amount of $0.00 for the award (transaction code A) and was filed on June 10, 2026. The filing’s footnote identifies the award as an option with a vesting condition.

Key Details

• Transaction date: June 9, 2026; Form 4 filed: June 10, 2026 (timely filing).
• Instrument: Derivative award (described in the filing footnote as an option) for 22,000 shares; reported acquisition price $0.00.
• Vesting: The option vests in full upon the earlier of (i) June 9, 2027 or (ii) the date of the next annual meeting of stockholders (per footnote).
• Shares owned after transaction: Not specified in the provided excerpt of the filing.
• Filing timeliness: Filed the day after the grant (appears timely); no 10b5-1 plan or tax-withholding noted in the provided details.

Context: This was an equity award (an option) granted to a director as compensation. Such derivative awards typically vest over time and are not the same as an immediate purchase of stock; they do not necessarily indicate the director bought or sold shares. The option must vest before it can be exercised into underlying shares.