Insider Transaction Report for William F. Masterson III

This filing details a transaction by William F. Masterson III, Senior Vice President at CABOT CORP. On June 12, 2026, Masterson acquired 2.8237 Phantom Stock Units, which are to be settled upon retirement or termination of employment. These units are linked to the company's Supplemental 401(k) Plan. The acquisition occurred at a price of $87.65 per unit, bringing the total post-transaction holdings to 526.6187 units. The underlying security for these units is CABOT CORP Common Stock. The transaction was reported on Form 4, signed by Jennifer Lombardi under power of attorney for Masterson.