Form 4 Filing for Rebecca Underwood

Rebecca Underwood, PRESIDENT & EVP FACILITIES of CLEAN HARBORS INC, reported the following transactions on March 13, 2026: 1. A disposition of 125 shares of Common Stock valued at $288.93 per share, due to payment of tax liability by withholding securities incident to vesting. This transaction resulted in 20,085 shares remaining. 2. A forfeiture of 1,401 shares of Common Stock with no value, due to the Company not achieving performance targets under its Long Term Equity Incentive Program. This resulted in 18,684 shares remaining. The filing date was March 17, 2026.