Other Events. On August 21, 2026, Cabot Corporation (“Cabot”) completed the issuance and sale of $350 million aggregate principal amount of 4.950% senior notes due 2029 (the “Notes”). The offering of the Notes was registered pursuant to an automatically effective shelf registration statement on Form S-3ASR under the Securities Act of 1933, as amended (Registration Statement No. 333-276078) (the “Registration Statement”), that was filed with the Securities and Exchange Commission on December 1…

Results of Operations and Financial Condition. On August 3, 2026, Cabot Corporation issued a press release announcing operating results for its fiscal quarter ended June 30, 2026. A copy of the press release is furnished herewith as Exhibit 99.1.

President and Chief Executive Officer — Sean D. Keohane: Mr. Keohane is retiring as President and CEO, with Erica McLaughlin succeeding him in the role.

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant . The information set forth above under

Termination of a Material Definitive Agreement. Concurrently with entering into the Credit Agreement, on May 12, 2026, the Company terminated (i) its $1 billion revolving credit agreement with JPMorgan Chase Bank, N.A. and the other lenders party thereto, which, by its terms, was scheduled to mature on August 6, 2027, and (ii) its €300 million revolving credit agreement with PNC Bank, National Association, and the other lenders party thereto, which, by its terms, was also scheduled to mature…

Entry into a Material Definitive Agreement. On May 12, 2026, Cabot Corporation (the “Company”) entered into a $1.3 billion unsecured revolving credit agreement (the “Credit Agreement”) with a syndicate of lenders arranged by JPMorgan Chase Bank, N.A. and JPMorgan SE, as Administrative Agents, JPMorgan Chase Bank, N.A., Citibank, N.A., U.S. Bank, National Association and PNC Capital Markets LLC, as Joint Lead Bookrunners and Joint Lead Arrangers, Bank of America, N.A., ING Bank N.V. Dublin Bra…

Results of Operations and Financial Condition. On May 5, 2026, Cabot Corporation issued a press release announcing operating results for its fiscal quarter ended March 31, 2026. A copy of the press release is furnished herewith as Exhibit 99.1.

Results of Operations and Financial Condition. On February 3, 2026, Cabot Corporation issued a press release announcing operating results for its fiscal quarter ended December 31, 2025. A copy of the press release is furnished herewith as Exhibit 99.1.

Director — Thierry Vanlancker: The filing describes a conditional resignation and reappointment of a sitting director solely to rebalance board classes, which is a routine administrative procedure rather than a genuine departure.

Results of Operations and Financial Condition. On November 3, 2025, Cabot Corporation issued a press release announcing operating results for its fiscal quarter ended September 30, 2025. A copy of the press release is furnished herewith as Exhibit 99.1.

Results of Operations and Financial Condition. On August 4, 2025, Cabot Corporation issued a press release announcing operating results for its fiscal quarter ended June 30, 2025. A copy of the press release is furnished herewith as Exhibit 99.1.

President — Hobart C. Kalkstein: The departure is an orderly retirement with a named internal successor and a transition period, indicating a planned succession rather than a sudden loss of leadership.

Results of Operations and Financial Condition. On May 5, 2025, Cabot Corporation issued a press release announcing operating results for its fiscal quarter ended March 31, 2025. A copy of the press release is furnished herewith as Exhibit 99.1.

Results of Operations and Financial Condition. On February 3, 2025, Cabot Corporation issued a press release announcing operating results for its fiscal quarter ended December 31, 2024. A copy of the press release is furnished herewith as Exhibit 99.1.

Results of Operations and Financial Condition. On November 4, 2024, Cabot Corporation issued a press release announcing operating results for its fiscal quarter ended September 30, 2024. A copy of the press release is furnished herewith as Exhibit 99.1.

Results of Operations and Financial Condition. On August 5, 2024, Cabot Corporation issued a press release announcing operating results for its fiscal quarter ended June 30, 2024. A copy of the press release is furnished herewith as Exhibit 99.1.

Director — Thierry Vanlancker: The filing discloses the routine election of a new director to the board and audit committee, which is a standard governance event rather than an executive departure.

Results of Operations and Financial Condition. On May 6, 2024, Cabot Corporation issued a press release announcing operating results for its fiscal quarter ended March 31, 2024. A copy of the press release is furnished herewith as Exhibit 99.1.