Form 8-K CABOT CORP For: Aug 12

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(D)

OF THE SECURITIES EXCHANGE ACT OF 1934

Date of report (Date of earliest event reported): August 12, 2026

CABOT CORPORATION

(Exact Name of Registrant as Specified in Its Charter)

Registrant’s Telephone Number, Including Area Code: (617) 345-0100

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

Securities registered pursuant to Section 12(b) of the Securities Exchange Act of 1934:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8.01. Other Events.

On August 12, 2026, Cabot Corporation (“Cabot”) entered into an Underwriting Agreement (the “Underwriting Agreement”) with Citigroup Global Markets Inc., J.P. Morgan Securities LLC, PNC Capital Markets LLC and U.S. Bancorp Investments, Inc., as representatives of the several underwriters named in Schedule 1 thereto, relating to the issuance and sale of $350 million aggregate principal amount of 4.950% 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 15, 2023. The Notes will be issued pursuant to a base indenture, as supplemented by a second supplemental indenture, in each case to be executed by and between Cabot and U.S. Bank Trust Company, National Association, as trustee. Cabot is expected to complete the issuance and sale of the Notes on or about August 21, 2026, subject to the satisfaction of customary closing conditions.

In order to furnish certain exhibits for incorporation by reference into the Registration Statement, Cabot is filing the Underwriting Agreement as Exhibit 1.1 to this Current Report on Form 8-K. Certain information relating to Part II, Item 14 “Other Expenses of Issuance and Distribution” of the Registration Statement is filed as Exhibit 99.1 to this Current Report on Form 8-K.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: August 14, 2026