William F. Masterson III - 21 Nov 2025 Form 3 Insider Report for CABOT CORP (CBT)

Role: Senior Vice President
Signature: By: Jennifer Lombardi, pursuant to a power of attorney from William F. Masterson, III
Issuer symbol: CBT
Transactions as of: 21 Nov 2025
Net transactions value: $0
Form type: 3
Filing time: 02 Dec 2025, 17:00:05 UTC
Next filing: 05 Dec 2025
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Masterson William F III	Senior Vice President	C/O CABOT CORPORATION, TWO SEAPORT LANE, SUITE 1400, BOSTON	By: Jennifer Lombardi, pursuant to a power of attorney from William F. Masterson, III	02 Dec 2025	0002098902

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
holding	CBT	Common Stock						3,724	21 Nov 2025	Direct	F1

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
holding	CBT	Phantom Stock							21 Nov 2025	Common Stock	290	$0.000000	Direct	F2

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Includes 942 performance based units earned on the basis of the Corporation's performance in fiscal years 2024 and 2025 (which remain subject to time-based vesting) and 1,801 units subject to time-based vesting.
F2	Each share of phantom stock is the economic equivalent of one share of Cabot Corporation common stock. The shares of phantom stock will be settled in shares of Cabot Corporation common stock upon termination of his employment with Cabot Corporation.

Remarks:

Exhibit-24 Power of Attorney attached.