X0201 42003-07-31 0000016040 CABOT CORP CBT 0001243739 BERUBE BRIAN A C/O CABOT CORPORATION, SUITE 1300 TWO SEAPORT LANE BOSTON MA 02210 0100Vice President/General CounselCommon Stock2003-07-314A0125008.40A35802DCommon Stock2891IThrough the Trustee of the Corporation's Retirement Savings Plan.Series B ESOP Convertible Preferred StockCommon Stock508835IThrough the Trustee of the Corporation's Retirement Savings PlanEach share is convertible into 146.4 shares of the Corporation's common stock.Under the Retirement Savings Plan, the Corporation allocates Series B ESOP Convertible Preferred Stock to each participant's account on a quarterly basis. Subject to certain terms and conditions of the Retirement Savings Plan, participants may elect to receive distributions of their vested account balance in the form of shares of the Corporation's common stock or cash. Generally, a participant is 20% vested in his account after 2 years of service with the Corporation; 40% vested after 3 years of service; 60% vested after 4 years of service; and 100% vested after 5 years of service.Michaela Allbee, pursuant to a power of attorney from Brian Berube2003-08-04