CABOT CORP — Director's Dealing 2005

Oct 4, 2005

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: CABOT CORP (CBT)
CIK: 0000016040
Period of Report: 2005-09-30

Reporting Person: CLARKESON JOHN S (Director)

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2005-09-30	Phantom Stock Units	$	A	490.76	Acquired	1988-08-08	Common Stock (490.76)	Direct

Footnotes

F1: 1 for 1

F2: Immediately exercisable

F3: The shares of phantom stock become payable in monthly installments upon the reporting person's termination of service as a director.

F4: On July 8 2005, Cabot's Board of Directors declared a dividend of $.16 per share on Cabot common stock, payable on September 9, 2005 to all holders of record of common stock on August 26, 2005. Mr. Clarkeson received a dividend on his phantom stock units totalling $875.57, which was immediately reinvested in phantom stock units at a price of $33.56 per share. As a result, 26.09 phantom stock units were allocated to Mr. Clarkeson on September 9, 2005.