CABOT CORP — Director's Dealing 2007

Dec 28, 2007

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: CABOT CORP (CBT)
CIK: 0000016040
Period of Report: 2007-12-26

Reporting Person: SPO ADVISORY CORP (10% Owner)
Reporting Person: SPO ADVISORY PARTNERS LP (10% Owner)
Reporting Person: SPO PARTNERS II LP (10% Owner)
Reporting Person: Elizabeth R. & William J. Patterson Foundation (10% Owner)
Reporting Person: SCULLY JOHN H (10% Owner)
Reporting Person: OBERNDORF WILLIAM E (10% Owner)
Reporting Person: PATTERSON WILLIAM J (10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2007-12-27	Common Stock	P	4300	$33.49	Acquired	9551800	Indirect
2007-12-27	Common Stock	P	6200	$33.50	Acquired	9558000	Indirect
2007-12-27	Common Stock	P	1300	$33.51	Acquired	9559300	Indirect
2007-12-27	Common Stock	P	1000	$33.52	Acquired	9560300	Indirect
2007-12-27	Common Stock	P	600	$33.53	Acquired	9560900	Indirect
2007-12-27	Common Stock	P	500	$33.54	Acquired	9561400	Indirect
2007-12-27	Common Stock	P	200	$33.55	Acquired	9561600	Indirect
2007-12-27	Common Stock	P	200	$33.56	Acquired	9561800	Indirect
2007-12-27	Common Stock	P	200	$33.58	Acquired	9562000	Indirect
2007-12-27	Common Stock	P	100	$33.59	Acquired	9562100	Indirect

Footnotes

F1: The entities directly acquiring the shares reported on this form are SPO Partners II, L.P. ("SPO Partners"), which bought 71,400 shares, and the Elizabeth R. & William J. Patterson Foundation ("WJPFND"), which bought 1,800 shares.

F2: Due to the purchases causing this filing and related filings today, 9,146,500 shares are owned directly by SPO Partners, and may be deemed to be indirectly beneficially owned by (i) SPO Advisory Partners, L.P. ("SPO Advisory"), the sole general partner of SPO Partners, (ii) SPO Advisory Corp. ("SPO Corp."), the sole general partner of SPO Advisory, and (iii) John H. Scully ("JHS"), William E. Oberndorf ("WEO") and William J. Patterson ("WJP"), the three controlling persons of SPO Corp. 415,600 shares are owned directly by San Francisco Partners, L.P. ("SF Partners"), and may be deemed to be indirectly beneficially owned by (i) SF Advisory Partners, L.P. ("SF Advisory"), the sole general partner of SF Partners, (ii) SPO Corp., the sole general partner of SF Advisory, and (iii) JHS, WEO and WJP, the three controlling persons of SPO Corp. These shares are represented in the running total in Column 5 above, which does not include 9,900 shares held by WJPFND.

F3: Additionally, (i) 333,650 shares of the issuer's common stock may be deemed to be indirectly beneficially owned by WEO solely in his capacity as a trustee for the William and Susan Oberndorf Trust, dated 10/15/98 ("Oberndorf Trust"), (ii) 100,000 shares may be deemed to be indirectly beneficially owned by WEO solely in his capacity as general partner of Oberndorf Family Partners, a California limited partnership, (iii) WEO owns 109,000 shares in his IRA, which is self-directed, and (iv) 10,000 shares may be deemed to be indirectly beneficially owned by WEO solely in his capacity as trustee for the accounts of his two children, Peter C. Oberndorf & William Ernst Oberndorf.