CABOT CORP — Director's Dealing 2006

Jan 11, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: CABOT CORP (CBT)
CIK: 0000016040
Period of Report: 2006-01-06

Reporting Person: SPO ADVISORY CORP (10% Owner)
Reporting Person: WILLIAM ERNST OBERNDORF TRUST (10% Owner)
Reporting Person: OBERNDORF FAMILY PARTNERS (10% Owner)
Reporting Person: WILLIAM & SUSAN OBERNDORF TRUST (10% Owner)
Reporting Person: OBERNDORF WILLIAM E (10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2006-01-06	Common Stock	P	420	$37.68	Acquired	186520	Indirect
2006-01-06	Common Stock	P	420	$37.69	Acquired	186940	Indirect
2006-01-06	Common Stock	P	8579	$37.70	Acquired	195519	Indirect
2006-01-06	Common Stock	P	3300	$37.71	Acquired	198819	Indirect
2006-01-06	Common Stock	P	1079	$37.72	Acquired	199898	Indirect
2006-01-06	Common Stock	P	2520	$37.73	Acquired	202418	Indirect
2006-01-06	Common Stock	P	1559	$37.74	Acquired	203977	Indirect
2006-01-06	Common Stock	P	32573	$37.75	Acquired	236550	Indirect
2006-01-09	Common Stock	P	400	$37.43	Acquired	236950	Indirect
2006-01-09	Common Stock	P	400	$37.44	Acquired	237350	Indirect
2006-01-09	Common Stock	P	500	$37.45	Acquired	237850	Indirect
2006-01-09	Common Stock	P	800	$37.46	Acquired	238650	Indirect
2006-01-09	Common Stock	P	1900	$37.47	Acquired	240550	Indirect
2006-01-09	Common Stock	P	500	$37.48	Acquired	241050	Indirect
2006-01-09	Common Stock	P	600	$37.49	Acquired	241650	Indirect
2006-01-09	Common Stock	P	94900	$37.50	Acquired	336550	Indirect
2006-01-06	Common Stock	P	280	$37.68	Acquired	336830	Indirect
2006-01-06	Common Stock	P	280	$37.69	Acquired	337110	Indirect
2006-01-06	Common Stock	P	5721	$37.70	Acquired	342831	Indirect
2006-01-06	Common Stock	P	2200	$37.71	Acquired	345031	Indirect
2006-01-06	Common Stock	P	721	$37.72	Acquired	345752	Indirect
2006-01-06	Common Stock	P	1680	$37.73	Acquired	347432	Indirect
2006-01-06	Common Stock	P	1041	$37.74	Acquired	348473	Indirect
2006-01-06	Common Stock	P	21727	$37.75	Acquired	370200	Indirect

Footnotes

F1: 7,648,600 shares of the issuer's common stock are owned directly by SPO Partners II, L.P. ("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. 309,400 shares of the issuer's common stock are owned directly by San Francisco Partners II, 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.

F2: Additionally, separate from the entities listed above, and as a result of the purchases causing this filing, (i) 293,500 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) 67,300 shares may be deemed to be indirectly beneficially owned by WEO solely in his capacity as trustee for the Oberndorf Trust, the sole general partner of Oberndorf Family Partners, a family partnership and (iii) 33,650 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 a trust for the benefit of himself and his wife.