CABOT CORP — Director's Dealing 2006

Feb 17, 2006

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: CABOT CORP (CBT)
CIK: 0000016040
Period of Report: 2006-02-15

Reporting Person: SPO ADVISORY CORP (10% Owner)
Reporting Person: OBERNDORF WILLIAM E (10% Owner)
Reporting Person: WEIMER BETTY JANE (10% Owner)
Reporting Person: PETER C OBERNDORF TRUST (10% Owner)
Reporting Person: WILLIAM ERNST OBERNDORF TRUST (10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2006-02-15	Common Stock	P	100	$37.21	Acquired	433750	Indirect
2006-02-15	Common Stock	P	1900	$37.24	Acquired	435650	Indirect
2006-02-15	Common Stock	P	1800	$37.25	Acquired	437450	Indirect
2006-02-15	Common Stock	P	700	$37.28	Acquired	438150	Indirect
2006-02-15	Common Stock	P	600	$37.29	Acquired	438750	Indirect
2006-02-15	Common Stock	P	2200	$37.30	Acquired	440950	Indirect
2006-02-15	Common Stock	P	1000	$37.31	Acquired	441950	Indirect
2006-02-15	Common Stock	P	100	$37.33	Acquired	442050	Indirect
2006-02-15	Common Stock	P	300	$37.34	Acquired	442350	Indirect
2006-02-15	Common Stock	P	400	$37.35	Acquired	442750	Indirect
2006-02-15	Common Stock	P	600	$37.36	Acquired	443350	Indirect
2006-02-15	Common Stock	P	1500	$37.37	Acquired	444850	Indirect
2006-02-15	Common Stock	P	2400	$37.38	Acquired	447250	Indirect
2006-02-15	Common Stock	P	400	$37.39	Acquired	447650	Indirect
2006-02-15	Common Stock	P	1000	$37.40	Acquired	448650	Indirect

Footnotes

F1: As a result of the purchases causing this filing, (i) 333,650 shares of the issuer's common stock may be deemed to be indirectly beneficially owned by William E. Oberndorf ("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 trustee for the Oberndorf Trust, the sole general partner of Oberndorf Family Partners, a family partnership and (iii) 15,000 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 and William Ernst Oberndorf, and in his capacity as legal representative of the account of his mother, Betty Jane Weimer.

F2: Additionally, separate from the entities listed above, 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"), 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, 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.