SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* SAN FRANCISCO PARTNERS II LP (Last) (First) (Middle) 591 REDWOOD HIGHWAY, SUITE 3215 (Street) MILL VALLEY CA 94941 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol CABOT CORP [ CBT ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 03/12/2009
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	03/12/2009		S		89,500	D	$8.97	0	I	See footnotes(1)(2)(3)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person* SAN FRANCISCO PARTNERS II LP (Last) (First) (Middle) 591 REDWOOD HIGHWAY, SUITE 3215 (Street) MILL VALLEY CA 94941 (City) (State) (Zip)

1. Name and Address of Reporting Person* SF ADVISORY PARTNERS LP (Last) (First) (Middle) 591 REDWOOD HIGHWAY , SUITE 3215 (Street) MILL VALLEY CA 94941 (City) (State) (Zip)

1. Name and Address of Reporting Person* SPO ADVISORY CORP (Last) (First) (Middle) 591 REDWOOD HIGHWAY, SUITE 3215 (Street) MILL VALLEY CA 94941 (City) (State) (Zip)

1. Name and Address of Reporting Person* SCULLY JOHN H (Last) (First) (Middle) 591 REDWOOD HIGHWAY, SUITE 3215 (Street) MILL VALLEY CA 94941 (City) (State) (Zip)

1. Name and Address of Reporting Person* OBERNDORF WILLIAM E (Last) (First) (Middle) 591 REDWOOD HIGHWAY, SUITE 3215 (Street) MILL VALLEY CA 94941 (City) (State) (Zip)

1. Name and Address of Reporting Person* PATTERSON WILLIAM J (Last) (First) (Middle) 591 REDWOOD HIGHWAY, SUITE 3215 (Street) MILL VALLEY CA 94941 (City) (State) (Zip)

1. Name and Address of Reporting Person* MCDERMOTT EDWARD H (Last) (First) (Middle) 591 REDWOOD HIGHWAY , SUITE 3215 (Street) MILL VALLEY CA 94941 (City) (State) (Zip)

Explanation of Responses:

1. The entity disposing of these shares is San Francisco Partners II, L.P. ("SF Partners") which sold 89,500 shares.

2. As a result of the sales causing this filing, 9,662,600 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 partners 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"), William J. Patterson ("WJP") and Edward H. McDermott ("EHM"), the four controlling persons of SPO Corp.

3. 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, and (iii) WEO owns 109,000 shares of the issuer's common stock in his IRA, which is self-directed.

Remarks:

The individuals listed in the Notes above (each a "Reporting Person") may be deemed to form a "group", as such term is defined in Rule 13d-5(b)(1) promulgated under the Securities Exchange Act of 1934, for purposes of this filing. This filing shall not be deemed as an admission by any Reporting Person that such person is, for purposes of Section 16 of the Securities Exchange Act of 1934 or otherwise, the beneficial owner of any equity securities covered by this statement. Each Reporting Person disclaims beneficial ownership of the reported securities except to the extent of such person's pecuniary interest, if any, therein.

	Kim M. Silva, Attorney-in-fact	03/16/2009
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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