SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13D Under the Securities Exchange Act of 1934 (Amendment No. 6)* CABOT CORPORATION (Name of Issuer) COMMON STOCK, PAR VALUE $1.00 PER SHARE (Title of Class of Securities) 127055101 (CUSIP Number) SPO Advisory Corp. 591 Redwood Highway, Suite 3215 Mill Valley, California 94941 (415) 383-6600 with a copy to: Alison S. Ressler Sullivan & Cromwell LLP 1888 Century Park East Los Angeles, California 90067-1725 (310) 712-6600 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) June 15, 2006 (Date of Event which Requires Filing of This Statement) If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this Schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box |_|. Note. Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for other parties to whom copies are to be sent. *The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page. The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).Page 2 of 20 pages CUSIP No. 127055101 - -------------------------------------------------------------------------------- 1. NAME OF REPORTING PERSON SPO Partners II, L.P. - -------------------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) |_| (b) |X| - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. SOURCE OF FUNDS WC - -------------------------------------------------------------------------------- 5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e) |_| - -------------------------------------------------------------------------------- 6. CITIZENSHIP OR PLACE OF ORGANIZATION Delaware - -------------------------------------------------------------------------------- 7. SOLE VOTING POWER 8,297,600 (1) ------------------------------------------------------ Number Of Shares 8. SHARED VOTING POWER Beneficially Owned By -0- Each Reporting Person ------------------------------------------------------ With 9. SOLE DISPOSITIVE POWER 8,297,600 (1) ------------------------------------------------------ 10. SHARED DISPOSITIVE POWER -0- - -------------------------------------------------------------------------------- 11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 8,297,600 (1) - -------------------------------------------------------------------------------- 12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES |_| - -------------------------------------------------------------------------------- 13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 13.08% - -------------------------------------------------------------------------------- 14. TYPE OF REPORTING PERSON PN - -------------------------------------------------------------------------------- (1) Power is exercised through its sole general partner, SPO Advisory Partners, L.P.
Page 3 of 20 pages CUSIP No. 127055101 - -------------------------------------------------------------------------------- 1. NAME OF REPORTING PERSON SPO Advisory Partners, L.P. - -------------------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) |_| (b) |X| - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. SOURCE OF FUNDS Not Applicable - -------------------------------------------------------------------------------- 5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e) |_| - -------------------------------------------------------------------------------- 6. CITIZENSHIP OR PLACE OF ORGANIZATION Delaware - -------------------------------------------------------------------------------- 7. SOLE VOTING POWER 8,297,600 (1)(2) ------------------------------------------------------ Number Of Shares 8. SHARED VOTING POWER Beneficially Owned By -0- Each Reporting Person ------------------------------------------------------ With 9. SOLE DISPOSITIVE POWER 8,297,600 (1)(2) ------------------------------------------------------ 10. SHARED DISPOSITIVE POWER -0- - -------------------------------------------------------------------------------- 11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 8,297,600 (1)(2) - -------------------------------------------------------------------------------- 12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES |_| - -------------------------------------------------------------------------------- 13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 13.08% - -------------------------------------------------------------------------------- 14. TYPE OF REPORTING PERSON PN - -------------------------------------------------------------------------------- (1) Solely in its capacity as the sole general partner of SPO Partners II, L.P. (2) Power is exercised through its sole general partner, SPO Advisory Corp.
Page 4 of 20 pages CUSIP No. 127055101 - -------------------------------------------------------------------------------- 1. NAME OF REPORTING PERSON San Francisco Partners II, L.P. - -------------------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) |_| (b) |X| - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. SOURCE OF FUNDS WC - -------------------------------------------------------------------------------- 5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e) |_| - -------------------------------------------------------------------------------- 6. CITIZENSHIP OR PLACE OF ORGANIZATION California - -------------------------------------------------------------------------------- 7. SOLE VOTING POWER 309,400 (1) ------------------------------------------------------ Number Of Shares 8. SHARED VOTING POWER Beneficially Owned By -0- Each Reporting Person ------------------------------------------------------ With 9. SOLE DISPOSITIVE POWER 309,400 (1) ------------------------------------------------------ 10. SHARED DISPOSITIVE POWER -0- - -------------------------------------------------------------------------------- 11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 309,400 (1) - -------------------------------------------------------------------------------- 12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES |_| - -------------------------------------------------------------------------------- 13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.49% - -------------------------------------------------------------------------------- 14. TYPE OF REPORTING PERSON PN - -------------------------------------------------------------------------------- (1) Power is exercised through its sole general partner, SF Advisory Partners, L.P.
Page 5 of 20 pages CUSIP No. 127055101 - -------------------------------------------------------------------------------- 1. NAME OF REPORTING PERSON SF Advisory Partners, L.P. - -------------------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) |_| (b) |X| - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. SOURCE OF FUNDS Not Applicable - -------------------------------------------------------------------------------- 5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e) |_| - -------------------------------------------------------------------------------- 6. CITIZENSHIP OR PLACE OF ORGANIZATION Delaware - -------------------------------------------------------------------------------- 7. SOLE VOTING POWER 309,400 (1)(2) ------------------------------------------------------ Number Of Shares 8. SHARED VOTING POWER Beneficially Owned By -0- Each Reporting Person ------------------------------------------------------ With 9. SOLE DISPOSITIVE POWER 309,400 (1)(2) ------------------------------------------------------ 10. SHARED DISPOSITIVE POWER -0- - -------------------------------------------------------------------------------- 11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 309,400 (1)(2) - -------------------------------------------------------------------------------- 12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES |_| - -------------------------------------------------------------------------------- 13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.49% - -------------------------------------------------------------------------------- 14. TYPE OF REPORTING PERSON PN - -------------------------------------------------------------------------------- (1) Solely in its capacity as the sole general partner of San Francisco Partners II, L.P. (2) Power is exercised through its sole general partner, SPO Advisory Corp.
Page 6 of 20 pages CUSIP No. 127055101 - -------------------------------------------------------------------------------- 1. NAME OF REPORTING PERSON SPO Advisory Corp. - -------------------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) |_| (b) |X| - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. SOURCE OF FUNDS Not Applicable - -------------------------------------------------------------------------------- 5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e) |_| - -------------------------------------------------------------------------------- 6. CITIZENSHIP OR PLACE OF ORGANIZATION Delaware - -------------------------------------------------------------------------------- 7. SOLE VOTING POWER 8,607,000 (1)(2) ------------------------------------------------------ Number Of Shares 8. SHARED VOTING POWER Beneficially Owned By -0- Each Reporting Person ------------------------------------------------------ With 9. SOLE DISPOSITIVE POWER 8,607,000 (1)(2) ------------------------------------------------------ 10. SHARED DISPOSITIVE POWER -0- - -------------------------------------------------------------------------------- 11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 8,607,000 (1)(2) - -------------------------------------------------------------------------------- 12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES |_| - -------------------------------------------------------------------------------- 13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 13.57% - -------------------------------------------------------------------------------- 14. TYPE OF REPORTING PERSON CO - -------------------------------------------------------------------------------- (1) Solely in its capacity as the sole general partner of SPO Advisory Partners, L.P. with respect to 8,297,600 of such shares; and solely in its capacity as the sole general partner of SF Advisory Partners, L.P. with respect to 309,400 of such shares. (2) Power is exercised through its three controlling persons, John H. Scully, William E. Oberndorf and William J. Patterson.
Page 7 of 20 pages CUSIP No. 127055101 - -------------------------------------------------------------------------------- 1. NAME OF REPORTING PERSON John H. Scully - -------------------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) |_| (b) |X| - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. SOURCE OF FUNDS Not Applicable - -------------------------------------------------------------------------------- 5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e) |_| - -------------------------------------------------------------------------------- 6. CITIZENSHIP OR PLACE OF ORGANIZATION USA - -------------------------------------------------------------------------------- 7. SOLE VOTING POWER -0- ------------------------------------------------------ Number Of Shares 8. SHARED VOTING POWER Beneficially Owned By 8,607,000 (1) Each Reporting Person ------------------------------------------------------ With 9. SOLE DISPOSITIVE POWER -0- ------------------------------------------------------ 10. SHARED DISPOSITIVE POWER 8,607,000 (1) - -------------------------------------------------------------------------------- 11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 8,607,000 (1) - -------------------------------------------------------------------------------- 12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES |_| - -------------------------------------------------------------------------------- 13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 13.57% - -------------------------------------------------------------------------------- 14. TYPE OF REPORTING PERSON IN - -------------------------------------------------------------------------------- (1) These shares may be deemed to be beneficially owned by Mr. Scully solely in his capacity as one of three controlling persons of SPO Advisory Corp.
Page 8 of 20 pages CUSIP No. 127055101 - -------------------------------------------------------------------------------- 1. NAME OF REPORTING PERSON William E. Oberndorf - -------------------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) |_| (b) |X| - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. SOURCE OF FUNDS Not Applicable - -------------------------------------------------------------------------------- 5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e) |_| - -------------------------------------------------------------------------------- 6. CITIZENSHIP OR PLACE OF ORGANIZATION USA - -------------------------------------------------------------------------------- 7. SOLE VOTING POWER -0- ------------------------------------------------------ Number Of Shares 8. SHARED VOTING POWER Beneficially Owned By 9,050,650 (1) Each Reporting Person ------------------------------------------------------ With 9. SOLE DISPOSITIVE POWER -0- ------------------------------------------------------ 10. SHARED DISPOSITIVE POWER 9,050,650 (1) - -------------------------------------------------------------------------------- 11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 9,050,650 (1) - -------------------------------------------------------------------------------- 12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES |_| - -------------------------------------------------------------------------------- 13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 14.27% - -------------------------------------------------------------------------------- 14. TYPE OF REPORTING PERSON IN - -------------------------------------------------------------------------------- (1) Of these shares, 8,607,000 shares may be deemed to be beneficially owned by Mr. Oberndorf solely in his capacity as one of the three controlling persons of SPO Advisory Corp., 333,650 shares may be deemed to be beneficially owned by Mr. Oberndorf solely in his capacity as a trustee of the William and Susan Oberndorf Trust, dated 10/19/98, 100,000 shares may be deemed to be beneficially owned by Mr. Oberndorf solely in his capacity as sole general partner of Oberndorf Family Partners, a California limited partnership, and 10,000 shares are owned by Mr. Oberndorf solely in his capacity as trustee for the account of his children.
Page 9 of 20 pages CUSIP No. 127055101 - -------------------------------------------------------------------------------- 1. NAME OF REPORTING PERSON William and Susan Oberndorf Trust, dated 10/19/98 - -------------------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) |_| (b) |X| - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. SOURCE OF FUNDS PF - -------------------------------------------------------------------------------- 5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e) |_| - -------------------------------------------------------------------------------- 6. CITIZENSHIP OR PLACE OF ORGANIZATION California - -------------------------------------------------------------------------------- 7. SOLE VOTING POWER 333,650 (1) ------------------------------------------------------ Number Of Shares 8. SHARED VOTING POWER Beneficially Owned By -0- Each Reporting Person ------------------------------------------------------ With 9. SOLE DISPOSITIVE POWER 333,650 (1) ------------------------------------------------------ 10. SHARED DISPOSITIVE POWER -0- - -------------------------------------------------------------------------------- 11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 333,650 (1) - -------------------------------------------------------------------------------- 12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES |_| - -------------------------------------------------------------------------------- 13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.53% - -------------------------------------------------------------------------------- 14. TYPE OF REPORTING PERSON OO - -------------------------------------------------------------------------------- (1) Power is exercised through its trustees, William E. Oberndorf and Susan C. Oberndorf.
Page 10 of 20 pages CUSIP No. 127055101 - -------------------------------------------------------------------------------- 1. NAME OF REPORTING PERSON Oberndorf Family Partners - -------------------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) |_| (b) |X| - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. SOURCE OF FUNDS WC - -------------------------------------------------------------------------------- 5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e) |_| - -------------------------------------------------------------------------------- 6. CITIZENSHIP OR PLACE OF ORGANIZATION California - -------------------------------------------------------------------------------- 7. SOLE VOTING POWER 100,000 (1) ------------------------------------------------------ Number Of Shares 8. SHARED VOTING POWER Beneficially Owned By -0- Each Reporting Person ------------------------------------------------------ With 9. SOLE DISPOSITIVE POWER 100,000 (1) ------------------------------------------------------ 10. SHARED DISPOSITIVE POWER -0- - -------------------------------------------------------------------------------- 11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 100,000 (1) - -------------------------------------------------------------------------------- 12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES |_| - -------------------------------------------------------------------------------- 13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.16% - -------------------------------------------------------------------------------- 14. TYPE OF REPORTING PERSON PN - -------------------------------------------------------------------------------- (1) Power is exercised through its sole general partner, William E. Oberndorf.
Page 11 of 20 pages CUSIP No. 127055101 - -------------------------------------------------------------------------------- 1. NAME OF REPORTING PERSON William J. Patterson - -------------------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) |_| (b) |X| - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. SOURCE OF FUNDS Not Applicable - -------------------------------------------------------------------------------- 5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e) |_| - -------------------------------------------------------------------------------- 6. CITIZENSHIP OR PLACE OF ORGANIZATION USA - -------------------------------------------------------------------------------- 7. SOLE VOTING POWER -0- ------------------------------------------------------ Number Of Shares 8. SHARED VOTING POWER Beneficially Owned By 8,607,000 (1) Each Reporting Person ------------------------------------------------------ With 9. SOLE DISPOSITIVE POWER -0- ------------------------------------------------------ 10. SHARED DISPOSITIVE POWER 8,607,000 (1) - -------------------------------------------------------------------------------- 11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 8,607,000 (1) - -------------------------------------------------------------------------------- 12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES |_| - -------------------------------------------------------------------------------- 13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 13.57% - -------------------------------------------------------------------------------- 14. TYPE OF REPORTING PERSON IN - -------------------------------------------------------------------------------- (1) These shares may be deemed to be beneficially owned by Mr. Patterson solely in his capacity as one of three controlling persons of SPO Advisory Corp.
Page 12 of 20 pages - -------------------------------------------------------------------------------- 1. NAME OF REPORTING PERSON Betty Jane Weimer - -------------------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) |_| (b) |X| - -------------------------------------------------------------------------------- 3. SEC Use Only - -------------------------------------------------------------------------------- 4. SOURCE OF FUNDS PF - -------------------------------------------------------------------------------- 5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) OR 2(e) |_| - -------------------------------------------------------------------------------- 6. CITIZENSHIP OR PLACE OF ORGANIZATION California - -------------------------------------------------------------------------------- 7. SOLE VOTING POWER 5,000 ------------------------------------------------------ Number Of Shares 8. SHARED VOTING POWER Beneficially Owned By -0- Each Reporting Person ------------------------------------------------------ With 9. SOLE DISPOSITIVE POWER 5,000 ------------------------------------------------------ 10. SHARED DISPOSITIVE POWER -0- - -------------------------------------------------------------------------------- 11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 5,000 - -------------------------------------------------------------------------------- 12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES |_| - -------------------------------------------------------------------------------- 13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.01% - -------------------------------------------------------------------------------- 14. TYPE OF REPORTING PERSON IN - --------------------------------------------------------------------------------
Page 13 of 20 pages This Amendment No. 6 amends the Schedule 13D (the "Original 13D") filed with the Securities and Exchange Commission ("SEC") on August 29, 2005 and as amended on September 14, 2005, September 26, 2005, October 20, 2005, November 8, 2005 and January 12, 2006. Unless otherwise stated herein, the Original 13D, as previously amended, remains in full force and effect. Terms used herein and not defined herein shall have the meanings ascribed thereto in the Original 13D. ITEM 2. IDENTITY AND BACKGROUND Item 2(a) is hereby amended and restated in its entirety as follows: "The undersigned hereby file this Schedule 13D Statement on behalf of SPO Partners II, L.P., a Delaware limited partnership ("SPO"), SPO Advisory Partners, L.P., a Delaware limited partnership ("SPO Advisory Partners"), San Francisco Partners II, L.P., a California limited partnership ("SFP"), SF Advisory Partners, L.P., a Delaware limited partnership ("SF Advisory Partners"), SPO Advisory Corp., a Delaware corporation ("SPO Advisory Corp."), John H. Scully ("JHS"), William E. Oberndorf ("WEO"), William J. Patterson ("WJP"), the William and Susan Oberndorf Trust, dated 10/19/98 ("Oberndorf Trust"), Oberndorf Family Partners, a California limited partnership ("OFP"), and Betty Jane Weimer ("BJW"). SPO, SPO Advisory Partners, SFP, SF Advisory Partners, SPO Advisory Corp., JHS, WEO, WJP, the Oberndorf Trust, OFP and BJW are sometimes hereinafter referred to as the "Reporting Persons." The Reporting Persons are making this single, joint filing because they may be deemed to constitute a "group" within the meaning of Section 13(d)(3) of the Securities Exchange Act of 1934, as amended (the "Act"), although neither the fact of this filing nor anything contained herein shall be deemed to be an admission by the Reporting Persons that a group exists." The following subsections are hereby added to Item 2(b)-(c) in appropriate alphabetical order as follows: "BJW "BJW's business address is 591 Redwood Highway, Suite 3215, Mill Valley, California 94941. She is retired."
Page 14 of 20 pages ITEM 3. SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION. Item 3 is hereby amended and restated in its entirety as follows: The source and amount of the funds used or to be used by the Reporting Persons to purchase Shares are as follows: NAME SOURCE OF FUNDS AMOUNT OF FUNDS - --------------------- --------------------------- --------------- SPO Contributions from Partners $266,984,142 SPO Advisory Partners Not Applicable Not Applicable SFP Contributions from Partners $10,038,218 SF Advisory Partners Not Applicable Not Applicable SPO Advisory Corp. Not Applicable Not Applicable JHS Not Applicable Not Applicable WEO Personal Funds (1) $373,188 WJP Not Applicable Not Applicable Oberndorf Trust Personal Funds (1) $12,237,424 OFP Contribution from Partners $ 3,635,448 BJW Personal Funds (1) $ 186,594 - ---------- (1) As used herein, the term "Personal Funds" includes sums borrowed from banks and brokerage firm margin accounts, none of which were borrowed or otherwise obtained for the specified purpose of acquiring, holding, trading or voting Shares. ITEM 5. INTEREST IN SECURITIES OF THE ISSUER. Item 5 is hereby amended and restated in its entirety as follows: (a) Percentage interest calculations for each Reporting Person are based upon the Issuer having 63,421,612 total outstanding shares of Common Stock as reported on the Issuer's 10-Q filed with the Securities and Exchange Commission on May 10, 2006. SPO The aggregate number of Shares that SPO owns beneficially, pursuant to Rule 13d-3 of the Act, is 8,297,600 Shares, which constitutes approximately 13.08% of the outstanding Shares. SPO Advisory Partners Because of its position as the sole general partner of SPO, SPO Advisory Partners may, pursuant to Rule 13d-3 of the Act, be deemed to be the beneficial owner of 8,297,600 Shares, which constitutes approximately 13.08% of the outstanding Shares.
Page 15 of 20 pages SFP The aggregate number of Shares that SFP owns beneficially, pursuant to Rule 13d-3 of the Act, is 309,400 Shares, which constitutes approximately 0.49% of the outstanding Shares. SF Advisory Partners Because of its position as the sole general partner of SFP, SF Advisory Partners may, pursuant to Rule 13d-3 of the Act, be deemed to be the beneficial owner of 309,400 Shares, which constitutes approximately 0.49% of the outstanding Shares. SPO Advisory Corp. Because of its positions as the sole general partner of each of SPO Advisory Partners and SF Advisory Partners, SPO Advisory Corp. may, pursuant to Rule 13d-3 of the Act, be deemed to be the beneficial owner of 8,607,000 Shares in the aggregate, which constitutes approximately 13.57% of the outstanding Shares. JHS Because of his position as a control person of SPO Advisory Corp., JHS may, pursuant to Rule 13d-3 of the Act, be deemed to be the beneficial owner of 8,607,000 Shares, which constitutes approximately 13.57% of the outstanding Shares. WEO Individually, and because of his positions as a control person of SPO Advisory Corp., a trustee of the Oberndorf Trust and sole general partner of OFP and as trustee for the account of his children, WEO may, pursuant to Rule 13d-3 of the Act, be deemed to be the beneficial owner of 9,050,650 Shares in the aggregate, which constitutes approximately 14.27% of the outstanding Shares. WJP Because of his position as a control person of SPO Advisory Corp., WJP may, pursuant to Rule 13d-3 of the Act, be deemed to be the beneficial owner of 8,607,000 Shares, which constitutes approximately 13.57% of the outstanding Shares. Oberndorf Trust The aggregate number of Shares that the Oberndorf Trust owns beneficially, pursuant to Rule 13d-3 of the Act, is 333,650 Shares, which constitutes approximately 0.53% of the outstanding Shares. OFP The aggregate number of Shares that OFP owns beneficially, pursuant to Rule 13d-3 of the Act, is 100,000 Shares, which constitutes approximately 0.16% of the outstanding Shares. BJW The aggregate number of Shares that BJW owns beneficially, pursuant to Rule 13d-3 of the Act, is 5,000 Shares, which constitutes approximately 0.01% of the outstanding Shares.
Page 16 of 20 pages To the best of the knowledge of each of the Reporting Persons, other than as set forth above, none of the persons named in Item 2 hereof is the beneficial owner of any Shares. (b) SPO Acting through its sole general partner, SPO has the sole power to vote or to direct the vote and to dispose or to direct the disposition of 8,297,600 Shares. SPO Advisory Partners Acting through its sole general partner and in its capacity as the sole general partner of SPO, SPO Advisory Partners has the sole power to vote or to direct the vote and to dispose or to direct the disposition of 8,297,600 Shares. SFP Acting through its sole general partner, SFP has the sole power to vote or to direct the vote and to dispose or to direct the disposition of 309,400 Shares. SF Advisory Partners Acting through its sole general partner and in its capacity as the sole general partner of SFP, SF Advisory Partners has the sole power to vote or to direct the vote and to dispose or to direct the disposition of 309,400 Shares. SPO Advisory Corp. Acting through its controlling persons and in its capacities as the sole general partner of each of SPO Advisory Partners and SF Advisory Partners, SPO Advisory Corp. has the sole power to vote or to direct the vote and to dispose or to direct the disposition of 8,607,000 Shares in the aggregate. JHS As one of three controlling persons of SPO Advisory Corp., which is the sole general partner of each of SPO Advisory Partners and SF Advisory Partners, JHS may be deemed to have shared power with WEO and WJP to vote or to direct the vote and to dispose or to direct the disposition of 8,607,000 Shares held by SPO and SFP in the aggregate. WEO As one of three controlling persons of SPO Advisory Corp., which is the sole general partner of each of SPO Advisory Partners and SF Advisory Partners, WEO may be deemed to have shared power with JHS and WJP to vote or to direct the vote and to dispose or to direct the disposition of 8,607,000 Shares held by SPO and SFP in the aggregate. WEO may be deemed to have shared power to vote or to direct the vote and to dispose or to direct the disposition of 333,650 Shares held in the Oberndorf Trust. Individually, and because of his position as the sole general partner of OFP, WEO has the sole power to vote or to direct the vote and to dispose or to direct the disposition of 100,000 Shares held by OFP. Solely in his capacity as trustee for the account of his children, WEO has the sole power to vote or to direct the vote and to dispose or to direct the disposition of 10,000 shares owned by his children. WJP As one of three controlling persons of SPO Advisory Corp., which is the sole general partner of each of SPO Advisory Partners and SF Advisory Partners, WJP may be deemed to have shared power with JHS and WEO to vote or to direct the vote and to dispose or to direct the disposition of 8,607,000 Shares held by SPO and SFP in the aggregate.
Page 17 of 20 pages Oberndorf Trust Acting through its trustees, Oberndorf Trust has the sole power to vote or to direct the vote and to dispose or to direct the disposition of 333,650 Shares in the aggregate. OFP OFP has the sole power to vote or to direct the vote and to dispose or to direct the disposition of 100,000 Shares. BJW BJW has the sole power to vote or to direct the vote and to dispose or to direct the disposition of 5,000 Shares. (c) During the past 60 days, the Reporting Persons purchased Shares in open market transactions as set forth on Schedule I attached hereto. Except as set forth in this paragraph (c), to the best of the knowledge of each of the Reporting Persons, none of the persons named in response to paragraph (a) has effected any transactions in Shares during the past 60 days. (d) Each of the Reporting Persons affirms that no person other than such Reporting Person has the right to receive or the power to direct the receipt of distributions with respect to, or the proceeds from the sale of, Shares owned by such Reporting Person. (e) Not applicable. ITEM 7. MATERIAL TO BE FILED AS EXHIBITS. Item 7 is hereby amended and restated in its entirety as follows: Exhibit A: Agreement pursuant to Rule 13d-1(k) Exhibit B: Power of Attorney
Page 18 of 20 pages SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. Dated June 19, 2006 By: /s/ Kim M. Silva -------------------------------- Kim M. Silva Attorney-in-Fact for: SPO PARTNERS II, L.P.(1) SPO ADVISORY PARTNERS, L.P.(1) SAN FRANCISCO PARTNERS II, L.P.(1) SF ADVISORY PARTNERS, L.P.(1) SPO ADVISORY CORP.(1) JOHN H. SCULLY(1) WILLIAM E. OBERNDORF(1) WILLIAM J. PATTERSON(1) WILLIAM AND SUSAN OBERNDORF TRUST, DATED 10/19/98 (1) OBERNDORF FAMILY PARTNERS (1) BETTY JANE WEIMER (2) (1) A Power of Attorney authorizing Kim M. Silva to act on behalf of this person or entity has been previously filed with the Securities and Exchange Commission. (2) A Power of Attorney authorizing Kim M. Silva to act on behalf of this person or entity is filed as Exhibit B.
Page 19 of 20 pages SCHEDULE I TO SCHEDULE 13D DATE OF PRICE PER WHERE/HOW TRANSACTION REPORTING PERSON TRANSACTION TYPE NUMBER OF SHARES SHARE ($) EFFECTED - --------------------- ----------- ---- ---------------- --------- --------------------- SPO Partners II, L.P. 6/13/06 Buy 100 31.67 Open Market/Broker SPO Partners II, L.P. 6/13/06 Buy 2,100 31.68 Open Market/Broker SPO Partners II, L.P. 6/13/06 Buy 3,500 31.68 Open Market/Broker SPO Partners II, L.P. 6/13/06 Buy 40,600 31.69 Open Market/Broker SPO Partners II, L.P. 6/13/06 Buy 107,500 31.70 Open Market/Broker SPO Partners II, L.P. 6/14/06 Buy 100 31.69 Open Market/Broker SPO Partners II, L.P. 6/14/06 Buy 71,000 31.70 Open Market/Broker SPO Partners II, L.P. 6/14/06 Buy 1,900 31.85 Open Market/Broker SPO Partners II, L.P. 6/14/06 Buy 100 31.86 Open Market/Broker SPO Partners II, L.P. 6/14/06 Buy 200 31.87 Open Market/Broker SPO Partners II, L.P. 6/14/06 Buy 500 31.88 Open Market/Broker SPO Partners II, L.P. 6/14/06 Buy 900 31.89 Open Market/Broker SPO Partners II, L.P. 6/14/06 Buy 67,700 31.90 Open Market/Broker SPO Partners II, L.P. 6/14/06 Buy 9,800 31.90 Open Market/Broker SPO Partners II, L.P. 6/15/06 Buy 343,000 32.50 Open Market/Broker
Page 20 of 20 pages EXHIBIT INDEX EXHIBIT DOCUMENT DESCRIPTION PAGE NO. - ------- ------------------------------------ -------- A Agreement Pursuant to Rule 13d-1(k) 1 B Power of Attorney 2
EXHIBIT A Pursuant to Rule 13d-1(k) of Regulation 13D-G of the General Rules and Regulations of the Securities and Exchange Commission under the Securities Exchange Act of 1934, as amended, the undersigned agrees that the statement to which this Exhibit is attached is filed on behalf of each of them in the capacities set forth below. Dated June 19, 2006 By: /s/ Kim M. Silva -------------------------------- Kim M. Silva Attorney-in-Fact for: SPO PARTNERS II, L.P.(1) SPO ADVISORY PARTNERS, L.P.(1) SAN FRANCISCO PARTNERS II, L.P.(1) SF ADVISORY PARTNERS, L.P.(1) SPO ADVISORY CORP.(1) JOHN H. SCULLY(1) WILLIAM E. OBERNDORF(1) WILLIAM J. PATTERSON(1) WILLIAM AND SUSAN OBERNDORF TRUST, DATED 10/19/98 (1) OBERNDORF FAMILY PARTNERS (1) BETTY JANE WEIMER (2) (1) A Power of Attorney authorizing Kim M. Silva to act on behalf of this person or entity has been previously filed with the Securities and Exchange Commission. (2) A Power of Attorney authorizing Kim M. Silva to act on behalf of this person or entity is filed as Exhibit B.
EXHIBIT B POWER OF ATTORNEY KNOW ALL PERSONS BY THESE PRESENTS, that Betty Jane Weimer (a "Grantor") has made, constituted and appointed, and by these presents do make, constitute and appoint, each of William E. Oberndorf and Kim M. Silva (each an "Attorney"), the true and lawful agent and attorney-in-fact, with full power of substitution and resubstitution, of the Grantor, for and in Grantor's name, place and stead, in any and all capacities, to do all or any of the following acts, matters and things: 1. To sign on behalf of the Grantor statements on Schedule 13D or 13G or Forms 3, 4 and 5, or amendments thereto pursuant to Section 13(d) or Section 16 under the Securities Exchange Act of 1934. 2. To do all such other acts and things as, in such Attorney's discretion, he or she deems appropriate or desirable for the purpose of filing such statements on Schedule 13D or 13G or Forms 3, 4 and 5, or amendments thereto. 3. To appoint in writing one or more substitutes who shall have the power to act on behalf of the Grantor as if that substitute or those substitutes shall have been originally appointed Attorney (s) by this Power of Attorney and/or to revoke any such appointment at any time without assigning any reason therefor. The Grantor hereby ratifies and confirms all that said agents and attorneys-in-fact or any substitute or substitutes may lawfully do or cause to be done by virtue hereof. This Power of Attorney shall remain in full force and effect until the undersigned is no longer required to file Forms 3, 4 and 5 or to file reports under Section 13(d) of the Securities Exchange Act of 1934 with respect to the undersigned's holdings of and transactions in securities issued by Cabot Corporation, unless earlier revoked by the undersigned in a signed writing delivered to the foregoing attorneys-in-fact. The words Grantor and Attorney shall include all grantors and attorneys under this Power of Attorney. [Signatures on the Following Pages.]IN WITNESS WHEREOF, each Grantor duly assents to this Power of Attorney by his, her or its signature as of the 19th day of June, 2006. By: /s/ Betty Jane Weimer ------------------------------ Name: Betty Jane Weimer