Edgar Filing: CABOT CORP

SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
SCHEDULE 13D

Under the Securities Exchange Act of 1934
(Amendment No. 5)*

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)

January 10, 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 24 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
7,648,600 (1)
------------------------------------------------------
Number Of Shares 8. SHARED VOTING POWER
Beneficially Owned By -0-
Each Reporting Person ------------------------------------------------------
With 9. SOLE DISPOSITIVE POWER
7,648,600 (1)
------------------------------------------------------
10. SHARED DISPOSITIVE POWER
-0-
--------------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
7,648,600 (1)
--------------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
SHARES |_|
--------------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
12.16%
--------------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON
PN
--------------------------------------------------------------------------------

(1) Power is exercised through its sole general partner, SPO Advisory Partners,
L.P.

Page 3 of 24 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
7,648,600 (1)(2)
------------------------------------------------------
Number Of Shares 8. SHARED VOTING POWER
Beneficially Owned By -0-
Each Reporting Person ------------------------------------------------------
With 9. SOLE DISPOSITIVE POWER
7,648,600 (1)(2)
------------------------------------------------------
10. SHARED DISPOSITIVE POWER
-0-
--------------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
7,648,600 (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)
12.16%
--------------------------------------------------------------------------------
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 24 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 24 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 24 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
7,958,000 (1)(2)
------------------------------------------------------
Number Of Shares 8. SHARED VOTING POWER
Beneficially Owned By -0-
Each Reporting Person ------------------------------------------------------
With 9. SOLE DISPOSITIVE POWER
7,958,000 (1)(2)
------------------------------------------------------
10. SHARED DISPOSITIVE POWER
-0-
--------------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
7,958,000 (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)
12.66%
--------------------------------------------------------------------------------
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 7,648,600 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 24 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 7,958,000 (1)
Each Reporting Person ------------------------------------------------------
With 9. SOLE DISPOSITIVE POWER
-0-
------------------------------------------------------
10. SHARED DISPOSITIVE POWER
7,958,000 (1)
--------------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
7,958,000 (1)
--------------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
SHARES |_|
--------------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
12.66%
--------------------------------------------------------------------------------
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 24 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 8,352,450 (1)
Each Reporting Person ------------------------------------------------------
With 9. SOLE DISPOSITIVE POWER
-0-
------------------------------------------------------
10. SHARED DISPOSITIVE POWER
8,352,450 (1)
--------------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
8,352,450 (1)
--------------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
SHARES |_|
--------------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
13.28%
--------------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON
IN
--------------------------------------------------------------------------------

(1) Of these shares, 7,958,000 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., 327,150 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 and 67,300 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.

Page 9 of 24 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
327,150 (1)
------------------------------------------------------
Number Of Shares 8. SHARED VOTING POWER
Beneficially Owned By -0-
Each Reporting Person ------------------------------------------------------
With 9. SOLE DISPOSITIVE POWER
327,150 (1)
------------------------------------------------------
10. SHARED DISPOSITIVE POWER
-0-
--------------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
327,150 (1)
--------------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
SHARES |_|
--------------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
0.52%
--------------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON
OO
--------------------------------------------------------------------------------

(1) Power is exercised through its trustees, William E. Oberndorf and Susan C.
Oberndorf.

Page 10 of 24 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
67,300 (1)
------------------------------------------------------
Number Of Shares 8. SHARED VOTING POWER
Beneficially Owned By -0-
Each Reporting Person ------------------------------------------------------
With 9. SOLE DISPOSITIVE POWER
67,300 (1)
------------------------------------------------------
10. SHARED DISPOSITIVE POWER
-0-
--------------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
67,300 (1)
--------------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
SHARES |_|
--------------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
0.11%
--------------------------------------------------------------------------------
14. TYPE OF REPORTING PERSON
PN
--------------------------------------------------------------------------------

(1) Power is exercised through its sole general partner, William E. Oberndorf.

Page 11 of 24 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 7,958,000 (1)
Each Reporting Person ------------------------------------------------------
With 9. SOLE DISPOSITIVE POWER
-0-
------------------------------------------------------
10. SHARED DISPOSITIVE POWER
7,958,000 (1)
--------------------------------------------------------------------------------
11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
7,958,000 (1)
--------------------------------------------------------------------------------
12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
SHARES |_|
--------------------------------------------------------------------------------
13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
12.66%
--------------------------------------------------------------------------------
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 24 pages

This Amendment No. 5 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 and
November 8, 2005. 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"), and Oberndorf Family Partners, a California limited partnership
("OFP"). SPO, SPO Advisory Partners, SFP, SF Advisory Partners, SPO Advisory
Corp., JHS, WEO, WJP, the Oberndorf Trust and OFP 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 subsection titled "WEO" of Item 2(b)-(c) is hereby amended and
restated in its entirety as follows:

"WEO's business address is 591 Redwood Highway, Suite 3215, Mill
Valley, California 94941. His present principal occupation is serving as a
managing director of SPO Partners & Co. WEO is one of three controlling persons
of SPO Advisory Corp., the sole general partner of SPO Advisory Partners and SF
Advisory Partners. WEO is also a trustee for the Oberndorf Trust and the sole
general partner of OFP."

The following subsections are hereby added to Item 2(b)-(c) in
appropriate alphabetical order as follows:

"OBERNDORF TRUST

"Oberndorf Trust is a living trust, established for the benefit of WEO
and his wife, Susan C. Oberndorf. WEO and Ms. Oberndorf are the trustees of
Oberndorf Trust. The principal business address of Oberndorf Trust, which also
serves as its principal office, is 591 Redwood Highway, Suite 3215, Mill Valley,
California 94941. Pursuant to Instruction C to Schedule 13D of the Act, certain
information with respect to WEO is set forth above. Ms. Oberndorf's business
address is 591 Redwood Highway, Suite 3215, Mill Valley, California 94941. Ms.
Oberndorf's present principal occupation is homemaker.

"OFP

"OFP is a California limited partnership, the principal business of
which is the purchase, sale, exchange, acquisition and holding of investment
securities. The principal business address of OFP, which also serves as its
principal office, is 591 Redwood Highway, Suite 3215, Mill Valley, California
94941. Pursuant to Instruction C to Schedule 13D of the Act, certain information
with respect to WEO, the sole general partner of OFP, is set forth above."

Page 13 of 24 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 $246,120,865
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) $14,430,442
WJP Not Applicable Not Applicable
Oberndorf Trust Personal Funds(1) $11,998,354
OFP Contribution from Partners $ 2,432,088

----------
(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 62,883,088 total outstanding shares of Common Stock
as reported on the Issuer's 10-K filed with the Securities and Exchange
Commission on December 14, 2005.

SPO

The aggregate number of Shares that SPO owns beneficially, pursuant to
Rule 13d-3 of the Act, is 7,648,600 Shares, which constitutes approximately
12.16% 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 7,648,600 Shares, which constitutes approximately 12.16%
of the outstanding Shares.

Page 14 of 24 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 7,958,000
Shares in the aggregate, which constitutes approximately 12.66% 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
7,958,000 Shares, which constitutes approximately 12.66% 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, WEO may, pursuant to Rule 13d-3 of the Act, be deemed to be the beneficial
owner of 8,352,450 Shares in the aggregate, which constitutes approximately
13.28% 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
7,958,000 Shares, which constitutes approximately 12.66% 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 327,150 Shares, which
constitutes approximately 0.52% of the outstanding Shares.

OFP

The aggregate number of Shares that OFP owns beneficially, pursuant to
Rule 13d-3 of the Act, is 67,300 Shares, which constitutes approximately 0.11%
of the outstanding Shares.

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.

Page 15 of 24 pages

(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 7,648,600
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 7,648,600
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 7,958,000 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 7,958,000 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 7,958,000 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 327,150 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 67,300 Shares held by OFP.

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 7,958,000 Shares held by
SPO and SFP in the aggregate.

Page 16 of 24 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 327,150
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 67,300 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 17 of 24 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 January 12, 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 (2)
OBERNDORF FAMILY PARTNERS (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 18 of 24 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. 11/11/05 Buy 10,000 31.64 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 100 31.69 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 100 31.70 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 400 31.75 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 200 31.80 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 200 31.83 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 500 31.85 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 400 31.86 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 300 31.87 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 200 31.88 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 500 31.90 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 2,600 31.91 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 300 31.92 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 3,300 31.93 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 2,500 31.94 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 1,800 31.95 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 4,400 31.96 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 1,400 31.97 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 3,500 31.98 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 3,300 31.99 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 1,500 32.00 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 100 32.01 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 1,200 32.02 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 1,000 32.03 Open Market/Broker

Page 19 of 24 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. 11/11/05 Buy 200 32.04 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 1,000 32.05 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 3,500 32.06 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 5,600 32.07 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 3,900 32.08 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 900 32.09 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 9,400 32.10 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 600 32.26 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 300 32.27 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 400 32.28 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 100 32.29 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 10,900 32.30 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 900 32.31 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 600 32.32 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 600 32.33 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 600 32.34 Open Market/Broker

SPO Partners II, L.P. 11/11/05 Buy 700 32.35 Open Market/Broker

SPO Partners II, L.P. 11/18/05 Buy 4,200 33.90 Open Market/Broker

SPO Partners II, L.P. 11/18/05 Buy 100,000 34.00 Privately Negotiated
Transaction

William and Susan Oberndorf 12/20/05 Buy 600 35.32 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 100 35.34 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 1,000 35.35 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 1,400 35.36 Open Market/Broker
Trust, dated 10/19/98

Page 20 of 24 pages

SCHEDULE I TO SCHEDULE 13D

DATE OF PRICE PER WHERE/HOW TRANSACTION
REPORTING PERSON TRANSACTION TYPE NUMBER OF SHARES SHARE ($) EFFECTED
--------------------- ----------- ---- ---------------- --------- ---------------------

William and Susan Oberndorf 12/20/05 Buy 3,000 35.37 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 200 35.38 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 500 35.39 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 3,900 35.40 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 14,400 35.41 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 300 35.42 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 6,100 35.45 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 3,600 35.46 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 1,500 35.47 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 4,600 35.48 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 8,300 35.49 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/20/05 Buy 50,500 35.50 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/21/05 Buy 200 35.47 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/21/05 Buy 50 35.48 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/21/05 Buy 150 35.49 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 12/21/05 Buy 42,650 35.50 Open Market/Broker
Trust, dated 10/19/98

Page 21 of 24 pages

SCHEDULE I TO SCHEDULE 13D

DATE OF PRICE PER WHERE/HOW TRANSACTION
REPORTING PERSON TRANSACTION TYPE NUMBER OF SHARES SHARE ($) EFFECTED
--------------------- ----------- ---- ---------------- --------- ---------------------

Oberndorf Family Partners 12/21/05 Buy 200 35.47 Open Market/Broker

Oberndorf Family Partners 12/21/05 Buy 50 35.48 Open Market/Broker

Oberndorf Family Partners 12/21/05 Buy 150 35.49 Open Market/Broker

Oberndorf Family Partners 12/21/05 Buy 42,650 35.50 Open Market/Broker

William and Susan Oberndorf 1/6/06 Buy 420 37.68 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 420 37.69 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 8,579 37.70 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 3,300 37.71 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 1,079 37.72 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 2,520 37.73 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 1,559 37.74 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 32,573 37.75 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 280 37.68 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 280 37.69 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 5,721 37.70 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 2,200 37.71 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 721 37.72 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 1,680 37.73 Open Market/Broker
Trust, dated 10/19/98

Page 22 of 24 pages

SCHEDULE I TO SCHEDULE 13D

DATE OF PRICE PER WHERE/HOW TRANSACTION
REPORTING PERSON TRANSACTION TYPE NUMBER OF SHARES SHARE ($) EFFECTED
--------------------- ----------- ---- ---------------- --------- ---------------------

William and Susan Oberndorf 1/6/06 Buy 1,041 37.74 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/6/06 Buy 21,727 37.75 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/9/06 Buy 400 37.43 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/9/06 Buy 400 37.44 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/9/06 Buy 500 37.45 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/9/06 Buy 800 37.46 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/9/06 Buy 1,900 37.47 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/9/06 Buy 500 37.48 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/9/06 Buy 600 37.49 Open Market/Broker
Trust, dated 10/19/98

William and Susan Oberndorf 1/9/06 Buy 94,900 37.50 Open Market/Broker
Trust, dated 10/19/98

Oberndorf Family Partners 1/9/06 Buy 600 37.35 Open Market/Broker

Oberndorf Family Partners 1/10/06 Buy 18,450 37.20 Open Market/Broker

Oberndorf Family Partners 1/10/06 Buy 300 37.44 Open Market/Broker

Oberndorf Family Partners 1/10/06 Buy 500 37.46 Open Market/Broker

Oberndorf Family Partners 1/10/06 Buy 400 37.47 Open Market/Broker

Oberndorf Family Partners 1/10/06 Buy 600 37.48 Open Market/Broker

Oberndorf Family Partners 1/10/06 Buy 800 37.49 Open Market/Broker

Oberndorf Family Partners 1/10/06 Buy 800 37.50 Open Market/Broker

Oberndorf Family Partners 1/10/06 Buy 100 37.53 Open Market/Broker

Page 23 of 24 pages

SCHEDULE I TO SCHEDULE 13D

DATE OF PRICE PER WHERE/HOW TRANSACTION
REPORTING PERSON TRANSACTION TYPE NUMBER OF SHARES SHARE ($) EFFECTED
--------------------- ----------- ---- ---------------- --------- ---------------------

Oberndorf Family Partners 1/10/06 Buy 300 37.55 Open Market/Broker

Oberndorf Family Partners 1/10/06 Buy 300 37.57 Open Market/Broker

Oberndorf Family Partners 1/10/06 Buy 700 37.59 Open Market/Broker

Oberndorf Family Partners 1/10/06 Buy 400 37.60 Open Market/Broker

Page 24 of 24 pages

EXHIBIT INDEX

EXHIBIT DOCUMENT DESCRIPTION PAGE NO.
------- ------------------------------------ --------
A Agreement Pursuant to Rule 13d-1(k) 1

B Power of Attorney 2