Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
BAKER JULIAN
  2. Issuer Name and Ticker or Trading Symbol
XOMA Corp [XOMA]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)
667 MADISON AVENUE, 21ST FLOOR
3. Date of Earliest Transaction (Month/Day/Year)
10/29/2012
(Street)

NEW YORK, NY US 10065
4. If Amendment, Date 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
(City)
(State)
(Zip)
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 10/29/2012   P   336,639 (1) A $ 3 1,922,230 I See Footnotes (2) (5) (6)
Common Stock 10/29/2012   P   4,282,419 (1) A $ 3 17,888,512 I See Footnotes (3) (5) (6)
Common Stock 10/29/2012   P   103,608 (1) A $ 3 463,839 I See Footnotes (4) (5) (6)
Common Stock               16,800 I See Footnote (7)

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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 Underlying Securities
(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 of Derivative Security: 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

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
BAKER JULIAN
667 MADISON AVENUE, 21ST FLOOR
NEW YORK, NY US 10065
  X   X    
BAKER BROS ADVISORS LLC
667 MADISON AVENUE 21ST FLOOR
NEW YORK, NY US 10065
  X   X    
667, L.P.
667 MADISON AVENUE 21ST FLOOR
NEW YORK, NY US 10065
  X   X    
Baker Brothers Life Sciences LP
667 MADISON AVENUE, 21ST FLOOR
NEW YORK, NY US 10065
  X   X    
14159, L.P.
667 MADISION AVENUE, 21ST FLOOR
NEW YORK, NY US 10065
  X   X    
BAKER FELIX
667 MADISON AVENUE, 21ST FLOOR
NEW YORK, NY US 10065
  X   X    

Signatures

 /s/ Julian C. Baker   10/31/2012
**Signature of Reporting Person Date

 BAKER BROS. ADVISORS, LLC Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing   10/31/2012
**Signature of Reporting Person Date

 Baker Bros. Advisors, LLC, Mgmt. Co. and Inv. Adviser to 667, L.P., pursuant to authority granted by Baker Biotech Capital, L.P., GP to 667, L.P. Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing   10/31/2012
**Signature of Reporting Person Date

 Baker Bros. Advisors, LLC, Mgmt. Co. and Inv. Adviser to BAKER BROTHERS LIFE SCIENCES, L.P. (   10/31/2012
**Signature of Reporting Person Date

 Baker Bros. Advisors, LLC, Mgmt. Co. and Inv. Adviser to 14159, L.P., pursuant to authority granted by 14159 Capital, L.P., GP to 14159, L.P. Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing   10/31/2012
**Signature of Reporting Person Date

Explanation of Responses:

* 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).
(1) On October 29, 2012, Baker Brothers Life Sciences, L.P. ("BBLS"), 14159, L.P. ("14159"), and 667, L.P. ("667", and together with BBLS and 14159, the "Funds") purchased 4,282,419, 103,608 and 336,639 shares of Xoma Corporation (the "Issuer"), respectively, pursuant to an underwritten public offering.
(2) After giving effect to the transaction reported herein, and as a result of their ownership interest in Baker Biotech Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of common stock reported in column 5 of Table I directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.
(3) After giving effect to the transaction reported herein, and as a result of their ownership interest in Baker Brothers Life Sciences Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of common stock reported in column 5 of Table I directly held by BBLS, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from BBLS.
(4) After giving effect to the transaction reported herein, and as a result of their ownership interest in 14159 Capital (GP), LLC, Julian C. Baker and Felix J. Baker may be deemed to have an indirect pecuniary interest in the Issuer's shares of common stock reported in Column 5 of Table I directly held by 14159, a limited partnership of which the sole general partner is 14159 Capital, L.P., a limited partnership of which the sole general partner is 14159 Capital (GP), LLC, due to 14159 Capital, L.P.'s right to receive an allocation of a portion of the profits from 14159.
(5) The aggregate beneficial ownership reported on this form is 20,291,381 shares of common stock.
(6) Baker Bros. Advisors, LLC (the "Adviser") serves as the Investment Adviser to the Funds. In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Julian C. Baker and Felix J. Baker are principals of the Adviser. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds. Julian C. Baker, Felix J. Baker and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that Julian C. Baker, Felix J. Baker and/or the Adviser are beneficial owners of such securities for purposes of Section 16 or any other purpose.
(7) Reflects Restricted Stock Units payable in common stock, which are scheduled to vest in substantially equal installments annually over three years beginning on August 14, 2013. The Restricted Stock Units were granted to Kelvin Neu, a Managing Director of the Adviser, as compensation for Mr. Neu's service on the Issuer's Board of Directors. Under the limited parnership agreements of the Funds, Mr. Neu is deemed to hold the Restricted Stock Units solely for the benefit of the Funds and the Funds may be deemed to be beneficial owners of the Restricted Stock Units.
 
Remarks:
Kelvin Neu, a Managing Director of Baker Bros. Advisors, LLC, is a director of Xoma Corporation ("the Issuer"). By virtue of their representation on the Board of Directors of the Issuer, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, the reporting persons are deemed directors by deputization of the Issuer.

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