Edgar Filing: XOMA LTD /DE/

forms_3.htm

As filed with the Securities and Exchange Commission on February 11, 2011

Registration No. 333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-3

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

XOMA Ltd.

(Exact name of registrant as specified in its charter)


Bermuda		52-2154066
(State or other jurisdiction of incorporation or organization)		(I.R.S. Employer Identification No.)

2910 Seventh Street

Berkeley, California 94710

(510) 204-7200

(Address, including zip code, and telephone number, including

area code, of registrant’s principal executive offices)

Christopher J. Margolin, Esq.

XOMA Ltd.

2910 Seventh Street

Berkeley, California 94710

(510) 204-7200

(Name, address, including zip code, and telephone number, including

area code, of agent for service)

Copy to:

Geoffrey E. Liebmann, Esq.

Cahill Gordon & Reindel LLP

80 Pine Street

New York, New York 10005

(212) 701-3000

Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this Registration Statement.

If the only securities being registered on this form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. o

If any of the securities being registered on this form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box. x

If this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

If this form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. o

If this form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. o

If this form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer o	Accelerated filer x
Non-accelerated filer o (Do not check if a smaller reporting company)	Smaller reporting company o

CALCULATION OF REGISTRATION FEE


Title of each class of securities to be registered	Amount to be registered	Proposed maximum aggregate price per unit	Proposed maximum aggregate offering price	Amount of registration fee(1)
Common Shares, par value $.0075 per share(2)	(3)	(4)	(4)
Preference Shares, par value $.05 per share	(3)	(4)	(4)
Debt Securities	(3)	(4)	(4)
Warrants	(3)	(4)	(4)
Total			$100,000,000	$11,610

(1)	Calculated pursuant to Rule 457(o) under the Securities Act.
(2)	Also relates to share purchase rights that are attached to all common shares of the registrant in accordance with the Shareholder Rights Agreement by and between the registrant and Wells Fargo Shareowner Services, dated February 26, 2003, as amended. These rights are not exercisable until the occurrence of events specified in the Rights Agreement, are evidenced by the certificates for the common shares and are transferred along with and only with the common shares. The value attributable to these rights, if any, is reflected in the value of the common shares.
(3)	There are being registered hereunder such indeterminate number of common shares and preference shares, such indeterminate principal amount of debt securities and such indeterminate number of warrants to purchase common shares, preference shares or debt securities as shall have an aggregate initial offering price not to exceed $100,000,000. If any debt securities are issued at an original issued discount, then the offering price of such debt securities shall be in such greater principal amount as shall result in an aggregate initial offering price not to exceed $100,000,000, less the aggregate dollar amount of all securities previously issued hereunder. Any securities registered hereunder may be sold separately or as units with other securities registered hereunder. The proposed maximum initial offering price per unit will be determined, from time to time, by the registrant in connection with the issuance by the registrant of the securities registered hereunder. The securities registered also include such indeterminate amounts and numbers of common shares, preference shares and debt securities as may be issued upon conversion of or exchange for preference shares or debt securities that provide for conversion or exchange, upon exercise of warrants or pursuant to the anti-dilution provisions of any such securities. In addition, pursuant to Rule 416 under the Securities Act, the shares being registered hereunder include such indeterminate number of common shares and preference shares as may be issuable with respect to the shares being registered hereunder as a result of stock splits, stock dividends or similar transactions.
(4)	The proposed maximum aggregate offering price per class of security will be determined from time to time by the registrant in connection with the issuance by the registrant of the securities registered hereunder and is not specified as to each class of security pursuant to General Instruction II.D. of Form S-3 under the Securities Act.

The registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment that specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933 or until the Registration Statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to said Section 8(a), may determine.

EXPLANATORY NOTE

This registration statement contains two prospectuses. One of these prospectuses, which we refer to as the base prospectus, covers the offering, issuance and sale from time to time, in one or more series or classes of the following securities:

·	our common shares;

·	our preference shares;

·	our debt securities, which may be senior or subordinated; and

·	warrants for the purchase of our common shares, preference shares and/or debt securities.

The specific terms of any securities to be offered pursuant to the base prospectus will be specified in a prospectus supplement.

A second prospectus, which we refer to as the MLV sales agreement prospectus, covers our common shares that we may offer, issue and sell under the At Market Issuance Sales Agreement entered into between us and McNicoll, Lewis & Vlak LLC on February 4, 2011. The MLV sales agreement prospectus will be identical to the base prospectus in all respects, except that the MLV sales agreement prospectus will contain a different cover page, plan of distribution section and legal matters section. The cover page, plan of distribution section and legal matters section to be contained in the MLV sales agreement prospectus are set forth following the base prospectus included herein.

The information in this prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting offers to buy these securities in any state where the offer or sale is not permitted.

Subject to Completion, Dated February 11, 2011

$100,000,000

Common Shares

Preference Shares

Debt Securities

Warrants

offered by

XOMA Ltd.

From time to time, we may offer up to $100,000,000 of any combination of the securities described in this prospectus.

We will provide specific terms of these offerings and securities in supplements to this prospectus. The prospectus supplement may also add, update or change information contained in this prospectus. You should read this prospectus, the information incorporated by reference in this prospectus and any prospectus supplement carefully before you invest.

Our common shares are traded on The NASDAQ Global Market under the symbol “XOMA.” On February 10, 2011, the last reported sale price of our common shares was $5.15 per share. You are urged to obtain current market quotations for our common shares. The applicable prospectus supplement will contain information, where applicable, as to any other listing on The NASDAQ Global Market or any securities market or other exchange of the securities, if any, covered by the prospectus supplement.

Investing in our securities involves a high degree of risk. See the section entitled “RISK FACTORS” contained in any supplements to this Prospectus and in our most recent Annual Report on Form 10-K and Quarterly Report on Form 10-Q, as well as any amendments thereto, as filed with the Securities and Exchange Commission, and which are incorporated herein by reference in their entirety.

This Prospectus may not be used to offer or sell any securities unless accompanied by a Prospectus Supplement.

The securities may be sold directly by us to investors, through agents designated from time to time or to or through underwriters or dealers. For additional information on the methods of sale, you should refer to the section entitled “PLAN OF DISTRIBUTION” in this prospectus. If any underwriters are involved in the sale of any securities with respect to which this prospectus is being delivered, the names of such underwriters and any applicable commissions or discounts and over-allotment options will be set forth in a prospectus supplement. The price to the public of such securities and the net proceeds we expect to receive from such sale will also be set forth in a prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

Consent under the Exchange Control Act 1972 (and its related regulations) has been obtained from the Bermuda Monetary Authority for the issue and transfer of XOMA’s shares, options, warrants, depositary receipts, rights, loan notes and other securities to and between non-residents of Bermuda for exchange control purposes provided our shares remain listed on an appointed stock exchange, which includes The NASDAQ Global Market. This prospectus may be filed with the Registrar of Companies in Bermuda in accordance with Bermuda law. In granting such consent and in accepting this prospectus for filing, neither the Bermuda Monetary Authority nor the Registrar of Companies in Bermuda accepts any responsibility for our financial soundness or the correctness of any of the statements made or opinions expressed in this prospectus.

The date of this prospectus is , 2011

TABLE OF CONTENTS


		Page
ABOUT THIS PROSPECTUS		1
ABOUT XOMA		1
RISK FACTORS		2
THE SECURITIES WE MAY OFFER		2
FORWARD-LOOKING INFORMATION		4
FINANCIAL RATIOS		5
USE OF PROCEEDS		5
DESCRIPTION OF SHARE CAPITAL		6
DESCRIPTION OF DEBT SECURITIES		10
DESCRIPTION OF WARRANTS		15
LEGAL OWNERSHIP OF SECURITIES		17
PLAN OF DISTRIBUTION		21
LEGAL MATTERS		22
EXPERTS		22
WHERE YOU CAN FIND MORE INFORMATION		22

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, or SEC, using a “shelf” registration process. Under this shelf registration process, we may sell common shares, preference shares, debt securities and warrants in one or more offerings up to a total dollar amount of $100,000,000. This prospectus provides you with a general description of the securities we may offer. Each time we sell any securities under this prospectus, we may provide a prospectus supplement that will contain more specific information about the terms of those securities. We may also add, update or change in a prospectus supplement any of the information contained in this prospectus or in documents we have incorporated by reference into this prospectus. This prospectus, together with the applicable prospectus supplements and the documents incorporated by reference into this prospectus, includes all material information relating to this offering. You should carefully read both this prospectus and the applicable prospectus supplement together with the additional information described under “WHERE YOU CAN FIND MORE INFORMATION” before buying securities in this offering. You should rely only on the information we have provided or incorporated by reference in this prospectus or any prospectus supplement. We have not authorized anyone to provide you with information different from that contained in this prospectus. No dealer, salesperson or other person is authorized to give any information or to represent anything not contained in this prospectus. You must not rely on any unauthorized information or representation. This prospectus is an offer to sell only the securities offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so. You should assume that the information in this prospectus or any prospectus supplement is accurate only as of the date on the front of the document and that any information we have incorporated by reference is accurate only as of the date of the document incorporated by reference, regardless of the time of delivery of this prospectus or any sale of a security.

ABOUT XOMA

XOMA Ltd., a Bermuda company (“XOMA” or “we”), is a leader in the discovery and development of therapeutic antibodies. XOMA discovers, develops and manufactures novel antibody therapeutics for its own proprietary pipeline as well as through license and collaborative agreements with pharmaceutical and biotechnology companies, and under its contracts with the U.S. government. XOMA’s proprietary product pipeline includes:

XOMA 052, a potent anti-IL-1 beta antibody entering Phase 3 clinical development in Behcet’s uveitis, for which it has been designated an orphan drug, and in Phase 2 clinical development for Type 2 diabetes with cardiovascular biomarkers, Type 1 diabetes, and with potential for the treatment of a wide range of inflammatory conditions. XOMA is developing XOMA 052 in collaboration with Les Laboratoires Servier.

·	XOMA 3AB, an antibody candidate in preclinical development to neutralize the botulinum toxin, among the most deadly potential bioterror threats, under development through funding provided by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health.

·	A preclinical pipeline with candidates in development for autoimmune, cardio-metabolic, inflammatory, ophthalmic and oncologic diseases.

XOMA has a premier antibody discovery and development platform that incorporates an unmatched collection of antibody phage display libraries and proprietary Human Engineering™, affinity maturation, Bacterial Cell Expression (BCE) and manufacturing technologies. BCE is a key breakthrough biotechnology for the discovery and manufacturing of antibodies and other proteins. As a result, 60 pharmaceutical and biotechnology companies have signed BCE licenses, and several licensed product candidates are in clinical development.

XOMA has a fully integrated product development infrastructure, extending from pre-clinical science to product approval at its Berkeley, California location.

RISK FACTORS

Except for the historical information contained in this prospectus or incorporated by reference, this prospectus (and the information incorporated by reference in this prospectus) contains forward-looking statements that involve risks and uncertainties. Our actual results could differ materially from those discussed here or incorporated by reference. Factors that could cause or contribute to such differences include those discussed in the section entitled “RISK FACTORS” contained in any supplements to this prospectus and in our most recent annual report on Form 10-K and quarterly reports on Form 10-Q filed with the SEC, as well as any amendments thereto reflected in subsequent filings with the SEC, which are incorporated herein by reference in their entirety.

Investment in our securities involves risks. Prior to making a decision about investing in our securities, you should consider carefully the risk factors, together with all of the other information contained or incorporated by reference in this prospectus and any prospectus supplement, including any additional specific risks described in any prospectus supplement. Each of these risk factors could adversely affect our business, operating results and financial condition, which may result in the loss of all or part of your investment.

Keep these risk factors in mind when you read forward-looking statements contained elsewhere or incorporated by reference in this prospectus and any prospectus supplement. These statements relate to our expectations about future events. Discussions containing forward-looking statements may be found, among other places, in “Business” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” incorporated by reference from our annual reports on Form 10-K and our quarterly reports on Form 10-Q, as well as any amendments thereto reflected in subsequent filings with the SEC. These forward-looking statements are based largely on our expectations and projections about future events and future trends affecting our business, and so are subject to risks and uncertainties, including the risks and uncertainties described below under “FORWARD-LOOKING INFORMATION,” that could cause actual results to differ materially from those anticipated in the forward-looking statements.

THE SECURITIES WE MAY OFFER

We may offer our common shares and preference shares, various series of debt securities and/or warrants to purchase any of such securities, with a total value of up to $100,000,000, from time to time under this prospectus at prices and on terms to be determined by market conditions at the time of offering. This prospectus provides you with a general description of the securities we may offer. Each time we offer a type or series of securities, we may provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities, including, to the extent applicable:

·	designation or classification;

·	aggregate principal amount or aggregate offering price;

·	maturity, if applicable;

·	rates and times of payment of interest or dividends, if any;

·	redemption, conversion or sinking fund terms, if any;

·	voting or other rights, if any;

·	conversion prices, if any; and

·	important federal income tax considerations.

The prospectus supplement also may add, update or change information contained in this prospectus or in documents we have incorporated by reference. However, no prospectus supplement shall offer a security that is not registered and described in this prospectus at the time of its effectiveness.

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We may sell the securities directly to or through agents, underwriters or dealers. We, and our agents or underwriters, reserve the right to accept or reject all or part of any proposed purchase of securities. If we do offer securities through agents or underwriters, we may include in the applicable prospectus supplement:

·	the names of those agents or underwriters;

·	applicable fees, discounts and commissions to be paid to them;

·	details regarding over-allotment options, if any; and

·	the net proceeds to us.

Common Shares. We may issue common shares from time to time. Holders of common shares are entitled to one vote per share on all matters submitted to a vote of shareholders. Subject to the rights of any series of preference shares issued from time to time, all actions submitted to a vote of shareholders shall be voted on by the holders of common shares, voting together as a single class (together with the Series A Preference Shares (as described below), if any), except as provided by law.

Preference Shares. We may issue preference shares from time to time, in one or more series. Our board of directors shall determine the rights, preferences, privileges and restrictions of the preference shares, including dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of any series. Convertible preference shares will be convertible into our common shares or convertible into or exchangeable for our other securities. Conversion may be mandatory or at your option and would be at prescribed conversion rates.

If we sell any series of preference shares under this prospectus and applicable prospectus supplements, we will fix the rights, preferences, privileges, qualifications and restrictions of the preference shares of such series in the resolutions creating that series. We will incorporate by reference into the registration statement of which this prospectus is a part the form of any resolutions that set out the terms of the series of preference shares we are offering before the issuance of such series of preference shares. We urge you to read the prospectus supplements related to the series of preference shares being offered, as well as the complete resolutions that set out the terms of such series of preference shares.

Debt Securities. We may offer debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. The senior debt securities will rank equally with any other unsecured and unsubordinated debt. The subordinated debt securities will be subordinate and junior in right of payment, to the extent and in the manner described in the instrument governing the debt, to all of our senior indebtedness. Convertible debt securities will be convertible into or exchangeable for our common shares or our other securities. Conversion may be mandatory or at your option and would be at prescribed conversion rates.

The debt securities will be issued under one or more documents called indentures, which are contracts between us and a to be named national banking association or other eligible party, as trustee. In this prospectus, we have summarized certain general features of the debt securities. We urge you, however, to read the prospectus supplements related to the series of debt securities being offered, as well as the complete indentures that contain the terms of the debt securities. Forms of indentures have been filed as exhibits to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part or will be incorporated by reference from reports we file with the SEC.

Warrants. We may issue warrants for the purchase of common shares, preference shares and/or debt securities in one or more series. We may issue warrants independently or together with common shares, preference shares and/or debt securities, and the warrants may be attached to or separate from these securities.

The warrants will be evidenced by warrant certificates issued under one or more warrant agreements, which are contracts between us and an agent for the holders of the warrants. In this prospectus, we have summarized certain general features of the warrants. We will incorporate by reference into the registration statement of which this prospectus is a part the form of warrant agreement, including a form of warrant certificate, that describes the terms of the series of warrants we are offering before the issuance of the related series of warrants. We urge you to read

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the prospectus supplements related to the series of warrants being offered, as well as the complete warrant agreements and warrant certificates that contain the terms of the applicable series of warrants.

FORWARD-LOOKING INFORMATION

Certain statements contained in this prospectus and the related documents incorporated by reference related to the sufficiency of our cash resources, as well as other statements related to current plans for product development and existing and potential collaborative and licensing relationships, or that otherwise relate to future periods, are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”) and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). These statements are based on assumptions that may not prove accurate. Actual results could differ materially from those anticipated due to certain risks inherent in the biotechnology industry and for companies engaged in the development of new products in a regulated market. Among other things, the period for which our cash resources are sufficient could be shortened if expenditures are made earlier or in larger amounts than anticipated or are unanticipated, if anticipated revenue or cost sharing arrangements do not materialize, or if funds are not otherwise available on acceptable terms. These and other risks, including those related to the generally unstable nature of current economic and financial market conditions; the results of discovery research and preclinical testing; the timing or results of pending and future clinical trials (including the design and progress of clinical trials; safety and efficacy of the products being tested; action, inaction or delay by the FDA, European or other regulators or their advisory bodies; and analysis or interpretation by, or submission to, these entities or others of scientific data); changes in the status of existing collaborative relationships; the ability of collaborators and other partners to meet their obligations; our ability to meet the demand of the United States government agency with which we have entered our government contracts; competition; market demands for products; scale-up and marketing capabilities; availability of additional licensing or collaboration opportunities; international operations; share price volatility; our financing needs and opportunities; uncertainties regarding the status of biotechnology patents; uncertainties as to the costs of protecting intellectual property; and risks associated with our status as a Bermuda company, are described in more detail in “RISK FACTORS” in any supplement to this prospectus. We undertake no obligation to publicly update any forward-looking statements, regardless of any new information, future events or other occurrences. We advise you, however, to consult any additional disclosures we make in our reports to the SEC on Forms 10-K, 10-Q and 8-K.

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FINANCIAL RATIOS

The following table sets forth our ratio of earnings to fixed charges and the amount of deficiency for periods in which the ratio indicates less than one-to-one coverage:


	Nine Months Ended September 30, 2010		Year Ended December 31,
			2009	2008		2007		2006		2005
Ratio of earnings to fixed charges (1)	N/A	(2)	1.9	N/A	(2)	N/A	(2)	N/A	(2)	1.5

(1)	For these purposes, earnings are defined as income before income taxes and fixed charges and fixed charges include interest expense and the portion of rental expense which is deemed to represent interest.

(2)	Earnings were insufficient to cover fixed charges by $51.0 million for the nine months ended September 30, 2010 and $45.6 million, $12.3 million, and $51.8 million for the years ended December 31, 2008, 2007 and 2006, respectively.

USE OF PROCEEDS

Unless otherwise provided in the applicable prospectus supplement, we intend to use the net proceeds from the sale of the securities under this prospectus for general corporate purposes, including research and development projects, including the development of additional indications for XOMA 052, the development or acquisition of new products or technologies, equipment acquisitions, general working capital and operating expenses.

We have not determined the amounts we plan to spend on any of the areas listed above or the timing of these expenditures. As a result, our management will have broad discretion to allocate the net proceeds from our sale of securities. We may set forth in the applicable prospectus supplement our intended use for the net proceeds received from the sale of any securities. Pending application of the net proceeds, we intend to invest the net proceeds in investment-grade, interest-bearing securities.

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DESCRIPTION OF SHARE CAPITAL

The following statements with respect to our share capital are subject to the detailed provisions of our memorandum of continuance and bye-laws. These statements do not purport to be complete and, while we believe the descriptions of the material provisions of the memorandum of continuance and bye-laws incorporated by reference are accurate statements with respect to such material provisions, such statements are subject to the detailed provisions in the memorandum of continuance and bye-laws, to which reference is hereby made for a full description of such provisions.

Common Shares

General

Our memorandum of continuance and bye-laws provide that our authorized common share capital is limited to 46,666,666 common shares, par value U.S.$.0075 per share. As of February 10, 2011, there were 29,510,963 common shares issued and outstanding.

Voting

The holders of common shares are entitled to one vote per share. Subject to the rights of any series of preference shares issued from time to time, all actions submitted to a vote of shareholders shall be voted on by the holders of common shares, voting together as a single class (together with the Series A Preference Shares (as described below) and any other shares having general voting rights, if any), except as provided by law.

Dividends

Holders of common shares are entitled to participate, on a share for share basis, with the holders of any other common shares issued and outstanding, with respect to any dividends declared by our board of directors, subject to the rights of holders of preference shares. Dividends will generally be payable in U.S. dollars. We have not paid cash dividends on the common shares. We currently do not intend to pay dividends and intend to retain any of our earnings for use in our business and the financing of our capital requirements for the foreseeable future. The payment of any future cash dividends on the common shares is necessarily dependent upon our earnings and financial needs, along with applicable legal and contractual restrictions.

Liquidation

Upon our liquidation, holders of our common shares will be entitled to receive any assets remaining after the payment of our debts and the expenses of the liquidation, subject to such special rights as may be attached to any other class of shares.

Redemption

The common shares are not subject to redemption either by us or the holders thereof.

Variation of Rights

Under our bye-laws, if at any time our share capital is divided into different classes of shares, the rights attached to any class (unless otherwise provided by the terms of the issue of the shares of that class) may be varied with the consent in writing of the holders of a majority of the issued shares of that class or with the sanction of a resolution passed by the holders of a majority of such shares at a separate general meeting.

Transfer Agent and Registrar

The transfer agent and branch registrar for our common shares is Wells Fargo Shareowner Services.

Listing on The NASDAQ Global Market

Our common shares are listed on The NASDAQ Global Market under the symbol “XOMA.”

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Preference Shares

General

Under our memorandum of continuance and bye-laws, we have the authority to issue 1,000,000 preference shares, par value U.S.$.05 per share. Of these, 210,000 preference shares have been designated Series A Preference Shares (the “Series A Preference Shares”) and 8,000 preference shares have been designated Series B Preference Shares (the “Series B Preference Shares”). Under our bye-laws, subject to the special rights attaching to any class of our shares not being varied and to any resolution approved by the holders of 75% of the issued shares entitled to vote in respect thereof, our board of directors may establish one or more classes or series of preference shares having the number of shares, designations, relative voting rights, dividend rates, liquidation and other rights, preferences and limitations that the board of directors fixes without any shareholder approval.

The following summary of terms of our preference shares is not complete. You should refer to the provisions of our memorandum of continuance and bye-laws and the resolutions containing the terms of each class or series of the preference shares which have been or will be filed with the SEC at or prior to the time of issuance of such class or series of preference shares and described in the applicable prospectus supplement. The applicable prospectus supplement may also state that any of the terms set forth herein are inapplicable to such series of preference shares, provided that the information set forth in such prospectus supplement does not constitute material changes to the information herein such that it alters the nature of the offering or the securities offered.

Issuances of preference shares are subject to the applicable rules of The NASDAQ Stock Market or other organizations on whose systems our preference shares may then be quoted or listed.

Depending upon the terms of preference shares established by our board of directors, any or all series of preference shares could have preferences over the common shares with respect to dividends and other distributions and upon our liquidation. Issuance of any such shares with voting powers, or issuance of additional common shares, would dilute the voting power of the issued and outstanding common shares.

Terms

The terms of each series of preference shares will be described in any prospectus supplement related to such series of preference shares. The board of directors in approving the creation of a series of preference shares has authority to determine, and the applicable prospectus supplement may set forth with respect to such series, the following terms, among others:

·	the number of shares constituting that series and the distinctive designation of that series;

·	the dividend rate on the shares of that series, if any, whether dividends will be cumulative and, if so, from which date or dates, and the relative rights of priority, if any, of payment of dividends on shares of that series;

·	the voting rights for shares of the series, if any, in addition to the voting rights provided by law;

the conversion or exchange privileges for shares of the series, if any (including, without limitation, conversion into common shares), and the terms and conditions of such conversion or exchange, including provisions for adjustment of the conversion or exchange rate in such events as the board will determine;

whether or not the shares of that series will be redeemable and, if so, the terms and conditions of such redemption, including the manner of selecting shares for redemption if less than all shares are to be redeemed, the date or dates upon or after which they will be redeemable, and the amount per share payable in case of redemption, which amount may vary under different conditions and at different redemption dates;

·	any sinking fund for the redemption or purchase of shares of that series and the terms and amount of such sinking fund;

the conditions and restrictions upon the creation of indebtedness of XOMA or any of our subsidiaries, upon the issue of any additional shares (including additional shares of such series or any other series) and upon the payment of dividends or the making of other distributions on, and the purchase, redemption or other acquisition by us or any of our subsidiaries of, any of our issued and outstanding shares;

·	the rights of the shares of that series in the event of our voluntary or involuntary liquidation, dissolution or winding up, and the relative rights of priority, if any, of payment of shares of that series; and

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·	any other relative participating, optional or other special rights, qualifications, limitations or restrictions of that series.

The Series A Preference Shares

There are no Series A Preference Shares issued and outstanding. Pursuant to the rights of the Series A Preference Shares, subject to the rights of holders of any shares of any series of preference shares ranking prior and superior, the holders of Series A Preference Shares are entitled to receive, when, as and if declared by our board of directors out of funds legally available for the purpose, quarterly dividends payable in cash on the first day of March, June, September and December in each year, commencing on the first dividend payment date after the first issuance of a share or fraction of a share of Series A Preference Shares, in an amount per share equal to the greater of (a) U.S.$1.00 or (b) 1,000 times the aggregate per share amount of all cash dividends, plus 1,000 times the aggregate per share amount of all non-cash dividends or other distributions, other than a dividend or bonus issue payable in common shares, declared on the common shares since the immediately preceding dividend payment date, or, with respect to the first dividend payment date, since the first issuance of Series A Preference Shares.

In addition to any other voting rights required by law, holders of Series A Preference Shares have the right to vote on all matters submitted to a vote of our shareholders with each share of Series A Preference Shares entitled to 1,000 votes. Except as otherwise provided by law, holders of Series A Preference Shares, holders of common shares and holders of any other shares having general voting rights vote together as one class on all matters submitted to a vote of our shareholders.

Unless otherwise provided in the rights attaching to a subsequently designated series of our preference shares, the Series A Preference Shares rank junior to any other series of preference shares subsequently issued as to the payment of dividends and distribution of assets on liquidation, dissolution or winding-up and rank senior to the common shares. Upon any liquidation, dissolution or winding-up of us, no distributions shall be made to holders of shares ranking junior to the Series A Preference Shares unless, prior thereto, the holders of Series A Preference Shares shall have received an amount equal to accrued and unpaid dividends and distributions, whether or not declared, to the date of such payment, plus an amount equal to the greater of (1) U.S.$100.00 per share or (2) an aggregate amount per share equal to 1,000 times the aggregate amount to be distributed per share to holders of common shares or to the holders of shares ranking on parity with the Series A Preference Shares, except distributions made ratably on the Series A Preference Shares and all other such parity shares in proportion to the total amount to which the holders of all such shares are entitled upon such liquidation, dissolution or winding-up.

If we enter into any consolidation, amalgamation, merger, combination or other transaction in which common shares are exchanged for or changed into cash, other securities and/or any other property, then any Series A Preference Shares issued and outstanding shall at the same time be similarly exchanged or changed in an amount per share equal to 1,000 times the aggregate amount of cash, securities and/or other property, as the case may be, into which or for which each common share is changed or exchanged.

The Series A Preference Shares are not redeemable.

Preference Share Purchase Rights

Our board of directors has adopted a shareholder rights agreement, or rights agreement. Pursuant to the rights agreement, we issued one preference share purchase right, or right, for each issued and outstanding common share. Each right entitles the holder to purchase from us a unit consisting of one one-thousandth of a Series A Preference Share at a cash exercise price of $30.00 per unit, subject to adjustment.

The rights are attached to all issued and outstanding common shares. The rights will separate from the common shares and will be distributed to holders of common shares upon the earliest of (i) ten business days after the first public announcement that a person or group of affiliated or associated persons (a person or group of affiliated or associated persons being referred to as an Acquiring Person) has acquired beneficial ownership of 20% or more of the common shares then issued and outstanding (the date of said announcement being referred to as the Share Acquisition Date), (ii) ten business days following the commencement of a tender offer or exchange offer that would result in a person or group of persons becoming an Acquiring Person or (iii) the declaration by our board of directors that any person is an “Adverse Person” (the earliest of such dates being referred to as the Distribution Date). For

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purposes of the rights agreement, beneficial ownership of our common shares is generally determined pursuant the applicable rules and regulations under the Exchange Act and beneficial owners of new notes or existing notes will be considered beneficial owners of the common shares into which their notes are convertible.

Our board of directors may generally declare a person to be an Adverse Person after a declaration that such person has become the beneficial owner of 10% or more of the issued and outstanding common shares and a determination that (i) such beneficial ownership by such person is intended to cause or is reasonably likely to cause us to repurchase the common shares owned by such person or to cause us to enter into other transactions not in our best long-term interests or (ii) such beneficial ownership is reasonably likely to cause a material adverse impact on our business or prospects. The rights are not exercisable until the Distribution Date and will expire on December 31, 2012, unless previously redeemed or exchanged by us.

In the event that a person becomes an Acquiring Person or our board of directors determines that a person is an Adverse Person, each holder of a right will thereafter have the right (each right being referred to as a Subscription Right) to receive upon exercise that number of units of Series A Preference Shares having a market value of two times the exercise price of the rights. In the event that, at any time following the Share Acquisition Date, (i) we consolidate with, or merge or amalgamate with and into, any person, and we are not the surviving corporation; (ii) any person consolidates or amalgamates with us, or merges or amalgamates with and into us and we are the continuing or surviving corporation of such transaction and, in connection with such transaction, all or part of the common shares are changed into or exchanged for other securities of any other person or cash or any other property, or (iii) 50% or more of our assets are sold or otherwise transferred, provision shall be made so that each holder of a right shall thereafter have the right (each right being referred to as a Merger Right) to receive, upon exercise, common shares of the acquiring company having a market value equal to two times the exercise price of the rights. Rights that are beneficially owned by an Acquiring or Adverse Person may, under certain circumstances, become null and void.

At any time after a person becomes an Acquiring Person or our board of directors determines that a person is an Adverse Person, our board of directors may exchange all or any part of the then outstanding and exercisable rights for common shares or units of Series A Preference Shares at an exchange ratio of one common share or one unit of Series A Preference Shares per right. Notwithstanding the foregoing, our board of directors generally will not be empowered to effect such exchange at any time after any person becomes the beneficial owner of 50% or more of the common shares then issued and outstanding.

The rights may be redeemed in whole, but not in part, at a price of U.S. $.001 per right by our board of directors at any time prior to the date on which a person is declared to be an Adverse Person, the tenth business day after the Share Acquisition Date, the occurrence of an event giving rise to the Merger Right or the expiration date of the rights agreement.

Prior to the earlier of the Distribution Date and the Share Acquisition Date, our board may amend the rights agreement as we deem necessary or desirable without the approval of any holders of rights or common shares. From and after the earlier of the Distribution Date and the Share Acquisition Date, the rights agreement may be amended without the approval of any holders of rights only to (i) cure an ambiguity, (ii) correct defective or inconsistent provisions, (iii) shorten or lengthen any time period in the rights agreement if directors in office prior to the acquisition of shares continue to represent a majority of the board, or (iv) change provisions as we deem necessary, but that will not adversely affect the interests of holders of the rights. Under no circumstances, however, can the rights agreement be amended to lengthen a time period relating to when the rights may be redeemed if the rights are not then redeemable.

The Series B Preference Shares

8,000 Series B Preference Shares have been designated for issuance, of which 2,959 Series B Preference Shares were issued upon conversion of the convertible subordinated loans to us made by Genentech in connection with the funding of our development costs for RAPTIVA® following the regulatory approval of RAPTIVA®. Pursuant to the rights of the Series B Preference Shares, the holders of Series B Preference Shares are not entitled to receive any dividends on the Series B Preference Shares.

The Series B Preference Shares rank senior with respect to rights on our liquidation, winding-up and dissolution to all classes of common shares. Upon any of our voluntary or involuntary liquidation, dissolution or winding-

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up, holders of Series B Preference Shares will be entitled to receive U.S. $10,000 per share of Series B Preference Shares before any distribution is made on the common shares. The holders of Series B Preference Shares have no voting rights, except as required under Bermuda law.

The holders of Series B Preference Shares have the right to convert Series B Preference Shares into common shares at a conversion price equal to approximately $116.25 per common share, subject to customary anti-dilution adjustments.

The Series B Preference Shares will be automatically converted into common shares at their then effective conversion rate immediately upon the transfer by the initial holder to any third party which is not an affiliate of such holder.

We will have the right, at any time and from time to time, to redeem any or all Series B Preference Shares for cash in an amount equal to the conversion price multiplied by the number of common shares into which each such share of Series B Preference Shares would then be convertible.

DESCRIPTION OF DEBT SECURITIES

The following description, together with the additional information we include in any applicable prospectus supplements, summarizes the material terms and provisions of the debt securities that we may offer under this prospectus. While the terms we have summarized below will apply generally to any future debt securities we may offer under this prospectus, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement. The terms of any debt securities we offer under a prospectus supplement may differ from the terms we describe below. However, no prospectus supplement shall fundamentally change the terms that are set forth in this prospectus or offer a security that is not registered and described in this prospectus at the time of its effectiveness. As of September 30, 2010, we had $13.5 million aggregate principal amount of debt outstanding. In January of 2011, we incurred 15 million euros aggregate principal amount of debt, which is secured by an interest in certain of our intellectual property rights relating to XOMA 052.

We will issue the senior debt securities under the senior indenture that we will enter into with the trustee to be named in the senior indenture. We will issue the subordinated debt securities under the subordinated indenture that we will enter into with the trustee to be named in the subordinated indenture. We have filed forms of these documents as exhibits to the registration statement which includes this prospectus. We use the term “indentures” in this prospectus to refer to both the senior indenture and the subordinated indenture.

The indentures will be qualified under the Trust Indenture Act of 1939. We use the term “debenture trustee” to refer to either the trustee under the senior indenture or the trustee under the subordinated indenture, as applicable.

The following summaries of material provisions of the senior debt securities, the subordinated debt securities and the indentures are subject to, and qualified in their entirety by reference to, all the provisions of the indenture applicable to a particular series of debt securities. We urge you to read the applicable prospectus supplements related to the debt securities that we sell under this prospectus, as well as the indenture that contains the terms of the debt securities. Except as we may otherwise indicate, the terms of the senior indenture and the subordinated indenture are identical.

General

We will describe in each prospectus supplement the following terms relating to a series of debt securities:

·	the title;

·	the principal amount being offered, and if a series, the total amount authorized and the total amount outstanding;

·	any limit on the amount that may be issued;

·	whether or not we will issue the series of debt securities in global form, the terms and who the depositary will be;

·	the maturity date;

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·	whether and under what circumstances, if any, we will pay additional amounts on any debt securities held by a person who is not a United States person for tax purposes, and whether we can redeem the debt securities if we have to pay such additional amounts;

·	the annual interest rate, which may be fixed or variable, or the method for determining the rate and the date interest will begin to accrue, the dates interest will be payable and the regular record dates for interest payment dates or the method for determining such dates;

·	whether or not the debt securities will be secured or unsecured, and the terms of any secured debt;

·	whether or not the debt securities will be convertible into or exchangeable for other of our securities, and identifying the securities into which the debt will be convertible or exchangeable and the terms of conversion;

·	the terms of the subordination of any series of subordinated debt;

·	the place where payments will be payable;

·	restrictions on transfer, sale or other assignment, if any;

·	our right, if any, to defer payment of interest and the maximum length of any such deferral period;

·	the date, if any, after which, and the price at which, we may, at our option, redeem the series of debt securities pursuant to any optional or provisional redemption provisions and the terms of those redemptions provisions;

the date, if any, on which, and the price at which we are obligated, pursuant to any mandatory sinking fund or analogous fund provisions or otherwise, to redeem, or at the holder’s option to purchase, the series of debt securities and the currency or currency unit in which the debt securities are payable;

·	whether the indenture will restrict our ability and/or the ability of our subsidiaries to:

·	incur additional indebtedness;

·	issue additional securities;

·	create liens;

·	pay dividends and make distributions in respect of our shares and the shares of our subsidiaries;

·	redeem shares;

·	place restrictions on our subsidiaries’ ability to pay dividends, make distributions or transfer assets;

·	make investments or other restricted payments;

·	sell or otherwise dispose of assets;

·	enter into sale-leaseback transactions;

·	engage in transactions with shareholders and affiliates;

·	issue or sell shares of our subsidiaries; or

·	effect an amalgamation, consolidation or merger;

·	whether the indenture will require us to maintain any interest coverage, fixed charge, cash flow-based, asset-based or other financial ratios;

·	a discussion of any material or special United States federal income tax considerations applicable to the debt securities;

·	information describing any book-entry features;

·	provisions for a sinking fund purchase or other analogous fund, if any;

·	whether the debt securities are to be offered at a price such that they will be deemed to be offered at an “original issue discount” as defined in paragraph (a) of Section 1273 of the Internal Revenue Code;

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·	the denominations in which we will issue the series of debt securities, if other than denominations of $1,000 and any integral multiple thereof; and

·	any other specific terms, preferences, rights or limitations of, or restrictions on, the debt securities, including any additional events of default or covenants provided with respect to the debt securities, and any terms that may be required by us or advisable under applicable laws or regulations.

Conversion or Exchange Rights

We will set forth in the prospectus supplement the terms on which a series of debt securities may be convertible into or exchangeable for our common shares or our other securities. We will include provisions as to whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of our common shares or other securities that the holders of the series of debt securities receive would be subject to adjustment.

Amalgamation, Consolidation, Merger or Sale

The indentures will not contain any covenant that restricts our ability to amalgamate, consolidate or merge, or sell, convey, transfer or otherwise dispose of all or substantially all of our assets. However, any successor to or acquiror of such assets must assume all of our obligations under the indentures or the debt securities, as appropriate. If the debt securities are convertible into or exchangeable for our other securities or securities of other entities, the person with whom we amalgamate, consolidate or merge or to whom we sell all of our property must make provisions for the conversion or exchange of the debt securities into securities that the holders of the debt securities would have received if they had converted the debt securities before the amalgamation, consolidation, merger or sale.

Events of Default Under the Indenture

The following are events of default under the indentures with respect to any series of debt securities that we may issue:

·	if we fail to pay interest when due and payable and our failure continues for 90 days and the time for payment has not been extended or deferred;

·	if we fail to pay the principal, premium or sinking fund payment, if any, when due and payable and the time for payment has not been extended or delayed;

if we fail to observe or perform any other covenant contained in the debt securities or the indentures, other than a covenant specifically relating to another series of debt securities, and our failure continues for 90 days after we receive notice from the debenture trustee or holders of at least 25% in aggregate principal amount of the outstanding debt securities of the applicable series; and

·	if specified events of bankruptcy, insolvency or reorganization occur.

If an event of default with respect to debt securities of any series occurs and is continuing, other than an event of default specified in the last bullet point above, the debenture trustee or the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series, by notice to us in writing, and to the debenture trustee if notice is given by such holders, may declare the unpaid principal of, premium, if any, and accrued interest, if any, due and payable immediately. If an event of default specified in the last bullet point above occurs with respect to us, the principal amount of and accrued interest, if any, of each issue of debt securities then outstanding shall be due and payable without any notice or other action on the part of the debenture trustee or any holder.

The holders of a majority in principal amount of the outstanding debt securities of an affected series may waive any default or event of default with respect to the series and its consequences, except defaults or events of default regarding payment of principal, premium, if any, or interest, unless we have cured the default or event of default in accordance with the indenture. Any waiver shall cure the default or event of default.

Subject to the terms of the indentures, if an event of default under an indenture shall occur and be continuing, the debenture trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any of the holders of the applicable series of debt securities, unless such holders have offered the debenture trustee reasonable indemnity. The holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any

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remedy available to the debenture trustee, or exercising any trust or power conferred on the debenture trustee, with respect to the debt securities of that series, provided that:

·	the direction so given by the holder is not in conflict with any law or the applicable indenture; and

·	subject to its duties under the Trust Indenture Act of 1939, the debenture trustee need not take any action that might involve it in personal liability or might be unduly prejudicial to the holders not involved in the proceeding.

A holder of the debt securities of any series will only have the right to institute a proceeding under the indentures or to appoint a receiver or trustee, or to seek other remedies if:

·	the holder has given written notice to the debenture trustee of a continuing event of default with respect to that series;

·	the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series have made written request, and such holders have offered reasonable indemnity to the debenture trustee to institute the proceeding as trustee; and

·	the debenture trustee does not institute the proceeding, and does not receive from the holders of a majority in aggregate principal amount of the outstanding debt securities of that series other conflicting directions within 90 days after the notice, request and offer.

These limitations do not apply to a suit instituted by a holder of debt securities if we default in the payment of the principal, premium, if any, or interest on, the debt securities.

We will periodically file statements with the debenture trustee regarding our compliance with specified covenants in the indentures.

Modification of Indenture; Waiver

We and the debenture trustee may change an indenture without the consent of any holders with respect to specific matters:

·	to fix any ambiguity, defect or inconsistency in the indenture;

·	to comply with the provisions described above under “Amalgamation, Consolidation, Merger or Sale”;

·	to comply with any requirements of the SEC in connection with the qualification of any indenture under the Trust Indenture Act of 1939;

·	to add to, delete from or revise the conditions, limitations, and restrictions on the authorized amount, terms, or purposes of issue, authentication and delivery of debt securities, as set forth in the indenture;

to provide for the issuance of and establish the form and terms and conditions of the debt securities of any series as provided under “General” to establish the form of any certifications required to be furnished pursuant to the terms of the indenture or any series of debt securities, or to add to the rights of the holders of any series of debt securities;

·	to evidence and provide for the acceptance of appointment hereunder by a successor trustee;

·	to provide for uncertificated debt securities and to make all appropriate changes for such purpose;

·	to add to our covenants such new covenants, restrictions, conditions or provisions for the protection of the holders, and to make the occurrence, or the occurrence and the continuance, of a default in any such additional covenants, restrictions, conditions or provisions an event of default; or

·	to change anything that does not materially adversely affect the interests of any holder of debt securities of any series.

In addition, under the indentures, the rights of holders of a series of debt securities may be changed by us and the debenture trustee with the written consent of the holders of at least a majority in aggregate principal amount of the outstanding debt securities of each series that is affected. However, we and the debenture trustee may only make the following changes with the consent of each holder of any outstanding debt securities affected:

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·	extending the fixed maturity of the series of debt securities;

·	reducing the principal amount, reducing the rate of or extending the time of payment of interest, or reducing any premium payable upon the redemption of any debt securities; or

·	reducing the percentage of debt securities, the holders of which are required to consent to any amendment, supplement, modification or waiver.

Discharge

Each indenture provides that we can elect to be discharged from our obligations with respect to one or more series of debt securities, except for specified obligations, including obligations to:

·	register the transfer or exchange of debt securities of the series;

·	replace stolen, lost or mutilated debt securities of the series;

·	maintain paying agencies;

·	hold monies for payment in trust;

·	recover excess money held by the debenture trustee;

·	compensate and indemnify the debenture trustee; and

·	appoint any successor trustee.

In order to exercise our rights to be discharged, we must deposit with the debenture trustee money or government obligations sufficient to pay all the principal of, any premium, if any, and interest on, the debt securities of the series on the dates payments are due.

Form, Exchange and Transfer

We will issue the debt securities of each series only in fully registered form without coupons and, unless we otherwise specify in the applicable prospectus supplement, in denominations of $1,000 and any integral multiple thereof. The indentures provide that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities that will be deposited with, or on behalf of, The Depository Trust Company or another depositary named by us and identified in a prospectus supplement with respect to that series. See “LEGAL OWNERSHIP OF SECURITIES” for a further description of the terms relating to any book-entry securities.

At the option of the holder, subject to the terms of the indentures and the limitations applicable to global securities described in the applicable prospectus supplement, the holder of the debt securities of any series can exchange the debt securities for other debt securities of the same series, in any authorized denomination and of like tenor and aggregate principal amount.

Subject to the terms of the indentures and the limitations applicable to global securities set forth in the applicable prospectus supplement, holders of the debt securities may present the debt securities for exchange or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed if so required by us or the security registrar, at the office of the security registrar or at the office of any transfer agent designated by us for this purpose. Unless otherwise provided in the debt securities that the holder presents for transfer or exchange, we will make no service charge for any registration of transfer or exchange, but we may require payment of any taxes or other governmental charges.

We will name in the applicable prospectus supplement the security registrar, and any transfer agent in addition to the security registrar, that we initially designate for any debt securities. We may at any time designate additional transfer agents or rescind the designation of any transfer agent or approve a change in the office through which any transfer agent acts, except that we will be required to maintain a transfer agent in each place of payment for the debt securities of each series.

If we elect to redeem the debt securities of any series, we will not be required to:

issue, register the transfer of, convert or exchange any debt securities of that series during a period beginning at the opening of business 15 days before the day of mailing of a notice of redemption of any debt securities that may be selected for redemption and ending at the close of business on the day of the mailing; or

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·	register the transfer of, convert or exchange any debt securities so selected for redemption, in whole or in part, except the unredeemed portion of any debt securities we are redeeming in part.

Information Concerning the Debenture Trustee

The debenture trustee, other than during the occurrence and continuance of an event of default under an indenture, undertakes to perform only those duties as are specifically set forth in the applicable indenture. Upon an event of default under an indenture, the debenture trustee must use the same degree of care as a prudent person would exercise or use in the conduct of his or her own affairs. Subject to this provision, the debenture trustee is under no obligation to exercise any of the powers given it by the indentures at the request of any holder of debt securities unless it is offered reasonable security and indemnity against the costs, expenses and liabilities that it might incur.

Payment and Paying Agents

Unless we otherwise indicate in the applicable prospectus supplement, we will make payment of the interest on any debt securities on any interest payment date to the person in whose name the debt securities, or one or more predecessor securities, are registered at the close of business on the regular record date for the interest.

We will pay principal of and any premium and interest on the debt securities of a particular series at the office of the paying agents designated by us, except that unless we otherwise indicate in the applicable prospectus supplement, we will make interest payments by check that we will mail to the holder or by wire transfer to certain holders. Unless we otherwise indicate in a prospectus supplement, we will designate the corporate trust office of the debenture trustee in the City of New York as our sole paying agent for payments with respect to debt securities of each series. We will name in the applicable prospectus supplement any other paying agents that we initially designate for the debt securities of a particular series. We will maintain a paying agent in each place of payment for the debt securities of a particular series.

All money we pay to a paying agent or the debenture trustee for the payment of the principal of or any premium or interest on any debt securities that remains unclaimed at the end of two years after such principal, premium or interest has become due and payable will be repaid to us, and the holder of the debt security thereafter may look only to us for payment thereof.

Governing Law

The indentures and the debt securities will be governed by and construed in accordance with the laws of the State of New York, except to the extent that the Trust Indenture Act of 1939 is applicable.

Subordination of Subordinated Debt Securities

The subordinated debt securities will be unsecured and will be subordinate and junior in priority of payment to certain of our other indebtedness to the extent described in a prospectus supplement. The subordinated indenture does not limit the amount of subordinated debt securities that we may issue. It also does not limit us from issuing any other secured or unsecured debt.

DESCRIPTION OF WARRANTS

The following description, together with the additional information we may include in any applicable prospectus supplements, summarizes the material terms and provisions of the warrants that we may offer under this prospectus and the related warrant agreements and warrant certificates. While the terms summarized below will apply generally to any warrants that we may offer, we will describe the particular terms of any series of warrants in more detail in the applicable prospectus supplement. If we indicate in the prospectus supplement, the terms of any warrants offered under that prospectus supplement may differ from the terms described below. However, no prospectus supplement shall fundamentally change the terms that are set forth in this prospectus or offer a security that is not registered and described in this prospectus at the time of its effectiveness. We will incorporate by reference into the registration statement of which this prospectus is a part the form of warrant agreement, including a form of warrant certificate, that describes the terms of the series of warrants we are offering before the issuance of the related series of

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warrants. The following summaries of material provisions of the warrants and the warrant agreements are subject to, and qualified in their entirety by reference to, all the provisions of the warrant agreement applicable to a particular series of warrants. We urge you to read the applicable prospectus supplements related to the warrants that we sell under this prospectus, as well as the complete warrant agreements that contain the terms of the warrants.

Terms

We will describe in the applicable prospectus supplement the terms of the series of warrants, including:

·	the offering price and aggregate number of warrants offered;

·	the currency for which the warrants may be purchased;

·	if applicable, the designation and terms of the securities with which the warrants are issued and the number of warrants issued with each such security or with a specified principal amount of such security;

·	if applicable, the date on and after which the warrants and the related securities will be separately transferable;

·	in the case of warrants to purchase debt securities, the principal amount of debt securities purchasable upon exercise of one warrant and the price at which, and currency in which, this principal amount of debt securities may be purchased upon such exercise;

·	in the case of warrants to purchase common shares or preference shares, the number of common shares or preference shares, as the case may be, purchasable upon the exercise of one warrant and the price at which these shares may be purchased upon such exercise;

·	the effect of any amalgamation, consolidation, merger, sale or other disposition of our business on the warrant agreements and the warrants;

·	the terms of any rights to redeem or call the warrants;

·	any provisions for changes to or adjustments in the exercise price or number of securities issuable upon exercise of the warrants;

·	the dates on which the right to exercise the warrants will commence and expire;

·	the manner in which the warrant agreements and warrants may be modified;

·	U.S. federal income tax consequences of holding or exercising the warrants;

·	the terms of the securities issuable upon exercise of the warrants; and

·	any other specific terms, preferences, rights or limitations of or restrictions on the warrants.

Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including:

·	in the case of warrants to purchase debt securities, the right to receive payments of principal of, or premium, if any, or interest on, the debt securities purchasable upon exercise or to enforce covenants in the applicable indenture; or

·	in the case of warrants to purchase common shares or preference shares, the right to receive dividends, if any, or, payments upon our liquidation, dissolution or winding up or to exercise voting rights, if any.

Exercise of Warrants

Each warrant will entitle the holder to purchase the securities that we specify in the applicable prospectus supplement at the exercise price that we describe in the applicable prospectus supplement. Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants at any time up to 5:00 P.M. New York time on the expiration date that we set forth in the applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants will become void.

Holders of the warrants may exercise the warrants by delivering the warrant certificate representing the warrants to be exercised together with specified information, and paying the required amount to the warrant agent in

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immediately available funds, as provided in the applicable prospectus supplement. We will set forth on the reverse side of the warrant certificate and in the applicable prospectus supplement the information that the holder of the warrant will be required to deliver to the warrant agent.

Upon receipt of the required payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement, we will issue and deliver the securities purchasable upon such exercise. If fewer than all of the warrants represented by the warrant certificate are exercised, then we will issue a new warrant certificate for the remaining amount of warrants. If we so indicate in the applicable prospectus supplement, holders of the warrants may surrender securities or rights to purchase securities as all or part of the exercise price for warrants.

Enforceability of Rights by Holders of Warrants

Each warrant agent will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action its right to exercise, and receive the securities purchasable upon exercise of, its warrants.

Outstanding Warrants

In June of 2009, we issued warrants to purchase common shares to certain institutional investors as part of a registered direct offering. The warrants represent the right to acquire an aggregate of up to 347,826 common shares over a five-year period beginning December 11, 2009 at an exercise price of $19.50 per share. As of September 30, 2010, all of these warrants were outstanding.

In February of 2010, we completed an underwritten offering of 2.8 million units, with each unit consisting of one common share and a warrant to purchase 0.45 of a common share. The warrants, which represent the right to acquire an aggregate of up to 1.26 million common shares, are exercisable beginning six months and one day after issuance and have a five-year term and an exercise price of $10.50 per share. As of September 30, 2010, all of these warrants were outstanding.

LEGAL OWNERSHIP OF SECURITIES

We can issue securities in registered form or in the form of one or more global securities. We describe global securities in greater detail below. We refer to those persons who have securities registered in their own names on the books that we or any applicable trustee, depositary or warrant agent maintain for this purpose as the “holders” of those securities. These persons are the legal holders of the securities. We refer to those persons who, indirectly through others, own beneficial interests in securities that are not registered in their own names, as “indirect holders” of those securities. As we discuss below, indirect holders are not legal holders, and investors in securities issued in book-entry form or in street name will be indirect holders.

Book-Entry Holders

We may issue securities in book-entry form only, as we will specify in any applicable prospectus supplement. This means securities may be represented by one or more global securities registered in the name of a financial institution that holds them as depositary on behalf of other financial institutions that participate in the depositary’s book-entry system. These participating institutions, which are referred to as participants, in turn, hold beneficial interests in the securities on behalf of themselves or their customers.

Only the person in whose name a security is registered is recognized as the holder of that security. Securities issued in global form will be registered in the name of the depositary or its participants. Consequently, for securities issued in global form, we will recognize only the depositary as the holder of the securities, and we will make all payments on the securities to the depositary. The depositary passes along the payments it receives to its participants, which in turn pass the payments along to their customers who are the beneficial owners. The depositary and its

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participants do so under agreements they have made with one another or with their customers; they are not obligated to do so under the terms of the securities.

As a result, investors in a book-entry security will not own securities directly. Instead, they will own beneficial interests in a global security, through a bank, broker or other financial institution that participates in the depositary’s book-entry system or holds an interest through a participant. As long as the securities are issued in global form, investors will be indirect holders, and not holders, of the securities.

Street Name Holders

We may terminate a global security or issue securities in non-global form. In these cases, investors may choose to hold their securities in their own names or in “street name.” Securities held by an investor in street name would be registered in the name of a bank, broker or other financial institution that the investor chooses, and the investor would hold only a beneficial interest in those securities through an account he or she maintains at that institution.

For securities held in street name, we will recognize only the intermediary banks, brokers and other financial institutions in whose names the securities are registered as the holders of those securities, and we will make all payments on those securities to them. These institutions pass along the payments they receive to their customers who are the beneficial owners, but only because they agree to do so in their customer agreements or because they are legally required to do so. Investors who hold securities in street name will be indirect holders, not holders, of those securities.

Legal Holders

Our obligations, as well as the obligations of any applicable trustee and of any third parties employed by us or a trustee, run only to the legal holders of the securities. We do not have obligations to investors who hold beneficial interests in global securities, in street name or by any other indirect means. This will be the case whether an investor chooses to be an indirect holder of a security or has no choice because we are issuing the securities only in global form.

For example, once we make a payment or give a notice to the holder, we have no further responsibility for the payment or notice even if that holder is required, under agreements with depositary participants or customers or by law, to pass it along to the indirect holders but does not do so. Similarly, we may want to obtain the approval of the holders to amend an indenture, to relieve us of the consequences of a default or of our obligation to comply with a particular provision of the indenture or for other purposes. In such an event, we would seek approval only from the holders, and not the indirect holders, of the securities. Whether and how the holders contact the indirect holders is up to the holders.

Special Considerations for Indirect Holders

If you hold securities through a bank, broker or other financial institution, either in book-entry form or in street name, you should check with your own institution to find out:

·	how it handles securities payments and notices;

·	whether it imposes fees or charges;

·	how it would handle a request for the holders’ consent, if ever required;

·	whether and how you can instruct it to send you securities registered in your own name so you can be a holder, if that is permitted in the future;

·	how it would exercise rights under the securities if there were a default or other event triggering the need for holders to act to protect their interests; and

·	if the securities are in book-entry form, how the depositary’s rules and procedures will affect these matters.

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Global Securities

A global security is a security that represents one or any other number of individual securities held by a depositary. Generally, all securities represented by the same global securities will have the same terms.

Each security issued in book-entry form will be represented by a global security that we deposit with and register in the name of a financial institution or its nominee that we select. The financial institution that we select for this purpose is called the depositary. Unless we specify otherwise in any applicable prospectus supplement, The Depository Trust Company, New York, New York, known as DTC, will be the depositary for all securities issued in book-entry form.

A global security may not be transferred to or registered in the name of anyone other than the depositary, its nominee or a successor depositary, unless special termination situations arise. We describe those situations below under “Special Situations When a Global Security Will Be Terminated.” As a result of these arrangements, the depositary, or its nominee, will be the sole registered owner and holder of all securities represented by a global security, and investors will be permitted to own only beneficial interests in a global security. Beneficial interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account with the depositary or with another institution that does. Thus, an investor whose security is represented by a global security will not be a holder of the security, but only an indirect holder of a beneficial interest in the global security.

If the prospectus supplement for a particular security indicates that the security will be issued in global form only, then the security will be represented by a global security at all times unless and until the global security is terminated. If termination occurs, we may issue the securities through another book-entry clearing system or decide that the securities may no longer be held through any book-entry clearing system.

Special Considerations for Global Securities

As an indirect holder, an investor’s rights relating to a global security will be governed by the account rules of the investor’s financial institution and of the depositary, as well as general laws relating to securities transfers. We do not recognize an indirect holder as a holder of securities and instead deal only with the depositary that holds the global security.

If securities are issued only in the form of a global security, an investor should be aware of the following:

·	An investor cannot cause the securities to be registered in his or her name, and cannot obtain non-global certificates for his or her interest in the securities, except in the special situations we describe below;

·	An investor will be an indirect holder and must look to his or her own bank or broker for payments on the securities and protection of his or her legal rights relating to the securities, as we describe above;

·	An investor may not be able to sell interests in the securities to some insurance companies and to other institutions that are required by law to own their securities in non-book-entry form;

·	An investor may not be able to pledge his or her interest in a global security in circumstances where certificates representing the securities must be delivered to the lender or other beneficiary of the pledge in order for the pledge to be effective;

The depositary’s policies, which may change from time to time, will govern payments, transfers, exchanges and other matters relating to an investor’s interest in a global security. We and any applicable trustee have no responsibility for any aspect of the depositary’s actions or for its records of ownership interests in a global security. We and the trustee also do not supervise the depositary in any way;

·	The depositary may, and we understand that DTC will, require that those who purchase and sell interests in a global security within its book-entry system use immediately available funds, and your broker or bank may require you to do so as well; and

Financial institutions that participate in the depositary’s book-entry system, and through which an investor holds its interest in a global security, may also have their own policies affecting payments, notices and other matters relating to the securities. There may be more than one financial intermediary in the chain of ownership for an investor. We do not monitor and are not responsible for the actions of any of those intermediaries.

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Special Situations When a Global Security Will Be Terminated

In a few special situations described below, the global security will terminate and interests in it will be exchanged for physical certificates representing those interests. After that exchange, the choice of whether to hold securities directly or in street name will be up to the investor. Investors must consult their own banks or brokers to find out how to have their interests in securities transferred to their own name, so that they will be direct holders. We have described the rights of holders and street name investors above.

The global security will terminate when the following special situations occur:

·	if the depositary notifies us that it is unwilling, unable or no longer qualified to continue as depositary for that global security and we do not appoint another institution to act as depositary within 90 days;

·	if we notify any applicable trustee that we wish to terminate that global security; or

·	if an event of default has occurred with regard to securities represented by that global security and has not been cured or waived.

Any prospectus supplement may also list additional situations for terminating a global security that would apply only to the particular series of securities covered by the prospectus supplement. When a global security terminates, the depositary, and not we or any applicable trustee, is responsible for deciding the names of the institutions that will be the initial direct holders.

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PLAN OF DISTRIBUTION

We may sell the securities through underwriters or dealers, through agents, or directly to one or more purchasers. A prospectus supplement or supplements will describe the terms of the offering of the securities, including:

·	the name or names of any underwriters, if any;

·	the purchase price of the securities and the proceeds we will receive from the sale;

·	any over-allotment options under which underwriters may purchase additional securities from us;

·	any agency fees or underwriting discounts and other items constituting agents’ or underwriters’ compensation;

·	any public offering price;

·	any discounts or concessions allowed or reallowed or paid to dealers; and

·	any securities exchange or market on which the securities may be listed.

If underwriters are used in the sale, they will acquire the securities for their own account and may resell the securities from time to time in one or more transactions at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the securities will be subject to the conditions set forth in the applicable underwriting agreement. We may offer the securities to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. Subject to certain conditions, the underwriters will be obligated to purchase all of the securities offered by the prospectus supplement. Any public offering price and any discounts or concessions allowed or reallowed or paid to dealers may change from time to time. We may use underwriters with whom we have a material relationship. We will describe in the prospectus supplement, naming the underwriter, the nature of any such relationship.

We may sell securities directly or through agents we designate from time to time. We will name any agent involved in the offering and sale of securities and we will describe any commissions we will pay the agent in the prospectus supplement. Unless the prospectus supplement states otherwise, our agent will act on a best-efforts basis for the period of its appointment.

We may authorize agents or underwriters to solicit offers by certain types of institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. We will describe the conditions to these contracts and the commissions we must pay for solicitation of these contracts in the prospectus supplement.

We may provide agents and underwriters with indemnification against civil liabilities related to this offering, including liabilities under the Securities Act, or contribution with respect to payments that the agents or underwriters may make with respect to these liabilities. Agents and underwriters may engage in transactions with, or perform services for, us in the ordinary course of business.

All securities we offer, other than common shares, will be new issues of securities with no established trading market. Any underwriters may make a market in these securities, but will not be obligated to do so and may discontinue any market making at any time without notice. We cannot guarantee the liquidity of the trading markets for any securities.

Any underwriter may engage in overallotment, stabilizing transactions, short covering transactions and penalty bids in accordance with Regulation M under the Exchange Act. Overallotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions permit bids to purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum. Short covering transactions involve purchases of the securities in the open market after the distribution is completed to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the securities originally sold by the dealer are purchased in a covering transaction to cover short positions. Those activities may cause the price of the securities to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of the activities at any time.

In compliance with the guidelines of the Financial Industry Regulatory Authority, or FINRA, the maximum consideration or discount to be received by any FINRA member or independent broker dealer may not exceed 8% of the aggregate amount of securities offered pursuant to this prospectus and any supplemental prospectus.

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We may offer rights to our existing shareholders to purchase additional common shares of ours. For any particular subscription rights, the applicable prospectus supplement will describe the terms of such rights, including the period during which such rights may be exercised, the manner of exercising such rights, the transferability of such rights and the number of common shares that may be purchased in connection with each right and the subscription price for the purchase of such common shares. In connection with a rights offering, we may enter into a separate agreement with one or more underwriters or standby purchasers to purchase any of our common shares not subscribed for in the rights offering by existing shareholders, which will be described in the applicable prospectus supplement.

LEGAL MATTERS

Certain matters under Bermuda law with respect to the validity of the securities being offered hereby will be passed upon by Conyers Dill & Pearman Limited, located in Hamilton, Bermuda. Certain matters under New York and U.S. federal law with respect to the validity of the securities being offered hereby will be passed upon by Cahill Gordon & Reindel LLP , located in New York, New York.

EXPERTS

Ernst & Young LLP, independent registered public accounting firm, has audited our consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2009, as set forth in their report, which is incorporated by reference in this prospectus and elsewhere in the registration statement. Our financial statements are incorporated by reference in reliance on Ernst & Young LLP’s report, given on their authority as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

We file reports, proxy statements, and other information with the SEC. The public may read and copy any materials filed by us at the SEC’s Public Reference Room at 100 F Street, N.E., Washington, D.C. 20549 or on the Internet site maintained by the SEC at http://www.sec.gov. Please call the SEC at 1-800-SEC-0330 for further information on the Public Reference Room. Our common shares are listed on The NASDAQ Global Market, and these reports, proxy statements, and other information are also available for inspection at the offices of The NASDAQ Stock Market.

This prospectus is part of a registration statement filed by us with the SEC. The full registration statement can be obtained from the SEC, as indicated above, or from us.

The SEC allows us to “incorporate by reference” the information we file with the SEC. This permits us to disclose important information to you by referring to these filed documents. Any information referred to in this way is considered part of this prospectus. We incorporate by reference the following documents that have been filed with the SEC (other than information furnished under Item 2.02 or Item 7.01 of Form 8-K and all exhibits related to such items):

our annual report on Form 10-K for the year ended December 31, 2009, the amendment to annual report on Form 10-K for the year ended December 31, 2009 filed on April 30, 2010 and the amendment to annual report on Form 10-K for the year ended December 31, 2009 filed on December 27, 2010 (file no. 0-14710);

·	our quarterly reports on Form 10-Q for the quarterly periods ended March 31, 2010, June 30, 2010 and September 30, 2010 and the amendment to quarterly report on Form 10-Q for the quarterly period ended September 30, 2010 filed on November 12, 2010 (file no. 0-14710);

our current reports on Form 8-K filed on February 2, 2010, March 2, 2010, May 28, 2010, July 21, 2010, July 23, 2010, August 3, 2010, August 6, 2010, August 18, 2010, September 2, 2010, October 26, 2010, November 15, 2010, December 29, 2010, January 4, 2011, January 7, 2011 and January 11, 2011 and current reports on Form 8-K/A filed on February 3, 2010, June 21, 2010, July 26, 2010; and

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·	the description of share capital in the registration statement on Form 8-A filed April 1, 2003 under Section 12 of the Exchange Act, including any amendment or report for the purpose of updating such description (file no. 0-14710).

Any information in any of the foregoing documents will automatically be deemed to be modified or superseded to the extent that information in this prospectus or in a later filed document that is incorporated or deemed to be incorporated herein by reference modifies or replaces such information.

We also incorporate by reference any future filings (other than current reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items) made with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, until we file a post-effective amendment which indicates the termination of the offering of the securities made by this prospectus. Information in such future filings updates and supplements the information provided in this prospectus. Any statements in any such future filings will automatically be deemed to modify and supersede any information in any document we previously filed with the SEC that is incorporated or deemed to be incorporated herein by reference to the extent that statements in the later filed document modify or replace such earlier statements.

You may request a copy of these filings, at no cost, by writing or telephoning us at the following address:

XOMA Ltd.

2910 Seventh Street

Berkeley, California 94710

(510) 204-7200

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Subject to Completion, Dated February 11, 2011

$100,000,000

XOMA Ltd.

Common Shares

This prospectus relates to the issuance and sale of our common shares from time to time through our sales agent, McNicoll, Lewis & Vlak LLC. These sales, if any, will be made pursuant to the terms of an At Market Issuance Sales Agreement entered into between us and our sales agent, the form of which was filed with the Securities and Exchange Commission with the registration statement of which this prospectus forms a part . Our sales agreement with McNicoll, Lewis & Vlak LLC is limited to the sale of up to a number of common shares not to exceed the amount that can be sold under the registration statement of which this prospectus forms a part, which amount, as of the date of this prospectus, is approximately $100.0 million.

Our common shares are quoted on The NASDAQ Global Market under the symbol “XOMA.” On February 10, 2011, the last reported sale price of our common shares on The NASDAQ Global Market was $5.15 per share. Sales of shares of our common shares under this prospectus, if any, may be made by any method permitted by law deemed to be an “at the market” offering as defined in Rule 415 under the Securities Act of 1933, as amended, which includes sales made directly on The NASDAQ Global Market, on any other existing trading market for our common shares or to or through a market maker, or in privately negotiated transactions, subject to our approval. The sales agent will make all sales using commercially reasonable efforts consistent with its normal trading and sales practices, on mutually agreeable terms between the sales agent and us. There is no arrangement for funds to be received in any escrow, trust, or similar arrangement.

Unless we and our sales agent otherwise agree, the commission to the sales agent for sales of common shares sold pursuant to the sales agreement will be 3% of the gross proceeds of the sales price per share. If different than 3%, the amount of any compensation to be received by the sales agent will be disclosed in a separate prospectus supplement for such shares. The net proceeds to us that we receive from sales of our common shares will depend on the number of shares actually sold and the offering price for such shares.

In connection with the sale of common shares on our behalf, the sales agent may be deemed an “underwriter” within the meaning of the Securities Act of 1933, as amended, and the compensation of the sales agent may be deemed to be underwriting commissions or discounts. We have agreed to provide indemnification and contribution to the sales agent against certain liabilities, including liabilities under the Securities Act of 1933.

Investing in our common shares involves a high degree of risk. Before buying any shares, you should read the discussion of material risks of investing in our common shares in the section entitled “RISK FACTORS” in this prospectus and the additional risk factors contained in our most recent Annual Report on Form 10-K and Quarterly Reports on Form 10-Q, as well as any amendments thereto, as filed with the Securities and Exchange Commission.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of the prospectus is , 2011.

PLAN OF DISTRIBUTION

We have entered into an At Market Issuance Sales Agreement with McNicoll, Lewis & Vlak LLC, under which we may sell common shares from time to time through McNicoll, Lewis & Vlak LLC, as our agent for the offer and sale of the common shares, in an aggregate amount not to exceed the amount that can be sold under the registration statement of which this prospectus forms a part, which amount, as of the date of this prospectus, is approximately $100.0 million. McNicoll, Lewis & Vlak LLC may sell the common shares by any method permitted by law deemed to be an “at the market” offering as defined in Rule 415 of the Securities Act, including without limitation sales made directly on The NASDAQ Global Market, on any other existing trading market for the common shares or to or through a market maker. McNicoll, Lewis & Vlak LLC may also sell the common shares in privately negotiated transactions, subject to our prior approval.

Each time that we wish to issue and sell common shares under the sales agreement, we will provide McNicoll, Lewis & Vlak LLC with a placement notice describing the number of shares to be issued, the time period during which sales are requested to be made, any limitation on the number of common shares that may be sold in any one day and any minimum price below which sales may not be made.

Upon receipt of a placement notice from us, and subject to the terms and conditions of the sales agreement, McNicoll, Lewis & Vlak LLC has agreed to use its commercially reasonable efforts consistent with its normal trading and sales practices to sell such shares up to the amount specified on such terms. Unless otherwise specified, the settlement between us and McNicoll, Lewis & Vlak LLC of our common shares will occur on the third trading day following the date on which the sale was made. The obligation of McNicoll, Lewis & Vlak LLC under the sales agreement to sell our common shares pursuant to a placement notice is subject to a number of conditions. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

We will pay McNicoll, Lewis & Vlak LLC a commission equal to 3% of the gross proceeds of the sales price of all common shares sold through it as sales agent under the sales agreement. Because there is no minimum offering amount required as a condition to closing this offering, the actual total public offering amount, commissions and proceeds to us, if any, are not determinable at this time. We estimate that the total expenses for the offering, excluding compensation payable to McNicoll, Lewis & Vlak LLC under the terms of the sales agreement, will be approximately $245,000.

In connection with the sale of our common shares contemplated in this prospectus, McNicoll, Lewis & Vlak LLC may be deemed to be an “underwriter” within the meaning of the Securities Act of 1933, as amended, and the compensation paid to McNicoll, Lewis & Vlak LLC may be deemed to be underwriting commissions or discounts. We have agreed to indemnify McNicoll, Lewis & Vlak LLC against certain civil liabilities, including liabilities under the Securities Act of 1933.

Sales of our common shares as contemplated in this prospectus will be settled through the facilities of The Depository Trust Company or by such other means as we and McNicoll, Lewis & Vlak LLC may agree upon.

The offering of our common shares pursuant to the sales agreement will terminate on the earliest of (1) the sale of all of our common shares subject to the sales agreement, or (2) termination of the sales agreement by us or McNicoll, Lewis & Vlak LLC. We and McNicoll, Lewis & Vlak LLC may each terminate the sales agreement at any time upon 60 days prior notice. McNicoll, Lewis & Vlak LLC may terminate the sales agreement at any time in certain circumstances, including the occurrence of a material adverse change that, in the sales agent’s reasonable judgment, may impair its ability to sell our common shares or a suspension or limitation of trading of our common shares on The NASDAQ Global Market.

This summary of the material provisions of the sales agreement does not purport to be a complete statement of its terms and conditions. A copy of the sales agreement was filed with the SEC with the registration statement of which this prospectus forms a part.

McNicoll, Lewis & Vlak LLC has no relationship with us other than its current role as a sales agent for our current and previous at-the-market offerings of common shares.

LEGAL MATTERS

Certain matters under Bermuda law with respect to the validity of the securities being offered hereby will be passed upon by Conyers Dill & Pearman Limited, located in Hamilton, Bermuda. Certain matters under New York and U.S. federal law will be passed upon by Cahill Gordon & Reindel LLP , located in New York, New York. McNicoll, Lewis & Vlak LLC is being represented in connection with this offering by DLA Piper LLP (US), New York, New York.

PART II

INFORMATION NOT REQUIRED IN THE PROSPECTUS

Item 14.

Other Expenses of Issuance and Distribution

The following table sets forth the estimated costs and expenses, other than underwriting discounts and commissions, payable by the registrant in connection with the offering of the securities being registered. All the amounts shown are estimates, except for the SEC registration fee.


SEC registration fee	$	11,610
Accounting fees and expenses		200,000
Legal fees and expenses		165,000
Printing and miscellaneous expenses		48,390
Total	$	425,000

Item 15.

Indemnification of Officers and Directors

Under Bermuda law, a company is permitted to indemnify any officer or director, out of the funds of the company, against (i) any liability incurred by him or her in defending any proceedings, whether civil or criminal, in which judgment is given in his or her favor, or in which he or she is acquitted, or in which relief from liability is granted to him or her by the court pursuant to the Companies Act 1981 of Bermuda and (ii) any loss or liability resulting from negligence, default, breach of duty or breach of trust, save for his or her fraud or dishonesty.

The bye-laws of XOMA provide for the indemnity by XOMA of the officers, directors and employees of XOMA to the fullest extent permitted by law.

XOMA’s bye-laws also provide that expenses (including attorneys’ fees) incurred by an officer or director of XOMA in defending any civil, criminal, administrative or investigative action, suit or proceeding shall be paid by XOMA in advance of the final disposition of such action, suit or proceeding upon receipt of an undertaking by or on behalf of such director or officer to repay such amount if it shall ultimately be determined that he is not entitled to be indemnified by XOMA pursuant to the Companies Act 1981 of Bermuda.

XOMA’s bye-laws also provide that an officer or director of XOMA shall not be personally liable to XOMA or its shareholders for monetary damages for any breach of fiduciary duty as a director or officer, except to the extent that such limitation is prohibited by the Companies Act 1981 of Bermuda.

The indemnification and advancement of expenses and the limitation of liability provided by XOMA’s bye-laws shall not be deemed exclusive of any other rights which any officer, director or employee, as such, may have or hereafter acquire under the Companies Act 1981 of Bermuda, any other provision of the bye-laws, or any agreement or otherwise. Any repeal or modification of the aforementioned provisions of XOMA’s bye-laws shall not adversely affect any right or protection existing at the time of such repeal or modification.

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Item 16.

Exhibits and Financial Statement Schedules

See the Index to Exhibits immediately following the signature pages hereto.


Item 17.		Undertakings

(a) The undersigned registrant hereby undertakes:

(1) To file, during any period during which offers or sales are being made, a post-effective amendment to this registration statement:

(i) To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;

(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or any decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low end or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than 20% change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement;

(iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

provided, however, that paragraphs (a)(1)(i), (a)(1)(ii) and (a)(1)(iii) of this section do not apply if the registration statement is on Form S-3, Form S-8 or Form F-3, and the information required to be included in a post-effective amendment by those paragraphs is contained in periodic reports filed with or furnished to the Commission by the registrant pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in this Registration Statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of this Registration Statement.

(2) That, for purposes of determining liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities to be offered therein, and the offering of such securities at that time shall be deemed to be an initial bona fide offering thereof.

(3) To remove from registration by means of a post-effective amendment any of the securities being registered which shall remain unsold at the termination of the offering.

(4) That, for the purpose of determining liability under the Securities Act of 1933 to any purchaser:

(i) Each prospectus filed by the registrant pursuant to Rule 424(b)(3)shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

(ii) Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5), or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii), or (x) for the purpose of providing the information required by section 10(a) of the Securities Act of 1933 shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering

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of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date.

(5) That, for the purpose of determining liability of the registrant under the Securities Act of 1933 to any purchaser in the initial distribution of the securities: The undersigned registrant undertakes that in a primary offering of securities of the undersigned registrant pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

(i) Any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424;

(ii) Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;

(iii) The portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by or on behalf of the undersigned registrant; and

(iv) Any other communication that is an offer in the offering made by the undersigned registrant to the purchaser.

(b) The undersigned hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the registrant’s annual report pursuant to section 13(a) or section 15(d) of the Exchange Act of 1934 that is incorporated by reference in this Registration Statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(c) The undersigned registrant hereby undertakes to supplement the prospectus, after the expiration of the subscription period, to set forth the results of the subscription offer, the transactions by the underwriters during the subscription period, the amount of unsubscribed securities to be purchased by the underwriters, and the terms of any subsequent reoffering thereof. If any public offering by the underwriters is to be made on terms differing from those set forth on the cover page of the prospectus, a post-effective amendment will be filed to set forth the terms of such offering.

(d) Insofar as indemnification for liabilities arising under the Securities Act may be permitted to directors, officers and controlling persons of the registrant pursuant to provisions described in Item 15, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

(e) The undersigned hereby undertakes to file an application for the purpose of determining the eligibility of the trustee to act under subsection (a) of Section 310 of the Trust Indenture Act (the “Act”) in accordance with the rules and regulations prescribed by the Securities and Exchange Commission under Section 305(b)(2) of the Act.

II-3

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized in the City of Berkeley, State of California, on February 11, 2011.

XOMA LTD.

By: /s/ Steven B. Engle

Name: Steven B. Engle

Title: Chairman of the Board, Chief Executive

Officer and President

II-4

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Steven B. Engle and Christopher J. Margolin, and each of them, as his true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution, for him and in his name, place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) and supplements to this registration statement, and to file the same, with the United States Securities and Exchange Commission and the Bermuda Registrar of Companies, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or any of them, or their or his substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed below by the following persons in the capacities and on the dates indicated.

Signature	Title	Date
/s/ Steven B. Engle Steven B. Engle	Chairman of the Board, Chief Executive Officer and President (Principal Executive Officer)	February 11, 2011
/s/ Patrick J. Scannon Patrick J. Scannon M.D., Ph.D.	Executive Vice President and Chief Medical Officer and Director	February 11, 2011
/s/ Fred Kurland Fred Kurland	Vice President, Finance and Chief Financial Officer (Principal Financial and Accounting Officer)	February 11, 2011
/s/ W. Denman Van Ness W. Denman Van Ness	Lead Independent Director	February 11, 2011
/s/ William K. Bowes, Jr. William K. Bowes, Jr.	Director	February 11, 2011
/s/ Charles J. Fisher, Jr. Charles J. Fisher, Jr., M.D.	Director	February 11, 2011
/s/ Peter Barton Hutt Peter Barton Hutt	Director	February 11, 2011
/s/ John Varian John Varian	Director	February 11, 2011
/s/ Timothy P. Walbert Timothy P. Walbert	Director	February 11, 2011
/s/ Jack L. Wyszomierski Jack L. Wyszomierski	Director	February 11, 2011

II-5

INDEX TO EXHIBITS


Exhibit Number		Description

1.1		Form of underwriting agreement (1)

1.2		At Market Issuance Sales Agreement dated February 4, 2011 between XOMA Ltd. and McNicoll, Lewis & Vlak LLC

3.1		Memorandum of Continuance of XOMA Ltd. (Exhibit 3.4) (2)

3.2		Bye-Laws of XOMA Ltd. (as amended) (Exhibit 3.2) (3)

4.1		Shareholder Rights Agreement dated as of February 26, 2003 by and between XOMA Ltd. and Mellon Investor Services LLC as Rights Agent (Exhibit 4.1) (3)

4.2		Resolution Regarding Preferences and Rights of Series A Preference Shares (Exhibit 4.2) (3)

4.3		Resolution Regarding Preferences and Rights of Series B Preference Shares (Exhibit 3) (4)

4.4		Form of Warrant (February 2010 Warrants) (Exhibit 10.2) (5)

4.5		Form of Amended and Restated Warrant (June 2009 Warrants) (Exhibit 10.6) (5)

4.6		Form of Senior Debt Indenture between XOMA Ltd. and one or more trustees to be named

4.6A		Form of Senior Note (1)

4.7		Form of Subordinated Debt Indenture between XOMA Ltd. and one or more trustees to be named

4.7A		Form of Subordinated Note (1)

4.8		Form of Common Share Warrant Agreement and Warrant Certificate (1)

4.9		Form of Preference Share Warrant Agreement and Warrant Certificate (1)

4.10		Form of Debt Securities Warrant Agreement and Warrant Certificate (1)

5.1		Legal Opinion of Conyers Dill & Pearman Limited

5.2		Legal Opinion of Cahill Gordon & Reindel LLP

12.1		Statements Regarding Computation of Ratio of Earnings to Fixed Charges

23.1		Consent of Independent Registered Public Accounting Firm

23.2		Consent of Conyers Dill & Pearman Limited (included in Exhibit 5.1)

23.3		Consent of Cahill Gordon & Reindel LLP (included in Exhibit 5.2)

24.1		Power of Attorney (set forth on the signature page hereto)

25.1		Form T-1 Statement of Eligibility of Trustee (1)

____________________

(1)	To be filed by amendment or as an exhibit to a report pursuant to Section 13(a), 13(c) or 15(d) of the Exchange Act.

(2)	Incorporated by reference to the referenced exhibit to XOMA’s Registration Statement on Form S-4 filed November 27, 1998, as amended.

(3)	Incorporated by reference to the referenced exhibit to XOMA’s Annual Report on Form 10-K for the fiscal year ended December 31, 2002 filed March 14, 2003.

(4)	Incorporated by reference to the referenced exhibit to XOMA’s Amendment No. 1 to Current Report on Form 8-K/A filed April 18, 2003.

(5)	Incorporated by reference to the referenced exhibit to XOMA’s Current Report on Form 8-K filed February 2, 2010.