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corporate PRESENTATION January 2020 NASDAQ: XOMA A Royalty Aggregation Company Exhibit 99.1

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DISCLAIMERS Certain statements in this presentation are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, including statements regarding: future potential monetization opportunities, active transactions with significant financial implications, collaborations poised for significant financial contribution, our library of potentially value-generating assets, future potential for milestone and royalty payments, the potential of our antibody discovery engine, potential out-licensing of our internal compounds and products, the ability of our partners and their licensees to successfully develop their pipeline programs, the productivity of acquired assets, our revenue forecasts, upcoming internal milestones and value catalysts, our future cash needs, our strategy for value creation, and other statements that relate to future periods. These statements are not guarantees of future performance and undue reliance should not be placed on them. They are based on assumptions that may not prove accurate, and 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. Potential risks to XOMA meeting these expectations are described in more detail in XOMA's most recent filing on Form 10-K and in other SEC filings. Consider such risks carefully when considering XOMA's prospects. Any forward-looking statements represent XOMA’s views only as of the date of this presentation and should not be relied upon as representing its views as of any subsequent date. XOMA disclaims any obligation to update any forward-looking statement, except as required by law. NOTE: All references to “portfolio” in this presentation are to milestone and/or royalty rights associated with a basket of drug products in development. All references to “assets” in this presentation are to milestone and/or royalty rights associated with individual drug product candidates in development.

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Acquire pre-commercial drug royalties Use portfolio approach to expand number of royalty positions Differentiate by focusing on development-stage assets with blockbuster potential licensed to large-cap partners Provide exposure, through royalties, to the upside potential of biotech Capital-efficient model where R&D costs are borne by partners Cash inflows from interim milestone payments Exposure risk mitigated through portfolio effects Expected value appreciation driven by: Advancement of assets by partners who spend hundreds of millions of dollars to develop XOMA royalty assets Acquisition of additional assets by XOMA to expand revenue potential and further mitigate risk Portfolio of 65+ assets in >30 disclosed indications today and growing XOMA SNAPSHOT

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XOMA’s Value Proposition Typical Small/ Mid-Cap Biotech PORTFOLIO SIZE 1 - 3 assets 65+ assets PORTFOLIO FOCUS Narrow Diversified PROBABILITY OF AN APPROVAL Low High RISK : RETURN High : High Low : Mid / High CAPITAL User Provider

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Basics of a royalty monetization TRANSACTION BIOTECH BIG PHARMA Capital Royalties & Milestones Royalties & Milestones STEP 1: Program Licensed STEP 2:

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Royalty Financings can Help Companies Raise Capital More Efficiently than Equity and is Less Onerous than Debt Equity Debt Royalty Financing Cost of Capital High Medium to High Low to Medium Dilution High Low NA Covenants/Restrictions Medium High Low Transaction Cost High Medium to High Low Control High Low to Medium NA Diligence/Disruption High Medium to High Low Collateral N/A All Assets Limited to Royalty Asset(s) Equity Royalty Financing Debt COST OF CAPITAL

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236 1,988 343 194 1,215 Biotech & Pharma License Transactions consist of: Milestone payments Royalty obligations Companies’ funding needs increase over time Bloomberg data PHASE 3 Licensing Deals: PHASE 2 Licensing Deals: PHASE 1 Licensing Deals: Preclinical/other Licensing Deals: Opportunities Abound for Royalty Monetization Total Industry Licensing Deals ’14-’18

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PRECLINICAL PHASE 1 PHASE 2 PHASE 3 APPROVAL COMMERCIAL > $100M $25M – $100M < $25M Capital per transaction Ligand Royalty Pharma HCRP XOMA is Positioned to Monetize Royalties on MID- TO EARLY-STAGE CLINICAL ASSETS

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THE BENEFITS TO ASSET SELLERS: Recognize value of non-dilutive, non-recourse financing Ability to monetize license- economics of mid-stage clinical assets Immediate cash infusion to advance high-priority internal programs to improve human health Acquire milestone and royalty rights to high-potential, fully funded assets Focus on mid-stage clinical assets Ever-increasing pipeline of potential opportunities Team focused on acquiring new royalty assets XOMA ACQUISITION STRATEGY IS DISTINCT

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KEY ATTRIBUTES OF XOMA TARGET ASSETS PRE-COMMERCIAL THERAPEUTIC ASSETS Therapeutic area agnostic LONG DURATION OF MARKET EXCLUSIVITY Patent expiration or regulatory exclusivity HIGH REVENUE POTENTIAL High unmet need or clear clinical benefit over alternatives STRONG DEVELOPER/MARKETER Assets partnered with high-quality pharma / biopharma companies Rx

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XOMA-AGENUS TRANSACTION Total  XOMA Investment: $15M 7 33% 10% 100% of Future Milestones​ Assets with Large-Cap Partners of Agenus’ Royalty Interest Immuno- Oncology Focus

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XOMA-ARONORA TRANSACTION Total  XOMA Investment: $9M 2 OF 5 100% 10% 100% of Future Milestones​ Assets with Large-Cap Partner of Aronora’s Royalty Interest Anti-Thrombotic Focus

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XOMA-PALOBIOFARMA TRANSACTION Total  XOMA Investment: $10M 1 OF 6 100% 1st 100% Diversification into Oral Compounds Assets with Large-Cap Partner Adenosine Receptor-Focused Clinical-Stage Assets

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XOMA PORTFOLIO PROFILE 65+ assets and growing > 60% of assets in clinical-stage development Many with blockbuster revenue potential TYPICAL XOMA ECONOMICS Development & Sales milestones Average royalty rate: ~2.5% Royalty term: 8 – 12 years post commercialization MEASURING XOMA’S INTRINSIC VALUE TODAY FULLY FUNDED PROGRAMS

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Preclinical PHASE 1 Phase 1/2 Phase 2 Phase 3 BLA filing 1 Total Future Development  Expenses by XOMA: $0 42 Assets with Large-Cap Partners 15 6 20 10 10+ XOMA’S PORTFOLIO: 65+ PARTNERED PROGRAMS

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EXAMPLES OF CONDITIONS & DISEASES XOMA PARTNERS ARE PURSUING Lupus Nephritis Thromboembolism Squamous Cell Carcinoma Systemic Lupus Erythematosus End Stage Renal Disease Pancreatic Cancer Kidney Transplant Metastatic Solid Tumors Anti-Botulism Liver Transplant Prostate Cancer Asthma Hidradenitis Suppurativa Urothelial Cancer Ulcerative Colitis Type 1 Diabetes Acute Myeloid Leukemia Non-muscle Invasive Bladder Cancer Sjogren’s Syndrome Colorectal Cancer Advanced Solid Tumors Graves' Disease Gastroesophageal Cancer Generalized Myasthenia Gravis Moderate to Severe Myasthenia Gravis Renal Cancer Rheumatoid Arthritis Non-Hodgkin Lymphoma Congenital hyperinsulinism Triple-negative Breast Cancer Multiple Myeloma Non-small Cell Lung Cancer

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XOMA’S PORTFOLIO: KEY HIGHLIGHTS (Does not include all assets, including certain assets subject to confidentiality agreements) PARTNER ASSET NAME TARGET ROYALTY RATE Bayer BAY1213790 Factor XIa Low single-digit Bayer BAY1831865 Factor XI Low single-digit Bayer/Aronora AB023 (xisomab 3G3) Factor XI Low single-digit Incyte INCAGN1876 GITR Mid-single-digit Incyte INCAGN1949 OX-40 Mid-single-digit Incyte INCAGN02390 TIM-3 Low to mid-single-digit Incyte INCAGN2385 LAG-3 Low to mid-single-digit Janssen Biotech JNJ-64407564 GPRC5D 0.75% Janssen Biotech JNJ-63723283 PD-1 0.75% Janssen Biotech JNJ-55920839 IFN 0.75% Janssen Biotech JNJ-63709178 CD123xCD3 0.75% Janssen Biotech JNJ-63898081 PSMA 0.75% Janssen Biotech JNJ-64232025 CD154 0.75% Merck MK-4830 ILT-4 Low single-digit Novartis CFZ533 (iscalimab) CD-40 Mid-single-digit to low-teens Novartis VPM087 (gevokizumab) IL-1ß High single-digit to mid-teens Novartis NIS793 TGFß Mid-single digit to low teens Novartis NIR178 adenosine A2A Low single-digit Takeda TAK-079 CD-38 4% Takeda (Molecular Templates) TAK-169 CD-38 4% PARTNER ASSET NAME TARGET ROYALTY RATE Adhera PRESTALIA ACE inhibitor and Ca channel blocker Up to double digit Alligator Bioscience (Janssen) JNJ-64457107 CD40 0.75% Aronora AB002 (ProCase) E-WE thrombin Low single-digit Aronora AB054 Factor XII Low single-digit AVEO ficlatuzumab Anti-HGF Low single-digit Compugen COM902 TIGIT Low single-digit Margaux Biologics XOMA 629 BPI Low to mid-single-digit Monopar (Formerly Tactic & Attenuon) MNPR-101 uPAR antibody None Ology XOMA 3AB, XOMA B, and XOMA E toxin serotypes Botulism 15% Palobiofarma PBF-680 adenosine A1 Low single-digit Palobiofarma PBF-677 adenosine A3 Low single-digit Palobiofarma PBF-999 adenosine A2A / Phosphodiesterase 10 (PDE-10) Low single-digit Palobiofarma PBF-1129 adenosine A2B Low single-digit Palobiofarma PBF-1650 adenosine A3 Low single-digit Rezolute RZ358 INSR High single-digit to mid-teens Rezolute AB101 Insulin Low single-digit Rezolute RZ402 Kallikrein Inhibitor Low single-digit Sesen (Formerly Eleven Bio & Viventia) Vicinium EpCAM antigens 2.50% > $1 billion in potential milestones

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Reference: Marin-Acevedo, J.A., Dholaria, B., Soyano, A.E. et al. Next generation of immune checkpoint therapy in cancer: new developments and challenges. J Hematol Oncol 11, 39 (2018) XOMA’s current royalty portfolio covers Capturing Immuno-Oncology’s Next Wave of the next generation of emerging and novel I-O targets >90%

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Eric Hughes, MD, Global Head Immunology, Hepatology and Dermatology Development Unit, Novartis “A pipeline in a product.”

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ASSETS BY PROJECTED PEAK SALES POTENTIAL XOMA’S SIGNIFICANT ROYALTY REVENUE POTENTIAL Example: If a partnered product were to achieve $1B in annual sales, and XOMA held a 3% royalty on that product, XOMA would receive $30M annual royalty revenue plus any interim revenue from development & regulatory milestones Royalty Rate at Projected Peak Sales < $500M $500M - $1B ≥ $1B < 2.5% 20+ 15 11 2.5% - 7.5% 4 4 8 7.5% - 15% 1 1 3 9 of 25+ with large-cap partners 13 of 20 with large-cap partners 18 of 22 with large-cap partners

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Increased number of royalty licenses by 40% since 3Q18 Acquired milestone & royalty interests in: 2 Bayer assets & 1 Bayer option & 2 unpartnered assets from Aronora 1 Novartis asset & 5 unpartnered assets from Palobiofarma Future assets from 2 technology platform companies Added 9 Janssen Biotech assets to royalty interest portfolio Received >$10M in milestones during 2019 Completed $22M Rights Offering; backstopped by BVF Partners Novartis Oncology clinical studies with gevokizumab started Iscalimab (CFZ533) data presentations - American Transplant Congress, European College of Rheumatology, 2019 R&D Day Multiple Phase 2 trials initiated with iscalimab Sesen Bio & Vicinium Positive top-line Phase 3 data on Vicinium – Jan ’19 Pre-BLA Meeting Outcomes: FDA recommends accelerated approval pathway; no additional trial required Rolling BLA initiated Dec ’19 Takeda TAK-079 & TAK-169 Data presentations at American Society of Hematology (ASH) Annual Meeting 2019 RECENT HIGHLIGHTS OPERATIONAL PARTNERS & PARTNERED ASSETS

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Looking ahead Acquire additional milestone and royalty interest assets to continue to grow the portfolio Maintain lean cost infrastructure and financial discipline Current balance sheet sufficient to fund operations for multiple years ~$1M per month core G&A expense OPERATIONAL NOVARTIS Iscalimab data readouts – 5 Phase 2 studies NOVARTIS TGFβ advancing to Phase 2 NOVARTIS Gevokizumab advancing to Phase 2 MERCK MK-4830 advancing to Phase 2 TAKEDA TAK-079 advancing to Phase 2 SESEN BIO Completed BLA Filing / PDUFA date PARTNERS & PARTNERED ASSETS

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XOMA holds 65+ current assets; pharmaceutical partners fund research & development and cover 100% of costs  XOMA sources royalty rights through deep industry network XOMA constructs an increasingly diverse and expanding portfolio to increase odds of success and mitigate binary risk XOMA has low-cost infrastructure; future potential revenues largely fall to bottom line Why XOMA’s portfolio IS valuable