Exhibit 99.1 XOMA Reports Fourth Quarter and Full Year 2023 Financial Results and Highlights Recent and Upcoming Events Expected to Drive Shareholder Value Raised up to $140 million of non-dilutive non-recourse capital through a royalty-backed loan related to VABYSMO® from funds managed by Blue Owl Capital Received $15.5 million in cash payments related to our growing royalty base and the achievement of certain development milestones during 2023 Added third commercial asset to XOMA’s portfolio with the acqu ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT For the transition period from __________to__________ Commission File No. 001-39801 XOMA Corporation (Exact name of registrant as specified in its charter) Delaware 52-2154066 (State or other ju ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT For the quarterly period ended June 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT For the transition period from __________to__________ Commission File No. 001-39801 XOMA Corporation (Exact name of registrant as specified in its charter) Delaware 52-2154066 (State or other jurisdi ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT For the quarterly period ended March 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT For the transition period from __________to__________ Commission File No. 001-39801 XOMA Corporation (Exact name of registrant as specified in its charter) Delaware 52-2154066 (State or other jurisd ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 or 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number 001-39801 XOMA CORPORATION (Exact name of registrant as specified in its charter) Delaware 52-2154066 (State or other jurisdiction ...