Company: XOMAP
Filing Date: 2025-10-03
Form Type: 424B5
Source: 0001193125-25-230393
Chunk: 1

Company: XOMA Royalty Corp
Filing Date: 2025-10-03
Form: 424B5
Chunk 1
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1933, as amended
(the “Securities Act”). The Agent is not required to sell any specific number or dollar amount of the depositary shares, but the Agent will make all sales using commercially reasonable efforts consistent with its normal trading and sales
practices on mutually agreed terms between the Agent and us. See “Plan of Distribution” for more information.

The depositary shares to which
this prospectus supplement and the accompanying prospectus relate will be offered and sold through or to the Agent over a period of time and from time to time. Under the Sales Agreement, the Agent will be entitled to compensation of up to 3.0% of
the gross proceeds of all depositary shares sold through or to it, as sales agent or principal. In connection with the sale of the depositary shares, the Agent will be deemed to be an “underwriter” within the meaning of the Securities
Act, and the compensation of the Agent will be deemed to be underwriting commissions or discounts. There is no arrangement to place proceeds of the offering in escrow, trust or similar arrangement. See “Plan of Distribution” for more
information.

Our depositary shares are trading on the Nasdaq Global Market (“Nasdaq”) under the symbol “XOMAO.” On October 1,
2025, the last reported sale price of our depositary shares on the Nasdaq Global Market was $25.62 per share.

Investing in the depositary shares and our preferred stock involves a high degree of risk. Please read the information contained in and incorporated by reference under the heading “ Risk Factors” beginning on page S-10 of this prospectus supplement and the accompanying prospectus, and under similar headings in the other documents that are incorporated by reference into this prospectus supplement and the accompanying prospectus.

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

H.C. Wainwright & Co.

The date of this prospectus supplement is October 3, 2025.

TABLE OF CONTENTS Prospectus Supplement

|                                                            |     | Page |      |
| About This Prospectus Supplement                           |     |      | S-1  |
| Prospectus Supplement Summary                              |     |      | S-2  |
| Risk Factors                                               |     |      | S-10 |
| Special Note Regarding Forward-Looking Statements          |     |