Company: OXY-WT
Filing Date: 2025-07-28
Form Type: 424B2
Source: 0001628280-25-036238
Chunk: 0

Company: OCCIDENTAL PETROLEUM CORP /DE/
Filing Date: 2025-07-28
Form: 424B2
Chunk 0
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#### Filed Pursuant to Rule 424(b)(2)

#### Registration No. 333-288999

#### Prospectus Supplement
(To Prospectus dated July 28, 2025)

#### 31,990,880 Shares

#### Common Stock
This prospectus supplement relates to the issuance and sale of up to 31,990,880 shares of its common stock, par value $0.20 per share (the “Common Stock”), by Occidental Petroleum Corporation (“Occidental”) upon the exercise of warrants issued by Occidental on August 3, 2020 (each, a “Warrant” and, collectively, the “Warrants”).

Our Common Stock is listed on the New York Stock Exchange (“NYSE”) under the symbol “OXY.” On July 28, 2025, the last reported sale price of our Common Stock on the NYSE was $45.55 per share.

The Warrants may be exercised at any time in accordance with their terms until August 3, 2027, which is seven years after the date of the original issuance. Each Warrant entitles the holder to purchase from us one share of our Common Stock at an initial exercise price of $22.00 per share. The Warrants have been issued by Occidental pursuant to a warrant agreement, dated July 24, 2020, between Occidental and Equiniti Trust Company, LLC, as Warrant Agent (the “Warrant Agreement”). The Warrants are listed on the NYSE under the symbol “OXY WS.”

Occidental will receive proceeds from the exercise of the Warrants. See “ Use of Proceeds ” in this prospectus supplement.

Investing in our Common Stock involves risks. Please read “

#### Risk Factors
” in this prospectus supplement and in the accompanying prospectus and other information included or incorporated by reference into this prospectus supplement and the accompanying prospectus.

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

<div align='center'>The date of this prospectus supplement is July 28, 2025.</div>

### TABLE OF CONTENTS

#### Prospectus Supplement
|                                     |     | Page  |
| ABOUT THIS PROSPECTUS SUPPLEMENT    |     | S-ii  |
| FORWARD-LOOKING STATEMENTS