The Selling Stockholder (as defined herein) is offering 29,560,619 shares of common stock, par value $0.20 per share (“common stock”), of Occidental Petroleum Corporation. We will not receive any of the proceeds of the sale of common stock being sold in this offering.

Occidental Petroleum Corporation common stock is traded on the New York Stock Exchange (“NYSE”) under the trading symbol “OXY.” On August 12, 2024, the last reported sale price of our common stock on the NYSE was $58.98 per share.

Investing in our common stock involves risks. See “Risk Factors” beginning on page S-3 of this prospectus supplement and on page 7 of the accompanying prospectus and other information included or incorporated by reference into this prospectus supplement and the accompanying prospectus.

In this prospectus supplement, if there is only one underwriter, the term “underwriters” shall mean either the singular or plural as the context requires.

The underwriters have agreed to purchase the shares of our common stock from the Selling Stockholder at a price of $58.15 per share, which will result in approximately $1.719 billion of proceeds to the Selling Stockholder before expenses. The underwriters may offer the shares of our common stock from time to time for sale in one or more transactions on the NYSE, in the over-the-counter market, through negotiated transactions or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or at negotiated prices. See “Underwriting” beginning on page S-8 for a description of the compensation payable to the underwriters.

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

The underwriters expect to deliver the shares to purchasers on or about August 14, 2024.

This document has two parts, a prospectus supplement and an accompanying prospectus dated August 2, 2024. This prospectus supplement and the accompanying prospectus are part of a registration statement on Form S-3 that we filed with the SEC utilizing a “shelf” registration process. Under this shelf registration process, the Selling Stockholder named in a prospectus supplement may, from time to time, offer and sell our common stock in one or more offerings or resales.

The accompanying prospectus provides you with a general description of our common stock, which the Selling Stockholder may offer pursuant to this prospectus supplement. This prospectus supplement, which describes certain matters relating to us and the specific terms of this offering of shares of our common stock, adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference herein and therein. Any statement that we make in the accompanying prospectus will be deemed modified or superseded by any inconsistent statement made by us in this prospectus supplement.

You should rely only on the information contained in or incorporated by reference into this prospectus supplement and the accompanying prospectus and any applicable free writing prospectuses. Neither we, the Selling Stockholder, nor the underwriters have authorized any person to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. This prospectus supplement, the accompanying prospectus and any applicable free writing prospectus do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the securities described in this prospectus supplement or an offer to sell or the solicitation of an offer to buy those securities in any circumstances or jurisdiction in which such offer or solicitation is unlawful. The information contained in this prospectus supplement and the accompanying prospectus is accurate only as of the respective dates on the front covers of this prospectus supplement and the accompanying prospectus, the information contained in any related free writing prospectus will be accurate only as of the date of that document, and the information contained in any document incorporated by reference into this prospectus supplement is accurate only as of the date of such document. Our business, financial condition, results of operations and prospects may have changed since those respective dates.

For investors outside the United States: neither we, the Selling Stockholder, nor the underwriters have done anything that would permit this offering or possession or distribution of this prospectus supplement and the accompanying prospectus in any jurisdiction where action for that purpose is required, other than in the United States. You are required to inform yourselves about and to observe any restrictions relating to this offering and the distribution of this prospectus supplement and the accompanying prospectus outside of the United States.

Unless otherwise expressly stated or the context otherwise requires, references to “dollars,” “$” and other similar references in this prospectus supplement, the accompanying prospectus and any related free writing prospectuses are to U.S. dollars. Unless otherwise expressly stated or the context otherwise requires, the words “Occidental,” “we,” “us” and “our” as used in this prospectus supplement refer to Occidental Petroleum Corporation and its subsidiaries.

This prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein and therein contain forward-looking statements that involve risks and uncertainties that could materially affect expected results of operations, liquidity, cash flows and business prospects. Actual outcomes or results may differ from anticipated results, sometimes materially. Forward-looking and other statements regarding our sustainability efforts and aspirations are not an indication that these statements are necessarily material to investors or require disclosure in our filings with the SEC. In addition, historical, current and forward-looking sustainability-related statements may be based on standards for measuring progress that are still developing, internal controls and processes that continue to evolve and assumptions that are subject to change in the future, including future rulemaking. Factors that could cause results to differ from those projected or assumed in any forward-looking statement include, but are not limited to:

Words such as “estimate,” “project,” “predict,” “will,” “would,” “should,” “could,” “may,” “might,” “anticipate,” “plan,” “intend,” “believe,” “expect,” “aim,” “goal,” “target,” “objective,” “commit,” “advance,” “likely” or similar expressions that convey the prospective nature of events or outcomes are generally indicative of forward-looking statements. You should not place undue reliance on these forward-looking statements, which speak only as of the date of this prospectus supplement or, in the case of documents incorporated by reference, as of the date of those documents. Unless legally required, we do not undertake any obligation to update, modify or withdraw any forward-looking statements as a result of new information, future events or otherwise. Material risks that may affect our results of operations and financial position appear under the heading “Risk Factors” and elsewhere in this prospectus supplement, the accompanying prospectus and our most recent Annual Report on Form 10-K, which is incorporated herein by reference, as well as in any of our subsequently-filed quarterly or current reports that are incorporated by reference in this prospectus supplement and the accompanying prospectus.

Investing in our common stock involves risks. Before you invest in our common stock, you should carefully consider the following risk factors, in addition to the other information contained or incorporated by reference in this prospectus supplement and the accompanying prospectus. Specifically, please see “Risk Factors” included in our Annual Report on Form 10-K for the year ended December 31, 2023, as such risks may be updated or supplemented in this prospectus supplement, and the other information in that and the other reports that we file with the SEC that are incorporated by reference in this prospectus supplement or the accompanying prospectus for a discussion of risk factors that may affect the business.

The market price of our common stock could vary significantly as a result of a number of factors, some of which are beyond our control. In the event of a drop in the market price of our common stock, you could lose a substantial part or all of your investment in our common stock. Among others, the following factors could affect our stock price:

The stock markets in general have experienced extreme volatility that has often been unrelated to the operating performance of particular companies. These broad market fluctuations may adversely affect the trading price of our common stock. Securities class action litigation has often been instituted against companies following periods of volatility in the overall market and in the market price of a company’s securities. Such litigation, if instituted against us, could result in substantial costs, divert our management’s attention and resources, and have a material adverse effect on our business, financial condition, results of operations and cash flows.

Our amended and restated certificate of incorporation authorizes our board of directors to issue new series of preferred stock without stockholder approval. Depending on the rights and terms of any new series created, and the reaction of the market to the series, your rights or the value of your common stock could be negatively affected. For example, subject to applicable law, our board of directors could create a series of preferred stock with preferential rights to dividends or assets upon liquidation, or with superior voting rights to our existing common stock. The ability of our board of directors to issue these new series of preferred stock could also prevent or delay a third party from acquiring us, even if doing so would be beneficial to our stockholders.

In addition, we are subject to the anti-takeover provisions of Section 203 of the Delaware General Corporation Law (the “DGCL”), which prohibits Delaware corporations from engaging in certain business combinations with an interested stockholder (generally, a 15% or greater stockholder) for a period of three years after the date of the transaction in which the person first becomes an interested stockholder, unless:

The application of Section 203 of the DGCL could have the effect of delaying or preventing a change of control of us.

Sales of substantial amounts of our common stock in the public market following this offering, or the perception that these sales could occur, could cause the market price of our common stock to decline. These sales, or the possibility that these sales may occur, also might make it more difficult for us to sell equity securities in the future at a time and at a price that we deem appropriate.

The trading market for our common stock depends in part on the research and reports that securities or industry analysts may publish about us or our business. If one or more of the analysts that covers our common stock downgrades our stock or publishes misleading or unfavorable research about our business, our stock price would likely decline. If one or more of the analysts ceases coverage of our common stock or fails to publish reports on us regularly, demand for our common stock could decrease, which could cause our common stock price or trading volume to decline.

The Selling Stockholder will receive the proceeds from the sale of shares of our common stock pursuant to this prospectus supplement. We will not receive any proceeds from the sale of these shares of common stock. We will generally bear the costs associated with the sale of the shares in this offering by the Selling Stockholder, other than underwriting discounts and commissions. See “Underwriting” and “Selling Stockholder.”

The following table sets forth information as of July 31, 2024 with respect to the beneficial ownership of our common stock by the Selling Stockholder as well as the number of shares of common stock that may be sold by the Selling Stockholder under this prospectus supplement.

In connection with the closing of the CrownRock Acquisition, we and the Selling Stockholder entered into a registration rights agreement, dated as of August 1, 2024 (the “Registration Rights Agreement”). Under the Registration Rights Agreement, the Selling Stockholder has certain underwritten offering demand rights and piggyback registration rights with respect to certain offerings conducted by Occidental for its own account or other Occidental shareholders.

The amounts and percentages of shares beneficially owned are reported on the basis of regulations of the SEC governing the determination of beneficial ownership of securities. Under SEC rules, a person is deemed to be a “beneficial owner” of a security if that person has or shares voting power or investment power, which includes the power to dispose of or to direct the disposition of such security. A person is also deemed to be a beneficial owner of any securities of which that person has a right to acquire beneficial ownership within 60 days. Securities that can be so acquired are deemed to be outstanding for purposes of computing such person’s ownership percentage, but not for purposes of computing any other person’s percentage. Under these rules, more than one person may be deemed to be a beneficial owner of the same securities, and a person may be deemed to be a beneficial owner of securities as to which such person has no economic interest.

Subject to the dividend rights of the holders of any outstanding series of preferred stock, the holders of shares of common stock will be entitled to receive dividends when, as and if declared by our board of directors. We will pay those dividends either in cash, shares of common stock, or otherwise, at the rate and on the date or dates as declared by our board of directors. Accruals of dividends on our common stock will not bear interest. As a Delaware corporation, we are subject to statutory limitations on the declaration and payment of dividends. On July 25, 2024, our board of directors declared a dividend of $0.22 per share of common stock. The dividend will be paid on October 15, 2024 to holders of record of our common stock on September 10, 2024. See the section of the accompanying prospectus captioned “Description of Capital Stock” beginning on page 9 for a detailed description of our capital stock.

J.P. Morgan Securities LLC, Morgan Stanley & Co. LLC and RBC Capital Markets, LLC are underwriters for this offering. The term “underwriters” shall mean either the singular or plural as context requires. Subject to the terms and conditions set forth in an underwriting agreement among us, the Selling Stockholder and the underwriters, the Selling Stockholder has agreed to sell to the underwriters, and the underwriters have agreed to purchase from the Selling Stockholder, 29,560,619 shares of common stock (the “shares”).

Subject to the terms and conditions set forth in the underwriting agreement, the underwriters have agreed to purchase all of the shares sold under the underwriting agreement if any of these shares are purchased. If the underwriters default, the underwriting agreement provides that the underwriting agreement may be terminated.

We and the Selling Stockholder have agreed to indemnify the underwriters against certain liabilities, including liabilities under the Securities Act of 1933, as amended (the “Securities Act”), or to contribute to payments the underwriters may be required to make in respect of those liabilities.

The underwriters are offering the shares, subject to prior sale, when, as and if accepted by them, subject to approval of legal matters by their counsel, including the validity of the shares, and other conditions contained in the underwriting agreement, such as the receipt by the underwriters of officer’s certificates and legal opinions. The underwriters reserve the right to withdraw, cancel or modify offers to the public and to reject orders in whole or in part.

The underwriters have agreed to purchase the shares from the Selling Stockholder at a price of $58.15 per share, which will result in approximately $1.719 billion of proceeds to the Selling Stockholder before expenses. The underwriters propose to offer the shares from time to time for sale in one or more transactions on the NYSE, in the over-the-counter market, through negotiated transactions or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or at negotiated prices. The underwriters may effect such transactions by selling the shares to or through dealers, and such dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters and/or purchasers for whom they may act as agents or to whom they may sell as principal. The offering of the shares by the underwriters is subject to receipt and acceptance and subject to the underwriters’ right to reject any order in whole or in part. In connection with the sale of the shares offered hereby, the underwriters may be deemed to have received compensation in the form of underwriting discounts.

We estimate that our total expenses related to this offering will be approximately $1.0 million.

Certain of the underwriters and their respective affiliates have, from time to time, performed, and may in the future perform, various financial advisory and investment banking services for us, for which they received or will receive customary fees and expenses. The underwriters are full service financial institutions engaged in various activities, which may include sales and trading, commercial and investment bank, advisory, investment management, investment research, principal investment, hedging, market making, brokerage and other financial and non-financial activities and services. For example, in connection with our term loan agreement dated December 28, 2023, pursuant to which, and subject to the terms and conditions set forth therein, the term loan lenders thereunder committed to provide a $4.7 billion senior unsecured term loan facility consisting of (i) a $2.0 billion 364-day tranche and (ii) a $2.7 billion 2-year tranche, the proceeds of which were used to finance a portion of the CrownRock Acquisition, an affiliate of J.P. Morgan Securities LLC acted as a syndication agent and is a lender and an affiliate of RBC Capital Markets, LLC acted as a documentation agent and is a lender.

In addition, in the ordinary course of their business activities, the underwriters and their affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers. Such investments and securities activities may involve securities and/or instruments of ours or our affiliates. If any of the underwriters or their affiliates has a lending relationship with us, certain of those underwriters or their affiliates routinely hedge, certain of those underwriters or their affiliates are likely to hedge and certain other of those underwriters or their affiliates may hedge, their credit exposure to us consistent with their customary risk management policies. Typically, these underwriters and their affiliates would hedge such exposure by entering into transactions which consist of either the purchase of credit default swaps or the creation of short positions in our securities. The underwriters and their affiliates may also make investment recommendations and/or publish or express independent research views in respect of such securities or financial instruments and may hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

We, our directors, executive officers and the Selling Stockholder, have agreed that, without the prior written consent of the underwriters, we and they will not, and will not publicly disclose an intention to, during the period ending 30 days after the date of the underwriting agreement (the “restricted period”):

whether any such transaction described above is to be settled by delivery of common stock or such other securities, in cash or otherwise. In addition, we and each such person agrees that, without the prior written consent of the underwriters, we or such other person will not, during the restricted period, make any demand for, or exercise any right with respect to, the registration of any shares of common stock or any security convertible into or exercisable or exchangeable for common stock.

The restrictions described in the immediately preceding paragraph do not apply to:

provided that (A) in the case of any transfer or distribution pursuant to clause (4), (7), (8), (9), (10), (11) and (17), such transfer shall not involve a disposition for value and each donee, devisee, transferee or distributee shall sign and deliver a lock up agreement substantially in the form of the agreed lock-up agreement (other than pursuant to pursuant to (11) and (17)), (B) in the case of any transfer or distribution pursuant to clause (3), (4), (5), (6), (7), (8) and (9), no filing under the Exchange Act or other public announcement shall be required or shall be voluntarily made during the restricted period, (C) in the case of any transfer or distribution pursuant to clause (10) no filing under the Exchange Act or other public announcement reporting a reduction in beneficial ownership of shares of common stock shall be required or shall be voluntarily made during the restricted period and (D) in the case of any transfer or distribution pursuant to clause (11), (12), (13), (15), (16) and (17) it shall

be a condition to such transfer that no public filing, report or announcement shall be voluntarily made and if any filing under Section 16(a) of the Exchange Act, or other public filing, report or announcement reporting a reduction in beneficial ownership of shares of common stock in connection with such transfer or distribution shall be legally required during the restricted period, such filing, report or announcement shall clearly indicate in the footnotes thereto the nature and conditions of such transfer.

Our shares of common stock are listed on the NYSE under the symbol “OXY.”

Until the distribution of the shares is completed, SEC rules may limit us, the underwriters and the Selling Stockholder from bidding for and purchasing our common stock. However, the underwriters may engage in transactions that stabilize the price of the common stock, such as bids or purchases to peg, fix or maintain that price.

In connection with the offering, the underwriters may purchase and sell our common stock in the open market. These transactions may include short sales, purchases on the open market to cover positions created by short sales and stabilizing transactions. Short sales involve the sale by the underwriters of a greater number of shares than they are required to purchase in the offering. Stabilizing transactions consist of various bids for or purchases of shares of common stock made by the underwriters in the open market prior to the completion of the offering.

Similar to other purchase transactions, the underwriters’ purchases to cover positions and stabilizing purchases, as well as other purchases by the underwriters for their own account, may have the effect of raising or maintaining the market price of our common stock or preventing or retarding a decline in the market price of our common stock. As a result, the price of our common stock may be higher than the price that might otherwise exist in the open market. The underwriters may conduct these transactions on the NYSE, in the over-the-counter market or otherwise.

Neither we nor the underwriters make any representation or prediction as to the direction or magnitude of any effect that the transactions described above may have on the price of our common stock. In addition, neither we nor the underwriters make any representations that the underwriters will engage in these transactions or that these transactions, once commenced, will not be discontinued without notice.

In connection with this offering, the underwriters and the Selling Stockholder may engage in passive market making transactions in the common stock on the NYSE in accordance with Rule 103 of Regulation M under the Exchange Act during a period before the commencement of offers or sales of common stock and extending through the completion of distribution. A passive market maker must display its bid at a price not in excess of the highest independent bid of that security. However, if all independent bids are lowered below the passive market maker’s bid, that bid must then be lowered when specified purchase limits are exceeded. Passive market making may cause the price of our common stock to be higher than the price that otherwise would exist in the open market in the absence of those transactions. The underwriters are not required to engage in passive market making and may end passive market making activities at any time.

In connection with the offering, the underwriters or securities dealers may distribute prospectuses by electronic means, such as e-mail.

This prospectus supplement is for distribution only to persons who (a) are outside the Abu Dhabi Global Market, or (b) are Authorised Persons or Recognised Bodies (as such terms are defined in the Financial Services and Markets Regulations 2015 (“FSMR”)), or (c) are persons to whom an invitation or inducement to engage in investment activity (within the meaning of section 18 of FSMR) in connection with the issue or sale of any securities may otherwise lawfully be communicated or caused to be communicated (all such persons together being referred to as “relevant persons”). This prospectus supplement is directed only at relevant persons and must not be acted on or relied on by persons who are not relevant persons. Any investment or investment activity to which this prospectus supplement relates is available only to relevant persons and will be engaged in only with relevant persons. This document relates to an “Exempt Offer” within the meaning of section 61(3)(a) of the FSMR and Rule 4.3.1 of the Market Rules of the Financial Services Regulatory Authority or otherwise in circumstances which do not require the publication of an “Approved Prospectus” (as defined in section 61(2) of the FSMR).

No placement document, prospectus, product disclosure statement or other disclosure document (including as defined in the Corporations Act 2001 (Cth), or “Corporations Act”) has been or will be lodged with the Australian Securities and Investments Commission, or “ASIC,” or any other governmental agency, in relation to the offering. This prospectus supplement and the accompanying prospectus do not constitute a prospectus, product disclosure statement or other disclosure document for the purposes of the Corporations Act, and do not purport to include the information required for a prospectus, product disclosure statement or other disclosure document under the Corporations Act. No action has been taken which would permit an offering of the common stock in circumstances that would require disclosure under Parts 6D.2 or 7.9 of the Corporations Act.

The common stock may not be offered for sale, nor may application for the sale or purchase of any common stock be invited in Australia (including an offer or invitation which is received by a person in Australia), neither this prospectus supplement nor the accompanying prospectus or any other offering material or advertisement relating to the common stock may be distributed or published in Australia, and any offer under this document is otherwise void and incapable of acceptance unless, in each case: (i) the offer, invitation or distribution is made to a ‘sophisticated investor’ in accordance with section 708(8) of the Corporations Act, including that the aggregate consideration payable on acceptance of the offer or invitation by each offeree or invitee is at least A$500,000 (or its equivalent in another currency, in either case, disregarding moneys lent by the person offering the common stock or making the invitation or its associates) or the offer or invitation otherwise does not require disclosure to investors in accordance with Parts 6D.2 or 7.9 of the Corporations Act; (ii) the offer, invitation or distribution complied with the conditions of the Australian financial services license of the person making the offer, invitation or distribution or an applicable exemption from the requirement to hold such license; (iii) the offer, invitation or distribution complies with all applicable Australian laws, regulations and directives (including, without limitation, the disclosure requirements set out in Chapter 6, and the licensing requirements set out in Chapter 7 of the Corporations Act); (iv) the offer or invitation does not constitute an offer or invitation to a person in Australia who is a “retail client” as defined for the purposes of Section 761G of the Corporations Act; and (v) such action does not require any document to be lodged with ASIC or the ASX.

This prospectus supplement and the accompanying prospectus contain general information only and do not take account of the investment objectives, financial situation or particular needs of any particular person. This prospectus supplement and the accompanying prospectus do not contain any securities recommendations or financial product advice. Before making an investment decision, investors need to consider whether the information in this prospectus supplement and the accompanying prospectus is appropriate to their needs, objectives and circumstances, and, if necessary, seek expert advice on those matters.

The common stock may be sold only to purchasers in certain provinces purchasing, or deemed to be purchasing, as principal that are “accredited investors,” as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario), and “permitted clients,” as defined in National

Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations. Any resale of the common stock must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.

Securities legislation in certain provinces or territories of Canada may provide a purchaser of the common stock with remedies for rescission or damages if this prospectus supplement or the accompanying prospectus (including any amendment hereto or thereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by such purchaser within the time limit prescribed by the securities legislation of such purchaser’s province or territory. Such purchaser should refer to any applicable provisions of the securities legislation of the purchaser’s province or territory for particulars of these rights or consult with a legal advisor.

Pursuant to section 3A.3 of National Instrument 33-105 Underwriting Conflicts, or “NI 33-105,” the underwriters are not required to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering.

This prospectus supplement and the accompanying prospectus relate to an “Exempt Offer” in accordance with the Offered Securities Rules of the Dubai Financial Services Authority (“DFSA”). This prospectus supplement and the accompanying prospectus are intended for distribution only to persons of a type specified in the Offered Securities Rules of the DFSA. It must not be delivered to, or relied on by, any other person. The DFSA has no responsibility for reviewing or verifying any documents in connection with Exempt Offers. The DFSA has not approved this prospectus supplement and the accompanying prospectus nor taken steps to verify the information set forth herein and has no responsibility for the prospectus supplement and the accompanying prospectus. The common stock to which this prospectus supplement and the accompanying prospectus relate may be illiquid and/or subject to restrictions on their resale. Prospective purchasers of the common stock offered should conduct their own due diligence on the common stock. If you do not understand the contents of this prospectus supplement and the accompanying prospectus you should consult an authorized financial advisor.

In relation to its use in the DIFC, this document is strictly private and confidential and is being distributed to a limited number of investors and must not be provided to any person other than the original recipient, and may not be reproduced or used for any other purpose. The interests in the securities may not be offered or sold directly or indirectly to the public in the DIFC.

The common stock is not intended to be offered, sold or otherwise made available to and should not be offered, sold or otherwise made available to any retail investor in the European Economic Area, or the “EEA.” For these purposes, a retail investor means a person who is one (or more) of: (i) a retail client as defined in point (11) of Article 4(1) of Directive 2014/65/EU, as amended, or “MiFID II”; or (ii) a customer within the meaning of Directive (EU) 2016/97, as amended, where that customer would not qualify as a professional client as defined in point (10) of Article 4(1) of MiFID II; or (iii) not a qualified investor as defined in Regulation (EU) 2017/1129, as amended, or the “Prospectus Regulation.” Consequently, no key information document required by Regulation (EU) No 1286/2014, as amended, or the “PRIIPs Regulation,” for offering or selling shares of the common stock or otherwise making them available to retail investors in the EEA has been prepared and therefore offering or selling shares of the common stock or otherwise making them available to any retail investor in the EEA may be unlawful under the PRIIPs Regulation. This prospectus supplement and the accompanying prospectus have been prepared on the basis that any offer of common stock in any member state of the EEA will be made pursuant to an exemption under the Prospectus Regulation from the requirement to publish a prospectus for offers of common stock. This prospectus supplement and the accompanying prospectus are not prospectuses for the purposes of the Prospectus Regulation.

The common stock has not been offered or sold and will not be offered or sold in Hong Kong, by means of any document, other than (a) to “professional investors” as defined in the Securities and Futures Ordinance (Cap. 571 of the Laws of Hong Kong), or the “SFO,” and any rules made thereunder; or (b) in other circumstances which do not result in the document being a “prospectus” as defined in the Companies (Winding

Up and Miscellaneous Provisions) Ordinance (Cap. 32 of the Laws of Hong Kong), or the “CO,” and which do not constitute an offer or invitation to the public within the meaning of the CO. No advertisement, invitation or document relating to the common stock has been or will be issued or has been or will be in the possession of any person for the purposes of issue, whether in Hong Kong or elsewhere, which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted to do so under the securities laws of Hong Kong) other than with respect to the common stock which are or are intended to be disposed of only to persons outside Hong Kong or only to “professional investors” as defined in the SFO and any rules made thereunder.

This prospectus supplement and the accompanying prospectus have not been reviewed or approved by any regulatory authorities in Hong Kong, including the Securities and Futures Commission of Hong Kong and the Companies Registry of Hong Kong and neither have this prospectus supplement and the accompanying prospectus been registered with the Registrar of Companies in Hong Kong. Accordingly, this prospectus supplement and the accompanying prospectus may not be issued, circulated or distributed in Hong Kong, and the common stock may not be offered for subscription to members of the public in Hong Kong. The recipients of this prospectus supplement and the accompanying prospectus are advised to exercise caution in relation to any offer of the common stock. If recipients are in any doubt about any of the contents of this prospectus supplement and the accompanying prospectus, they should obtain independent professional advice. Each person acquiring the common stock will be required, and is deemed by the acquisition of the common stock, to confirm that it, he or she is aware of the restriction on offers of the common stock described in this prospectus supplement and the accompanying prospectus and the relevant offering documents and that it, he or she is not acquiring and has not been offered any common stock in circumstances that contravene any such restrictions.

In the State of Israel this prospectus supplement shall not be regarded as an offer to the public to purchase shares of common stock under the Israeli Securities Law, 5728—1968, which requires a prospectus to be published and authorized by the Israel Securities Authority, if it complies with certain provisions of Section 15 of the Israeli Securities Law, 5728–1968, including, inter alia, if: (i) the offer is made, distributed or directed to not more than 35 investors, subject to certain conditions (the “Addressed Investors”), or (ii) the offer is made, distributed or directed to certain qualified investors defined in the First Addendum of the Israeli Securities Law, 5728—1968, subject to certain conditions (the “Qualified Investors”). The Qualified Investors shall not be taken into account in the count of the Addressed Investors and may be offered to purchase securities in addition to the 35 Addressed Investors. We have not and will not take any action that would require us to publish a prospectus in accordance with and subject to the Israeli Securities Law, 5728—1968. We have not and will not distribute this prospectus supplement or make, distribute or direct an offer to subscribe for our common stock to any person within the State of Israel, other than to Qualified Investors and up to 35 Addressed Investors.

Qualified Investors may have to submit written evidence that they meet the definitions set out in of the First Addendum to the Israeli Securities Law, 5728—1968. In particular, we may request, as a condition to be offered common stock, that Qualified Investors will each represent, warrant, and certify to us and/or to anyone acting on our behalf: (i) that it is an investor falling within one of the categories listed in the First Addendum to the Israeli Securities Law, 5728—1968; (ii) which of the categories listed in the First Addendum to the Israeli Securities Law, 5728—1968 regarding Qualified Investors is applicable to it; (iii) that it will abide by all provisions set forth in the Israeli Securities Law, 5728—1968 and the regulations promulgated thereunder in connection with the offer to be issued common stock; (iv) that the shares of common stock that it will be issued are, subject to exemptions available under the Israeli Securities Law, 5728—1968: (a) for its own account; (b) for investment purposes only; and (c) not issued with a view to resale within the State of Israel, other than in accordance with the provisions of the Israeli Securities Law, 5728—1968; and (v) that it is willing to provide further evidence of its Qualified Investor status. Addressed Investors may have to submit written evidence in respect of their identity and may have to sign and submit a declaration containing, inter alia, the Addressed Investor’s name, address, and passport number or Israeli identification number.

The common stock has not been and will not be registered pursuant to Article 4, Paragraph 1 of the Financial Instruments and Exchange Act of Japan (Act No. 25 of April 13, 1948, as amended), or the “FIEA.” Accordingly, none of the common stock may be offered or sold, directly or indirectly, in Japan or to, or for the

account or the benefit of, any “resident” of Japan (which term as used herein means any person resident in Japan, including any corporation or other entity organized under the laws of Japan), or to others for re-offering or resale, directly or indirectly, in Japan to the account or for the benefit of, any resident of Japan, except pursuant to an exemption from the registration requirements of, and otherwise in compliance with, the FIEA and any other applicable laws, regulations and ministerial guidelines of Japan in effect at the relevant time.

This prospectus supplement and the accompanying prospectus may not be circulated or distributed in the People’s Republic of China (“PRC”) and the common stock may not be offered or sold, and will not be offered or sold, directly or indirectly, to any resident of the PRC or to persons for re-offering or resale, directly or indirectly, to any resident of the PRC except pursuant to applicable laws, rules and regulations of the PRC. For the purpose of this paragraph only, the PRC does not include Taiwan and the special administrative regions of Hong Kong and Macau.

The offering of the common stock has not been registered with the Commissione Nazionale per le Società e la Borsa (“CONSOB”) pursuant to Italian securities legislation and, accordingly, no common stock may be offered, sold or delivered, nor may copies of this prospectus supplement or of any other document relating to the common stock be distributed in the Republic of Italy, except:

Any offer, sale or delivery of the common stock or distribution of copies of this prospectus supplement or any other document relating to the common stock in the Republic of Italy under (a) or (b) above must:

This prospectus supplement and the accompanying prospectus have not been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, this prospectus supplement and the accompanying prospectus and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of the common stock may not be circulated or distributed, nor may the common stock be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to any person in Singapore other than: (i) to an institutional investor (as defined in Section 4A of the Securities and Futures Act 2001 of Singapore, as modified or amended from time to time ((the “SFA”)) pursuant to Section 274 of the SFA; (ii) to a relevant person (as defined in Section 275(2) of the SFA) pursuant to Section 275(1) of the SFA, or any person pursuant to Section 275(1A) of the SFA, and in accordance with the conditions specified in Section 275 of the SFA and (where applicable) Regulation 3 of the Securities and Futures (Classes of Investors) Regulations 2018 of Singapore; or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA, in each case subject to the conditions set forth in the SFA.

Where the common stock is subscribed or purchased under Section 275 of the SFA by a relevant person which is: (i) a corporation (which is not an accredited investor (as defined in Section 4A of the SFA)) the sole

business of which is to hold investments and the entire share capital of which is owned by one or more individuals, each of whom is an accredited investor; or (ii) a trust (where the trustee is not an accredited investor) whose sole purpose is to hold investments and each beneficiary of the trust is an individual who is an accredited investor, then securities or securities-based derivatives contracts (each term as defined in Section 2(1) of the SFA) of that corporation or the beneficiaries’ rights and interest (howsoever described) in that trust shall not be transferred within six months after that corporation or that trust has acquired the common stock pursuant to an offer made in reliance on an exemption under Section 275 of the SFA except: (1) to an institutional investor under Section 274 of the SFA or to a relevant person as defined in Section 275(2) of the SFA, or to any person arising from an offer referred to in Section 275(1A) or Section 276(4)(i)(B) of the SFA; (2) where no consideration is or will be given for the transfer; (3) where the transfer is by operation of law; (4) as specified in Section 276(7) of the SFA; or (5) as specified in Regulation 37A of the Securities and Futures (Offers of Investments) (Securities and Securities-based Derivatives Contracts) Regulations 2018 of Singapore.

In connection with Section 309B of the SFA and the Securities and Futures (Capital Markets Products) Regulations 2018 of Singapore, or “CMP Regulations 2018,” unless otherwise specified before an offer of common stock, Occidental has determined, and hereby notifies all relevant persons (as defined in Section 309A(1) of the SFA), that the shares of common stock are “prescribed capital markets products” (as defined in the CMP Regulations 2018) and Excluded Investment Products (as defined in MAS Notice SFA 04-N12: Notice on the Sale of Investment Products and MAS Notice FAA-N16: Notice on Recommendations on Investment Products).

The common stock has not been and will not be registered under the Financial Investments Services and Capital Markets Act of Korea and the decrees and regulations thereunder (the “FSCMA”) and the common stock has been and will be offered in Korea as a private placement under the FSCMA. None of the common stock may be offered, sold and delivered directly or indirectly, or offered or sold to any person for re-offering or resale, directly or indirectly, in Korea or to any resident of Korea except pursuant to the applicable laws and regulations of Korea, including the FSCMA and the Foreign Exchange Transaction Law of Korea and the decrees and regulations thereunder (the “FETL”). For a period of one year from the issue date of the common stock, any acquirer of the common stock who was solicited to buy the common stock in Korea is prohibited from transferring any of the common stock to another person in any way other than as a whole to one transferee. Furthermore, the purchaser of the common stock shall comply with all applicable regulatory requirements (including but not limited to requirements under the FETL) in connection with the purchase of the common stock.

The common stock will not be offered, sold or delivered directly or indirectly, or offered or sold to any person for re-offering or resale, directly or indirectly, in Korea or to any resident of Korea, except pursuant to an exemption from the registration requirements of, and otherwise in compliance with, the FSCMA, the FETL and other relevant laws and regulations of Korea.

This prospectus supplement and the accompanying prospectus are not intended to constitute an offer or solicitation to purchase or invest in the common stock described herein. The common stock may not be publicly offered, sold or advertised, directly or indirectly, in, into or from Switzerland and will not be listed on the SIX Swiss Exchange, or the “SIX,” or on any other exchange or regulated trading facility in Switzerland. Neither this prospectus supplement, the accompanying prospectus nor any other offering or marketing material relating to the common stock constitutes a prospectus as such term is understood pursuant to article 652a or article 1156 of the Swiss Code of Obligations or the disclosure standards for listing prospectuses under art. 27 ff. of the SIX Listing Rules or the listing rules of any other stock exchange or regulated trading facility in Switzerland, and neither this prospectus supplement, the accompanying prospectus nor any other offering or marketing material relating to the common stock may be publicly distributed or otherwise made publicly available in Switzerland.

Neither this document nor any other offering or marketing material relating to the offering, us, or the common stock have been or will be filed with or approved by any Swiss regulatory authority. In particular, this document will not be filed with, and the offer of common stock will not be supervised by, the Swiss Financial Market Supervisory Authority, and the offer of common stock has not been and will not be authorized under the Swiss Federal Act on

Collective Investment Schemes, or the “CISA.” The investor protection afforded to acquirers of interests in collective investment schemes under the CISA does not extend to acquirers of the common stock.

The common stock has not been, and will not be, registered with the Financial Supervisory Commission of Taiwan, the Republic of China, or “Taiwan,” pursuant to applicable securities laws and regulations. No person or entity in Taiwan is authorized to distribute or otherwise intermediate the offering of the common stock or the provision of information relating to this prospectus supplement and the accompanying prospectus. The common stock may be made available for purchase outside Taiwan by investors residing in Taiwan (either directly or through properly licensed Taiwan intermediaries acting on behalf of such investors), but may not be issued, offered or sold in Taiwan. No subscription or other offer to purchase the common stock shall be binding on us until received and accepted by us or any underwriter outside of Taiwan, or the “Place of Acceptance,” and the purchase/sale contract arising therefrom shall be deemed a contract entered into in the Place of Acceptance.

The common stock has not been, and is not being, publicly offered, sold, promoted or advertised in the United Arab Emirates (including the Abu Dhabi Global Market and the DFIC) other than in compliance with the laws, regulations and rules of the United Arab Emirates, the Abu Dhabi Global Market and the DFIC governing the issue, offering and sale of securities. Further, this prospectus supplement and the accompanying prospectus do not constitute a public offer of securities in the United Arab Emirates (including the Abu Dhabi Global Market and the DFIC) and are not intended to be a public offer. This prospectus supplement and the accompanying prospectus have not been approved by or filed with the Central Bank of the United Arab Emirates, the Securities and Commodities Authority, the Financial Services Regulatory Authority or the DFSA.

The common stock is not intended to be offered, sold or otherwise made available to and should not be offered, sold or otherwise made available to any retail investor in the United Kingdom, or the “UK.” For these purposes, (a) a retail investor means a person who is one (or more) of: (i) a retail client as defined in point (8) of Article 2 of Regulation (EU) No 2017/565 as it forms part of domestic law by virtue of the European Union (Withdrawal) Act 2018, or the “EUWA”; (ii) a customer within the meaning of the provisions of the Financial Services and Markets Act 2000, as amended, or the “FSMA,” and any rules or regulations made under the FSMA to implement Directive (EU) 2016/97, where that customer would not qualify as a professional client, as defined in point (8) of Article 2(1) of Regulation (EU) No 600/2014 as it forms part of the domestic law by virtue of the EUWA; or (iii) not a qualified investor as defined in Article 2 of Regulation (EU) 2017/1129 as it forms part of domestic law by virtue of the EUWA, or the “UK Prospectus Regulation”; and (b) the expression “offer” includes the communication in any form and by any means of sufficient information on the terms of the offer and the common stock to be offered so as to enable an investor to decide to purchase or subscribe for the common stock. Consequently, no key information document required by Regulation (EU) No 1286/2014 as it forms part of domestic law by virtue of the EUWA, or the “UK PRIIPs Regulation,” for offering or selling shares of the common stock or otherwise making them available to retail investors in the UK has been prepared and therefore offering or selling shares of the common stock or otherwise making them available to any retail investor in the UK may be unlawful under the UK PRIIPs Regulation.

This prospectus supplement has been prepared on the basis that any offer of the common stock in the UK will be made pursuant to an exemption under the UK Prospectus Regulation from the requirement to publish a prospectus for offers of the common stock. This prospectus supplement is not a prospectus for the purposes of the UK Prospectus Regulation.

This prospectus supplement is only being distributed to and is only directed at (i) persons who are outside the UK or (ii) investment professionals falling within Article 19(5) of the FSMA (Financial Promotion) Order 2005, as amended, or the “Financial Promotion Order,” or (iii) high net worth companies, and other persons to whom it may otherwise be lawfully communicated, falling within Article 49(2)(a) to (d) of the Financial Promotion Order (all such persons together being referred to as “relevant persons”). The common stock is only available to, and any invitation. offer or agreement to subscribe, purchase or otherwise acquire such common stock will be engaged in only with, relevant persons. Any person who is not a relevant person should not act or rely on this document or any of its contents.

Cravath, Swaine & Moore LLP will pass upon the validity of the shares of common stock offered hereby. The validity of the shares of common stock offered hereby will be passed upon for the underwriters by Weil, Gotshal & Manges LLP. Certain legal matters in connection with this offering will be passed upon for the Selling Stockholder by Vinson & Elkins LLP, Dallas, Texas.

The consolidated financial statements of Occidental Petroleum Corporation and subsidiaries as of December 31, 2023 and 2022, and for each of the years in the three-year period ended December 31, 2023 and management’s assessment of the effectiveness of internal control over financial reporting as of December 31, 2023 have been incorporated by reference herein in reliance upon the reports of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing.

The consolidated financial statements of CrownRock, L.P. as of and for the year ended December 31, 2023 incorporated by reference in this prospectus supplement have been so incorporated in reliance on the report of BDO USA, P.C., independent auditors, given on the authority of said firm as experts in auditing and accounting.

Certain information with respect to the oil and gas reserves associated with Occidental’s oil and gas properties is confirmed in the process review letter of Ryder Scott Company, L.P., independent petroleum engineering consultants, and has been incorporated by reference herein, upon the authority of said firm as experts with respect to the matters covered by such process review letter and in giving such process review letter.

Certain information with respect to the oil and gas reserves associated with CrownRock’s oil and gas properties is confirmed in the report of Cawley, Gillespie & Associates, Inc., independent petroleum engineering consultants, with respect to estimates of reserves and future net revenues of CrownRock as of December 31, 2023, and has been incorporated by reference herein, upon the authority of said firm as experts with respect to the matters covered by such report and in giving such report.

We are subject to the information reporting requirements of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). In accordance with the Exchange Act, we file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC file number is 001-09210. The SEC maintains a website that contains reports, proxy statements and other information about issuers, like us, that file electronically with the SEC. The address of that site is at www.sec.gov. Such reports, proxy statements and other information filed by us can also be read through the Investor Relations section of our website at www.oxy.com. Information on our website does not constitute part of, and is not incorporated by reference in, this prospectus supplement or the accompanying prospectus and should not be relied upon in connection with making any investment decision with respect to our common stock.

The SEC allows us to “incorporate by reference” the information that we file with the SEC. This permits us to disclose important information to you by referencing these filed documents. Any information referenced this way is considered part of this prospectus supplement, and any such information filed with the SEC subsequent to the date of this prospectus supplement will automatically be deemed to update and supersede this information. This prospectus supplement incorporates by reference the documents listed below that we have previously filed with the SEC. They contain important information about us and our financial condition.

We also incorporate by reference all documents we may subsequently file with the SEC pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act from the date of this prospectus supplement until the termination of the offering to which this prospectus supplement relates. Information furnished under Items 2.02 or 7.01 (and corresponding information furnished under Item 9.01 or included as an exhibit) in any past or future Current Report on Form 8-K that we file with the SEC, unless otherwise expressly specified in such report, is not incorporated by reference in this prospectus supplement.

We will provide, without charge upon written or oral request, a copy of any or all of the documents which are incorporated by reference into this prospectus supplement. Requests should be directed to: