Phillips 66 (PSX) 424B3Prospectus supplement

Filed Pursuant to Rule 424(b)(3)
Registration Nos. 333-266428 and 333-266428-01

The information in this preliminary prospectus supplement is not complete and may change. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities and they are not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

SUBJECT TO COMPLETION, DATED FEBRUARY 26, 2024

PRELIMINARY PROSPECTUS SUPPLEMENT

(To Prospectus dated July 29, 2022)

$    

Phillips 66 Company

$        % Senior Notes due   

$     5.300% Senior Notes due 2033

$        % Senior Notes due   

fully and unconditionally

guaranteed by

Phillips 66

Phillips 66 Company is offering $    aggregate principal amount of notes, consisting of $  aggregate principal amount of Senior Notes due   bearing interest at   % per year, or the “   notes,” $    aggregate principal amount of Senior Notes due 2033 bearing interest at 5.300% per year, or the “additional 2033 notes,” and $   aggregate principal amount of Senior Notes due  bearing interest at  % per year, or the “   notes.” The additional 2033 notes are being offered as additional notes under the indenture, dated May 5, 2022, pursuant to which Phillips 66 Company issued $500,000,000 aggregate principal amount of 5.300% Senior Notes due 2033, or the “existing 2033 notes.” We refer to the additional 2033 notes and the existing 2033 notes, collectively, as the “2033 notes.” The additional 2033 notes and the existing 2033 notes will be treated as a single series of senior debt securities under the indenture and, immediately upon settlement, the additional 2033 notes will have the same CUSIP number as and will trade interchangeably with the existing 2033 notes. The    notes will mature on   ,   , the 2033 notes will mature on June 30, 2033, and the    notes will mature on   ,    . We use the term “notes” to refer to all series of notes collectively. The notes will be fully and unconditionally guaranteed by Phillips 66.

Phillips 66 Company will pay interest on the   notes semi-annually on   and    of each year, beginning on   , 2024.

Phillips 66 Company will pay interest on the 2033 notes semi-annually on June 30 and December 30 of each year, beginning on June 30, 2024. Phillips 66 Company will pay interest on the   notes semi-annually on    and     of each year, beginning on    , 2024.

Phillips 66 Company may elect to redeem any or all of the notes at any time at the prices specified in this prospectus supplement plus accrued and unpaid interest to the redemption date. The redemption prices are described beginning on page S-10 of this prospectus supplement.

Investing in the notes involves risks. See “Risk Factors” on page S-7 of this prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved 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.

Delivery of the notes in book-entry form only will be made through The Depository Trust Company, Clearstream Banking S.A. and the Euroclear system on or about   , 2024, against payment in immediately available funds.

Joint Book-Running Managers

, 2024

You should rely only on the information we have included or incorporated by reference in this prospectus supplement, the accompanying prospectus and any free writing prospectus that we provide to you. We have not, and the underwriters have not, authorized anyone to provide you with any other information. If you receive any unauthorized information, you must not rely on it. We and the underwriters are offering to sell the notes only in places where sales are permitted. You should assume that the information we have included in this prospectus supplement or the accompanying prospectus is accurate only as of the date of this prospectus supplement or the accompanying prospectus and that any information we have incorporated by reference is accurate only as of the date of the document incorporated by reference.

This document is in two parts. The first part is this prospectus supplement, which describes the terms of this offering of notes and certain terms of the notes and the guarantees. The second part is the accompanying prospectus, which gives more general information. If the information varies between this prospectus supplement and the accompanying prospectus, you should rely on the information in this prospectus supplement.

TABLE OF CONTENTS

PROSPECTUS SUPPLEMENT

PROSPECTUS

S-i

S-1

S-2

S-3

S-4

S-5

S-6

RISK FACTORS

You should carefully consider the risk factors set forth under the caption “Risk Factors” in the 2023 Annual Report for risks related to Phillips 66 and Phillips 66 Company before making an investment decision. For more information, see “Where You Can Find More Information.”

S-7

USE OF PROCEEDS

We expect the net proceeds from the offering of the notes to be approximately $   , after deducting underwriting discounts and estimated expenses of the offering that we will pay. We intend to use the net proceeds of this offering for general corporate purposes, including to repay certain indebtedness, which may include the redemption of all or a portion of the DCP 2025 Notes, the repayment of a portion of the outstanding borrowings under the Term Loan, and/or the repayment of all or a portion of Phillips 66’s outstanding commercial paper borrowings under its commercial paper program.

The DCP 2025 Notes bear interest at a rate of 5.75% per year and mature on July 15, 2025. To the extent that a portion of the proceeds from this offering are used to redeem all or a portion of the DCP 2025 Notes, Phillips 66 Company intends to loan DCP Operating the funds necessary for the redemption under an intercompany credit facility.

As of February 22, 2024, the outstanding principal amount under the Term Loan was $1.25 billion. The net proceeds of the Term Loan were used for general corporate purposes. The Term Loan matures on June 20, 2026 and bears interest based on the adjusted term Secured Overnight Financing Rate that was 6.40% as of February 22, 2024.

As of February 22, 2024, the weighted average interest rate on our commercial paper borrowings was approximately 5.47% per annum and the weighted average maturity of our commercial paper borrowings was approximately 3.51 days.

Certain of the underwriters and/or their respective affiliates hold a portion of the DCP 2025 Notes, are acting as lenders and/or agents under the Term Loan and/or hold a portion of Phillips 66’s outstanding commercial paper. Accordingly, to the extent we use a portion of the net proceeds to redeem all or a portion of the DCP 2025 Notes or to repay a portion of the outstanding borrowings under the Term Loan or for the repayment of all or a portion of our outstanding commercial paper borrowings, such underwriters and/or their respective affiliates may receive more than 5% of the net proceeds of this offering, not including underwriting compensation, thus creating a “conflict of interest” within the meaning of FINRA Rule 5121. FINRA Rule 5121 requires prominent disclosure of the nature of the conflict of interest in the prospectus supplement for the public offering. Pursuant to FINRA Rule 5121(a)(1)(C), the appointment of a “qualified independent underwriter” is not necessary in connection with this offering as the notes offered hereby are “investment grade rated” (as defined in FINRA Rule 5121). See “Underwriting – Conflicts of Interest.”

For additional information about the Term Loan Agreement and our commercial paper program, please read “Management’s Discussion and Analysis of Financial Condition and Results of Operation — Capital Resources and Liquidity — Significant Sources of Capital” in our 2023 Annual Report.

S-8

DESCRIPTION OF THE NOTES

We have summarized selected provisions of the notes below. Phillips 66 Company issued the existing 2033 notes under the senior indenture, dated as of May 5, 2022, among Phillips 66 Company, as issuer, Phillips 66, as guarantor, and U.S. Bank Trust Company, National Association, as trustee (the “indenture”). Phillips 66 Company will issue the additional 2033 notes as additional notes under the indenture, and the additional 2033 notes will be treated with the existing 2033 notes as a single series of senior debt securities under the indenture. The    notes and the    notes will also be issued under the indenture. Each series of notes is a separate series of senior debt securities of Phillips 66 Company described in the accompanying prospectus, and this summary supplements that description. We urge you to read that description for other provisions that may be important to you.

In this summary description of the notes, unless we state otherwise or the context clearly indicates otherwise, all references to Phillips 66 mean Phillips 66 only and all references to Phillips 66 Company mean Phillips 66 Company only.

General

The    notes will mature on    ,    , and will bear interest at   % per year. Interest on the    notes will accrue from   , 2024. In respect of the    notes, Phillips 66 Company:

The additional 2033 notes constitute a further issuance of Phillips 66 Company’s 5.300% Senior Notes due 2033, which were issued originally on March 29, 2023. The additional 2033 notes offered by this prospectus supplement and the existing 2033 notes will be treated as a single series of senior debt securities under the indenture described herein, including for purposes of determining whether the required percentage of holders of 2033 notes have given their approval or consent to an amendment or waiver or joined in directing the trustee to take certain actions on behalf of all holders of 2033 notes. The additional 2033 notes offered hereby will have the same CUSIP number as the existing 2033 notes. After the consummation of this offering, $    in aggregate principal amount of 2033 notes will be outstanding and the additional 2033 notes offered hereby will represent approximately   % of all 2033 notes issued and outstanding.

The additional 2033 notes will mature on June 30, 2033, and will bear interest at 5.300% per year. Interest on the additional 2033 notes will accrue from December 30, 2023 (the most recent interest payment date for the existing 2033 notes). Accordingly, the purchase price for the additional 2033 notes will include interest that will be deemed to have accrued on the additional 2033 notes from December 30, 2023 (the most recent interest payment date for the existing 2033 notes) to, but excluding, the delivery date of the additional 2033 notes, which is expected to be   , 2024. In respect of the additional 2033 notes, Phillips 66 Company:

The    notes will mature on    ,    , and will bear interest at   % per year. Interest on the    notes will accrue from   , 2024. In respect of the    notes, Phillips 66 Company:

S-9

Phillips 66 Company will issue the notes only in fully registered form, without coupons, in minimum denominations of $2,000 and any integral multiples of $1,000 above that amount.

The    notes will be limited initially to $    in aggregate principal amount. Phillips 66 Company issued the existing 2033 notes in an aggregate principal amount of $500 million and will issue the additional 2033 notes offered hereby in an aggregate principal amount of $   . The    notes will be limited initially to $    in aggregate principal amount. We may, however, “reopen” each series of notes and issue an unlimited principal amount of additional notes of that series in the future without the consent of the holders. We may reopen a series of notes only if the additional notes issued will be fungible with the original notes of the series for U.S. federal income tax purposes.

As described in the prospectus, whether Phillips 66 is in compliance with a restrictive covenant regarding limitations on liens will depend on whether the board of directors of Phillips 66 has determined that a refinery or manufacturing plant is a principal property. Though it has not yet done so, under the terms of the indenture, Phillips 66’s board of directors has broad discretion to determine from time to time after the issuance of any senior debt securities under the indenture that a refinery or manufacturing plant is not a principal property and therefore such refinery or manufacturing plant is not subject to the covenants in the indenture.

Guarantee

Phillips 66 will fully and unconditionally guarantee on a senior unsecured basis the full and prompt payment of the principal of and any premium and interest on each series of the notes when and as the payment becomes due and payable, whether at maturity or otherwise. The guarantee will provide that in the event of a default in the payment of principal of or any premium or interest on any of the notes, the holder of that note or the trustee may institute legal proceedings directly against Phillips 66 to enforce the guarantee without first proceeding against Phillips 66 Company. The guarantee will rank equally with all of Phillips 66’s other unsecured and unsubordinated debt from time to time outstanding. The obligations of Phillips 66 under its guarantee will be limited to the maximum amount as will result in the obligations of Phillips 66 under its guarantee not constituting a fraudulent transfer or conveyance.

Redemption

Prior to     (the date that is     prior to the maturity date of the     notes) (the “   Par Call Date”), March 30, 2033 (the date that is three months prior to the maturity date of the 2033 notes) (the “2033 Par Call Date”) and     (the date that is     prior to the maturity date of the     notes) (the “    Par Call Date” and, together with the    Par Call Date and the 2033 Par Call Date, each, a “Par Call Date”), Phillips 66 Company may elect to redeem the applicable series of notes, at its option, in whole or in part, at any time and from time to time, at a redemption price (expressed as a percentage of principal amount and rounded to three decimal places) equal to the greater of:

S-10

On or after the applicable Par Call Date, Phillips 66 Company may redeem the applicable series of notes, in whole or in part, at any time and from time to time, at a redemption price equal to 100% of the principal amount of the notes of such series being redeemed plus accrued and unpaid interest thereon to the redemption date.

For purposes of the foregoing discussion of optional redemption, the following definitions are applicable:

“Business Day” means, any day that is not a Saturday, a Sunday or a day on which banking institutions in any of The City of New York, New York, Houston, Texas or a Place of Payment (as defined in the indenture) are authorized or obligated by law, regulation or executive order to remain closed.

“Treasury Rate” means, with respect to any redemption date, the yield determined by Phillips 66 Company in accordance with the following two paragraphs.

The Treasury Rate shall be determined by Phillips 66 Company after 4:15 p.m., New York City time (or after such time as yields on U.S. government securities are posted daily by the Board of Governors of the Federal Reserve System), on the third Business Day preceding the applicable redemption date based upon the yield or yields for the most recent day that appear after such time on such day in the most recent statistical release published by the Board of Governors of the Federal Reserve System designated as “Selected Interest Rates (Daily)—H.15” (or any successor designation or publication) (“H.15”) under the caption “U.S. government securities–Treasury constant maturities–Nominal” (or any successor caption or heading) (“H.15 TCM”). In determining the Treasury Rate, Phillips 66 Company shall select, as applicable: (1) the yield for the Treasury constant maturity on H.15 exactly equal to the period from the applicable redemption date to the applicable Par Call Date (the “Remaining Life”); or (2) if there is no such Treasury constant maturity on H.15 exactly equal to the Remaining Life, the two yields—one yield corresponding to the Treasury constant maturity on H.15 immediately shorter than and one yield corresponding to the Treasury constant maturity on H.15 immediately longer than the Remaining Life—and shall interpolate to the applicable Par Call Date on a straight-line basis (using the actual number of days) using such yields and rounding the result to three decimal places; or (3) if there is no such Treasury constant maturity on H.15 shorter than or longer than the Remaining Life, the yield for the single Treasury constant maturity on H.15 closest to the Remaining Life. For purposes of this paragraph, the applicable Treasury constant maturity or maturities on H.15 shall be deemed to have a maturity date equal to the relevant number of months or years, as applicable, of such Treasury constant maturity from the applicable redemption date.

If on the third Business Day preceding the redemption date H.15 TCM is no longer published, Phillips 66 Company shall calculate the Treasury Rate based on the rate per annum equal to the semi-annual equivalent yield to maturity at 11:00 a.m., New York City time, on the second Business Day preceding such redemption date of the United States Treasury security maturing on, or with a maturity that is closest to, the applicable Par Call Date, as applicable. If there is no United States Treasury security maturing on the applicable Par Call Date but there are two or more United States Treasury securities with a maturity date equally distant from the applicable Par Call Date, one with a maturity date preceding the applicable Par Call Date and one with a maturity date following the applicable Par Call Date, Phillips 66 Company shall select the United States Treasury security with a maturity date preceding the applicable Par Call Date. If there are two or more United States Treasury securities maturing on the applicable Par Call Date or two or more United States Treasury securities meeting the criteria of the preceding sentence, Phillips 66 Company shall select from among these two or more United States Treasury securities the United States Treasury security that is trading closest to par based upon the average of the bid and asked prices for such United States Treasury securities at 11:00 a.m., New York City time. In determining the Treasury Rate in accordance with the terms of this paragraph, the semiannual yield to maturity of the applicable United States Treasury security shall be based upon the average of the bid and asked prices (expressed as a percentage of principal amount) at 11:00 a.m., New York City time, of such United States Treasury security, and rounded to three decimal places.

Phillips 66 Company’s actions and determinations in determining the redemption price shall be conclusive and binding for all purposes, absent manifest error.

S-11

Notice of any optional redemption will be mailed or electronically delivered (or otherwise transmitted in accordance with the depositary’s procedures) at least 10 days but not more than 60 days before the redemption date to each holder of notes to be redeemed.

In the case of a partial redemption, selection of the notes for redemption will be made on a pro rata basis or, in the case of global notes, in accordance with the depositary’s procedures. No notes of a principal amount of $2,000 or less will be redeemed in part. If any note is to be redeemed in part only, the notice of redemption that relates to the note will state the portion of the principal amount of the note to be redeemed. A new note in a principal amount equal to the unredeemed portion of the note will be issued in the name of the holder of the note upon surrender for cancellation of the original note. For so long as the notes are held by DTC, the redemption of the notes shall be done in accordance with the policies and procedures of the depositary.

Unless Phillips 66 Company defaults in payment of the redemption price, on and after the redemption date interest will cease to accrue on the notes or portions thereof called for redemption.

Ranking

The notes will constitute senior unsecured debt of Phillips 66 Company and will rank equally with Phillips 66 Company’s other senior unsecured debt from time to time outstanding; senior to its subordinated debt from time to time outstanding; and effectively junior to its secured debt and to all debt and other liabilities of its subsidiaries from time to time outstanding. Phillips 66’s guarantee of the notes will rank equally with all of its other unsecured and unsubordinated debt from time to time outstanding; senior to its subordinated debt from time to time outstanding; and effectively junior to its secured debt and to all debt and other liabilities of its subsidiaries, other than Phillips 66 Company, from time to time outstanding.

As of December 31, 2023, as adjusted to give effect to the issuance of the notes (but not any use of proceeds therefrom), Phillips 66 and Phillips 66 Company would have had an aggregate of $  billion of consolidated long-term debt. A substantial portion of such debt would have been either issued or guaranteed by Phillips 66, Phillips 66 Company or both on a basis that would have ranked equally in right of payment with the notes and the related guarantees. In addition, a substantial portion of such debt has been issued by DCP Midstream Operating, LP, a wholly owned subsidiary of DCP Midstream, LP. See Note 14 – Debt, in the Notes to Consolidated Financial Statements in the 2023 Annual Report.

Paying Agents and Transfer Agents

The trustee will be appointed as paying agent and transfer agent for the notes. Payments on the notes will be made in U.S. dollars at the office of the trustee and any paying agent. At our option, however, payments may be made by wire transfer for notes held in book-entry form or by wire transfer or by check mailed to the address of the person entitled to the payment as it appears in the security register.

Other

We will make all payments on the notes without withholding or deducting any taxes or other governmental charges imposed by a United States jurisdiction, unless we are required to do so by applicable law. A holder of the notes may, however, be subject to U.S. federal income taxes, and taxes may be withheld on certain payments on the notes, as described under the caption “Material U.S. Federal Income Tax Considerations.” If we are required to withhold taxes, we will not pay any additional, or gross up, amounts with respect to the withholding or deduction.

We may at any time purchase notes on the open market or otherwise at any price. We will surrender all notes that we redeem or purchase to the trustee for cancellation. We may not reissue or resell any of these notes.

S-12

Book-Entry Delivery and Settlement

Global Notes

We will issue the notes in the form of one or more permanent global notes in definitive, fully registered, book-entry form. The global notes will be deposited with or on behalf of DTC and registered in the name of Cede & Co., as nominee of DTC, or will remain in the custody of the trustee.

DTC, Clearstream and Euroclear

Beneficial interests in the global notes will be represented through book-entry accounts of financial institutions acting on behalf of beneficial owners as direct and indirect participants in DTC. Investors may hold interests in the global notes through either DTC (in the United States), Clearstream Banking, société anonyme, Luxembourg (“Clearstream”), or Euroclear Bank S.A./N.V. (the “Euroclear Operator”), as operator of the Euroclear System (in Europe) (“Euroclear”), either directly if they are participants of such systems or indirectly through organizations that are participants in such systems. Clearstream and Euroclear will hold interests on behalf of their participants through customers’ securities accounts in Clearstream’s and Euroclear’s names on the books of their U.S. depositaries, which in turn will hold such interests in customers’ securities accounts in the U.S. depositaries’ names on the books of DTC. Citibank, N.A. will act as the U.S. depositary for Clearstream, and JPMorgan Chase Bank, N.A. will act as the U.S. depositary for Euroclear.

DTC has advised us as follows:

We have provided the descriptions of the operations and procedures of DTC, Clearstream and Euroclear in this prospectus supplement solely as a matter of convenience. These operations and procedures are solely within the control of those organizations and are subject to change by them from time to time. None of Phillips 66, Phillips 66 Company, the underwriters nor the trustee takes any responsibility for these operations or procedures, and you are urged to contact DTC, Clearstream and Euroclear or their participants directly to discuss these matters.

S-13

We expect that under procedures established by DTC:

The laws of some jurisdictions may require that purchasers of securities take physical delivery of those securities in definitive form. Accordingly, the ability to transfer interests in the notes represented by a global note to those persons may be limited. In addition, because DTC can act only on behalf of its participants, who in turn act on behalf of persons who hold interests through participants, the ability of a person having an interest in notes represented by a global note to pledge or transfer those interests to persons or entities that do not participate in DTC’s system, or otherwise to take actions in respect of such interest, may be affected by the lack of a physical definitive security in respect of such interest.

So long as DTC or its nominee is the registered owner of a global note, DTC or that nominee will be considered the sole owner or holder of the notes represented by that global note for all purposes under the indenture and under the notes. Except as provided below, owners of beneficial interests in a global note will not be entitled to have notes represented by that global note registered in their names, will not receive or be entitled to receive physical delivery of certificated notes and will not be considered the owners or holders thereof under the indenture or under the notes for any purpose, including with respect to the giving of any direction, instruction or approval to the trustee. Accordingly, each holder owning a beneficial interest in a global note must rely on the procedures of DTC and, if that holder is not a direct or indirect participant, on the procedures of the participant through which that holder owns its interest, to exercise any rights of a holder of notes under the indenture or the global note.

None of Phillips 66, Phillips 66 Company, the underwriters nor the trustee will have any responsibility or liability for any aspect of the records relating to or payments made on account of notes by DTC, Clearstream or Euroclear, or for maintaining, supervising or reviewing any records of those organizations relating to the notes.

Payments on the notes represented by the global notes will be made to DTC or its nominee, as the case may be, as the registered owner thereof. We expect that DTC or its nominee, upon receipt of any payment on the notes represented by a global note, will credit participants’ accounts with payments in amounts proportionate to their respective beneficial interests in the global note as shown in the records of DTC or its nominee. We also expect that payments by participants to owners of beneficial interests in the global note held through such participants will be governed by standing instructions and customary practice as is now the case with securities held for the accounts of customers registered in the names of nominees for such customers. The participants will be responsible for those payments.

Distributions on the notes held beneficially through Clearstream will be credited to cash accounts of its customers in accordance with its rules and procedures, to the extent received by the U.S. depositary for Clearstream.

Securities clearance accounts and cash accounts with the Euroclear Operator are governed by the Terms and Conditions Governing Use of Euroclear and the related Operating Procedures of the Euroclear System, and applicable Belgian law (collectively, the “Terms and Conditions”). The Terms and Conditions govern transfers of securities and cash within Euroclear, withdrawals of securities and cash from Euroclear, and receipts of payments with respect to securities in Euroclear. All securities in Euroclear are held on a fungible basis without attribution of specific certificates to specific securities clearance accounts. The Euroclear Operator acts under the Terms and

S-14

Conditions only on behalf of Euroclear participants and has no record of or relationship with persons holding through Euroclear participants.

Distributions on the notes held beneficially through Euroclear will be credited to the cash accounts of its participants in accordance with the Terms and Conditions, to the extent received by the U.S. depositary for Euroclear.

Clearance and Settlement Procedures

Initial settlement for the notes will be made in immediately available funds. Secondary market trading between DTC participants will occur in the ordinary way in accordance with DTC rules and will be settled in immediately available funds. Secondary market trading between Clearstream customers and/or Euroclear participants will occur in the ordinary way in accordance with the applicable rules and operating procedures of Clearstream and Euroclear and will be settled using the procedures applicable to conventional eurobonds in immediately available funds.

Cross-market transfers between persons holding directly or indirectly through DTC, on the one hand, and directly or indirectly through Clearstream customers or Euroclear participants, on the other, will be effected in DTC in accordance with DTC rules on behalf of the relevant European international clearing system by the U.S. depositary; however, such cross-market transactions will require delivery of instructions to the relevant European international clearing system by the counterparty in such system in accordance with its rules and procedures and within its established deadlines (European time). The relevant European international clearing system will, if the transaction meets its settlement requirements, deliver instructions to the U.S. depositary to take action to effect final settlement on its behalf by delivering or receiving the notes in DTC, and making or receiving payment in accordance with normal procedures for same-day funds settlement applicable to DTC. Clearstream customers and Euroclear participants may not deliver instructions directly to their U.S. depositaries.

Because of time-zone differences, credits of the notes received in Clearstream or Euroclear as a result of a transaction with a DTC participant will be made during subsequent securities settlement processing and dated the business day following the DTC settlement date. Such credits or any transactions in the notes settled during such processing will be reported to the relevant Clearstream customers or Euroclear participants on such business day. Cash received in Clearstream or Euroclear as a result of sales of the notes by or through a Clearstream customer or a Euroclear participant to a DTC participant will be received with value on the DTC settlement date but will be available in the relevant Clearstream or Euroclear cash account only as of the business day following settlement in DTC.

Although DTC, Clearstream and Euroclear have agreed to the foregoing procedures to facilitate transfers of the notes among participants of DTC, Clearstream and Euroclear, they are under no obligation to perform or continue to perform such procedures and such procedures may be changed or discontinued at any time.

Certificated Notes

We will issue certificated notes to each person that DTC identifies as the beneficial owner of the notes represented by the global notes upon surrender by DTC of the global notes if:

S-15

Neither we nor the trustee will be liable for any delay by DTC, its nominee or any direct or indirect participant in identifying the beneficial owners of the related notes. We and the trustee may conclusively rely on, and will be protected in relying on, instructions from DTC or its nominee for all purposes, including with respect to the registration and delivery, and the respective principal amounts, of the notes to be issued.

S-16

MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS

The following section provides a summary of material U.S. federal income tax considerations that may be relevant to the acquisition, ownership and disposition of the notes. This discussion is based upon the provisions of the Internal Revenue Code of 1986, as amended (the “Code”), applicable Treasury Regulations promulgated thereunder (the “Treasury Regulations”), judicial authority and administrative interpretations, all as of the date of this prospectus supplement, and all of which are subject to change, possibly with retroactive effect, or to different interpretations. We cannot assure you that the Internal Revenue Service (the “IRS”) will not challenge one or more of the tax consequences described in this discussion, and we have not obtained, nor do we intend to obtain, a ruling from the IRS or an opinion of counsel with respect to the U.S. federal tax consequences of acquiring, holding or disposing of the notes.

This discussion is limited to holders who purchase the notes in this offering for a price equal to the issue price of the notes (i.e., the first price at which a substantial amount of the notes is sold for cash other than to bond houses, brokers or similar persons or organizations acting in the capacity of underwriters, placement agents or wholesalers) and who hold the notes as capital assets (generally, property held for investment). This discussion does not address the tax considerations arising under the laws of any state, local, foreign or other jurisdiction, or any income tax treaty, U.S. estate or gift tax laws or the 3.8% Medicare tax on net investment income. In addition, this discussion does not address all tax considerations that may be important to a particular holder in light of the holder’s investment or other circumstances, or to certain categories of holders that may be subject to special rules, such as dealers in securities or currencies, traders in securities that have elected the mark-to-market method of accounting for their securities, persons holding notes as part of a hedge, straddle, conversion or other “synthetic security” or other risk reduction transaction, U.S. expatriates, regulated investment companies, real estate investment trusts, persons subject to the alternative minimum tax, entities that are tax-exempt for U.S. federal income tax purposes, financial institutions, insurance companies, persons required to recognize any item of gross income for U.S. federal income tax purposes with respect to the notes no later than when such item is taken into account on an applicable financial statement, and partnerships and other pass-through entities and holders of interests therein.

If a partnership or other entity classified as a partnership for U.S. federal income tax purposes holds notes, the tax treatment of a partner of such partnership generally will depend on the tax status of the partner and the tax treatment of the partnership. Partnerships holding notes and their partners should consult with their own tax advisors as to the particular U.S. federal income tax consequences of the purchase, ownership and disposition of the notes.

Redemption

In certain circumstances described under “Description of the Notes – Redemption,” we may be obligated to make payments on the notes in excess of stated interest and principal. We intend to take the position that the notes should not be treated as contingent payment debt instruments for U.S. federal income tax purposes because the likelihood of these additional payments (or any other contingencies under the terms of the notes) occurring will be treated as remote. If the IRS were to successfully challenge such position, such that the notes are treated as contingent payment debt instruments, the U.S. federal income tax consequences of purchasing, owning and disposing of the notes may differ materially from those described below (including the accrual of ordinary interest income at a higher rate than the stated interest rate on the notes, and the treatment of gain on a taxable disposition of the notes as ordinary income rather than capital gain). Our determination is binding on a holder, unless the holder explicitly discloses a contrary treatment in a statement attached to its timely filed U.S. federal income tax return for the taxable year during which the notes were acquired. Holders are urged to consult their own tax advisors regarding the potential application to the notes of the contingent payment debt instrument rules and the consequences thereof. The remainder of this discussion assumes that the notes are not treated as contingent payment debt instruments.

S-17

Qualified Reopening

It is anticipated, and the following discussion assumes, that the additional 2033 notes will be issued with no more than a de minimis amount of original issue discount, and therefore we intend to treat the additional 2033 notes as issued pursuant to a “qualified reopening” of the existing 2033 notes. For U.S. federal income tax purposes, debt instruments issued in a qualified reopening are deemed to be part of the same issue as the original debt instruments. Under the treatment described in this paragraph, all of the additional 2033 notes issued pursuant to this prospectus supplement will be deemed to have the same issue date and the same issue price as the existing 2033 notes for U.S. federal income tax purposes. The remainder of this discussion assumes that the issuance of the additional 2033 notes offered hereby will be treated as a qualified reopening of the existing 2033 notes.

Pre-issuance accrued interest

A portion of the purchase price for the additional 2033 notes will be attributable to the amount of interest accrued on the additional 2033 notes after December 30, 2023, and prior to the date the additional 2033 notes are issued (“pre-issuance accrued interest”). We intend to take the position that a portion of the first interest payment on the additional 2033 notes, equal to the amount of the pre-issuance accrued interest, is a nontaxable return of a portion of the purchase price for the additional 2033 notes rather than interest on the additional 2033 notes. Your tax basis in the additional 2033 notes will not include the portion of the purchase price attributable to the pre-issuance accrued interest.

Tax Consequences to U.S. Holders

You are a “U.S. holder” for purposes of this discussion if you are a beneficial owner of a note and you are for U.S. federal income tax purposes:

Interest on the Notes

Subject to the above discission on pre-issuance accrued interest, interest on the notes generally will be taxable to you as ordinary income at the time it is received or accrued in accordance with your regular method of accounting for U.S. federal income tax purposes.

Amortizable Bond Premium

If you purchase the additional 2033 notes for a price (excluding any amount attributable to pre-issuance accrued interest as described above) in excess of the stated principal amount of the additional 2033 notes, you will have acquired the additional 2033 notes with bond premium. Generally, you may elect to amortize bond premium under the constant yield method over the remaining term of the additional 2033 notes. If you elect to amortize bond premium, it will apply to all taxable debt instruments having bond premium that you own or subsequently acquire on or after the first day of the first taxable year to which the election applies and may not be revoked without the consent of the IRS. Additionally, if you elect to amortize bond premium, you will be required to reduce your basis in the additional 2033 notes by the amount of premium amortized during your

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holding period. Amortizable bond premium will be treated as an offset to interest income of the additional 2033 notes rather than as a separate item of deduction. If you do not elect to amortize bond premium, then that premium will decrease the gain or increase the loss you would otherwise recognize on the disposition of the additional 2033 notes.

Sale, Redemption, Exchange, Retirement or other Taxable Disposition of the Notes

You generally will recognize capital gain or loss on the sale, redemption, exchange, retirement or other taxable disposition of a note. This gain or loss will equal the difference between the proceeds you receive (excluding any proceeds attributable to accrued but unpaid interest, which will be recognized as ordinary interest income to the extent you have not previously included the accrued interest in gross income) and your tax basis in the note. Your proceeds will include the amount of any cash and the fair market value of any other property received for the note. Your tax basis in the note generally will equal the amount you paid for the note, subject to certain adjustments. The gain or loss generally will be long-term capital gain or loss if you held the note for more than one year at the time of the sale, redemption, exchange, retirement or other taxable disposition. Long-term capital gains of individuals, estates and trusts currently are subject to a reduced rate of U.S. federal income tax. The deductibility of capital losses is subject to limitation.

Information Reporting and Backup Withholding

Information reporting will apply to payments of interest on, and the proceeds of the sale, redemption, exchange, retirement or other taxable disposition of, notes held by you, and backup withholding will apply to such payments unless you provide us or other appropriate person with a taxpayer identification number, certified under penalties of perjury, as well as certain other information or otherwise establish an exemption from backup withholding. Backup withholding is not an additional tax. Any amount withheld under the backup withholding rules is allowable as a credit against your U.S. federal income tax liability, if any, and a refund may be obtained if the amounts withheld exceed your actual U.S. federal income tax liability and you timely provide the required information or appropriate claim form to the IRS.

Tax Consequences to Non-U.S. Holders

You are a “non-U.S. holder” for purposes of this discussion if you are a beneficial owner of a note and you are an individual, corporation, estate or trust that is not a U.S. holder.

Interest on the Notes

Subject to the discussions below on backup withholding and Foreign Account Tax Compliance Act (“FATCA”) withholding, interest income on a note that you receive will not be subject to U.S. federal income or withholding tax if you are a non-U.S. holder and the interest is not effectively connected with the conduct of a trade or business in the United States by you and you:

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If the portfolio interest exemption is not available with respect to interest on a note, then such interest may be subject to such U.S. federal income and withholding tax at a rate of 30%. To claim an exemption from (or reduction in) withholding under the benefits of an applicable income tax treaty, you must provide a properly completed IRS Form W-8BEN or IRS Form W-8BEN-E, as applicable.

Interest on a note that is effectively connected with the conduct of a trade or business in the United States by a non-U.S. holder is not subject to withholding if such a holder provides a properly completed IRS Form W-8ECI. However, such a holder generally will be subject to U.S. federal income tax on such interest on a net income basis at rates applicable to a United States person (as defined in the Code), and such a holder who is a foreign corporation also may be subject to the 30% U.S. branch profits tax in respect of such interest, unless reduced or eliminated by an applicable treaty.

Sale, Redemption, Exchange, Retirement or other Taxable Disposition of the Notes

Subject to the discussions below regarding backup and FATCA withholding, you generally will not be subject to U.S. federal income or withholding tax on any gain realized on the sale, redemption, exchange, retirement or other taxable disposition of a note unless (i) the gain is effectively connected with your conduct of a trade or business in the United States (as described immediately below) or (ii) you are an individual who is present in the United States for 183 days or more in the taxable year in which the sale, redemption, exchange, retirement or other taxable disposition occurs and certain other conditions are met, in which case you generally will be subject to U.S. federal income tax on such gain at a flat rate of 30% (unless a lower applicable income tax treaty rate applies).

If you are engaged in a trade or business in the United States and gain on a note is effectively connected with the conduct of such trade or business (and, if required by an applicable income tax treaty, such gain is attributable to a permanent establishment maintained by you within the United States), you generally will be subject to U.S. federal income tax at regular graduated income tax rates in the same manner as if you were a United States person (as defined in the Code), subject to any modification provided under an applicable income tax treaty. If you are a foreign corporation for U.S. federal income tax purposes, such gain also may be subject to a U.S. branch profits tax at the rate of 30%, or lower applicable treaty rate, of its earnings and profits for the taxable year, subject to adjustments, that are effectively connected with your conduct of a trade or business in the United States.

Non-U.S. holders described in the preceding paragraph are urged to consult their own advisors regarding the U.S. tax consequences to them of a sale or other disposition of notes.

Information Reporting and Backup Withholding

The interest on a note generally will be reported to the IRS on IRS Form 1042-S. Generally, neither information reporting on IRS Form 1099 nor backup withholding will apply to principal or interest payments or to amounts received on the sale, redemption, exchange, retirement or other taxable disposition of a note if an IRS Form W-8BEN or IRS Form W-8BEN-E, as applicable, is provided to us or other appropriate person and if, in the case of amounts received on the sale, redemption, exchange, retirement or other taxable disposition of a note, certain other conditions are met. However, the exemption from backup withholding and information reporting requirements does not apply if the withholding agent or an intermediary knows or has reason to know that such exemption is not available to you.

Foreign Account Tax Compliance Act

Under FATCA, withholding at a rate of 30% generally will be required in certain circumstances on certain payments in respect of the notes (including payments of interest and, subject to the discussion of proposed Treasury Regulations below, payments of gross proceeds from the sale or other disposition of notes) made to or

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through certain foreign financial entities (including investment funds) that do not qualify for an exemption from these rules, unless the entities either (i) enter into, and comply with, an agreement with the IRS to undertake certain diligence and to report, on an annual basis, information with respect to interests in, and accounts maintained by, the institution that are owned by certain U.S. persons (as defined in the Code) and by certain non-U.S. entities that are wholly or partially owned by U.S. persons (as defined in the Code) and to withhold 30% on certain payments, or (ii) if required under an intergovernmental agreement between the United States and an applicable foreign country, undertakes such diligence and reports such information to its local tax authority, which will exchange such information with the U.S. authorities. An intergovernmental agreement between the United States and an applicable foreign country, or future Treasury Regulations or other guidance, may modify these requirements. Accordingly, the entity through which the notes are held will affect the determination of whether such withholding is required. Similarly, in certain circumstances, payments of interest in respect of notes (and, subject to the discussion below, payment of gross proceeds from the sale or other disposition of notes) held by or through a non-financial foreign entity that does not qualify under certain exemptions generally will be subject to withholding at a rate of 30%, unless such entity either (i) certifies that such entity does not have any “substantial United States owners” or (ii) provides certain information regarding the entity’s “substantial United States owners,” which we will in turn provide to the IRS, as required. We will not pay any additional amounts to holders of notes in respect of any such amounts withheld. Prospective holders should consult their tax advisors regarding the possible implications of these rules on their investment in the notes.

As noted above, withholding under FATCA can apply to payments of gross proceeds from the sale or other disposition of a note, in addition to interest payments. However, Treasury Regulations have been proposed that would entirely eliminate FATCA withholding on payments of gross proceeds. Taxpayers generally may rely on these proposed Treasury Regulations until the promulgation of final Treasury Regulations addressing the matter.

This summary of material U.S. federal income tax considerations is intended for general information only and is not to be construed as tax advice. You are urged to consult your tax advisor with respect to the application of U.S. federal tax laws (including estate and gift tax laws) to your particular situation as well as any tax consequences under the laws of any state, local, foreign or other taxing jurisdiction or under any applicable tax treaty.

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UNDERWRITING (CONFLICTS OF INTEREST)

We and the underwriters for the offering named below, for whom Mizuho Securities USA LLC, MUFG Securities Americas Inc., RBC Capital Markets, LLC, Scotia Capital (USA) Inc., SMBC Nikko Securities America, Inc. and Truist Securities, Inc. are acting as representatives, have entered into an underwriting agreement with respect to the notes. Subject to certain conditions, each underwriter has severally agreed to purchase the principal amount of notes indicated in the following table at the public offering prices, less the underwriting discounts, set forth on the cover page of this prospectus supplement.

The underwriters are committed to take and pay for all of the notes being offered, if any are taken.

The underwriters propose to offer the notes directly to the public at the applicable public offering price set forth on the cover page of this prospectus supplement. The following table shows the underwriting discount to be paid to the underwriters in connection with this offering (expressed as a percentage of the principal amount of the applicable series of notes).

The underwriters may allow, and such dealers may reallow, a concession to certain other dealers not in excess of:

After the initial offering of the notes to the public, the representatives may change the public offering prices and concessions. The offering of the notes by the underwriters is subject to receipt and acceptance and subject to the underwriters’ right to reject any order in whole or in part.

The     notes are a new issue of securities with no established trading market. The additional 2033 notes will constitute one series with the existing 2033 notes, for which a trading market already exists. The     notes are a new issue of securities with no established trading market. We have been advised by the underwriters that the underwriters intend to make a market in each series of the notes but are not obligated to do so and may discontinue market making at any time without notice. No assurance can be given as to the liquidity of the trading markets for the notes.

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In connection with the offering, the underwriters may purchase and sell notes in the open market. These transactions may include short sales, stabilizing transactions and purchases to cover positions created by short sales. Short sales involve the sale by the underwriters of a greater number of notes than they are required to purchase in the offering. Stabilizing transactions consist of certain bids or purchases made for the purpose of preventing or retarding a decline in the market price of the notes while the offering is in progress.

The underwriters also may impose a penalty bid. This occurs when a particular underwriter repays to the underwriters a portion of the underwriting discount received by it because the representatives have repurchased notes sold by or for the account of such underwriter in stabilizing or short covering transactions.

These activities by the underwriters, as well as other purchases by the underwriters for their own accounts, may stabilize, maintain or otherwise affect the market prices of the notes. As a result, the prices of the notes may be higher than the prices that otherwise might exist in the open market. If these activities are commenced, they may be discontinued by the underwriters at any time. These transactions may be effected in the over-the-counter market or otherwise.

We estimate that our share of the total expenses of the offering, excluding underwriting discounts and commissions, will be approximately $    .

We have agreed to indemnify the several underwriters against certain liabilities, including liabilities under the Securities Act of 1933.

Certain underwriters and their affiliates have from time to time provided, and in the future may provide, certain investment banking and financial advisory services to us and our affiliates, for which they have received, and in the future would receive, customary fees. For example, certain of the underwriters and/or their affiliates are acting as lenders and/or agents under Phillip 66 Company’s $5 billion revolving credit facility entered into on June 23, 2022 and the Term Loan.

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 have a lending relationship with us, certain of those underwriters or their affiliates routinely hedge, and certain other of those underwriters 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 that consist of either the purchase of credit default swaps or the creation of short positions in our securities, including potentially the notes offered hereby. Any such credit default swaps or short positions could adversely affect future trading prices of the notes offered hereby. 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 intend to use the net proceeds of this offering for general corporate purposes, including to repay certain indebtedness, which may include the redemption of all or a portion of the DCP 2025 Notes, the repayment of a portion of the outstanding borrowings under the Term Loan, and/or the repayment of all or a portion of Phillips 66’s outstanding commercial paper borrowings. See “—Conflicts of Interest.”

Conflicts of Interest

Certain of the underwriters and/or their respective affiliates hold a portion of the DCP 2025 Notes, are acting as lenders and/or agents under the Term Loan and/or hold a portion of Phillips 66’s outstanding commercial paper. Accordingly, to the extent we use a portion of the net proceeds to redeem all or a portion of

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the DCP 2025 Notes or to repay a portion of the outstanding borrowings under the Term Loan or for the repayment of all or a portion of our outstanding commercial paper borrowings, such underwriters and/or their respective affiliates may receive more than 5% of the net proceeds of this offering, not including underwriting compensation, thus creating a “conflict of interest” within the meaning of FINRA Rule 5121. FINRA Rule 5121 requires prominent disclosure of the nature of the conflict of interest in the prospectus supplement for the public offering. Pursuant to FINRA Rule 5121(a)(1)(C), the appointment of a “qualified independent underwriter” is not necessary in connection with this offering as the notes offered hereby are “investment grade rated” (as defined in FINRA Rule 5121).

Notice to Prospective Investors in the European Economic Area

The notes are 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 (“EEA”). For these purposes,

Consequently no key information document required by Regulation (EU) No 1286/2014 (as amended, the “PRIIPs Regulation”) for offering or selling the notes or otherwise making them available to retail investors in the EEA has been prepared and therefore offering or selling the notes 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 notes 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 notes. This prospectus supplement and the accompanying prospectus are not a prospectus for the purposes of the Prospectus Regulation.

Notice to Prospective Investors in the United Kingdom

The notes are 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 (“UK”). For these purposes, 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 (“EUWA”) or (ii) a customer within the meaning of the provisions of the Financial Services and Markets Act 2000 (as amended, the “FSMA”) and any rules or regulations made under the FSMA to implement the Insurance Distribution Directive (EU), 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 domestic law by virtue of the EUWA. Consequently, no key information document required by Regulation (EU) No 1286/2014 as it forms part of domestic law by virtue of the EUWA (the “UK PRIIPs Regulation”) for offering or selling the notes or otherwise making them available to retail investors in the UK has been prepared and therefore offering or selling the notes or otherwise making them available to any retail investor in the UK may be unlawful under the UK PRIIPs Regulation.

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In the UK, this prospectus supplement and the accompanying prospectus are for distribution only to persons who (i) have professional experience in matters relating to investments falling within Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005 (as amended, the “Order”), (ii) are persons falling within Article 49(2)(a) to (d) (“high net worth companies, unincorporated associations etc.”) of the Order or (iii) are persons to whom an invitation or inducement to engage in investment activity (within the meaning of Section 21 of the FSMA) in connection with the issue or sale of any notes may otherwise lawfully be communicated or caused to be communicated (all such persons together being referred to as “relevant persons”). This prospectus supplement and the accompanying prospectus are 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 and the accompanying prospectus relate is available only to and will be engaged in only with relevant persons. Any person who is not a relevant person should not act or rely on this prospectus supplement, the accompanying prospectus or any of its contents.

Notice to Prospective Investors in Switzerland

This prospectus supplement is not intended to constitute an offer or solicitation to purchase or invest in the bonds. The bonds may not be publicly offered, directly or indirectly, in Switzerland within the meaning of the Swiss Financial Services Act (“FinSA”) and no application has or will be made to admit the bonds to trading on any trading venue (exchange or multilateral trading facility) in Switzerland. Neither this prospectus supplement nor any other offering or marketing material relating to the bonds constitutes a prospectus pursuant to the FinSA, and neither this prospectus supplement nor any other offering or marketing material relating to the bonds may be publicly distributed or otherwise made publicly available in Switzerland.

Notice to Prospective Investors in Japan

The notes have not been and will not be registered pursuant to Article 4, Paragraph 1 of the Financial Instruments and Exchange Act. Accordingly, none of the notes nor any interest therein may be offered or sold, directly or indirectly, in Japan or to, or for 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 or to or for the benefit of a resident of Japan, except pursuant to an exemption from the registration requirements of, and otherwise in compliance with, the Financial Instruments and Exchange Act and any other applicable laws, regulations and ministerial guidelines of Japan in effect at the relevant time.

Notice to Prospective Investors in People’s Republic of China

The notes are not being offered or sold and may not be offered or sold, directly or indirectly, in the People’s Republic of China, or the “PRC” (for such purposes, not including the Hong Kong and Macau Special Administrative Regions or Taiwan), except as permitted by the securities laws of the PRC.

Notice to Prospective Investors in Hong Kong

Each underwriter (i) has not offered or sold and will not offer or sell in Hong Kong, by means of any document, any notes other than (a) to “professional investors” as defined in the Securities and Futures Ordinance (Cap. 571) of Hong Kong (the “SFO”) and any rules made under that Ordinance; 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 Hong Kong or which do not constitute an offer to the public within the meaning of that Ordinance; and (ii) has not issued or had in its possession for the purposes of issue, and will not issue or have in its possession for the purposes of issue, whether in Hong Kong or elsewhere, any advertisement, invitation or document relating to the Notes, 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 notes which are or are intended to be disposed of only to persons

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outside Hong Kong or only to “professional investors” as defined in the SFO and any rules made under that Ordinance.

Notice to Prospective Investors in Singapore

This prospectus supplement and the accompanying prospectus have not been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, each underwriter has not offered or sold any notes or caused such notes to be made the subject of an invitation for subscription or purchase and will not offer or sell such notes or cause such notes to be made the subject of an invitation for subscription or purchase, and has not circulated or distributed, nor will it circulate or distribute, this prospectus supplement, the accompanying prospectus or any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of such notes, whether directly or indirectly, to persons in Singapore other than (i) to an institutional investor under Section 274 of the Securities and Futures Act, Chapter 289 of Singapore (the “SFA”), (ii) to a relevant person pursuant to Section 275(1), or any person pursuant to Section 275(1A), and in accordance with the conditions specified in Section 275, of the SFA, or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA.

Where the notes are subscribed or purchased under Section 275 of the SFA by a relevant person which is:

Singapore SFA Product Classification—In connection with Section 309B of the SFA and the CMP Regulations 2018, unless otherwise specified before an offer of notes, the Company has determined, and hereby notifies all relevant persons (as defined in Section 309A(1) of the SFA) that the notes 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).

Notice to Prospective Investors in Canada

The notes may be sold only to purchasers 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 are permitted clients, as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations. Any resale of the notes must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.

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Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus supplement (including any amendment thereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser’s province or territory. The 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 (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.

Notice to Prospective Investors in Australia

No placement document, offering memorandum, product disclosure statement or other disclosure document has been lodged with the Australian Securities and Investments Commission (“ASIC”), in relation to the offering. This prospectus does not constitute a prospectus, product disclosure statement or other disclosure document under the Corporations Act 2001 (the “Corporations Act”), and does not purport to include the information required for a prospectus, product disclosure statement or other disclosure document under the Corporations Act.

Any offer in Australia of the securities may only be made to persons (the “Exempt Investors”) who are “sophisticated investors” (within the meaning of section 708(8) of the Corporations Act), “professional investors” (within the meaning of section 708(11) of the Corporations Act) or otherwise pursuant to one or more exemptions contained in section 708 of the Corporations Act so that it is lawful to offer the securities without disclosure to investors under Chapter 6D of the Corporations Act.

The securities applied for by Exempt Investors in Australia must not be offered for sale in Australia in the period of 12 months after the date of allotment under the offering, except in circumstances where disclosure to investors under Chapter 6D of the Corporations Act would not be required pursuant to an exemption under section 708 of the Corporations Act or otherwise or where the offer is pursuant to a disclosure document which complies with Chapter 6D of the Corporations Act.

Any person acquiring securities must observe such Australian on-sale restrictions. This prospectus supplement and the accompanying prospectus contain general information only and does not take account of the investment objectives, financial situation or particular needs of any particular person. It does 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 are appropriate to their needs, objectives and circumstances, and, if necessary, seek expert advice on those matters.

Notice to Prospective Investors in Dubai

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. They 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 or the accompanying prospectus nor taken steps to verify the information set forth herein and has no responsibility for the prospectus supplement or the accompanying prospectus. The securities to which this prospectus supplement relates may be illiquid and/or subject to restrictions on their resale. Prospective purchasers of the securities offered should conduct their own due diligence on the securities. If you do not understand the contents of this prospectus supplement you should consult an authorized financial advisor.

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Notice to Prospective Investors in the Republic of Italy

The offering of the notes has not been registered with the Commissione Nazionale per le Società e la Borsa (“CONSOB”) pursuant to Italian securities legislation and, accordingly, no notes may be offered, sold or delivered, directly or indirectly, nor copies of this prospectus supplement, the accompanying prospectus, any pricing supplement or any other documents relating to the notes may be distributed in Italy, either on the primary or the secondary market, except:

Any offer, sale or delivery of the notes or distribution of copies of this prospectus supplement, the accompanying prospectus, any pricing supplement or any other documents relating to the notes in Italy must be, in any event, conducted:

Any investor purchasing the notes is solely responsible for ensuring that any offer or resale of the notes by such investor occurs in compliance with applicable laws and regulations.

Notice to Prospective Investors in Korea

The securities have 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 securities have been and will be offered in Korea as a private placement under the FSCMA. None of the securities may 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 the applicable laws and regulations of Korea, including the FSCMA and the Foreign Exchange Transaction Law of Korea and the decrees and regulations thereunder, or the FETL. The securities have not been listed on any of securities exchanges in the world including, without limitation, the Korea Exchange in Korea. Furthermore, the purchaser of the securities shall comply with all applicable regulatory requirements (including, but not limited to, requirements under the FETL) in connection with the purchase of the securities. By the purchase of the securities, the relevant holder thereof will be deemed to represent and warrant that if it is in Korea or is a resident of Korea, it purchased the securities pursuant to the applicable laws and regulations of Korea.

Notice to Prospective Investors in Taiwan

The notes may be made available for purchase from outside Taiwan by investors residing in Taiwan either directly or through a duly licensed Taiwan intermediary, but may not be offered or sold in Taiwan. Any

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subscriptions of notes shall only become effective upon acceptance by the relevant Issuer or the relevant Agent outside Taiwan and shall be deemed a contract entered into in the jurisdiction of incorporation of the relevant Issuer or Agent, as the case may be.

Notice to Prospective Investors in the United Arab Emirates

The securities have not been, and are not being, publicly offered, sold, promoted or advertised in the United Arab Emirates (including the Dubai International Financial Centre) other than in compliance with the laws of the United Arab Emirates (and the Dubai International Financial Centre) 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 Dubai International Financial Centre) 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 or the Dubai Financial Services Authority.

Notice to Prospective Investors in the Abu Dhabi Global Market

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).

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LEGAL MATTERS

Bracewell LLP, Houston, Texas, our outside counsel, will issue an opinion about certain legal matters in connection with the offering of the notes for us. Cravath, Swaine & Moore LLP, New York, New York, will issue an opinion about certain legal matters in connection with the offering for the underwriters.

EXPERTS

The consolidated financial statements of Phillips 66 appearing in Phillips 66’s Annual Report (Form 10-K) for the year ended December 31, 2023, and the effectiveness of Phillips 66’s internal control over financial reporting as of December 31, 2023, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their reports thereon, included therein, and incorporated herein by reference which, as to the consolidated financial statements as of December 31, 2023 and 2022, and for the year ended December 31, 2023, and the period from August 17, 2022 through December 31, 2022, and the effectiveness of internal control over financial reporting as of December 31, 2023, are based in part on the reports of Deloitte & Touche LLP, independent registered public accounting firm, for the audit of DCP Midstream, LP, a consolidated subsidiary of Phillips 66. The consolidated financial statements of DCP Midstream, LP (consolidated with the financial statements of Phillips 66 beginning on August 17, 2022, but not presented separately within the Phillips 66 Annual Report on Form 10-K) as of December 31, 2023 and 2022, and for each of the two years in the period ended December 31, 2023 have been audited by Deloitte & Touche LLP, as stated in their report thereon, which is incorporated herein by reference. The consolidated financial statements of Phillips 66, referred to above, are incorporated herein by reference in reliance upon the respective reports of such firms given upon their authority as experts in accounting and auditing.

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PROSPECTUS

We will provide specific terms of any offering in one or more supplements to this prospectus. The securities may be offered separately or together in any combination and as a separate series. You should read this prospectus and any prospectus supplement carefully before you invest in our securities.

Our common stock is listed on the New York Stock Exchange under the symbol “PSX.”

If any offering involves underwriters, dealer or agents, arrangements with them will be described in the prospectus supplement that relates to that offering.

Investing in our securities involves risks that are referenced in the “Risk Factors” section on page 5 of this prospectus.

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

The date of this prospectus is July 29, 2022.

TABLE OF CONTENTS

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ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement on Form S-3 that we have filed with the U.S. Securities and Exchange Commission using a “shelf” registration process. Using this process, we may offer any combination of the securities described in this prospectus in one or more offerings. This prospectus provides you with a general description of the securities we may offer. Each time we use this prospectus to offer securities, we will provide a prospectus supplement and, if applicable, a pricing supplement that will describe the specific terms of the offering. The prospectus supplement and any pricing supplement may also add to, update or change the information contained in this prospectus. Please carefully read this prospectus, the prospectus supplement and any pricing supplement, in addition to the information contained in the documents we refer to under the heading “Where You Can Find More Information.”

Except as otherwise indicated, references in this prospectus to “Phillips 66,” “PSX,” the “Company,” “we,” “us” and “our” refer to Phillips 66 and its consolidated subsidiaries.

ABOUT PHILLIPS 66

Phillips 66, headquartered in Houston, Texas, was incorporated in Delaware in 2011. Phillips 66 manufactures, transports and markets products that drive the global economy. The diversified energy company’s portfolio includes Midstream, Chemicals, Refining, and Marketing and Specialties businesses. Phillips 66 has employees around the globe who are committed to safely and reliably providing energy and improving lives while pursuing a lower-carbon future. Phillips 66’s principal executive offices are located at 2331 CityWest Blvd., Houston, Texas, and its telephone number at that location is (832)  765-3010. The company’s internet website is www.phillips66.com.

ABOUT PHILLIPS 66 COMPANY

Phillips 66 Company, a Delaware corporation, is a direct, wholly-owned subsidiary of Phillips 66. Its principal executive offices are located at 2331 CityWest Blvd., Houston, Texas, and its telephone number at that location is (832) 765-3010. We may refer to Phillips 66 Company in this prospectus as “P66Co.”

WHERE YOU CAN FIND MORE INFORMATION

Phillips 66 files annual, quarterly and current reports, proxy statements and other information with the Securities and Exchange Commission (the “SEC”). The SEC maintains an Internet site that contains information Phillips 66 has filed electronically with the SEC, which you can access over the Internet at http://www.sec.gov. You can also obtain information about Phillips 66 at the offices of the New York Stock Exchange, 20 Broad Street, New York, New York 10005. Phillips 66 Company does not file separate reports, proxy statements or other information with the SEC under the Securities Exchange Act of 1934 (the “Exchange Act”).

This prospectus is part of a registration statement on Form S-3 we have filed with the SEC relating to the securities we may offer. As permitted by SEC rules, this prospectus does not contain all of the information we have included in the registration statement and the accompanying exhibits and schedules we file with the SEC. You may refer to the registration statement, exhibits and schedules for more information about us and the securities. The registration statement, exhibits and schedules are available at the SEC’s public reference room or through its Internet site.

The SEC allows us to “incorporate by reference” the information we have filed with it, which means that we can disclose important information to you by referring you to those documents. The information we incorporate

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by reference is an important part of this prospectus, and later information that we file with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings Phillips 66 makes with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Exchange Act until the termination of this offering. The documents we incorporate by reference are:

We will provide without charge to each person, including any beneficial owner, to whom this prospectus is delivered, a copy of any document incorporated by reference into this prospectus, other than exhibits to any such document not specifically described above, upon oral request or written request or by making a request on our website at www.phillips66.com:

Phillips 66

Investor Relations Department

2331 CityWest Blvd.

Houston, Texas 77042

Telephone: 832-765-3010

You should rely only on the information contained or incorporated by reference in this prospectus, the prospectus supplement and any pricing supplement. We have not authorized any person, including any salesman or broker, to provide information other than that provided in this prospectus, the prospectus supplement or any pricing supplement. We have not authorized anyone to provide you with different information. We are not making an offer of the securities in any jurisdiction where the offer is not permitted. You should assume that the information in this prospectus, the prospectus supplement and any pricing supplement is accurate only as of the date on its cover page and that any information we have incorporated by reference is accurate only as of the date of the document incorporated by reference.

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FORWARD-LOOKING INFORMATION

This prospectus, including the information we incorporate by reference, includes 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. You can identify our forward-looking statements by the words “anticipate,” “estimate,” “believe,” “budget,” “continue,” “could,” “intend,” “may,” “plan,” “potential,” “predict,” “seek,” “should,” “will,” “would,” “expect,” “objective,” “projection,” “forecast,” “goal,” “guidance,” “outlook,” “effort,” “target” and similar expressions.

We based the forward-looking statements on our current expectations, estimates and projections about ourselves and the industries in which we operate in general. We caution you that these statements are not guarantees of future performance as they involve assumptions that, while made in good faith, may prove to be incorrect, and involve risks and uncertainties we cannot predict. In addition, we based many of these forward-looking statements on assumptions about future events that may prove to be inaccurate. Accordingly, our actual outcomes and results may differ materially from what we have expressed or forecast in the forward-looking statements. Any differences could result from a variety of factors, including the following:

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RISK FACTORS

You should carefully consider any specific risks set forth under the caption “Risk Factors” in the applicable prospectus supplement, under the caption “Risk Factors” included in our 2021 Annual Report on Form 10-K, and under the caption “Risk Factors” in any of our subsequent annual reports on Form 10-K and quarterly reports on Form 10-Q incorporated by reference in this prospectus, before making an investment decision. For more information, see “Where You Can Find More Information.”

USE OF PROCEEDS

Unless we inform you otherwise in the prospectus supplement, the net proceeds from the sale of the securities will be used for general corporate purposes, including repayment or refinancing of debt, acquisitions, working capital, capital expenditures and repurchases and redemptions of securities. Pending any specific application, we may initially invest funds in short-term marketable securities or apply them to the reduction of other short-term indebtedness.

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DESCRIPTION OF THE DEBT SECURITIES

The debt securities of Phillips 66 covered by this prospectus will be Phillips 66’s general unsecured obligations. Phillips 66 will issue senior debt securities fully and unconditionally guaranteed by P66Co on a senior unsecured basis. The senior debt securities of Phillips 66 will be issued under an indenture, dated as of April 9, 2020, among Phillips 66, as issuer, P66Co, as guarantor, and U.S. Bank Trust Company, National Association, as trustee. We refer to this indenture as the “Phillips 66 senior indenture.” Phillips 66 will issue subordinated debt securities under an indenture to be entered into between Phillips 66 and U.S. Bank Trust Company, National Association, as trustee. We refer to this indenture as the “subordinated indenture.”

The debt securities of P66Co covered by this prospectus will be P66Co’s general unsecured obligations. P66Co will issue senior debt securities fully and unconditionally guaranteed by Phillips 66 on a senior unsecured basis. The senior debt securities of P66Co will be issued under an indenture, dated as of May 5, 2022, among P66Co, as issuer, Phillips 66, as guarantor, and U.S. Bank Trust Company, National Association, as trustee. We refer to this indenture as the “P66Co senior indenture.”

We refer to the Phillips 66 senior indenture and the P66Co senior indenture as the “senior indentures” and to the debt securities issued thereunder as the “senior debt securities.” We refer to the senior indentures and the subordinated indenture collectively as the “indentures.” The Phillips 66 senior indenture and the P66Co senior indenture are substantially identical, except for the identity of the issuer and guarantor. The Phillips 66 senior indenture and the subordinated indenture will be substantially identical, except for provisions relating to subordination and covenants.

We have summarized material provisions of the indentures, the debt securities and the guarantees below. This summary is not complete. We have filed the senior indentures and the form of the subordinated indenture with the SEC as exhibits to the registration statement of which this prospectus forms a part, and you should read the indentures for provisions that may be important to you.

In this summary description of the debt securities, unless we state otherwise or the context clearly indicates otherwise, all references to Phillips 66 mean Phillips 66 only and all references to P66Co mean Phillips 66 Company only.

Provisions Applicable to Each Indenture

General. Neither the Phillips 66 senior indenture nor the subordinated indenture limits the amount of debt securities that may be issued under that indenture, and neither limits the amount of other unsecured debt or securities that Phillips 66 may issue. Phillips 66 may issue debt securities under the Phillips 66 senior indenture and the subordinated indenture from time to time in one or more series, each in an amount authorized prior to issuance.

The P66Co senior indenture does not limit the amount of debt securities that may be issued under that indenture and does not limit the amount of other unsecured debt or securities that P66Co may issue. P66Co may issue debt securities under the P66Co senior indenture from time to time in one or more series, each in an amount authorized prior to issuance.

Phillips 66 conducts substantially all of its operations through subsidiaries, and those subsidiaries generate substantially all of Phillips 66’s operating income and cash flow. As a result, distributions or advances from those subsidiaries are the principal source of funds necessary to meet the debt service obligations of Phillips 66. Contractual provisions or laws, as well as the subsidiaries’ financial condition and operating requirements, may limit the ability of Phillips 66 to obtain cash from its subsidiaries that it requires to pay its debt service obligations, including any payments required to be made under the debt securities. Although P66Co owns certain operating assets directly, it conducts a substantial portion of its operations through subsidiaries. Accordingly,

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contractual provisions or laws, as well as its subsidiaries’ financial condition and operating requirements, may limit the ability of P66Co to obtain cash from its subsidiaries that it requires to pay its debt service obligations, including any payments required to be made under the debt securities. The subsidiaries of Phillips 66 and P66Co are legally distinct and have no obligations to pay amounts due on the indebtedness of Phillips 66 or P66Co, or to make funds available for such payment. In addition, subsidiaries of Phillips 66 and P66Co will be permitted under the terms of the indentures to incur additional indebtedness that may restrict or prohibit the making of distributions, the payment of dividends or the making of loans by such subsidiaries to Phillips 66 and P66Co. The agreements governing future indebtedness of our subsidiaries may not permit our subsidiaries to provide Phillips 66 or P66Co, as applicable, with sufficient dividends, distributions or loans to fund payments on the debt securities when due.

Other than the restrictions contained in the senior indentures on liens and sale/leaseback transactions described below under “—Provisions Applicable Solely to Senior Debt Securities—Restrictive Covenants,” the indentures do not contain any covenants or other provisions designed to protect holders of the debt securities in the event Phillips 66 or P66Co participates in a highly leveraged transaction or upon a change of control. The indentures do not contain provisions that give holders the right to require Phillips 66 or P66Co to repurchase their securities in the event of a decline in Phillips 66’s or P66Co’s credit ratings for any reason, including as a result of a takeover, recapitalization or similar restructuring or otherwise.

Terms. The prospectus supplement relating to any series of debt securities being offered will include specific terms relating to the offering. These terms will include some or all of the following:

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Phillips 66 and P66Co may sell the debt securities at a discount, which may be substantially below their stated principal amount. These debt securities may bear no interest or interest at a rate that at the time of issuance is below market rates. If Phillips 66 or P66Co sells these debt securities, it will describe in the applicable prospectus supplement any material United States federal income tax consequences and other special considerations.

If Phillips 66 or P66Co sells any of the debt securities for any foreign currency or currency unit or if payments on the debt securities are payable in any foreign currency or currency unit, it will describe in the prospectus supplement the restrictions, elections, tax consequences, specific terms and other information relating to those debt securities and the foreign currency or currency unit.

Consolidation, Merger and Sale of Assets. The indentures generally permit a consolidation or merger involving Phillips 66 or, with respect to the senior indentures, P66Co. They also permit Phillips 66 or, with respect to the senior indentures, P66Co, as applicable, to lease, transfer or dispose of all or substantially all of its assets. Each of Phillips 66 and, with respect to the senior indentures, P66Co has agreed, however, that it will not consolidate with or merge into any entity (other than, with respect to the senior indentures, Phillips 66 or P66Co, as applicable) or lease, transfer or dispose of all or substantially all of its assets to any entity (other than, with respect to the senior indentures, Phillips 66 or P66Co, as applicable) unless:

Upon any such consolidation, merger or asset lease, transfer or disposition involving Phillips 66 or, with respect to the senior indentures, P66Co, the resulting entity or transferee will be substituted for Phillips 66 or, with respect to the senior indentures, P66Co, as applicable, under the applicable indenture and debt securities. In the case of an asset transfer or disposition other than a lease, Phillips 66 or, with respect to the senior indentures, P66Co, as applicable, will be released from the applicable indenture.

Events of Default. Unless Phillips 66 or P66Co informs you otherwise in the applicable prospectus supplement, the following are events of default with respect to a series of debt securities:

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A default under one series of debt securities will not necessarily be a default under another series. The trustee may withhold notice to the holders of the debt securities of any default or event of default (except in any payment on the debt securities) if the trustee in good faith considers it in the interest of the holders of the debt securities to do so.

If an event of default for any series of debt securities occurs and is continuing, the trustee or the holders of at least 25% in principal amount of the outstanding debt securities of the series affected by the default (or, in some cases, 25% in principal amount of all debt securities issued under the applicable indenture that are affected, voting as one class) may declare the principal of and all accrued and unpaid interest on those debt securities to be due and payable. If an event of default relating to certain events of bankruptcy, insolvency or reorganization occurs, the principal of and interest on all the debt securities issued under the applicable indenture will become immediately due and payable without any action on the part of the trustee or any holder. The holders of a majority in principal amount of the outstanding debt securities of the series affected by the default (or, in some cases, of all debt securities issued under the applicable indenture that are affected, voting as one class) may in some cases rescind this accelerated payment requirement.

A holder of a debt security of any series issued under an indenture may pursue any remedy under that indenture only if:

This provision does not, however, affect the right of a holder of a debt security to sue for enforcement of any overdue payment.

In most cases, holders of a majority in principal amount of the outstanding debt securities of a series (or of all debt securities issued under the applicable indenture that are affected, voting as one class) may direct the time, method and place of:

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The senior indentures require Phillips 66 and Phillips 66 Company, and the subordinated indenture will require Phillips 66, to file each year with the trustee a written statement as to their compliance with the covenants contained in the applicable indenture.

Modification and Waiver. Each indenture may be amended or supplemented with respect to the debt securities of any series if the holders of a majority in principal amount of the outstanding debt securities of a series issued under that indenture that are affected by the amendment or supplement consent to it. Without the consent of the holder of each debt security affected, however, no modification may:

Each indenture may be amended or supplemented or any provision of that indenture may be waived without the consent of any holders of debt securities issued under that indenture in certain circumstances, including:

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The holders of a majority in principal amount of the outstanding debt securities of any series may waive any existing or past default or event of default with respect to those debt securities. Those holders may not, however, waive any default or event of default in any payment on any debt security or compliance with a provision that cannot be amended or supplemented without the consent of each holder affected.

Discharge. Phillips 66 and, with respect to the senior indentures, P66Co may be discharged from their obligations under an indenture with respect to one or more series of notes issued under that indenture when:

and, in the case of clause (i), (ii) or (iii) above, Phillips 66 or, with respect to the senior indentures, P66Co has irrevocably deposited or caused to be deposited with the trustee as funds (immediately available to the holders in the case of clause (i)) in trust for such purpose (x) cash in an amount, or (y) government obligations, maturing as to principal and interest at such times and in such amounts as will ensure the availability of cash in an amount or (z) a combination thereof, which will be sufficient without consideration of any reinvestment of interest, in the opinion (in the case of clauses (y) and (z)) of a nationally recognized firm of independent public accountants expressed in a written certification thereof delivered to the trustee, to pay and discharge the entire indebtedness on the debt securities of such series for principal and interest to the date of such deposit (in the case of debt securities that have become due and payable) or for principal, premium, if any, and interest to the stated maturity or redemption date, as the case may be.

Phillips 66 or P66Co will be required to deliver to the trustee under the applicable indenture an officer’s certificate stating that all conditions precedent to satisfaction and discharge of that indenture with respect to the debt securities of such series have been complied with, together with an opinion of counsel to the same effect.

Defeasance. When we use the term defeasance, we mean discharge from some or all of the obligations of Phillips 66 and, with respect to the senior indentures, P66Co under the indentures. If any combination of funds or government securities are deposited with the trustee under an indenture sufficient to make payments on the debt securities of a series issued under that indenture on the dates those payments are due and payable, then, at the option of Phillips 66, or with respect to the P66Co senior indenture, P66Co, either of the following will occur:

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If a series of debt securities is defeased, the holders of the debt securities of the series affected will not be entitled to the benefits of the applicable indenture, except for obligations to register the transfer or exchange of debt securities, replace stolen, lost or mutilated debt securities or maintain paying agencies and hold moneys for payment in trust. In the case of covenant defeasance, the obligation of Phillips 66 or, with respect to the P66Co senior indenture, P66Co to pay principal, premium and interest on the debt securities and, if applicable, P66Co’s or Phillips 66’s guarantees of the payments will also survive.

Unless we inform you otherwise in the prospectus supplement, we will be required to deliver to the trustee an opinion of counsel that the deposit and related defeasance would not cause the holders of the debt securities to recognize income, gain or loss for U.S. federal income tax purposes. If we elect legal defeasance, that opinion of counsel must be based upon a ruling from the U.S. Internal Revenue Service or a change in law to that effect.

Reports. If Phillips 66 or, with respect to the senior indentures, P66Co is subject to the requirements of Section 13 or 15(d) of the Exchange Act, Phillips 66 or P66Co, as the case may be, shall file with the trustee, within 15 days after it files the same with the SEC, copies of the annual and quarterly reports and the information, documents and other reports (or such portions of any of the foregoing as the SEC may by rules and regulations prescribe) that Phillips 66 or, with respect to the senior indentures, P66Co is required to file with the SEC pursuant to Section 13 or 15(d) of the Exchange Act. If an indenture is qualified under the Trust Indenture Act of 1939, as amended (the “Trust Indenture Act”), but not otherwise, Phillips 66 and, with respect to the senior indentures, P66Co shall also comply with the provisions of the Trust Indenture Act Section 314(a). Delivery of such reports, information and documents to the trustee shall be for informational purposes only, and the trustee’s receipt thereof will not constitute actual or constructive notice of any information contained therein or determinable from information contained therein, including the compliance of Phillips 66 or P66Co with any of its covenants under the applicable indenture (as to which the trustee is entitled to rely exclusively on an officers’ certificate). The trustee will not be obligated to monitor or confirm, on a continuing basis or otherwise, Phillips 66’s or, with respect to the senior indentures, P66Co’s compliance with the covenants in the indenture with respect to the filing of such reports and such information, documents and other reports with the SEC.

If neither Phillips 66 nor P66Co is subject to the requirements of Section 13 or 15(d) of the Exchange Act, we will furnish to all holders of the notes and prospective purchasers of debt securities designated by the holders of the debt securities, promptly upon their request, the information required to be delivered pursuant to Rule 144A(d)(4) promulgated under the Securities Act.

Governing Law. New York law will govern the indentures and the debt securities.

Trustee. U.S. Bank Trust Company, National Association is the trustee under the senior indentures and will be the trustee under the subordinated indenture. U.S. Bank Trust Company, National Association serves as trustee relating to a number of series of debt securities of Phillips 66 and its subsidiaries as of June 30, 2022. Affiliates of U.S. Bank Trust Company, National Association may perform certain commercial banking services for us for which they may receive customary fees.

If an event of default occurs under an indenture and is continuing, the trustee under that indenture will be required to use the degree of care and skill of a prudent person in the conduct of that person’s own affairs. The trustee will become obligated to exercise any of its powers under that indenture at the request of any of the holders of any debt securities issued under that indenture only after those holders have offered the trustee indemnity satisfactory to it.

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Each indenture contains limitations on the right of the trustee, if it becomes a creditor of Phillips 66 or, if applicable, P66Co, to obtain payment of claims or to realize on certain property received for any such claim, as security or otherwise. The trustee is permitted to engage in other transactions with Phillips 66 and, if applicable, P66Co. If, however, it acquires any conflicting interest, it must eliminate that conflict or resign within 90 days after ascertaining that it has a conflicting interest and after the occurrence of a default under the applicable indenture, unless the default has been cured, waived or otherwise eliminated within the 90-day period.

Form, Exchange, Registration and Transfer. The debt securities will be issued in registered form, without interest coupons. There will be no service charge for any registration of transfer or exchange of the debt securities. However, payment of any transfer tax or similar governmental charge payable for that registration may be required.

Debt securities of any series will be exchangeable for other debt securities of the same series, the same total principal amount and the same terms but in different authorized denominations in accordance with the applicable indenture. Holders may present debt securities for registration of transfer at the office of the security registrar or any transfer agent designated by Phillips 66 or P66Co, as applicable. The security registrar or transfer agent will effect the transfer or exchange if its requirements and the requirements of the applicable indenture are met.

The trustee will be appointed as security registrar for the debt securities. If a prospectus supplement refers to any transfer agents Phillips 66 or, if applicable, P66Co initially designates, Phillips 66 or, if applicable, P66Co may at any time rescind that designation or approve a change in the location through which any transfer agent acts. Phillips 66 and P66Co are required to maintain an office or agency for transfers and exchanges in each place of payment. Phillips 66 and P66Co may at any time designate additional transfer agents for any series of debt securities.

In the case of any redemption, Phillips 66 or, if applicable, P66Co will not be required to register the transfer or exchange of:

Payment and Paying Agents. Unless we inform you otherwise in a prospectus supplement, payments on the debt securities will be made in U.S. dollars at the office of the trustee and any paying agent. At the option of Phillips 66, or with respect to the P66Co senior debt securities, P66Co, however, payments may be made by wire transfer for global debt securities or by check mailed to the address of the person entitled to the payment as it appears in the security register. Unless we inform you otherwise in a prospectus supplement, interest payments may be made to the person in whose name the debt security is registered at the close of business on the record date for the interest payment.

Unless we inform you otherwise in a prospectus supplement, the trustee under the applicable indenture will be designated as the paying agent for payments on debt securities issued under that indenture.

Phillips 66 or P66Co, as applicable, may at any time designate additional paying agents or rescind the designation of any paying agent or approve a change in the office through which any paying agent acts.

If the principal of or any premium or interest on debt securities of a series is payable on a day that is not a business day, the payment will be made on the following business day. For these purposes, unless we inform you otherwise in a prospectus supplement, a “business day” is any day that is not a Saturday, a Sunday or a day on

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which banking institutions in any of New York, New York, or Houston, Texas or a place of payment on the debt securities of that series is authorized or obligated by law, regulation or executive order to remain closed.

Subject to the requirements of any applicable abandoned property laws, the trustee and paying agent will pay to us upon written request any money held by them for payments on the debt securities that remains unclaimed for two years after the date upon which that payment has become due. After payment to us, holders entitled to the money must look to us for payment. In that case, all liability of the trustee or paying agent with respect to that money will cease.

Book-Entry Debt Securities. The debt securities of a series may be issued in the form of one or more global debt securities that would be deposited with a depositary or its nominee identified in the prospectus supplement. Global debt securities may be issued in either temporary or permanent form. We will describe in the prospectus supplement the terms of any depositary arrangement and the rights and limitations of owners of beneficial interests in any global debt security.

Provisions Applicable Solely to Senior Debt Securities

Ranking. The Phillips 66 senior debt securities will constitute senior debt of Phillips 66 and will rank equally with all of its unsecured and unsubordinated debt from time to time outstanding. The P66Co senior debt securities will constitute senior debt of P66Co and will rank equally with all of its unsecured and unsubordinated debt from time to time outstanding.

Guarantee. Pursuant to the Phillips 66 senior indenture, P66Co will fully and unconditionally guarantee on a senior unsecured basis the full and prompt payment of the principal of and any premium and interest on the senior debt securities issued by Phillips 66 when and as the payment becomes due and payable, whether at maturity or otherwise. The guarantees provide that in the event of a default in the payment of principal of or any premium or interest on a Phillips 66 senior debt security, the holder of that debt security may institute legal proceedings directly against P66Co to enforce the guarantees without first proceeding against Phillips 66. The guarantees will rank equally with all of P66Co’s other unsecured and unsubordinated debt from time to time outstanding.

Pursuant to the P66Co senior indenture, Phillips 66 will fully and unconditionally guarantee on a senior unsecured basis the full and prompt payment of the principal of and any premium and interest on the senior debt securities issued by P66Co when and as the payment becomes due and payable, whether at maturity or otherwise. The guarantees provide that in the event of a default in the payment of principal of or any premium or interest on a P66Co senior debt security, the holder of that debt security may institute legal proceedings directly against Phillips 66 to enforce the guarantees without first proceeding against P66Co. The guarantees will rank equally with all of Phillips 66’s other unsecured and unsubordinated debt from time to time outstanding.

Restrictive Covenants. Phillips 66 has agreed to two principal restrictions on its activities for the benefit of holders of the Phillips 66 senior debt securities and P66Co debt securities. The restrictive covenants summarized below will apply to a series of senior debt securities (unless waived or amended) as long as any of those debt securities are outstanding, unless the prospectus supplement for the series states otherwise. We have used in this summary description capitalized terms that we have defined below under “—Glossary.”

Limitation on Liens

Phillips 66 has agreed that it and its Principal Domestic Subsidiaries will issue, assume or guarantee Debt for borrowed money secured by a lien upon a Principal Property or shares of stock or Debt of any Principal Domestic Subsidiary only if the outstanding senior debt securities are secured equally and ratably with or prior to the Debt secured by that lien. If the senior debt securities are so secured, Phillips 66 has the option to secure any

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of its and its Subsidiaries’ other Debt or obligations equally and ratably with or prior to the Debt secured by the lien and equally and ratably with the senior debt securities. This covenant has exceptions that permit:

(a) with respect to the Phillips 66 senior indenture, liens existing on the date Phillips 66 first issued a series of debt securities under such indenture and, with respect to the P66Co senior indenture, liens existing on the date P66Co first issued a series of debt securities under such indenture;

(b) liens on the property, assets, stock, equity or Debt of any entity existing at the time Phillips 66 or a Subsidiary acquires that entity or its property or at the time the entity becomes a Subsidiary or a Principal Domestic Subsidiary or at the time such entity is merged into or consolidated with Phillips 66 or any Subsidiary or at the time of a sale, lease or other disposition of the properties of an entity (or a division thereof) as an entirety or substantially as an entirety to Phillips 66 or a Subsidiary;

(c) liens on assets either:

(d) liens in favor of Phillips 66 or any Subsidiary;

(e) liens securing industrial development, pollution control or other revenue bonds issued or guaranteed by the United States of America, or any State, or any department, agency, instrumentality or political subdivision of either;

(f) liens on personal property, other than shares of stock or Debt of any Principal Domestic Subsidiary, securing loans maturing not more than one year from the date of the creation thereof;

(g) statutory liens or landlords’, carriers’, warehousemans’, mechanics’, suppliers’, materialmen’s, repairmen’s or other like liens arising in the ordinary course of business and with respect to amounts not yet delinquent or being contested in good faith by appropriate proceedings; and

(h) any extensions, substitutions, replacements or renewals of the above-described liens or any Debt secured by these liens provided that:

In addition, without securing the senior debt securities as described above, Phillips 66 and its Principal Domestic Subsidiaries may issue, assume or guarantee Debt that this covenant would otherwise restrict in a total principal amount that, when added to all other outstanding Debt of Phillips 66 and its Principal Domestic

Subsidiaries that this covenant would otherwise restrict and the total amount of Attributable Debt deemed outstanding for Sale/Leaseback Transactions, does not at any one time exceed a “basket” equal to 10% of Consolidated Adjusted Net Assets, in the case of the Phillips 66 senior indenture, and 15% of Consolidated Adjusted Net Assets, in the case of the P66Co senior indenture. When calculating this total principal amount, we

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exclude from the calculation Attributable Debt from Sale/Leaseback Transactions in connection with which Phillips 66 or a Subsidiary has purchased property or retired or defeased Debt as described in clause (b) below under “Limitation on Sale/Leaseback Transactions.”

The following type of transaction does not create “Debt” secured by “liens” within the meaning of the senior indentures: the mortgage or pledge of any property of Phillips 66 or a Subsidiary in favor of the United States or any State, or any department, agency, instrumentality or political subdivision of either, to secure partial, progress, advance or other payments pursuant to the provisions of any contract or statute.

Limitation on Sale/Leaseback Transactions

Phillips 66 has agreed that it and any of its Principal Domestic Subsidiaries will enter into a Sale/Leaseback Transaction with any Person (other than Phillips 66 or a Subsidiary) only if at least one of the following applies:

(a) Phillips 66 or that Principal Domestic Subsidiary could incur Debt in a principal amount equal to the Attributable Debt for that Sale/Leaseback Transaction and, without violating the “Limitation on Liens” covenant, could secure that Debt by a lien on the property to be leased without equally and ratably securing the senior debt securities.

(b) Within a period commencing 12 months prior to the consummation of such Sale/Leaseback Transaction and ending 12 months after the consummation thereof, Phillips 66 or any Subsidiary shall have applied an amount equal to all or a portion of the net proceeds of such Sale/Leaseback Transaction either:

To the extent that any net proceeds are not applied for the purposes described in (b), such proceeds will be subject to the limitation described in (a). For purposes of these calculations, the net proceeds of the Sale/Leaseback Transaction means the net proceeds of the sale or transfer of the property leased in the Sale/Leaseback Transaction (or, if greater, the fair value of that property at the time of the Sale/Leaseback Transaction as determined by Phillips 66’s board of directors).

Glossary

“Attributable Debt” means the present value of the rental payments during the remaining term of the lease included in the Sale/Leaseback Transaction. To determine that present value, we use a discount rate equal to the lease rate of the Sale/Leaseback Transaction. For these purposes, rental payments do not include any amounts required to be paid for taxes, maintenance, repairs, insurance, assessments, utilities, operating and labor costs and other items that do not constitute payments for property rights. In the case of any lease that the lessee may terminate by paying a penalty, if the net amount (including payment of the penalty) would be reduced if the lessee terminated the lease on the first date that it could be terminated, then this lower net amount will be used.

“Consolidated Adjusted Net Assets” means the total amount of assets of Phillips 66 and its consolidated subsidiaries less:

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Phillips 66 will calculate its Consolidated Adjusted Net Assets based on its most recent quarterly balance sheet.

“Debt” means all notes, bonds, debentures or other similar evidences of debt for money borrowed.

“Funded Debt” means all Debt (including Debt incurred under any revolving credit, letter of credit or working capital facility) that matures on or is renewable to a date more than one year after the date the Debt is originally incurred.

“Person” means any individual, corporation, partnership, limited liability company, joint venture, incorporated or unincorporated association, joint-stock company, trust, unincorporated organization or government or other agency, instrumentality or political subdivision thereof or other entity of any kind.

“Principal Domestic Subsidiary” means Phillips 66 Company and any Subsidiary (1) that has substantially all its assets in the United States, (2) that owns a Principal Property and (3) in which Phillips 66’s capital investment, together with the outstanding balance of any intercompany loans to that Subsidiary and any debt of that Subsidiary guaranteed by Phillips 66 or any other Subsidiary, exceeds $100 million.

“Principal Property” means any refinery or manufacturing plant located in the United States, in each case owned by Phillips 66 or a Subsidiary. This term excludes any refinery or plant that in the opinion of Phillips 66’s board of directors is not of material importance to the total business conducted by Phillips 66 and its consolidated subsidiaries. This term also excludes any transportation or marketing facilities or assets.

“Sale/Leaseback Transaction” means any arrangement with any Person under which Phillips 66 or a Subsidiary leases any Principal Property that Phillips 66 or that Subsidiary has sold or transferred or will sell or transfer to that Person. This term excludes the following:

“Subsidiary” means an entity at least a majority of the outstanding voting stock of which is owned, directly or indirectly, by Phillips 66 or by one or more other Subsidiaries, or by Phillips 66 and one or more other Subsidiaries.

Provisions Applicable Solely to Subordinated Debt Securities

Ranking. The subordinated debt securities will rank junior to all Senior Debt of Phillips 66 and may rank equally with or senior to other subordinated debt of Phillips 66 that may be outstanding from time to time.

Subordination. Under the subordinated indenture, payment of the principal of and any premium and interest on the subordinated debt securities will generally be subordinated and junior in right of payment to the prior payment in full of all Senior Debt. Unless Phillips 66 informs you otherwise in the prospectus supplement, Phillips 66 may not make any payment of principal of or any premium or interest on the subordinated debt securities if it fails to pay the principal, interest, premium or any other amounts on any Senior Debt when due.

The subordination does not affect Phillips 66’s obligation, which is absolute and unconditional, to pay, when due, the principal of and any premium and interest on the subordinated debt securities. In addition, the subordination will not prevent the occurrence of any default under the subordinated indenture.

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The subordinated indenture will not limit the amount of Senior Debt that Phillips 66 may incur. As a result of the subordination of the subordinated debt securities, if Phillips 66 becomes insolvent, holders of subordinated debt securities may receive less on a proportionate basis than other creditors.

Unless Phillips 66 informs you otherwise in the prospectus supplement, “Senior Debt” will mean all debt, including guarantees, of Phillips 66, unless such debt states that it is not senior to the subordinated debt securities or other junior debt of Phillips 66. Senior Debt with respect to a series of subordinated debt securities could include other series of debt securities issued under the subordinated indenture.

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DESCRIPTION OF CAPITAL STOCK

The following description of Phillips 66’s common stock, preferred stock, Certificate of Incorporation (as defined below) and By-Laws (as defined below) is a summary only and is subject to the complete text of Phillips 66’s Certificate of Incorporation and By-Laws, which we have filed as exhibits to the registration statement of which this prospectus forms a part. You should read those documents for provisions that may be important to you.

Phillips 66 is authorized to issue 2.5 billion shares of common stock, par value $0.01 per share, and 500 million shares of preferred stock, par value $0.01 per share.

Common Stock

Voting Rights—Each share of our common stock is entitled to one vote on all matters submitted to a vote of stockholders. Members of our Board of Directors are elected by a majority of the votes cast in person or by proxy and entitled to vote, including votes to withhold authority and excluding abstentions. Holders of shares of our common stock do not have cumulative voting rights. In other words, a holder of a single share of common stock cannot cast more than one vote for each position to be filled on our Board of Directors. A consequence of not having cumulative voting rights is that the holders of a majority of the shares of common stock entitled to vote in the election of directors can elect all directors standing for election, which means that the holders of the remaining shares will not be able to elect any directors.

Other Rights—In the event of any liquidation, dissolution or winding up of Phillips 66, after the satisfaction in full of the liquidation preferences of holders of any preferred shares, holders of shares of our common stock are entitled to ratable distribution of the remaining assets available for distribution to stockholders. The shares of our common stock are not subject to redemption by operation of a sinking fund or otherwise. Holders of shares of our common stock are not entitled to preemptive rights.

Fully Paid—The issued and outstanding shares of our common stock are fully paid and non-assessable. This means the full purchase price for the outstanding shares of our common stock has been paid and the holders of such shares will not be assessed any additional amounts for such shares. Any additional shares of common stock that we may issue in the future will also be fully paid and non-assessable.

Phillips 66 common stock is traded on the New York Stock Exchange under the trading symbol “PSX.” The transfer agent for the common stock is Computershare Trust Company N.A.

Preferred Stock

Our Board of Directors, without further action by the holders of our common stock, may issue shares of our preferred stock. Our Board of Directors is vested with the authority to fix by resolution the designations, preferences and relative, participating, optional or other special rights, and such qualifications, limitations or restrictions thereof, including, without limitation, redemption rights, dividend rights, liquidation preferences and conversion or exchange rights of any class or series of preferred stock, and to fix the number of classes or series of preferred stock, the number of shares constituting any such class or series and the voting powers for each class or series.

The authority of our Board of Directors to issue preferred stock could potentially be used to discourage attempts by third parties to obtain control of our company through a merger, tender offer, proxy contest or otherwise by making such attempts more difficult or more costly. Our Board of Directors may issue preferred stock with voting rights or conversion rights that, if exercised, could adversely affect the voting power of the holders of common stock. No current agreements or understandings exist with respect to the issuance of preferred stock, and our Board of Directors has no present intention to issue any shares of preferred stock.

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The prospectus supplement relating to any series of preferred stock Phillips 66 is offering will include specific terms relating to the offering and the name of any transfer agent for that series. We will file the form of the preferred stock with the SEC before we issue any of it, and you should read it for provisions that may be important to you. The prospectus supplement will include some or all of the following terms:

Anti-Takeover Provisions of Phillips 66’s Certificate of Incorporation and By-Laws

Phillips 66’s Amended and Restated Certificate of Incorporation (the “Certificate of Incorporation”) and Phillips 66’s Amended and Restated By-Laws (the “By-Laws”) contain provisions that could delay or make more difficult the acquisition of control of Phillips 66 through a hostile tender offer, open market purchases, proxy contest, merger or other takeover attempt that a stockholder might consider in his or her best interest, including those attempts that might result in a premium over the market price of Phillips 66’s common stock.

Authorized but Unissued Stock

Phillips 66 has 2.5 billion authorized shares of common stock and 500 million authorized shares of preferred stock. One of the consequences of Phillips 66’s authorized but unissued common stock and undesignated preferred stock may be to enable Phillips 66’s Board of Directors to make more difficult or to discourage an attempt to obtain control of Phillips 66. If, in the exercise of its fiduciary obligations, Phillips 66’s Board of Directors determined that a takeover proposal was not in Philips 66’s best interest, our Board of Directors could authorize the issuance of those shares without stockholder approval, subject to limits imposed by the New York Stock Exchange. The shares could be issued in one or more transactions that might prevent or make the completion of a proposed change of control transaction more difficult or costly by:

In this regard, the Certificate of Incorporation grants Phillips 66’s Board of Directors broad power to establish the rights and preferences of the authorized and unissued preferred stock. Phillips 66’s Board of Directors could establish one or more series of preferred stock that entitle holders to:

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Size of Board and Vacancies; Removal

Phillips 66’s Certificate of Incorporation provides for a classified board of directors. Class I directors have a current term expiring in 2025, Class II directors have a current term expiring in 2023 and Class III directors have a current term expiring in 2024. At each annual meeting of stockholders, directors will be elected to succeed the class of directors whose terms have expired. This classification of Phillips 66’s Board of Directors could have the effect of increasing the length of time necessary to change the composition of a majority of the Board of Directors; in general, at least two annual meetings of stockholders will be necessary for stockholders to effect a change in a majority of the members of the Board of Directors.

Phillips 66’s Certificate of Incorporation and By-Laws provide, subject to the rights of holders of a series of shares of preferred stock to elect one or more directors pursuant to any provisions of any certificate of designation relating to any such series, that the number of directors will be fixed exclusively by a majority of the entire Board of Directors from time to time. Phillips 66’s By-Laws provide that directors may be removed, only for cause, by the affirmative vote of the holders of at least a majority of the voting power of Phillips 66 entitled to vote generally for the election of directors, voting together as a single class. Phillips 66’s By-Laws also provide that, unless the Board of Directors determines otherwise, vacancies, however created, may be filled only by a majority of the remaining directors, even if less than a quorum.

Stockholder Action by Written Consent

Phillips 66’s Certificate of Incorporation and By-Laws provide that our stockholders may act only at an annual or special meeting of stockholders and may not act by written consent.

Stockholder Meetings

Phillips 66’s Certificate of Incorporation and By-Laws provide that only a majority of our entire Board of Directors or the chairman of our Board of Directors may call a special meeting of our stockholders.

Requirements for Advance Notice of Stockholder Nominations and Proposals

Phillips 66’s By-Laws contain advance-notice and other procedural requirements that apply to stockholder nominations of persons for election to Phillips 66’s Board of Directors at any annual meeting of stockholders and to stockholder proposals that stockholders take any other action at any annual meeting. In the case of any annual meeting, a stockholder proposing to nominate a person for election to Phillips 66’s Board of Directors or proposing that any other action be taken must give our corporate secretary written notice of the proposal not less than 90 days and not more than 120 days before the first anniversary of the date of the immediately preceding year’s annual meeting of stockholders. These stockholder proposal deadlines are subject to exceptions if the annual meeting date is more than 30 days before or after such anniversary date, in which case notice by such stockholder, to be timely, must be so delivered not earlier than the close of business on the 120th day prior to the date of such annual meeting and not later than the close of business on the later of the 90th day prior to the date of such annual meeting or, if the first public announcement of the date of such annual meeting is less than

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100 days prior to the date of such meeting, the tenth day following the day on which Phillips 66 first makes a public announcement of the date of the annual meeting. If the chairman of Phillips 66’s Board of Directors or a majority of the Board of Directors calls a special meeting of stockholders for the election of directors, a stockholder proposing to nominate a person for that election must give our corporate secretary written notice of the proposal not earlier than the close of business on the 120th day prior to the date of such special meeting and not later than close of business on the later of the 90th day prior to the date of such special meeting or, if the first public announcement of the date of the special meeting is less than 100 days prior to the date of such meeting, the tenth day following the day on which public announcement is first made of the date of the special meeting and of the nominees proposed by the Board of Directors. Phillips 66’s By-Laws prescribe specific information that any such stockholder notice must contain.

These advance-notice provisions may have the effect of precluding a contest for the election of our directors or the consideration of stockholder proposals if the proper procedures are not followed, and of discouraging or deterring a third party from conducting a solicitation of proxies to elect its own slate of directors or to approve its own proposal, without regard to whether consideration of those nominees or proposals might be harmful or beneficial to us and our stockholders.

Proxy Access

Phillips 66’s By-laws provide that a stockholder, or a group of up to 20 stockholders, that has continuously owned at least three percent of the outstanding capital stock of Phillips 66 for three years, may nominate and include in Phillips 66’s annual meeting proxy materials a number of director nominees not to exceed the greater of two or 20% of the number of Phillips 66’s directors then serving on the Board of Directors (rounded down to the nearest whole number), provided that the stockholder(s) and the nominee(s) satisfy the requirements specified in the By-laws. Such nominations are subject to additional eligibility, procedural and disclosure requirements set forth in the By-laws, including the requirement that Phillips 66 must receive notice of such nominations not less than 90 days nor more than 120 days prior to the anniversary date of the immediately preceding annual meeting of stockholders.

Amendment of Certificate of Incorporation and By-Laws

Phillips 66’s Certificate of Incorporation provides that stockholders may, with the approval of greater than a majority of the voting power entitled to vote generally in the election of directors, adopt, amend and repeal the By-Laws at any regular or special meeting of stockholders, provided the notice of intention to adopt, amend or repeal the By-Laws has been included in the notice of that meeting, although the approval of greater than 80 percent of the voting power entitled to vote generally in the election of directors will be required to amend certain By-Laws and related provisions of the Certificate of Incorporation. Phillips 66’s Certificate of Incorporation also confers on the Board of Directors the power to adopt, amend or repeal the By-Laws.

Exclusive Forum

Phillips 66’s Certificate of Incorporation provides that the Court of Chancery of the State of Delaware will be the sole and exclusive forum for any derivative action or proceeding brought on our behalf, any action asserting a claim of breach of a fiduciary duty owed by any of Phillips 66’s directors or officers to us or our stockholders, creditors or other constituents, any action asserting a claim against us or any of Phillips 66’s directors or officers arising pursuant to any provision of the Delaware General Corporation Law (the “DGCL”) or our Certificate of Incorporation or By-Laws (as either may be amended from time to time) or any action asserting a claim against us or any of our directors or officers governed by the internal affairs doctrine; provided, that if (and only if) the Court of Chancery of the State of Delaware dismisses any such action for lack of subject matter jurisdiction, such action may be brought in another court sitting in the State of Delaware.

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Limitation on Liability of Directors

Section 145 of the DGCL provides that a corporation may indemnify directors and officers as well as other employees and individuals against expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement in connection with any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative, in which such person is made a party by reason of the fact that the person is or was a director, officer, employee or agent of the corporation (other than an action by or in the right of the corporation—a “derivative action”), if such person acted in good faith and in a manner such person reasonably believed to be in or not opposed to the best interests of the corporation and, with respect to any criminal action or proceeding, had no reasonable cause to believe such person’s conduct was unlawful. A similar standard is applicable in the case of derivative actions, except that indemnification only extends to expenses (including attorneys’ fees) incurred in connection with the defense or settlement of such action, and the statute requires court approval before there can be any indemnification where the person seeking indemnification has been found liable to the corporation. The statute provides that it is not exclusive of other indemnification that may be granted by a corporation’s by-laws, disinterested director vote, stockholder vote, agreement or otherwise.

Phillips 66’s Certificate of Incorporation provides that no director will be liable to Phillips 66 or its stockholders for monetary damages for breach of fiduciary duty as a director, except to the extent such exemption from liability or limitation on liability is not permitted under the DGCL, as now in effect or as amended. Currently, Section 102(b)(7) of the DGCL requires that liability be imposed for the following:

Delaware Statutory Business Combination Provision

As a Delaware corporation, Phillips 66 is subject to Section 203 of the DGCL. In general, Section 203 prevents an “interested stockholder,” which is defined generally as a person owning 15 percent or more of a Delaware corporation’s outstanding voting stock or any affiliate or associate of that person, from engaging in a broad range of “business combinations” with the corporation for three years following the date on which that person became an interested stockholder unless:

Under Section 203, the restrictions described above also do not apply to specific business combinations proposed by an interested stockholder following the announcement or notification of designated extraordinary transactions involving the corporation and a person who had not been an interested stockholder during the

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previous three years or who became an interested stockholder with the approval of a majority of the corporation’s directors, if a majority of the directors who were directors prior to any person’s becoming an interested stockholder during the previous three years, or were recommended for election or elected to succeed those directors by a majority of those directors, approve or do not oppose that extraordinary transaction.

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DESCRIPTION OF WARRANTS

Phillips 66 may issue warrants to purchase any combination of debt securities, common stock, preferred stock, rights or other securities of Phillips 66 or any other entity. Phillips 66 may issue warrants independently or together with other securities. Warrants sold with other securities may be attached to or separate from the other securities. Phillips 66 will issue warrants under one or more warrant agreements between it and a warrant agent that we will name in the prospectus supplement.

The prospectus supplement relating to any warrants Phillips 66 is offering will include specific terms relating to the offering. We will file the form of any warrant agreement with the SEC, and you should read the warrant agreement for provisions that may be important to you. The prospectus supplement will include some or all of the following terms:

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DESCRIPTION OF DEPOSITARY SHARES

General

Phillips 66 may elect to offer shares of its preferred stock represented by depositary shares. The shares of any series of the preferred stock underlying the depositary shares will be deposited under a separate deposit agreement between Phillips 66 and a bank or trust company we will name in the prospectus supplement.

Subject to the terms of the deposit agreement, each holder of a depositary share will be entitled, proportionately, to all the rights, preferences and privileges of the preferred stock represented by that depositary share, including dividend, voting, redemption, conversion, exchange and liquidation rights. The depositary shares will be evidenced by depositary receipts issued under the deposit agreement. Each receipt will represent the applicable interest in a number of shares of a particular series of the preferred stock, which we will describe in the prospectus supplement.

We have summarized below selected provisions that would likely be included in a deposit agreement, the related depositary shares and depositary receipts evidencing those shares. This summary is not complete. We will file a form of deposit agreement and a form of depositary receipt with the SEC before Phillips 66 issues any depositary shares, and you should read those documents for provisions that may be important to you.

A holder of depositary shares will be entitled to receive the whole number of shares of preferred stock underlying those depositary shares. Holders will not be entitled to receive fractional shares. If the depositary receipts delivered by the holder evidence a number of depositary shares in excess of the whole number of shares to be withdrawn, the depositary will deliver to that holder at the same time a new depositary receipt for the excess number of depositary shares.

Dividends and Other Distributions

The depositary will distribute all cash dividends or other cash distributions received with respect to the preferred stock to the record holders of depositary receipts in proportion to the number of depositary shares owned by those holders.

If there is a distribution other than in cash, the depositary will distribute property received by it to the record holders of depositary receipts in proportion, insofar as possible, to the number of depositary shares owned by those holders. If the depositary determines that it is not feasible to make such a distribution, it may, with Phillips 66’s approval, adopt any method that it deems equitable and practicable to effect the distribution, including a sale of the property and distribution of the net proceeds from the sale to the holders.

The amount distributed in any of the above cases will be reduced by any amount Phillips 66 or the depositary is required to withhold on account of taxes.

Conversion and Exchange

If any preferred stock underlying the depositary shares is subject to provisions relating to its conversion or exchange as described in the prospectus supplement, each record holder of depositary shares will have the right or obligation to convert or exchange those depositary shares in accordance with those provisions.

Redemption of Depositary Shares

Whenever Phillips 66 redeems a share of preferred stock held by the depositary, the depositary will redeem on the same redemption date a proportionate number of depositary shares representing the shares of preferred stock redeemed. The redemption price per depositary share will be equal to the aggregate redemption price

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payable with respect to the number of shares of preferred stock underlying the depositary shares. If fewer than all the depositary shares are to be redeemed, the depositary shares to be redeemed will be selected by lot or proportionately as Phillips 66 may determine.

Voting

Upon receipt of notice of any meeting at which the holders of the preferred stock underlying the depositary shares are entitled to vote, the depositary will mail the information contained in the notice to the record holders of the depositary receipts. Each record holder of the depositary receipts on the record date, which will be the same date as the record date for the preferred stock, may then instruct the depositary as to the exercise of the voting rights pertaining to the number of shares of preferred stock underlying that holder’s depositary shares. The depositary will try, as far as practicable, to vote the number of shares of preferred stock underlying the depositary shares in accordance with the instructions, and Phillips 66 will agree to take all reasonable action that the depositary deems necessary to enable the depositary to do so. The depositary will abstain from voting the preferred stock to the extent that it does not receive specific written instructions from holders of depositary shares representing the preferred stock.

Record Date

Whenever:

the depositary will in each instance fix a record date, which will be the same as the record date for the preferred stock, for the determination of the holders of depositary receipts:

Amendment and Termination of the Deposit Agreement

Phillips 66 and the depositary may at any time agree to amend the form of depositary receipt and any provision of the deposit agreement. However, any amendment that adversely alters the rights of holders of depositary shares in any material respect will not be effective unless the amendment has been approved by the holders of at least a majority of the depositary shares then outstanding. The deposit agreement may be terminated by Phillips 66 or by the depositary only if all outstanding depositary shares have been redeemed or if a final distribution on the underlying preferred stock has been made to the holders of the depositary shares in connection with the liquidation, dissolution or winding up of Phillips 66.

Charges of Depositary

Phillips 66 will pay all charges of the depositary, including charges in connection with:

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Holders of depositary shares will pay taxes (including any transfer taxes) and other governmental charges and any other charges expressly provided in the deposit agreement to be at the expense of those holders.

Resignation and Removal of Depositary

The depositary may at any time resign or be removed by Phillips 66. Any resignation or removal will become effective upon the acceptance by the depositary’s successor of its appointment. If Phillips 66 has not appointed a successor depositary and the successor depositary has not accepted its appointment within 60 days after the depositary delivered a resignation notice to Phillips 66, the depositary may terminate the deposit agreement.

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DESCRIPTION OF STOCK PURCHASE CONTRACTS

AND STOCK PURCHASE UNITS

Phillips 66 may issue stock purchase contracts, including contracts obligating holders to purchase from Phillips 66, and Phillips 66 to sell to the holders, or for Phillips 66 to issue in exchange for other securities, a specified number of shares of Phillips 66 common stock or preferred stock (or a range of numbers of shares in accordance with a predetermined formula) at a future date or dates or upon the occurrence of specified events. The price per share of common stock or preferred stock may be fixed at the time the stock purchase contracts are issued or may be determined by reference to a specific formula set forth in the stock purchase contracts.

Phillips 66 may issue the stock purchase contracts separately or as a part of units, often known as stock purchase units, consisting of a stock purchase contract and any combination of:

securing the holder’s obligations to purchase the common stock or preferred stock under the stock purchase contracts.

The stock purchase contracts may require Phillips 66 to make periodic payments to the holders of the stock purchase units or vice versa, and those payments may be unsecured or prefunded on some basis. The stock purchase contracts may require holders to secure their obligations in a specified manner, and in specified circumstances, Phillips 66 may deliver newly issued prepaid stock purchase contracts, often known as prepaid securities, upon release to a holder of any collateral securing that holder’s obligations under the original stock purchase contract.

The applicable prospectus supplement will describe the terms of any stock purchase contracts or stock purchase units and, if applicable, prepaid securities. That description will not be complete. For more information, you should review the stock purchase contracts and, if applicable, the collateral arrangements and depositary arrangements relating to those stock purchase contracts or stock purchase units and any prepaid securities and the document(s) under which the prepaid securities will be issued. We will file forms of these documents with the SEC before we issue any stock purchase contracts or stock purchase units and, if applicable, prepaid securities.

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PLAN OF DISTRIBUTION

We may sell the securities in and outside the United States through underwriters or dealers, directly to purchasers or through agents.

Sale Through Underwriters or Dealers

If we use underwriters in the sale of securities, the underwriters will acquire the securities for their own account. The underwriters may resell the securities from time to time in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of sale. Underwriters may offer securities to the public either through underwriting syndicates represented by one or more managing underwriters or directly by one or more firms acting as underwriters. Unless we inform you otherwise in the prospectus supplement, the obligations of the underwriters to purchase the securities will be subject to conditions, and the underwriters will be obligated to purchase all of the securities if they purchase any of them. The underwriters may change from time to time any initial public offering price and any discounts or concessions allowed or reallowed or paid to dealers. We will include in the prospectus supplement the names of the principal underwriters and the amounts underwritten.

During and after an offering through underwriters, the underwriters may purchase and sell the securities in the open market. These transactions may include overallotment and stabilizing transactions and purchases to cover syndicate short positions created in connection with the offering. The underwriters may also impose a penalty bid, whereby selling concessions allowed to syndicate members or other broker-dealers for the offered securities sold for their account may be reclaimed by the syndicate if such offered securities are repurchased by the syndicate in stabilizing or covering transactions. These activities may stabilize, maintain or otherwise affect the market price of the offered securities, which may be higher than the price that might otherwise prevail in the open market. If commenced, these activities may be discontinued at any time.

If we use dealers in the sale of securities, we will sell the securities to them as principals. They may then resell those securities to the public at varying prices determined by the dealers at the time of resale. The dealers participating in any sale of the securities may be deemed to be underwriters within the meaning of the Securities Act of 1933 with respect to any sale of those securities. We will include in the prospectus supplement the names of the dealers and the terms of the transaction.

Direct Sales and Sales Through Agents

We may sell the securities directly. In that event, no underwriters or agents would be involved. We may also sell the securities through agents we designate from time to time. In the prospectus supplement, we will name any agent involved in the offer or sale of the securities, and we will describe any commissions payable by us to the agent. Unless we inform you otherwise in the prospectus supplement, any agent will agree to use its reasonable best efforts to solicit purchases for the period of its appointment.

We may sell the securities directly to institutional investors or others who may be deemed to be underwriters within the meaning of the Securities Act of 1933 with respect to any sale of those securities. We will describe the terms of any such sales in the prospectus supplement.

Delayed Delivery Contracts

If we so indicate in the prospectus supplement, we may authorize agents, underwriters or dealers to solicit offers from certain types of institutions to purchase securities from us at the public offering price under delayed delivery contracts. These contracts would provide for payment and delivery on a specified date in the future. The contracts would be subject only to those conditions described in the prospectus supplement. The prospectus supplement will describe the commission payable for solicitation of those contracts.

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Remarketing

We may offer and sell any of the securities in connection with a remarketing upon their purchase, in accordance with a redemption or repayment by their terms or otherwise, by one or more remarketing firms acting as principals for their own accounts or as our agents. We will identify any remarketing firm, the terms of any remarketing agreement and the compensation to be paid to the remarketing firm in the prospectus supplement. Remarketing firms may be deemed underwriters under the Securities Act of 1933.

Derivative Transactions

We may enter into derivative transactions with third parties or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement indicates, in connection with those derivatives, the third parties may sell securities covered by this prospectus and the applicable prospectus supplement, including in short sale transactions. If so, the third parties may use securities pledged by us or borrowed from us or others to settle those sales or to close out any related open borrowings of stock, and may use securities received from us in settlement of those derivatives to close out any related open borrowings of stock. The third parties in these sale transactions will be underwriters and will be identified in the applicable prospectus supplement or in a post-effective amendment to the registration statement of which this prospectus forms a part.

General Information

We may have agreements with the agents, dealers and underwriters to indemnify them against civil liabilities, including liabilities under the Securities Act of 1933, or to contribute with respect to payments that the agents, dealers or underwriters may be required to make. Agents, dealers and underwriters may engage in transactions with us or perform services for us in the ordinary course of their businesses.

Each series of offered securities will be a new issue and, other than our common stock, which is listed on the New York Stock Exchange, will have no established trading market. We may elect to list any series of offered securities on an exchange, but we are not obligated to do so. It is possible that one or more underwriters may make a market in a series of offered securities. However, they will not be obligated to do so and may discontinue market making at any time without notice. We cannot assure you that a liquid trading market for any of our offered securities will develop.

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VALIDITY OF THE SECURITIES

The validity of the offered securities and other matters in connection with any offering of the securities will be passed upon for us by Bracewell LLP, Houston, Texas, our outside counsel. Any underwriters will be advised about legal matters relating to any offering by their own legal counsel.

EXPERTS

The consolidated financial statements of Phillips 66 appearing in Phillips 66’s Annual Report (Form 10-K) for the year ended December 31, 2021, and the effectiveness of Phillips 66’s internal control over financial reporting as of December 31, 2021, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their reports thereon, included therein, and incorporated herein by reference. Such financial statements are, and audited financial statements to be included in subsequently filed documents will be, incorporated herein in reliance upon the reports of Ernst & Young LLP pertaining to such financial statements and the effectiveness of our internal control over financial reporting as of the respective dates (to the extent covered by consents filed with the Securities and Exchange Commission) given on the authority of such firm as experts in accounting and auditing.

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$    

Phillips 66 Company

$       % Senior Notes due    

$    5.300% Senior Notes due 2033 

$       % Senior Notes due    

fully and unconditionally

guaranteed by

Phillips 66

PRELIMINARY PROSPECTUS SUPPLEMENT

Joint Book-Running Managers

Mizuho

MUFG

RBC Capital Markets

Scotiabank

SMBC Nikko

Truist Securities

    , 2024