CenterPoint Energy (CNP) 8-KEntry into a Material Definitive Agreement

Exhibit 4.2

CENTERPOINT ENERGY, INC.

To

THE BANK OF NEW YORK MELLON TRUST COMPANY, NATIONAL ASSOCIATION

(successor to JPMorgan Chase Bank, National Association (formerly JPMorgan Chase Bank))

Trustee

SUPPLEMENTAL INDENTURE NO. 15

Dated as of May 10, 2024

$700,000,000 5.40% Senior Notes due 2029

CENTERPOINT ENERGY, INC.

SUPPLEMENTAL INDENTURE NO. 15

$700,000,000 5.40% Senior Notes due 2029

SUPPLEMENTAL INDENTURE No. 15, dated as of May 10, 2024, between CENTERPOINT ENERGY, INC., a Texas corporation (the “Company”), and THE BANK OF NEW YORK MELLON TRUST COMPANY, NATIONAL ASSOCIATION (successor to JPMorgan Chase Bank, National Association (formerly JPMorgan Chase Bank)), as Trustee (the “Trustee”).

RECITALS

The Company has heretofore executed and delivered to the Trustee an Indenture, dated as of May 19, 2003 (the “Original Indenture” and, as hereby supplemented and amended, the “Indenture”), providing for the issuance from time to time of one or more series of the Company’s Securities.

Pursuant to the terms of the Indenture, the Company desires to provide for the establishment of a new series of Securities to be designated as the “5.40% Senior Notes due 2029” (the “Notes”), the form and substance of such Notes and the terms, provisions and conditions thereof to be set forth as provided in the Original Indenture and this Supplemental Indenture No. 15.

Section 301 of the Original Indenture provides that various matters with respect to any series of Securities issued under the Indenture may be established in an indenture supplemental to the Indenture.

Subparagraph (7) of Section 901 of the Original Indenture provides that the Company and the Trustee may enter into an indenture supplemental to the Indenture to establish the form or terms of Securities of any series as permitted by Sections 201 and 301 of the Original Indenture.

For and in consideration of the premises and the issuance of the series of Securities provided for herein, it is mutually covenanted and agreed, for the equal and proportionate benefit of the Holders of the Securities of such series, as follows:

ARTICLE I

Relation to Indenture; Additional Definitions

Section 101 Relation to Indenture. This Supplemental Indenture No. 15 constitutes an integral part of the Original Indenture.

Section 102 Additional Definitions. For all purposes of this Supplemental Indenture No. 15:

1

Capitalized terms used herein shall have the meaning specified herein or in the Original Indenture, as the case may be;

“Affiliate” of, or a Person “affiliated” with, a specific Person means a Person that directly, or indirectly through one or more intermediaries, controls, or is controlled by, or is under common control with, the Person specified. For purposes of this definition, “control” (including the terms “controlled by” and “under common control with”) means the possession, direct or indirect, of the power to direct or cause the direction of the management and policies of a Person, whether through the ownership of voting shares, by contract, or otherwise;

“Business Day” means, with respect to any Note, any day other than a Saturday, a Sunday or a day on which banking institutions in The City of New York are authorized or required by law, regulation or executive order to close. If any Interest Payment Date, Stated Maturity or Redemption Date of a Note falls on a day that is not a Business Day, the required payment will be made on the next succeeding Business Day with the same force and effect as if made on the relevant date that the payment was due and no interest will accrue on such payment for the period from and after the Interest Payment Date, Stated Maturity or Redemption Date, as the case may be, to the date of that payment on the next succeeding Business Day. The definition of “Business Day” in this Supplemental Indenture No. 15 and the provisions described in the preceding sentence shall supersede the definition of Business Day in the Original Indenture and Section 113 of the Original Indenture;

“CERC Corp.” means CenterPoint Energy Resources Corp., a Delaware corporation, and any successor thereto; provided, that at any given time, there shall not be more than one such successor;

“Corporate Trust Office” means the principal office of the Trustee at which at any particular time its corporate trust business shall be administered, which office as of the date hereof is located at: 601 Travis Street, 16th Floor, Houston, Texas 77002, Attention: Global Corporate Trust; telephone: (713) 483-6817; telecopy: (713) 483-7038;

“Finance Lease” means a lease that, in accordance with accounting principles generally accepted in the United States of America, would be recorded as a finance lease on the balance sheet of the lessee, but excluding, for the avoidance of doubt, any operating leases or any other non-finance leases;

“Houston Electric” means CenterPoint Energy Houston Electric, LLC, a Texas limited liability company, and any successor thereto; provided, that at any given time, there shall not be more than one such successor;

“H.15” has the meaning set forth in Section 302 hereof;

“H.15 TCM” has the meaning set forth in Section 302 hereof;

2

The term “Indebtedness” as applied to any Person, means bonds, debentures, notes and other instruments or arrangements representing obligations created or assumed by such Person, in respect of: (i) obligations for money borrowed (other than unamortized debt discount or premium); (ii) obligations evidenced by a note or similar instrument given in connection with the acquisition of any business, properties or assets of any kind; (iii) obligations as lessee under a Finance Lease; and (iv) any amendments, renewals, extensions, modifications and refundings of any such indebtedness or obligations listed in clause (i), (ii) or (iii) above. All indebtedness of such type, secured by a lien upon property owned by such Person although such Person has not assumed or become liable for the payment of such indebtedness, shall also for all purposes hereof be deemed to be indebtedness of such Person. All indebtedness for borrowed money incurred by any other Persons which is directly guaranteed as to payment of principal by such Person shall for all purposes hereof be deemed to be indebtedness of any such Person, but no other contingent obligation of such Person in respect of indebtedness incurred by any other Persons shall for any purpose be deemed to be indebtedness of such Person;

“Interest Payment Date” has the meaning set forth in Section 204(a) hereof;

“Issue Date” has the meaning set forth in Section 204(a) hereof;

“Maturity Date” has the meaning set forth in Section 203 hereof;

“Notes” has the meaning set forth in the second paragraph of the Recitals hereof;

“Original Indenture” has the meaning set forth in the first paragraph of the Recitals hereof;

“Par Call Date” has the meaning set forth in Section 301 hereof;

“Regular Record Date” has the meaning set forth in Section 204(a) hereof;

“Remaining Life” has the meaning set forth in Section 302 hereof;

“Treasury Rate” has the meaning set forth in Section 302 hereof;

All references herein to Articles and Sections, unless otherwise specified, refer to the corresponding Articles and Sections of this Supplemental Indenture No. 15; and

The terms “herein,” “hereof,” “hereunder” and other words of similar import refer to this Supplemental Indenture No. 15.

ARTICLE II

The Series of Securities

Section 201 Title of the Securities. The Notes shall be designated as the “5.40% Senior Notes due 2029.”

3

Section 202 Limitation on Aggregate Principal Amount. The Trustee shall authenticate and deliver the Notes for original issue on the Issue Date in the aggregate principal amount of $700,000,000, upon a Company Order for the authentication and delivery thereof and satisfaction of Sections 301 and 303 of the Original Indenture. Such order shall specify the amount of the Notes to be authenticated, the date on which the original issue of Notes is to be authenticated and the name or names of the initial Holder or Holders. The aggregate principal amount of the Notes that may initially be outstanding shall not exceed $700,000,000; provided, however, that the authorized aggregate principal amount of the Notes may be increased above such amount by a Board Resolution to such effect.

Section 203 Stated Maturity. The Stated Maturity of the Notes shall be June 1, 2029 (the “Maturity Date”).

Section 204 Interest and Interest Rates.

(a) The Notes shall bear interest at a rate of 5.40% per year, from and including May 10, 2024 (the “Issue Date”) to, but excluding, the Maturity Date. Such interest shall be payable semiannually in arrears on June 1 and December 1 of each year (each an “Interest Payment Date”), beginning December 1, 2024, to the persons in whose names the Notes (or one or more Predecessor Securities) are registered at the close of business on May 15 and November 15 (each a “Regular Record Date”) (whether or not a Business Day), as the case may be, immediately preceding such Interest Payment Date.

(b) Any such interest not so punctually paid or duly provided for shall forthwith cease to be payable to the Holder on such Regular Record Date and shall either (i) be paid to the Person in whose name such Note (or one or more Predecessor Securities) is registered at the close of business on the Special Record Date for the payment of such Defaulted Interest to be fixed by the Trustee, notice whereof shall be given to Holders of the Notes not less than 10 days prior to such Special Record Date, or (ii) be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange or automated quotation system on which the Notes may be listed or traded, and upon such notice as may be required by such exchange or automated quotation system, all as more fully provided in the Indenture.

(c) The amount of interest payable for any period shall be computed on the basis of a 360-day year of twelve 30-day months. The amount of interest payable for any partial period shall be computed on the basis of a 360-day year of twelve 30-day months and the days elapsed in any partial month. In the event that any date on which interest is payable on a Note is not a Business Day, then a payment of the interest payable on such date will be made on the next succeeding day which is a Business Day (and without any interest or other payment in respect of any such delay) with the same force and effect as if made on the date the payment was originally payable.

(d) Any principal and premium, if any, and any installment of interest, which is overdue shall bear interest at the rate of 5.40% per annum (to the extent permitted by law) for the Notes from the dates such amounts are due until they are paid or made available for payment, and such interest shall be payable on demand.

4

Section 205 Paying Agent; Place of Payment. The Trustee shall initially serve as the Paying Agent for the Notes. The Company may appoint and change any Paying Agent or approve a change in the office through which any Paying Agent acts without notice, other than notice to the Trustee. The Company or any of its Subsidiaries or any of their Affiliates may act as Paying Agent. The Place of Payment where the Notes may be presented or surrendered for payment shall be the Corporate Trust Office of the Trustee. At the option of the Company, payment of interest may be made (i) by check mailed to the address of the Person entitled thereto as such address shall appear in the Security Register, (ii) by wire transfer in immediately available funds at such place and to such account as may be designated in writing by the Person entitled thereto as specified in the Security Register or (iii) by wire transfer in immediately available funds in accordance with the procedures of The Depository Trust Company with respect to the Notes registered in the name of Cede & Co.

Section 206 Place of Registration or Exchange; Notices and Demands With Respect to the Notes. The place where the Holders of the Notes may present the Notes for registration of transfer or exchange and may make notices and demands to or upon the Company in respect of the Notes shall be the Corporate Trust Office of the Trustee.

Section 207 Percentage of Principal Amount. The Notes shall be initially issued at 99.790% of their principal amount, plus accrued interest, if any, from the Issue Date.

Section 208 Global Securities. The Notes shall be issuable in whole or in part in the form of one or more Global Securities. Such Global Securities shall be deposited with, or on behalf of, The Depository Trust Company, New York, New York, which shall act as Depositary with respect to the Notes. Such Global Securities shall bear the legends set forth in the form of Security attached as Exhibit A hereto.

Section 209 Form of Securities. The Notes shall be substantially in the form attached as Exhibit A hereto.

Section 210 Securities Registrar. The Trustee shall initially serve as the Security Registrar for the Notes.

Section 211 Sinking Fund Obligations. The Company shall have no obligation to redeem or purchase any Notes pursuant to any sinking fund or analogous requirement or upon the happening of a specified event or at the option of a Holder thereof.

Section 212 Defeasance and Discharge; Covenant Defeasance.

(a) Article Fourteen of the Original Indenture, including without limitation Sections 1402 and 1403 thereof (as modified by Section 212(b) hereof), shall apply to the Notes.

(b) Solely with respect to the Notes issued hereby, the first sentence of Section 1403 of the Original Indenture is hereby deleted in its entirety, and the following is substituted in lieu thereof:

“Upon the Company’s exercise of its option (if any) to have this Section 1403 applied to any Securities or any series of Securities, as the case may be, (1) the Company shall be released from its obligations under Article Eight and under any covenants provided pursuant to Section 301(20), 901(2) or 901(7) for the benefit of the Holders of such Securities and (2) the occurrence of any event specified in

5

Sections 501(4) (with respect to Article Eight and to any such covenants provided pursuant to Section 301(20), 901(2) or 901(7)) and 501(7) shall be deemed not to be or result in an Event of Default, in each case with respect to such Securities as provided in this Section 1403 on and after the date the conditions set forth in Section 1404 are satisfied (hereinafter called “Covenant Defeasance”).”

ARTICLE III

Optional Redemption of the Notes

Section 301 Redemption Price. Prior to May 1, 2029 (the “Par Call Date”), the Notes shall be redeemable, at the option of the Company, 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 (1)(a) the sum of the present values of the remaining scheduled payments of principal and interest on the Notes to be redeemed discounted to the Redemption Date (assuming the Notes to be redeemed matured on the Par Call Date) on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the applicable Treasury Rate plus 15 basis points less (b) interest accrued to the Redemption Date, and (2) 100% of the principal amount of the Notes to be redeemed, plus, in either case, accrued and unpaid interest thereon, if any, to, but excluding, the Redemption Date. On or after the Par Call Date, the Notes shall be redeemable, at the option of the Company, 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 to be redeemed plus accrued and unpaid interest thereon, if any, to, but excluding, the Redemption Date.

Section 302 Calculation. “Treasury Rate” means, with respect to any Redemption Date, the yield determined by the Company in accordance with the following two paragraphs.

The treasury rate shall be determined by the 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 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, the Company shall select, as applicable: (1) the yield for the Treasury constant maturity on H.15 exactly equal to the period from the Redemption Date to the 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 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 Redemption Date.

6

If on the third Business Day preceding the Redemption Date H.15 TCM or any successor designation or publication is no longer published, the 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 Par Call Date, as applicable. If there is no United States Treasury security maturing on the Par Call Date but there are two or more United States Treasury securities with a maturity date equally distant from the Par Call Date, one with a maturity date preceding the Par Call Date and one with a maturity date following the Par Call Date, the Company shall select the United States Treasury security with a maturity date preceding the Par Call Date. If there are two or more United States Treasury securities maturing on the Par Call Date or two or more United States Treasury securities meeting the criteria of the preceding sentence, the 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 semi-annual 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.

The Company’s actions and determinations in determining the Redemption Price shall be conclusive and binding for all purposes, absent manifest error. The Trustee shall have no responsibility for the calculation of such amount.

Section 303 Partial Redemption. If fewer than all of the Notes are to be redeemed by the Company pursuant to this Article III, not more than 60 days prior to the Redemption Date, the particular Notes or portions thereof for redemption will be selected from the outstanding Notes not previously called by lot by the Trustee. The Trustee may select for redemption Notes and portions of Notes in minimum amounts of $2,000 or whole multiples of $1,000. A new Note in principal amount equal to the unredeemed portion of the original Note shall be issued upon the cancellation of the original Note. In the case of a partial redemption of Notes registered in the name of Cede & Co., the Notes to be redeemed will be determined in accordance with the procedures of The Depository Trust Company.

Section 304 Notice of Optional Redemption.

(a) The Trustee, at the written direction of the Company, will send a notice of redemption prepared by the Company to each holder of Notes to be redeemed by first-class mail (or in accordance with the procedures of The Depository Trust Company with respect to Notes registered in the name of Cede & Co.) at least 10 days and not more than 60 days prior to the date fixed for redemption. Unless the Company defaults on payment of the Redemption Price, interest will cease to accrue on the Notes or portions thereof called for redemption on the Redemption Date. If any Note is to be redeemed in part only, the notice of redemption shall state the portion of the principal amount to be redeemed.

7

(b) Notice of any redemption of the Notes may, at the Company’s discretion, be given subject to one or more conditions precedent, including, but not limited to, completion of a corporate transaction that is pending (such as an equity or equity-linked offering, an incurrence of Indebtedness or an acquisition or other strategic transaction involving a change of control in the Company or another entity). If such redemption is so subject to satisfaction of one or more conditions precedent, such notice shall describe each such condition, and such notice may be rescinded in the event that any or all such conditions shall not have been satisfied or otherwise waived by the Redemption Date. Once notice of redemption is mailed or sent, subject to the satisfaction of any conditions precedent provided in the notice of redemption, the Notes called for redemption will become due and payable on the Redemption Date and at the applicable Redemption Price, plus accrued and unpaid interest to the Redemption Date. The Company shall notify holders of Notes called for redemption of any such rescission as soon as practicable after the Company determines that such conditions precedent will not be able to be satisfied or the Company is not able or willing to waive such conditions precedent.

ARTICLE IV

Remedies

Section 401 Additional Events of Default; Acceleration of Maturity

(a) Solely with respect to the Notes issued hereby, Section 501(5) of the Original Indenture is hereby deleted in its entirety, and the following is substituted in lieu thereof as an Event of Default in addition to the other events set forth in Section 501 of the Original Indenture:

“(5) the entry by a court having jurisdiction in the premises of (A) a decree or order for relief in respect of the Company, CERC Corp. or Houston Electric in an involuntary case or proceeding under any applicable federal or state bankruptcy, insolvency, reorganization or other similar law or (B) a decree or order adjudging the Company, CERC Corp. or Houston Electric, bankrupt or insolvent, or approving as properly filed a petition seeking reorganization, arrangement, adjustment or composition of or in respect of the Company, CERC Corp. or Houston Electric, under any applicable federal or state law, or appointing a custodian, receiver, liquidator, assignee, trustee, sequestrator or other similar official of the Company, CERC Corp. or Houston Electric or of any substantial part of its respective property, or ordering the winding up or liquidation of its respective affairs, and the continuance of any such decree or order for relief or any such other decree or order unstayed and in effect for a period of 90 consecutive days; provided that any specified event in (A) or (B) involving CERC Corp. or Houston Electric shall not constitute an Event of Default if, at the time such event occurs, CERC Corp. or Houston Electric, as the case may be, shall no longer be an Affiliate of the Company; or”

8

(b) Solely with respect to the Notes issued hereby, Section 501(6) of the Original Indenture is hereby deleted in its entirety, and the following is substituted in lieu thereof as an Event of Default in addition to the other events set forth in Section 501 of the Original Indenture:

“(6) the commencement by the Company, CERC Corp. or Houston Electric of a voluntary case or proceeding under any applicable federal or state bankruptcy, insolvency, reorganization or other similar law or of any other case or proceeding to be adjudicated a bankrupt or insolvent, or the consent by any of them to the entry of a decree or order for relief in respect of the Company, CERC Corp. or Houston Electric in an involuntary case or proceeding under any applicable federal or state bankruptcy, insolvency, reorganization or other similar law or to the commencement of any bankruptcy or insolvency case or proceeding against any of them, or the filing by any of them of a petition or answer or consent seeking reorganization or relief under any applicable federal or state law, or the consent by any of them to the filing of such petition or to the appointment of or taking possession by a custodian, receiver, liquidator, assignee, trustee, sequestrator or other similar official of the Company, CERC Corp. or Houston Electric or of any substantial part of its respective property, or the making by any of them of an assignment of a substantial part of its respective property for the benefit of creditors, or the admission by any of them in writing of the inability of any of the Company, CERC Corp. or Houston Electric to pay its respective debts generally as they become due, or the taking of corporate action by the Company, CERC Corp. or Houston Electric in furtherance of any such action; provided that any such specified event involving CERC Corp. or Houston Electric shall not constitute an Event of Default if, at the time such event occurs, CERC Corp. or Houston Electric, as the case may be, shall no longer be an Affiliate of the Company; or”

(c) Solely with respect to the Notes issued hereby, and pursuant to Section 501(7) of the Original Indenture, Section 501(7) of the Original Indenture is hereby deleted in its entirety, and the following is substituted in lieu thereof, as an “Event of Default” in addition to the other events set forth in Section 501 of the Original Indenture:

“(7) The default by the Company in a scheduled payment at maturity, upon redemption or otherwise, in the aggregate principal amount of $125 million or more, after the expiration of any applicable grace period, of any Indebtedness or the acceleration of any Indebtedness of the Company in such aggregate principal amount so that it becomes due and payable prior to the date on which it would otherwise have become due and payable and such payment default is not cured or such acceleration is not rescinded within 30 days after notice to the Company in accordance with the terms of the Indebtedness.”

9

Section 402 Amendment of Certain Provisions. Solely with respect to the Notes issued hereby, references to “25%” in Article Five of the Indenture are hereby deleted in their entirety and “33%” is substituted in lieu thereof.

ARTICLE V

Miscellaneous Provisions

Section 501 The Indenture, as supplemented and amended by this Supplemental Indenture No. 15, is in all respects hereby adopted, ratified and confirmed.

Section 502 This Supplemental Indenture No. 15 may be executed in any number of counterparts, each of which shall be an original, but such counterparts shall together constitute but one and the same instrument. The words “execution,” “executed,” “signed,” signature,” and words of like import in this Supplemental Indenture No. 15 shall include images of manually executed signatures transmitted by facsimile, email or other electronic format (including, without limitation, “pdf,” “tif” or “jpg”) and other electronic signatures (including, without limitation, DocuSign and AdobeSign). The use of electronic signatures and electronic records (including, without limitation, any contract or other record created, generated, sent, communicated, received, or stored by electronic means) shall be of the same legal effect, validity and enforceability as a manually executed signature or use of a paper-based record-keeping system to the fullest extent permitted by applicable law, including the Federal Electronic Signatures in Global and National Commerce Act, the New York State Electronic Signatures and Records Act and any other applicable law, including, without limitation, any state law based on the Uniform Electronic Transactions Act or the Uniform Commercial Code. Without limitation to the foregoing, and anything in this Supplemental Indenture No. 15 to the contrary notwithstanding, (a) any Officers’ Certificate, Company Order, Opinion of Counsel, Security, certificate of authentication appearing on or attached to any Security or other certificate, Opinion of Counsel, instrument, agreement or other document delivered pursuant to this Supplemental Indenture No. 15 may be executed, attested and transmitted by any of the foregoing electronic means and formats, (b) all references in Section 303 or elsewhere in the Indenture to the execution, attestation or authentication of any Security or any certificate of authentication appearing on or attached to any Security by means of a manual or facsimile signature shall be deemed to include signatures that are made or transmitted by any of the foregoing electronic means or formats (provided that any electronic signature is a true representation of the signer’s actual signature), and (c) any requirement in Section 303 or elsewhere in the Indenture that any signature be made under a corporate seal (or facsimile thereof) shall not be applicable to the Securities of such series.

Section 503 THIS SUPPLEMENTAL INDENTURE NO. 15 AND EACH NOTE SHALL BE DEEMED TO BE A CONTRACT MADE UNDER THE LAWS OF THE STATE OF NEW YORK AND SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

Section 504 If any provision in this Supplemental Indenture No. 15 limits, qualifies or conflicts with another provision hereof which is required to be included herein by any provisions of the Trust Indenture Act, such required provision shall control.

10

Section 505 In case any provision in this Supplemental Indenture No. 15 or the Notes shall be invalid, illegal or unenforceable, the validity, legality and enforceability of the remaining provisions shall not in any way be affected or impaired thereby.

IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture No. 15 to be duly executed, as of the day and year first written above.

Attest:

11

Exhibit A

[FORM OF FACE OF SECURITY]

[IF THIS SECURITY IS TO BE A GLOBAL SECURITY -] THIS SECURITY IS A GLOBAL SECURITY WITHIN THE MEANING OF THE INDENTURE HEREINAFTER REFERRED TO AND IS REGISTERED IN THE NAME OF A DEPOSITARY OR A NOMINEE OF A DEPOSITARY. THIS SECURITY IS EXCHANGEABLE FOR SECURITIES REGISTERED IN THE NAME OF A PERSON OTHER THAN THE DEPOSITARY OR ITS NOMINEE ONLY IN THE LIMITED CIRCUMSTANCES DESCRIBED IN THE INDENTURE AND MAY NOT BE TRANSFERRED EXCEPT AS A WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY.

[FOR AS LONG AS THIS GLOBAL SECURITY IS DEPOSITED WITH OR ON BEHALF OF THE DEPOSITORY TRUST COMPANY IT SHALL BEAR THE FOLLOWING LEGEND.] UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION (“DTC”), TO CENTERPOINT ENERGY, INC. OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE, OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

CENTERPOINT ENERGY, INC.

5.40% Senior Notes due 2029

A-1

This Security is not an Original Issue Discount Security

within the meaning of the within-mentioned Indenture.

CENTERPOINT ENERGY, INC., a corporation duly organized and existing under the laws of the State of Texas (herein called the “Company,” which term includes any successor Person under the Indenture referred to below), for value received, hereby promises to pay to

***CEDE & Co.***

, or its registered assigns, the principal sum of         DOLLARS on the Stated Maturity specified above, and to pay interest thereon from the Original Interest Accrual Date specified above or from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually in arrears on the Interest Payment Dates specified above in each year, commencing on December 1, 2024, and at Maturity, at the Interest Rate per annum specified above, until the principal hereof is paid or made available for payment, provided that any principal and premium, and any such installment of interest, which is overdue shall bear interest at the rate of 5.40% per annum (to the extent permitted by applicable law), from the dates such amounts are due until they are paid or made available for payment, and such interest shall be payable on demand. The amount of interest payable for any period shall be computed on the basis of twelve 30-day months and a 360-day year. The amount of interest payable for any partial period shall be computed on the basis of a 360-day year of twelve 30-day months and the days elapsed in any partial month. In the event that any date on which interest is payable on this Security is not a Business Day, then a payment of the interest payable on such date will be made on the next succeeding day which is a Business Day (and without any interest or other payment in respect of any such delay) with the same force and effect as if made on the date the payment was originally payable. A “Business Day” shall mean any day other than a Saturday, a Sunday or a day on which banking institutions in The City of New York are authorized or required by law, regulation or executive order to close. The interest so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Person in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on the Regular Record Date for such interest, which shall be May 15 and November 15 (whether or not

A-2

a Business Day), as the case may be, next preceding such Interest Payment Date. Any such interest not so punctually paid or duly provided for shall forthwith cease to be payable to the Holder on such Regular Record Date and shall either be paid to the Person in whose name this Security (or one or more Predecessor Securities) is registered at the close of business on a Special Record Date for the payment of such Defaulted Interest to be fixed by the Trustee, notice whereof shall be given to Holders of Securities of this series not less than 10 days prior to such Special Record Date, or be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange or automated quotation system on which the Securities of this series may be listed or traded, and upon such notice as may be required by such exchange or automated quotation system, all as more fully provided in said Indenture.

Payment of the principal of (and premium, if any) and any such interest on this Security will be made at the Corporate Trust Office of the Trustee, in such coin or currency of the United States of America as at the time of payment is legal tender for payment of public and private debts; provided, however, that at the option of the Company payment of interest may be made (i) by check mailed to the address of the Person entitled thereto as such address shall appear in the Security Register or (ii) by wire transfer in immediately available funds at such place and to such account as may be designated in writing by the Person entitled thereto as specified in the Security Register.

Reference is hereby made to the further provisions of this Security set forth on the reverse hereof, which further provisions shall for all purposes have the same effect as if set forth at this place.

Unless the certificate of authentication hereon has been executed by the Trustee referred to on the reverse hereof by manual, facsimile or electronic signature (provided that any electronic signature is a true representation of the signer’s actual signature), this Security shall not be entitled to any benefit under the Indenture or be valid or obligatory for any purpose.

A-3

IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed.

Attest:

CERTIFICATE OF AUTHENTICATION

This is one of the Securities of the series designated therein referred to in the within-mentioned Indenture.

A-4

SCHEDULE A

The initial aggregate principal amount of Securities evidenced by the Certificate to which this Schedule is attached is $      . The notations on the following table evidence decreases and increases in the aggregate principal amount of Securities evidenced by such Certificate.

A-5

[FORM OF REVERSE SIDE OF SECURITY]

CENTERPOINT ENERGY, INC.

5.40% SENIOR NOTES DUE 2029

This Security is one of a duly authorized issue of securities of the Company (herein called the “Securities”), issued and to be issued in one or more series under an Indenture, dated as of May 19, 2003 (herein called the “ Indenture,” which term shall have the meaning assigned to it in such instrument), between the Company and The Bank of New York Mellon Trust Company, National Association (successor to JPMorgan Chase Bank, National Association (formerly JPMorgan Chase Bank)), as Trustee (herein called the “Trustee,” which term includes any successor trustee under the Indenture), to which Indenture and all indentures supplemental thereto reference is hereby made for a statement of the respective rights, limitations of rights, duties and immunities thereunder of the Company, the Trustee and the Holders of the Securities and of the terms upon which the Securities are, and are to be, authenticated and delivered. This Security is one of the series designated on the face hereof, initially limited in aggregate principal amount to $700,000,000; provided, however, that the authorized aggregate principal amount of the Securities may be increased above such amount by a Board Resolution to such effect.

Prior to May 1, 2029 (the “Par Call Date”), the Company may redeem this Security 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 (1)(a) the sum of the present values of the remaining scheduled payments of principal and interest thereon discounted to the Redemption Date (assuming this Security, or such portion to be redeemed, matured on the Par Call Date) on a semi-annual basis (assuming a 360-day year consisting of twelve 30-day months) at the applicable Treasury Rate plus 15 basis points less (b) interest accrued to the Redemption Date, and (2) 100% of the principal amount of this Security to be redeemed, plus, in either case, accrued and unpaid interest thereon, if any, to, but excluding, the Redemption Date.

On or after the Par Call Date, the Company may redeem this Security, 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 this Security (or such portion to be redeemed) plus accrued and unpaid interest on the principal amount being redeemed, if any, to, but excluding, the Redemption Date.

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

The Treasury Rate shall be determined by the 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 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

A-6

treasury rate, the Company shall select, as applicable: (1) the yield for the Treasury constant maturity on H.15 exactly equal to the period from the Redemption Date to the 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 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 Redemption Date.

If on the third Business Day preceding the Redemption Date H.15 TCM or any successor designation or publication is no longer published, the 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 Par Call Date, as applicable. If there is no United States Treasury security maturing on the Par Call Date but there are two or more United States Treasury securities with a maturity date equally distant from the Par Call Date, one with a maturity date preceding the Par Call Date and one with a maturity date following the Par Call Date, the Company shall select the United States Treasury security with a maturity date preceding the Par Call Date. If there are two or more United States Treasury securities maturing on the Par Call Date or two or more United States Treasury securities meeting the criteria of the preceding sentence, the 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 semi-annual 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.

The Company’s actions and determinations in determining the Redemption Price shall be conclusive and binding for all purposes, absent manifest error. The Trustee shall have no responsibility for the calculation of such amount.

In the event of redemption of this Security in part only, a new Security or Securities of this series and of like tenor for the unredeemed portion hereof will be issued in the name of the Holder hereof upon the cancellation hereof.

The Securities of this series are not entitled to the benefit of any sinking fund.

The Indenture contains provisions for satisfaction and discharge of the entire indebtedness of this Security upon compliance by the Company with certain conditions set forth in the Indenture.

A-7

The Indenture contains provisions for defeasance at any time of the entire indebtedness of this Security or certain restrictive covenants and Events of Default with respect to this Security, in each case upon compliance with certain conditions set forth in the Indenture.

If an Event of Default with respect to Securities of this series shall occur and be continuing, the principal of the Securities of this series may be declared due and payable in the manner and with the effect provided in the Indenture.

The Indenture permits, with certain exceptions as therein provided, the amendment thereof and the modification of the rights and obligations of the Company and the rights of the Holders of the Securities to be affected under the Indenture at any time by the Company and the Trustee with the consent of the Holders of a majority in principal amount of the Securities at the time Outstanding to be affected. The Indenture also contains provisions permitting the Holders of specified percentages in principal amount of the Securities at the time Outstanding, on behalf of the Holders of all Securities of such series, to waive compliance by the Company with certain provisions of the Indenture and certain past defaults under the Indenture and their consequences. Any such consent or waiver by the Holder of this Security shall be conclusive and binding upon such Holder and upon all future Holders of this Security and of any Security issued upon the registration of transfer hereof or in exchange herefor or in lieu hereof, whether or not notation of such consent or waiver is made upon this Security.

As provided in and subject to the provisions of the Indenture, the Holder of this Security shall not have the right to institute any proceeding with respect to the Indenture or for the appointment of a receiver or trustee or for any other remedy thereunder, unless such Holder shall have previously given the Trustee written notice of a continuing Event of Default with respect to the Securities of this series, the Holders of not less than 33% in principal amount of the Securities of this series at the time Outstanding shall have made written request to the Trustee to institute proceedings in respect of such Event of Default as Trustee and offered the Trustee reasonable indemnity, and the Trustee shall not have received from the Holders of a majority in principal amount of Securities of this series at the time Outstanding a direction inconsistent with such request, and shall have failed to institute any such proceeding, for 60 days after receipt of such notice, request and offer of indemnity. The foregoing shall not apply to any suit instituted by the Holder of this Security for the enforcement of any payment of principal hereof or any premium or interest hereon on or after the respective due dates expressed herein.

No reference herein to the Indenture and no provision of this Security or of the Indenture shall alter or impair the obligation of the Company, which is absolute and unconditional, to pay the principal of and any premium and interest on this Security at the times, place and rate, and in the coin or currency, herein prescribed.

As provided in the Indenture and subject to certain limitations therein set forth, the transfer of this Security is registrable in the Security Register, upon surrender of this Security for registration of transfer at the office or agency of the Company in any place where the principal of and any premium and interest on this Security are payable, duly endorsed by, or accompanied by a written instrument of transfer in form satisfactory to the Company and the Security Registrar duly executed by the Holder hereof or his attorney duly authorized in writing, and thereupon one or more new Securities of this series and of like tenor, of authorized denominations and for the same aggregate principal amount, will be issued to the designated transferee or transferees. No service charge shall be made for any such registration of transfer or exchange, but the Company may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection therewith.

A-8

Prior to due presentment of this Security for registration of transfer, the Company, the Trustee and any agent of the Company or the Trustee may treat the Person in whose name this Security is registered as the owner hereof for all purposes, whether or not this Security be overdue, and neither the Company, the Trustee nor any such agent shall be affected by notice to the contrary.

The Securities of this series are issuable only in registered form without coupons in minimum denominations of $2,000 and integral multiples of $1,000 in excess thereof. As provided in the Indenture and subject to certain limitations therein set forth, Securities of this series are exchangeable for a like aggregate principal amount of Securities of this series and of like tenor of a different authorized denomination, as requested by the Holder surrendering the same.

All terms used in this Security which are defined in the Indenture shall have the meanings assigned to them in the Indenture.

THE INDENTURE AND THIS SECURITY SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

A-9