1 EXHIBIT 4.1 ================================================================================ SECOND SUPPLEMENTAL INDENTURE Dated as of April 5, 2001 to INDENTURE Dated as of March 13, 2001 between NRG ENERGY, INC. and THE BANK OF NEW YORK, as Trustee ================================================================================ 2 SECOND SUPPLEMENTAL INDENTURE, dated as of April 5, 2001 (this "Second Supplemental Indenture"), to the Indenture, dated as of March 13, 2001 (the "Base Indenture"), between NRG ENERGY, INC., a Delaware corporation (the "Company"), and THE BANK OF NEW YORK, a New York banking corporation (the "Trustee"), as supplemented by the First Supplemental Indenture, dated as of March 13, 2001 (the "First Supplemental Indenture"), between the Company and the Trustee. WHEREAS, the Company and the Trustee have heretofore executed and delivered the Base Indenture to provide for the issuance from time to time of Securities (as defined in the Base Indenture) of the Company, to be issued in one or more Series (as defined in the Base Indenture); WHEREAS, Sections 2.1, 2.2 and 7.1 of the Base Indenture provide, among other things, that the Company and the Trustee may enter into indentures supplemental to the Base Indenture for, among other things, the purpose of establishing the designation, form, terms and provisions of Securities of any Series as permitted by Sections 2.1, 2.2 and 7.1 of the Base Indenture; WHEREAS, the Company (i) desires the issuance of two new separate Series of Securities to be designated as hereinafter provided and (ii) has requested the Trustee to enter into this Second Supplemental Indenture for the purpose of establishing the designation, form, terms and provisions of the Securities of such Series; WHEREAS, all action on the part of the Company necessary to authorize the issuance of said Securities under the Base Indenture and this Second Supplemental Indenture has been duly taken. NOW, THEREFORE, THIS SECOND SUPPLEMENTAL INDENTURE WITNESSETH: That, in order to establish the designation, form, terms and provisions of, and to authorize the authentication and delivery of, said Securities, and in consideration of the acceptance of said Securities by the Holders thereof and of other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto hereby agree as follows: 3 ARTICLE I DEFINITIONS (a) Capitalized terms used herein and not otherwise defined herein shall have the respective meanings ascribed thereto in the Base Indenture. (b) The rules of interpretation set forth in the Base Indenture shall be applied hereto as if set forth in full herein. (c) For all purposes of this Second Supplemental Indenture, except as otherwise expressly provided or unless the context otherwise requires, the following terms shall have the following respective meanings (such meanings shall apply equally to both the singular and plural forms of the respective terms): "Change of Control" means the occurrence of one or more of the following events: (i) Xcel or its successors ceases to own a majority of the outstanding Voting Stock of the Issuer, (ii) at any time following the occurrence of the event described in the preceding clause (i), a Person or group (as that term is used in Section 13(d)(3) of the Exchange Act) of Persons (other than Xcel) shall have become the beneficial owner directly or indirectly, or shall have acquired the absolute power to direct the vote, of more than 35% of the outstanding Voting Stock of the Issuer or (iii) during any twelve-month period, individuals who at the beginning of such period constitute the Board of Directors (together with any new directors whose election or nomination was approved by a majority of the directors then in office who were either directors at the beginning of such period or who were previously so approved) shall cease for any reason to constitute a majority of the Board of Directors. Notwithstanding the foregoing, a Change of Control shall be deemed not to have occurred with respect to a Series of Securities if one or more of the above events occurs or circumstances exist and, after giving effect thereto, the Securities of such Series are rated Investment Grade. "Comparable Treasury Issue" means the United States Treasury security selected by Banc of America Securities LLC, Salomon Smith Barney Inc., or any of their respective affiliates as having a maturity comparable to the remaining term of the Notes that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of the Notes. "Comparable Treasury Price" means the average of three Reference Treasury Dealer Quotations obtained by the Trustee in respect of the Notes to be redeemed on the applicable redemption date. 2 4 "Make Whole Amount" means, with respect to the Notes at any time, the sum of the present values of the Remaining Scheduled Payments discounted, on a semiannual basis (assuming a 360 day year consisting of twelve 30-day months), at a rate equal to the Treasury Rate plus 35 basis points in the case of the Senior Notes due 2011 and 40 basis points in the case of the Senior Notes due 2031. The Make Whole Amount shall be computed as of the third Business Day prior to the applicable redemption date, and certified, by an Investment Banker. "Notes" means the Senior Notes due 2011 and the Senior Notes due 2031. "Reference Treasury Dealer Quotation" means, with respect to each Reference Treasury Dealer and any redemption date, the average, as determined by the Trustee, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Trustee by a Reference Treasury Dealer at 3:30 p.m., New York City time, on the third Business Day preceding the redemption date. "Reference Treasury Dealers" means Banc of America Securities LLC and Salomon Smith Barney Inc. (so long as they continue to be primary U.S. Government securities dealers) and any two other primary U.S. Government securities dealers chosen by the Company. If Banc of America Securities LLC or Salomon Smith Barney Inc. ceases to be a primary U.S. Government securities dealer, the Company will appoint in its place another nationally recognized investment banking firm that is a primary U.S. Government securities dealer. "Remaining Scheduled Payments" means, with respect to each Note that the Company is redeeming, the remaining scheduled payments of the principal and interest that would be due after the related redemption date if such Note were not redeemed. However, if the redemption date is not a scheduled interest payment date with respect to that Note, the amount of the next succeeding scheduled interest payment on that Note will be reduced by the amount of interest accrued on such Note to the redemption date. "Senior Notes due 2011" shall have the meaning ascribed thereto in Section 2.1(a) hereof. "Senior Notes due 2031" shall have the meaning ascribed thereto in Section 2.1(a) hereof. 3 5 "Treasury Rate" means, with respect to any redemption date, an annual rate equal to the semiannual equivalent yield to maturity of the Comparable Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for the redemption date. The semiannual equivalent yield to maturity will be computed as of the third Business Day immediately preceding the redemption date. ARTICLE II GENERAL TERMS AND CONDITIONS OF THE NOTES 2.1 SECTION Designation and Principal Amount. (a) There is hereby authorized two new separate Series of Securities designated the 7.75% Senior Notes due 2011 (the "Senior Notes due 2011") and the 8.625% Senior Notes due 2031 (the "Senior Notes due 2031"). (b) The aggregate principal amount of the two new separate Series of Securities authorized by this Second Supplemental Indenture shall be limited (except as otherwise provided in Article II of the Base Indenture) to $690,000,000, with the aggregate principal amount of the respective Securities limited to $350,000,000 for the Senior Notes due 2011 and $340,000,000 for the Senior Notes due 2031. (c) The Notes may be issued from time to time upon written order of the Company to the Trustee for the authentication and delivery of the Notes pursuant to Section 2.2 of the Base Indenture (d) The Notes shall have and be subject to such other terms as provided in the Base Indenture and shall be evidenced by one or more Securities of that Series in the form of Exhibit A to the Base Indenture. (e) The Notes shall be issuable in minimum denominations of $100,000 and integral multiples of $1,000 in excess thereof. 2.2 SECTION Maturity. (a) The date upon which the Senior Notes due 2011 shall become due and payable at final maturity, together with any accrued and unpaid interest, is April 1, 2011 (the "2011 Notes Maturity Date"). 4 6 (b) The date upon which the Senior Notes due 2031 shall become due and payable at final maturity, together with any accrued and unpaid interest, is April 1, 2031 (the "2031 Notes Maturity Date" and, together with the 2011 Notes Maturity Date, the "Maturity Dates"). 2.3 SECTION Interest. (a) The Notes will bear interest at the Interest Rates (as defined below) from April 5, 2001, until the principal thereof becomes due and payable. Interest on the Notes will be payable semi-annually in arrears on April 1 and October 1 of each year, commencing October 1, 2001, to the Person in whose name any such Note or any predecessor Note is registered, at the close of business on the regular record date for such interest installment, which, in the case of a Global Security, shall be the close of business on the March 15 and September 15 next preceding such Interest Payment Date. Notwithstanding the foregoing sentence, if the Notes are no longer in book-entry only form, the regular record dates for the Notes, shall be the March 15 and September 15 prior to the applicable Interest Payment Date. (b) The interest rate in respect of the Senior Notes due 2011 will be 7.75% per annum (the "2011 Notes Interest Rate") and the interest rate in respect of the Senior Notes due 2031 will be 8.625% per annum (the "2031 Notes Interest Rate" and, together with the 2011 Notes Interest Rate, the "Interest Rates"). (c) In the event that any date on which interest is payable on the Notes is not a Business Day, then payment of interest payable on such date will be made on the next succeeding day which is a Business Day, with the same force and effect as if made on such date, and no interest shall accrue on the amount so payable from the period from and after such Interest Payment Date or Maturity Date, as the case may be (each date on which interest is actually payable, an "Interest Payment Date"). 2.4 SECTION Global Securities. Each Series of Notes shall be issued in the form of one or more Global Securities in an aggregate principal amount equal to the aggregate principal amount of all outstanding Notes of that Series, to be registered in the name of the U.S. Depositary, or its nominee, and delivered by the Trustee to or upon the order of the U.S. Depositary for crediting to the accounts of its participants pursuant to the written instructions of the Company. The Company upon any such presentation shall execute one or more Global Securities in such aggregate principal amount and deliver the same to the Trustee for authentication and delivery in accordance with the Base Indenture 5 7 and this Second Supplemental Indenture. Payments on Notes issued as one or more Global Securities will be made to the U.S. Depositary. ARTICLE III REDEMPTION OF THE NOTES 3.1 SECTION Optional Redemption of the Notes. The Company at its option may, at any time, redeem the Notes, in whole or in part, upon payment of a redemption price equal to (A) the greater of (i) 100% of the principal amount of the Notes to be redeemed and (ii) the Make Whole Amount, plus (B) accrued and unpaid interest, if any, on the principal amount of Notes being redeemed to the redemption date. 3.2 SECTION No Sinking Fund. The Notes are not entitled to the benefit of any sinking fund. ARTICLE IV ORIGINAL ISSUE OF NOTES 4.1 SECTION Original Issue of Senior Notes due 2011. The Senior Notes due 2011 in the aggregate principal amount of $350,000,000 may, upon execution of this Second Supplemental Indenture, be executed by the Company and delivered to the Trustee for authentication, and the Trustee shall thereupon authenticate and deliver said Notes to or upon the written order of the Company pursuant to Section 2.2 of the Base Indenture without any further action of the Company. 4.2 SECTION Original Issue of Senior Notes due 2031. The Senior Notes due 2031 in the aggregate principal amount of $340,000,000 may, upon execution of this Second Supplemental Indenture, be executed by the Company and delivered to the Trustee for authentication, and the Trustee shall thereupon authenticate and deliver said Notes to or upon the written 6 8 order of the Company pursuant to Section 2.2 of the Base Indenture without any further action of the Company. ARTICLE V MISCELLANEOUS 5.1 SECTION Ratification of Base Indenture and First Supplemental Indenture. The Base Indenture and the First Supplemental Indenture, as supplemented by this Second Supplemental Indenture, are in all respects ratified and confirmed, and this Second Supplemental Indenture shall be deemed part of the Base Indenture in the manner and to the extent herein and therein provided. 5.2 SECTION Trustee Not Responsible for Recitals. The recitals contained herein and in the Notes, except with respect to the Trustee's certificates of authentication, shall be taken as the statements of the Company, and the Trustee assumes no responsibility for the correctness of the same. The Trustee makes no representations as to the validity or sufficiency of this Second Supplemental Indenture or of the Notes. 5.3 SECTION Governing Law. THIS SECOND SUPPLEMENTAL INDENTURE AND EACH NOTE OF EACH SERIES CREATED HEREUNDER SHALL, PURSUANT TO SECTION 5-1401 OF THE NEW YORK GENERAL OBLIGATIONS LAW, BE GOVERNED BY THE LAW OF THE STATE OF NEW YORK, WITHOUT REFERENCE TO THE CHOICE OF LAW PROVISIONS THEREOF (OTHER THAN SUCH SECTION 5-1401). 5.4 SECTION Separability . In case any one or more of the provisions contained in this Second Supplemental Indenture or in the Notes shall for any reason be held to be invalid, illegal or unenforceable in any respect, such invalidity, illegality or unenforceability shall not affect any other provisions of this Second Supplemental Indenture or of the Notes, but this Second Supplemental Indenture and the Notes shall be construed as if such invalid or illegal or unenforceable provision had never been contained herein or therein. 7 9 5.5 SECTION Counterparts. This Second Supplemental Indenture may be executed in any number of counterparts, each of which when so executed shall be deemed to be an original, but all such counterparts shall together constitute but one and the same instrument. 8 10 IN WITNESS WHEREOF, the parties have caused this Second Supplemental Indenture to be duly executed by their respective officers thereunto duly authorized as of the date first above written. NRG ENERGY, INC. By: -------------------------------------- Name: Title: THE BANK OF NEW YORK, as Trustee By: -------------------------------------- Name: Title: