Southern Indiana Gas and Electric Company with Deutsche Bank Trust Company Americas, as Trustee _______________ Supplemental Indenture Relating to the First Mortgage Bonds Series 2015 (Mount Vernon) due 2055 Series 2015 (Warrick) due 2055 Dated as of September 1, 2015

Supplemental Indenture, dated as of September 1, 2015 (this “Supplemental Indenture”), between Southern Indiana Gas and Electric Company, a corporation organized and existing under the laws of the State of Indiana (hereinafter called the “Company”), party of the first part, and Deutsche Bank Trust Company Americas, a corporation organized and existing under the laws of the State of New York, formerly known as Bankers Trust Company, as Trustee under the Mortgage hereinafter referred to, party of the second part.

Whereas, the Company heretofore executed and delivered to Deutsche Bank Trust Company Americas, formerly known as Bankers Trust Company, as trustee (hereinafter called the “Trustee”), a certain Indenture of Mortgage and Deed of Trust dated as of April 1, 1932, to secure an issue of bonds of the Company, issued and to be issued in series, from time to time, in the manner and subject to the conditions set forth in the said Indenture, and the said Indenture has been amended and supplemented by Supplemental Indentures dated as of August 31, 1936, October 1, 1937, March 22, 1939, July 1, 1948, June 1, 1949, October 1, 1949, January 1, 1951, April 1, 1954, March 1, 1957, October 1, 1965, September 1, 1966, August 1, 1968, May 1, 1970, August 1, 1971, April 1, 1972, October 1, 1973, April 1, 1975, January 15, 1977, April 1, 1978, June 4, 1981, January 20, 1983, November 1, 1983, March 1, 1984, June 1, 1984, November 1, 1984, July 1, 1985, November 1, 1985, June 1, 1986, November 15, 1986, January 15, 1987, December 15, 1987, December 13, 1990, April 1, 1993, May 1, 1993, June 1, 1993, July 1, 1999, March 1, 2000, August 1, 2004, October 1, 2004, April 1, 2005, March 1, 2006, December 1, 2007, August 1, 2009, April 1, 2013 and September 1, 2014, which Indenture as so amended and supplemented is hereinafter referred to as the “Mortgage” and as further supplemented by this Supplemental Indenture is hereinafter referred to as the “Indenture”; and

Whereas, Section 108 of the Mortgage provides that the Company and the Trustee may, from time to time, enter into such indentures supplemental to the Mortgage as shall be deemed by them necessary or desirable; and

Whereas, the Company has entered into (i) a Loan Agreement dated as of September 1, 2015 (the “Mount Vernon 2015 Loan Agreement”), with the City of Mount Vernon, Indiana (the “City”), pursuant to which the City issued $23,000,000 aggregate principal amount of its Environmental Improvement Revenue Bonds, Series 2015 (Southern Indiana Gas and Electric Company Project) (the “Mount Vernon 2015 Bonds”), pursuant to and in accordance with the terms of an Indenture dated as of September 1, 2015 (the “Mount Vernon 2015 Indenture”), between the City and Wells Fargo Bank, National Association, as trustee (the “Issuer Trustee”), at the request of and for the benefit of the Company, in order to provide funds to loan to the Company for the purpose of (a) financing a portion of the costs of acquisition, construction, installation and equipping of certain solid waste disposal facilities described in Exhibit A to the Mount Vernon 2015 Loan Agreement and (b) paying certain costs of issuance relating to the Mount Vernon 2015 Bonds; and (ii) a Loan Agreement dated as of September 1, 2015 (the “Warrick 2015 Loan Agreement”), with Warrick County, Indiana (the “County”), pursuant to which the County issued $15,200,000 aggregate principal amount of its Environmental Improvement Revenue Bonds, Series 2015 (Southern Indiana Gas and Electric Company Projects) (the “Warrick 2015 Bonds” and together with the Mount Vernon 2015 Bonds, the “Issuer Bonds”), pursuant to and in accordance with the terms of an Indenture dated as of September 1, 2015 (the “Warrick 2015 Indenture”), between the County and the Issuer Trustee in order to provide funds to loan to the Company for the purpose of (a) financing a portion of the costs of acquisition, construction, installation and equipping of certain solid waste disposal facilities described in Exhibit A to the Warrick 2015 Loan Agreement and (b) paying certain costs of issuance relating to the Warrick 2015 Bonds; and

Whereas, the Company has determined that it would be in its best interests, given the current status of the financial markets, to initially evidence and secure the Company’s obligations relating to the (i) Mount Vernon 2015 Bonds under the Mount Vernon 2015 Loan Agreement with the Company’s first mortgage bonds

and (ii) Warrick 2015 Bonds under the Warrick 2015 Loan Agreement with the Company’s first mortgage bonds; and

Whereas, the Company by appropriate company action in conformity with the terms of the Indenture has duly determined to create (i) a new series of bonds which shall be issued under the Indenture in an aggregate principal amount of $23,000,000 and be designated as “First Mortgage Bonds, Series 2015 (Mount Vernon) due 2055” (hereinafter sometimes referred to as “Bonds of the Fifty-third Series”), the bonds of which series are to bear interest at the rate from time to time borne by the Mount Vernon 2015 Bonds and are subject to certain optional and mandatory redemption rights and obligations set forth herein and (ii) a new series of bonds which shall be issued under the Indenture in an aggregate principal amount of $15,200,000 and be designated as “First Mortgage Bonds, Series 2015 (Warrick) due 2055” (hereinafter sometimes referred to as “Bonds of the Fifty-fourth Series”), the bonds of which series are to bear interest at the rate from time to time borne by the Warrick 2015 Bonds and are subject to certain optional and mandatory redemption rights and obligations set forth herein; and

Whereas, all things necessary to make the Bonds of the Fifty-third Series and the Bonds of the Fifty-fourth Series when authenticated by the Trustee and issued as in the Indenture provided, the valid, binding and legal obligations of the Company, entitled in all respects to the security of the Indenture, have been done and performed, and the creation, execution and delivery of this Supplemental Indenture has in all respects been duly authorized; and

Whereas, the Company and the Trustee deem it advisable to enter into this Supplemental Indenture for the purposes above stated and for the purpose of describing the Bonds of the Fifty-third Series and the Bonds of the Fifty-fourth Series and of providing the terms and conditions of redemption of each such Series;

Now, Therefore, This Supplemental Indenture Witnesseth: That Southern Indiana Gas and Electric Company, in consideration of the premises and of one dollar to it duly paid by the Trustee at or before the ensealing and delivery of these presents, the receipt whereof is hereby acknowledged, and of the purchase and acceptance of the bonds issued or to be issued hereunder by the holders or registered owners thereof, and in order to secure the payment of the principal, premium, if any, and interest of all bonds at any time issued and outstanding under the Indenture, according to their tenor and effect, and the performance of all of the provisions hereof and of said bonds, hath granted, bargained, sold, released, conveyed, assigned, transferred, pledged, set over and confirmed and by these presents doth grant, bargain, sell, release, convey, assign, transfer, pledge, set over and confirm unto Deutsche Bank Trust Company Americas, formerly known as Bankers Trust Company, as Trustee, and to its successor or successors in said trust, and to its and their assigns forever, all the properties, real, personal and mixed, tangible and intangible of the character described in the granting clauses of the aforesaid Indenture of Mortgage and Deed of Trust dated as of April 1, 1932 or in any indenture supplemental thereto acquired by the Company on or after the date of the execution and delivery of said Indenture of Mortgage and Deed of Trust (except any in said Indenture of Mortgage and Deed of Trust or in any indenture supplemental thereto expressly excepted) and does hereby confirm that the Company will not cause or consent to a partition, either voluntary or through legal proceedings, of property, whether herein described or heretofore or hereafter acquired, in which its ownership shall be as a tenant in common, except as permitted by and in conformity with the provisions of the Indenture and particularly of Article X thereof.

Together with all and singular the tenements, hereditaments and appurtenances belonging or in any wise appertaining to the aforesaid property or any part thereof, with the reversion and reversions, remainder and remainders and (subject to the provisions of Article X of the Indenture), the tolls, rents, revenues, issues, earnings, income, product and profits thereof, and all the estate, right, title, interest and claim whatsoever,

at law as well as in equity, which the Company now has or may hereafter acquire in and to the aforesaid property and franchises and every part and parcel thereof.

To Have and to Hold all such properties, real, personal and mixed, mortgaged, pledged or conveyed by the Company as aforesaid, or intended so to be, unto the Trustee and its successors and assigns forever.

In Trust, Nevertheless, upon the terms and trusts of the Indenture, for those who shall hold the bonds and coupons issued and to be issued thereunder, or any of them, without preference, priority or distinction as to lien of any of said bonds and coupons over any others thereof by reason of priority in the time of the issue or negotiation thereof, or otherwise howsoever, subject, however, to the provisions in reference to extended, transferred or pledged coupons and claims for interest set forth in the Indenture (and subject to any sinking funds that may be created for the benefit of any particular series).

Provided, However, and these presents are upon the condition that, if the Company, its successors or assigns, shall pay or cause to be paid, the principal of, premium, if any, and interest on said bonds, at the times and in the manner stipulated therein and herein, and shall keep, perform and observe all and singular the covenants and promises in said bonds and in the Indenture expressed to be kept, performed and observed by or on the part of the Company, then this Supplemental Indenture and the estate and rights hereby granted shall cease, determine and be void, otherwise to be and remain in full force and effect.

It Is Hereby Covenanted, Declared and Agreed, by the Company, that all such bonds and coupons are to be issued, authenticated and delivered, and that all property subject or to become subject hereto is to be held, subject to the further covenants, conditions, uses and trusts in the Indenture set forth, and the Company, for itself and its successors and assigns, does hereby covenant and agree to and with the Trustee and its successor or successors in such trust, for the benefit of those who shall hold said bonds and interest coupons, or any of them, as follows:

The form of the definitive registered bond without coupons of the Bonds of the Fifty-third Series and the Trustee’s certificate of authentication to be borne by such bonds are to be substantially in the following forms, respectively:

No. _____                            $23,000,000

Southern Indiana Gas and Electric Company, a corporation of the State of Indiana (hereinafter called the “Company”), for value received, hereby promises to pay to Wells Fargo Bank, National Association, as trustee under the Issuer Indenture hereinafter referred to, or registered assigns Twenty-Three Million dollars, on September 1, 2055 at the office or agency of the Company in the Borough of Manhattan, The City of New York, N.Y., in any coin or currency of the United States of America which at the time of payment is legal tender for the payment of public and private debts, and to pay to the registered owner hereof interest thereon at the same rate or rates of interest as the Environmental Improvement Revenue Bonds, Series 2015 (Southern Indiana Gas and Electric Company Project) (the “Issuer Bonds”) due September 1, 2055 and issued by the City of Mount Vernon, Indiana (the “Issuer”), under the Indenture dated as of September 1, 2015, as the same may be supplemented and amended from time to time in accordance with its terms (the “Issuer Indenture”), between the Issuer and Wells Fargo Bank, National Association, as trustee (the “Issuer Trustee”) (as determined in accordance with the Issuer Indenture); provided, however, that in no event shall the rate of interest borne by the bonds of this series exceed 12% per annum. Such interest, in like coin or currency, payable at said office or agency on the same dates as interest on the Issuer Bonds, or if this bond shall be duly called for redemption, until the redemption date, or if the Company shall default in the payment of the principal hereof, until the Company’s obligation to pay principal shall be discharged as provided in the hereinafter defined Mortgage, is paid until the principal sum is paid in full discharge under the Mortgage.

The Company has agreed to pay the principal of, premium, if any, and interest on the Issuer Bonds pursuant to a Loan Agreement dated as of September 1, 2015, as the same may be supplemented and amended from time to time in

accordance with its terms (the “Agreement”) between the Company and the Issuer. Pursuant to the granting clause of the Issuer Indenture, this bond is issued to the Issuer Trustee to secure any and all obligations of the Company under the Agreement with respect to payment of the Issuer Bonds. Payment of principal of, premium, if any, or interest on, the Issuer Bonds shall constitute payments on this bond as further provided herein and in the Issuer Indenture, pursuant to which this bond has been authorized.

Upon any payment of the principal of, premium, if any, and interest on, all or any portion of the Issuer Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 10.1 of the Issuer Indenture, a principal amount of this bond equal to the principal amount of such Issuer Bonds shall, to the extent of such payment of principal, premium, if any, and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such bonds shall be surrendered to the Trustee for cancellation as provided in Section 10.1 of the Issuer Indenture. The Trustee (as hereinafter defined) may at any time and all times conclusively assume that the obligation of the Company to make payments under the Agreement with respect to the principal of, premium, if any, and interest on, the Issuer Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Issuer Trustee signed by one of its officers stating (i) that timely payment of principal of, or interest on, the Issuer Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Issuer Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

The provisions of this bond are continued on the reverse hereof and such continued provisions shall for all purposes have the same effect as though fully set forth at this place.

This bond shall not become obligatory until Deutsche Bank Trust Company Americas, the Trustee under the Mortgage, or its successor thereunder, shall have signed the form of certificate endorsed hereon.

In Witness Whereof, Southern Indiana Gas and Electric Company has caused this bond to be signed in its name by its President or a Vice President, by his signature or a facsimile thereof, and a facsimile of its corporate seal to be imprinted hereon, attested by its Secretary or an Assistant Secretary, by his signature or a facsimile thereof.

Dated: __________, 2015

This bond is one of the bonds of the series designated therein, described in the within‑mentioned Mortgage.

This bond is one of an issue of First Mortgage Bonds of the Company, issuable in series, and is one of the series designated in the title hereof, all issued and to be issued under and equally secured (except as to any sinking fund established in accordance with the provisions of the Mortgage hereinafter mentioned for the bonds of any particular series) by an Indenture of Mortgage and Deed of Trust, dated as of April 1, 1932, executed by the Company to Deutsche Bank Trust Company Americas, formerly known as Bankers Trust Company, as Trustee (the “Trustee”), as amended and supplemented by indentures supplemental thereto (herein referred to as the “Mortgage”), to which reference is made for a description of the property mortgaged and pledged, the nature and extent of the security, the rights of the holders of the bonds in respect thereof and the terms and conditions upon which the bonds are secured.

The bonds of this series are issued and to be issued in order to evidence and secure a loan made by the Issuer to the Company pursuant to the Agreement. In order to provide moneys to fund such loan, the Issuer has issued the Issuer Bonds under and pursuant to the Issuer Indenture. Payments made by the Company of principal, premium, if any, and interest on the bonds of this series are intended to be sufficient to permit payments of principal, premium, if any, and interest to be made on the Issuer Bonds. Upon certain terms and conditions, moneys held under and pursuant to the Issuer Indenture, including moneys so held from the proceeds of the sale of the Issuer Bonds or earnings on the investment of such proceeds, or redemption of the Issuer Bonds shall be credited to or used for the payment of the bonds of this series and to the extent so credited or used shall satisfy a like amount otherwise due hereunder.

The bonds of this series are subject to optional and mandatory redemption, in whole or in part, as the case may be, on each date that Issuer Bonds are to be redeemed. The principal amount of the bonds of this series to be redeemed

on any such date shall be equal to the principal amount of Issuer Bonds called for redemption on that date. All redemptions of bonds of this series shall be at the redemption prices that correspond to the redemption prices for the Issuer Bonds.

If and whenever the Trustee or the Company is notified that an event of default has occurred and is continuing under Section 7.1(D) of the Issuer Indenture or Section 6.1(a) or Section 6.1(b) of the Agreement, and provided that the principal of all Issuer Bonds then outstanding and the interest thereon shall have been declared immediately due and payable, then not later than two business days following the occurrence of the foregoing events, the Company shall, upon not less than 30 days’ and not more than 45 days’ prior written notice given in the manner provided in the Mortgage, call for redemption on a redemption date selected by it not later than 45 days following the date of such notice, all of the bonds of this series then outstanding, and shall on such redemption date redeem the same at a price equal to 100% of the principal amount thereof together with accrued interest thereon to the redemption date, except that such requirement or redemption shall be deemed to be waived if, prior to the date fixed for such redemption of the bonds of this series, such event of default is waived or cured.

In case a completed default, as defined in the Mortgage, shall occur, the principal of this bond and all other bonds of the Company at any such time outstanding under the Mortgage may be declared or may become due and payable, upon the conditions and in the manner and with the effect provided in the Mortgage. The Mortgage provides that such declaration may in certain events be waived by the holders of a majority in principal amount of the bonds entitled to vote then outstanding.

As provided in Section 5.9 of the Issuer Indenture, from and after the Release Date (as defined in the Issuer Indenture), the obligations of the Company with respect to this bond shall be deemed to be satisfied and discharged, this bond shall cease to secure in any manner the Company’s obligations under the Agreement with respect to the payment of any Issuer Bonds outstanding under the Issuer Indenture, and, pursuant to Section 5.9 of the Issuer Indenture, the Issuer Trustee shall forthwith deliver this bond to the Trustee for cancellation.

The bonds of this series are issuable as registered bonds without coupons in denominations of $1,000 and authorized multiples thereof. In the manner and upon payment of the charges prescribed in the Mortgage, registered bonds without coupons of this series may be exchanged for a like aggregate principal amount of fully registered bonds without coupons of other authorized denominations of the same series, upon presentation and surrender thereof, for cancellation, to the Trustee at its principal corporate trust office in the Borough of Manhattan, The City of New York, N.Y.

No recourse shall be had for the payment of the principal of or interest on this bond against any incorporator or any past, present or future subscriber to the capital stock, stockholder, officer or director of the Company or of any predecessor or successor corporation, either directly or through the Company or any predecessor or successor corporation, under any rule of law, statute or constitution or by the enforcement of any assessment or otherwise, all such liability of incorporators, subscribers, stockholders, officers and directors being released by the holder or owner hereof by the acceptance of this bond and being likewise waived and released by the terms of the Mortgage.

The form of the definitive registered bond without coupons of the Bonds of the Fifty-fourth Series and the Trustee’s certificate of authentication to be borne by such bonds are to be substantially in the following forms, respectively:

No. _____                            $15,200,000

Southern Indiana Gas and Electric Company, a corporation of the State of Indiana (hereinafter called the “Company”), for value received, hereby promises to pay to Wells Fargo Bank, National Association, as trustee under the Issuer Indenture hereinafter referred to, or registered assigns Fifteen Million Two Hundred Thousand dollars, on September 1, 2055 at the office or agency of the Company in the Borough of Manhattan, The City of New York, N.Y., in any coin or currency of the United States of America which at the time of payment is legal tender for the payment of public and private debts, and to pay to the registered owner hereof interest thereon at the same rate or rates of interest as the Environmental Improvement Revenue Bonds, Series 2015 (Southern Indiana Gas and Electric Company Projects) (the “Issuer Bonds”) due September 1, 2055 and issued by Warrick County, Indiana (the “Issuer”), under the Indenture dated as of September 1, 2015, as the same may be supplemented and amended from time to time in accordance with its terms (the “Issuer Indenture”), between the Issuer and Wells Fargo Bank, National Association, as trustee (the “Issuer Trustee”) (as determined in accordance with the Issuer Indenture); provided, however, that in no event shall the rate of interest borne by the bonds of this series exceed 12% per annum. Such interest, in like coin or currency, payable at said office or agency on the same dates as interest on the Issuer Bonds, or if this bond shall be duly called for redemption, until the redemption date, or if the Company shall default in the payment of the principal hereof, until the Company’s obligation to pay principal shall be discharged as provided in the hereinafter defined Mortgage, is paid until the principal sum is paid in full discharge under the Mortgage.

The Company has agreed to pay the principal of, premium, if any, and interest on the Issuer Bonds pursuant to a Loan Agreement dated as of September 1, 2015, as the same may be supplemented and amended from time to time in

accordance with its terms (the “Agreement”) between the Company and the Issuer. Pursuant to the granting clause of the Issuer Indenture, this bond is issued to the Issuer Trustee to secure any and all obligations of the Company under the Agreement with respect to payment of the Issuer Bonds. Payment of principal of, premium, if any, or interest on, the Issuer Bonds shall constitute payments on this bond as further provided herein and in the Issuer Indenture, pursuant to which this bond has been authorized.

Upon any payment of the principal of, premium, if any, and interest on, all or any portion of the Issuer Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 10.1 of the Issuer Indenture, a principal amount of this bond equal to the principal amount of such Issuer Bonds shall, to the extent of such payment of principal, premium, if any, and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such bonds shall be surrendered to the Trustee for cancellation as provided in Section 10.1 of the Issuer Indenture. The Trustee (as hereinafter defined) may at any time and all times conclusively assume that the obligation of the Company to make payments under the Agreement with respect to the principal of, premium, if any, and interest on, the Issuer Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Issuer Trustee signed by one of its officers stating (i) that timely payment of principal of, or interest on, the Issuer Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Issuer Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

The provisions of this bond are continued on the reverse hereof and such continued provisions shall for all purposes have the same effect as though fully set forth at this place.

This bond shall not become obligatory until Deutsche Bank Trust Company Americas, the Trustee under the Mortgage, or its successor thereunder, shall have signed the form of certificate endorsed hereon.

In Witness Whereof, Southern Indiana Gas and Electric Company has caused this bond to be signed in its name by its President or a Vice President, by his signature or a facsimile thereof, and a facsimile of its corporate seal to be imprinted hereon, attested by its Secretary or an Assistant Secretary, by his signature or a facsimile thereof.

Dated: __________, 2015

This bond is one of the bonds of the series designated therein, described in the within‑mentioned Mortgage.

This bond is one of an issue of First Mortgage Bonds of the Company, issuable in series, and is one of the series designated in the title hereof, all issued and to be issued under and equally secured (except as to any sinking fund established in accordance with the provisions of the Mortgage hereinafter mentioned for the bonds of any particular series) by an Indenture of Mortgage and Deed of Trust, dated as of April 1, 1932, executed by the Company to Deutsche Bank Trust Company Americas, formerly known as Bankers Trust Company, as Trustee (the “Trustee”), as amended and supplemented by indentures supplemental thereto (herein referred to as the “Mortgage”), to which reference is made for a description of the property mortgaged and pledged, the nature and extent of the security, the rights of the holders of the bonds in respect thereof and the terms and conditions upon which the bonds are secured.

The bonds of this series are issued and to be issued in order to evidence and secure a loan made by the Issuer to the Company pursuant to the Agreement. In order to provide moneys to fund such loan, the Issuer has issued the Issuer Bonds under and pursuant to the Issuer Indenture. Payments made by the Company of principal, premium, if any, and interest on the bonds of this series are intended to be sufficient to permit payments of principal, premium, if any, and interest to be made on the Issuer Bonds. Upon certain terms and conditions, moneys held under and pursuant to the Issuer Indenture, including moneys so held from the proceeds of the sale of the Issuer Bonds or earnings on the investment of such proceeds, or redemption of the Issuer Bonds shall be credited to or used for the payment of the bonds of this series and to the extent so credited or used shall satisfy a like amount otherwise due hereunder.

The bonds of this series are subject to optional and mandatory redemption, in whole or in part, as the case may be, on each date that Issuer Bonds are to be redeemed. The principal amount of the bonds of this series to be redeemed on any such date shall be equal to the principal amount of Issuer Bonds called for redemption on that date. All redemptions of bonds of this series shall be at the redemption prices that correspond to the redemption prices for the Issuer Bonds.

If and whenever the Trustee or the Company is notified that an event of default has occurred and is continuing under Section 7.1(D) of the Issuer Indenture or Section 6.1(a) or Section 6.1(b) of the Agreement, and provided that the principal of all Issuer Bonds then outstanding and the interest thereon shall have been declared immediately due and payable, then not later than two business days following the occurrence of the foregoing events, the Company shall, upon not less than 30 days’ and not more than 45 days’ prior written notice given in the manner provided in the Mortgage, call for redemption on a redemption date selected by it not later than 45 days following the date of

such notice, all of the bonds of this series then outstanding, and shall on such redemption date redeem the same at a price equal to 100% of the principal amount thereof together with accrued interest thereon to the redemption date, except that such requirement or redemption shall be deemed to be waived if, prior to the date fixed for such redemption of the bonds of this series, such event of default is waived or cured.

In case a completed default, as defined in the Mortgage, shall occur, the principal of this bond and all other bonds of the Company at any such time outstanding under the Mortgage may be declared or may become due and payable, upon the conditions and in the manner and with the effect provided in the Mortgage. The Mortgage provides that such declaration may in certain events be waived by the holders of a majority in principal amount of the bonds entitled to vote then outstanding.

As provided in Section 5.9 of the Issuer Indenture, from and after the Release Date (as defined in the Issuer Indenture), the obligations of the Company with respect to this bond shall be deemed to be satisfied and discharged, this bond shall cease to secure in any manner the Company’s obligations under the Agreement with respect to the payment of any Issuer Bonds outstanding under the Issuer Indenture, and, pursuant to Section 5.9 of the Issuer Indenture, the Issuer Trustee shall forthwith deliver this bond to the Trustee for cancellation.

The bonds of this series are issuable as registered bonds without coupons in denominations of $1,000 and authorized multiples thereof. In the manner and upon payment of the charges prescribed in the Mortgage, registered bonds without coupons of this series may be exchanged for a like aggregate principal amount of fully registered bonds without coupons of other authorized denominations of the same series, upon presentation and surrender thereof, for cancellation, to the Trustee at its principal corporate trust office in the Borough of Manhattan, The City of New York, N.Y.

No recourse shall be had for the payment of the principal of or interest on this bond against any incorporator or any past, present or future subscriber to the capital stock, stockholder, officer or director of the Company or of any predecessor or successor corporation, either directly or through the Company

or any predecessor or successor corporation, under any rule of law, statute or constitution or by the enforcement of any assessment or otherwise, all such liability of incorporators, subscribers, stockholders, officers and directors being released by the holder or owner hereof by the acceptance of this bond and being likewise waived and released by the terms of the Mortgage.

Bonds of the Fifty-third Series shall mature, subject to prior redemption, on the date set forth in the form of bond relating hereto hereinbefore set forth, and shall bear interest at the rate from time to time borne by the Mount Vernon 2015 Bonds; provided, however, that in no event shall the rate of interest borne by the Bonds of the Fifty-third Series exceed 12% per annum. Such interest shall be payable on the same dates as interest on the Mount Vernon 2015 Bonds, and all bonds of said series shall be designated as hereinbefore in the fifth Whereas clause set forth. Principal of, premium, if any, and interest on said bonds shall be payable, to the extent specified in the form of bond hereinabove set forth, in any coin or currency of the United States of America which at the time of payment is legal tender for the payment of public and private debts, at the office or agency of the Company in the Borough of Manhattan, The City of New York, N.Y. Definitive bonds of said series may be issued, originally or otherwise, only as registered bonds without coupons; and they and the Trustee’s certificate of authentication shall be substantially in the forms hereinbefore recited, respectively. Definitive registered Bonds of the Fifty-third Series may be issued in the denomination of $1,000 and in such other denominations (in multiples of $1,000) as the Board of Directors of the Company shall approve, and execution and delivery to the Trustee for authentication shall be conclusive evidence of such approval. In the manner and upon payment of the charges prescribed in the Indenture, registered bonds without coupons of said series may be exchanged for a like aggregate principal amount of fully registered bonds without coupons of other authorized denominations of the same series, upon presentation and surrender thereof for cancellation to the Trustee at its principal corporate trust office in the Borough of Manhattan, The City of New York, N.Y. However, notwithstanding the provisions of Section 12 of the Indenture, no charge shall be made upon any transfer or exchange of bonds of said series other than for any tax or taxes or other governmental charge required to be paid by the Company. The form of the temporary bonds of said series shall be in substantially the form of the form of registered bond hereinbefore recited with such appropriate changes therein as are required on account of the temporary nature thereof. Said temporary bonds of said series shall be in registered form without coupons, registrable as to principal, and shall be exchangeable for definitive bonds of said series when prepared.

The person in whose name any registered bond without coupons of the Fifty-third Series is registered at the close of business on any record date (as hereinbelow defined) with respect to any interest payment date shall be entitled to receive the interest payable on such interest payment date notwithstanding the cancellation of such registered bond upon any transfer or exchange thereof subsequent to the record date and prior to such interest payment date, except if and to the extent the Company shall default in the payment of the interest due on such interest payment date, in which case such defaulted interest shall be paid to the person in whose name such bond is registered either at the close of business on the day preceding the date of payment of such defaulted interest or on a subsequent record date for such payment if one shall have been established as hereinafter provided. A subsequent record date may be established by or on behalf of the Company by notice mailed to the holders of bonds not less than ten days preceding such record date, which record date shall be not more than 30 days prior to the subsequent interest payment date. The term “record date” as used in this Section with respect to any regular interest payment date shall mean the Interest Payment Date (as defined in the Mount Vernon 2015 Indenture).

Except as provided in this Section, every registered bond without coupons of the Fifty-third Series shall be dated and shall bear interest as provided in Section 10 of the Indenture; provided, however, that so long as there is no existing default in the payment of interest on the bonds, the holder of any bond authenticated

by the Trustee between the record date for any interest payment date and such interest payment date shall not be entitled to the payment of the interest due on such interest payment date and shall have no claim against the Company with respect thereto; and provided, further, that, if and to the extent the Company shall default in the payment of the interest due on such interest payment date, then any such bond shall bear interest from the interest payment date to which interest has been paid.

Upon any payment of the principal of, premium, if any, and interest on, all or any portion of the Mount Vernon 2015 Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 10.1 of the Mount Vernon 2015 Indenture, the Bonds of the Fifty-third Series in a principal amount equal to the principal amount of such Mount Vernon 2015 Bonds shall, to the extent of such payment of principal, premium, if any, and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such Bonds of the Fifty-third Series shall be surrendered to the Trustee for cancellation as provided in and subject to the terms of Section 10.1 of the Mount Vernon 2015 Indenture. The Trustee may at any time and all times conclusively assume that the obligation of the Company under the Mount Vernon 2015 Loan Agreement to make payments with respect to the principal of, premium, if any, and interest on the Mount Vernon 2015 Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Issuer Trustee signed by one of its officers stating (i) that timely payment of principal of, premium, if any, or interest on, the Mount Vernon 2015 Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Issuer Trustee pursuant to the Mount Vernon 2015 Loan Agreement, and (iii) the amount of the arrearage.

Bonds of the Fifty-fourth Series shall mature, subject to prior redemption, on the date set forth in the form of bond relating hereto hereinbefore set forth, and shall bear interest at the rate from time to time borne by the Warrick 2015 Bonds; provided, however, that in no event shall the rate of interest borne by the Bonds of the Fifty-fourth Series exceed 12% per annum. Such interest shall be payable on the same dates as interest on the Warrick 2015 Bonds, and all bonds of said series shall be designated as hereinbefore in the fifth Whereas clause set forth. Principal of, premium, if any, and interest on said bonds shall be payable, to the extent specified in the form of bond hereinabove set forth, in any coin or currency of the United States of America which at the time of payment is legal tender for the payment of public and private debts, at the office or agency of the Company in the Borough of Manhattan, The City of New York, N.Y. Definitive bonds of said series may be issued, originally or otherwise, only as registered bonds without coupons; and they and the Trustee’s certificate of authentication shall be substantially in the forms hereinbefore recited, respectively. Definitive registered Bonds of the Fifty-fourth Series may be issued in the denomination of $1,000 and in such other denominations (in multiples of $1,000) as the Board of Directors of the Company shall approve, and execution and delivery to the Trustee for authentication shall be conclusive evidence of such approval. In the manner and upon payment of the charges prescribed in the Indenture, registered bonds without coupons of said series may be exchanged for a like aggregate principal amount of fully registered bonds without coupons of other authorized denominations of the same series, upon presentation and surrender thereof for cancellation to the Trustee at its principal corporate trust office in the Borough of Manhattan, The City of New York, N.Y. However, notwithstanding the provisions of Section 12 of the Indenture, no charge shall be made upon any transfer or exchange of bonds of said series other than for any tax or taxes or other governmental charge required to be paid by the Company. The form of the temporary bonds of said series shall be in substantially the form of the form of registered bond hereinbefore recited with such appropriate changes therein as are required on account of the temporary nature thereof. Said temporary bonds of said series shall be in registered form without coupons, registrable as to principal, and shall be exchangeable for definitive bonds of said series when prepared.

The person in whose name any registered bond without coupons of the Fifty-fourth Series is registered at the close of business on any record date (as hereinbelow defined) with respect to any interest payment date shall be entitled to receive the interest payable on such interest payment date notwithstanding the cancellation of such registered bond upon any transfer or exchange thereof subsequent to the record date and prior to such interest payment date, except if and to the extent the Company shall default in the payment of the interest due on such interest payment date, in which case such defaulted interest shall be paid to the person in whose name such bond is registered either at the close of business on the day preceding the date of payment of such defaulted interest or on a subsequent record date for such payment if one shall have been established as hereinafter provided. A subsequent record date may be established by or on behalf of the Company by notice mailed to the holders of bonds not less than ten days preceding such record date, which record date shall be not more than 30 days prior to the subsequent interest payment date. The term “record date” as used in this Section with respect to any regular interest payment date shall mean the Interest Payment Date (as defined in the Warrick 2015 Indenture).

Except as provided in this Section, every registered bond without coupons of the Fifty-fourth Series shall be dated and shall bear interest as provided in Section 10 of the Indenture; provided, however, that so long as there is no existing default in the payment of interest on the bonds, the holder of any bond authenticated by the Trustee between the record date for any interest payment date and such interest payment date shall not be entitled to the payment of the interest due on such interest payment date and shall have no claim

against the Company with respect thereto; and provided, further, that, if and to the extent the Company shall default in the payment of the interest due on such interest payment date, then any such bond shall bear interest from the interest payment date to which interest has been paid.

Upon any payment of the principal of, premium, if any, and interest on, all or any portion of the Warrick 2015 Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 10.1 of the Warrick 2015 Indenture, the Bonds of the Fifty-fourth Series in a principal amount equal to the principal amount of such Warrick 2015 Bonds shall, to the extent of such payment of principal, premium, if any, and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such Bonds of the Fifty-fourth Series shall be surrendered to the Trustee for cancellation as provided in and subject to the terms of Section 10.1 of the Warrick 2015 Indenture. The Trustee may at any time and all times conclusively assume that the obligation of the Company under the Warrick 2015 Loan Agreement to make payments with respect to the principal of, premium, if any, and interest on the Warrick 2015 Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Issuer Trustee signed by one of its officers stating (i) that timely payment of principal of, premium, if any, or interest on, the Warrick 2015 Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Issuer Trustee pursuant to the Warrick 2015 Loan Agreement, and (iii) the amount of the arrearage.

Section 1.    The Bonds of the Fifty-third Series shall be subject to redemption by the Company prior to maturity in the events and in the manner and at the redemption prices set forth in the form of Bond contained in Part IA hereof and not otherwise.

Section 2.    In the manner provided by the provisions of Article IX of the Indenture, notice of redemption shall be mailed not less than 30 days and not more than 45 days prior to the date of redemption, to the registered owner of the Bonds of the Fifty-third Series, at the address thereof as the same shall appear on the transfer register of the Company; provided, however, that the owners of all of the Bonds of the Fifty-third Series may agree in writing with the Company to a shorter notice period with respect to their respective series, and such agreement, if filed with the Trustee, shall be binding on the Company.

Section 1.    The Bonds of the Fifty-fourth Series shall be subject to redemption by the Company prior to maturity in the events and in the manner and at the redemption prices set forth in the form of Bond contained in Part IB hereof and not otherwise.

Section 2.    In the manner provided by the provisions of Article IX of the Indenture, notice of redemption shall be mailed not less than 30 days and not more than 45 days prior to the date of redemption, to the registered owner of the Bonds of the Fifty-fourth Series, at the address thereof as the same shall appear on the transfer register of the Company; provided, however, that the owners of all of the Bonds of the Fifty-fourth Series may agree in writing with the Company to a shorter notice period with respect to their respective series, and such agreement, if filed with the Trustee, shall be binding on the Company.

Section 1.    The Company covenants that the provisions of Section 36A of the Indenture and of Section 1.02 of the Supplemental Indenture dated as of July 1, 1948, which are to remain in effect so long as any bonds of the series referred to in said Section shall be outstanding under the Indenture, shall remain in full force and effect so long as any Bonds of the Fifty-third Series or Bonds of the Fifty-fourth Series shall be outstanding under the Indenture.

Section 2.    Except as herein otherwise expressly provided, no duties, responsibilities or liabilities are assumed, or shall be construed to be assumed, by the Trustee by reason of this Supplemental Indenture, other than as set forth in the Mortgage. The Trustee shall not be responsible for the recitals herein or in the bonds (except the Trustee’s certificate of authentication), all of which are made by the Company solely.

Section 3.    As supplemented and amended by this Supplemental Indenture, the Mortgage is in all respects ratified and confirmed, and the Mortgage and this Supplemental Indenture shall be read, taken and construed as one and the same instrument.

Section 4.    This Supplemental Indenture may be executed in several counterparts and all such counterparts executed and delivered, each as an original, shall constitute but one and the same instrument.

In Witness Whereof, Southern Indiana Gas and Electric Company, party of the first part hereto, and Deutsche Bank Trust Company Americas, party of the second part hereto, have caused these presents to be executed in their respective names by their respective Presidents or one or more of their Vice Presidents, Assistant Vice Presidents or Associates and their respective seals to be hereunto affixed and attested by their respective Secretaries or one of their Assistant Secretaries, Vice Presidents, Assistant Vice Presidents or Associates, all as of the day and year first above written.

(Seal)

On this 28th day of August, 2015, before me, the undersigned, a notary public in and for the county and state aforesaid, personally came M. Naveed Mughal, to me known, who being by me duly sworn, did depose and say that he is Vice President and Treasurer of Southern Indiana Gas and Electric Company, one of the corporations described in and which executed the foregoing instrument; that Southern Indiana Gas and Electric Company has an address of One Vectren Square, Evansville, Indiana 47708; that he knows the seal of the said corporation; that the seal affixed to said instrument is such corporate seal; that it was so affixed by order of the Board of Directors of said corporation and that he signed his name thereto by like order; and the said M. Naveed Mughal acknowledged the execution of the foregoing instrument on behalf of the said corporation as the voluntary act and deed of the said corporation for the uses and purposes therein set forth.

In Witness Whereof, I have hereunto set my hand and seal the day and year first above written.

On this 25th day of August, 2015, before me, the undersigned, a notary public in and for the county and state aforesaid, personally came Jeffrey Schoenfeld, to me known, who being by me duly sworn, did depose and say that he resides at 103 Bowne Court, Matawan, NJ 07747 and personally came Chris Niesz, to me known, who being by me duly sworn, did depose and say that he resides at 359 2nd Street, Apt. 4E, Hoboken, NJ 07030; that each is, respectively, an Vice President and an Assistant Vice President of Deutsche Bank National Trust Company, and duly authorized to sign on behalf of Deutsche Bank Trust Company Americas, one of the corporations described in and which executed the foregoing instrument; that each knows the seal of the said corporation; that the seal affixed to said instrument is such corporate seal; that it was so affixed by order of the Board of Directors of said corporation and that each signed his or her name thereto by like order; and the said Jeffrey Schoenfeld and the said Chris Niesz acknowledged the execution of the foregoing instrument on behalf of the said corporation as the voluntary act and deed of the said corporation for the uses and purposes therein set forth.

In Witness Whereof, I have hereunto set my hand and seal the day and year first above written.

This instrument was prepared by William M. Libit.

I, William M. Libit, affirm, under the penalties for perjury, that I have taken reasonable care to redact each Social Security number in this document, unless required by law.

Prepared by and upon

recordation return to:

William M. Libit

Chapman and Cutler LLP

111 West Monroe Street

Chicago, Illinois 60603