Document:

EX-4.3

 Exhibit 4.3 
  

					
	REGISTERED		 	REGISTERED	  

 THIS NOTE IS A GLOBAL NOTE REGISTERED IN THE NAME OF THE DEPOSITARY (REFERRED TO HEREIN) OR A NOMINEE THEREOF
AND, UNLESS AND UNTIL IT IS EXCHANGED IN WHOLE FOR THE INDIVIDUAL NOTES REPRESENTED HEREBY AS PROVIDED IN THE INDENTURE REFERRED TO BELOW, THIS NOTE 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 OR BY THE DEPOSITARY OR ANY SUCH NOMINEE TO A SUCCESSOR DEPOSITARY OR A NOMINEE OF SUCH SUCCESSOR DEPOSITARY. UNLESS THIS NOTE IS PRESENTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY (55 WATER STREET, NEW YORK, NEW YORK), TO THE TRUSTEE FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR SUCH OTHER
NAME AS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY AND ANY PAYMENT IS MADE TO CEDE & CO., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL SINCE THE
REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN. 
 UNION ELECTRIC COMPANY 

3.65% SENIOR SECURED NOTE DUE 2045 
  

			
	CUSIP: 906548 CL4		NUMBER: 1
	ISIN: US906548CL42		
		
	ORIGINAL ISSUE DATE: April 6, 2015		PRINCIPAL AMOUNT: $250,000,000
		
	INTEREST RATE: 3.65%		MATURITY DATE: April 15, 2045

 UNION ELECTRIC COMPANY, a corporation of the State of Missouri (the “COMPANY”), for value received
hereby promises to pay to CEDE & CO. or registered assigns, the principal sum of TWO HUNDRED FIFTY MILLION DOLLARS ($250,000,000) on the Maturity Date set forth above, and to pay interest thereon from and including the Original Issue Date
specified above or from and including the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually in arrears on April 15 and October 15 in each
year, commencing October 15, 2015, and on the Maturity Date, at the per annum Interest Rate set forth above until the principal hereof is paid or made available for payment. No interest shall accrue on the Maturity Date, so long as the
principal amount of this Note is paid on the Maturity Date. The interest so payable and punctually paid or duly provided for on any such Interest Payment Date (except for interest payable on the Maturity Date set forth above or, if applicable,
upon redemption or acceleration), will, as provided in the Indenture (as defined below), be paid to the Person in whose name this Note is registered at the close of business on the Regular Record Date for such interest, which shall be the
April 1 or October 1 as the case may be, whether or not a Business Day, next preceding such Interest Payment Date; provided, 

 
that the first Interest Payment Date for any part of this Note, the Original Issue Date of which is after a Regular Record Date but prior to the applicable Interest Payment Date, shall be the
Interest Payment Date following the next succeeding Regular Record Date; and provided further, that interest payable on the Maturity Date set forth above or, if applicable, upon redemption or acceleration, shall be payable to the Person to whom
principal shall be payable. Except as otherwise provided in the Indenture, 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 be paid to the
Person in whose name this Note 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 Noteholders not more than fifteen days nor fewer
than ten days prior to such Special Record Date. Payment of the principal of and interest and premium on this Note shall be payable pursuant to Section 2.12(a) of the Indenture. 

This Note is a Global Note in respect of a duly authorized issue of 3.65% Senior Secured Notes due 2045 (the “NOTES OF THIS SERIES”,
which term includes any Global Notes representing such Notes) of the Company issued and to be issued under an Indenture dated as of August 15, 2002, between the Company and The Bank of New York Mellon, as trustee (herein called the
“TRUSTEE”, which term includes any successor Trustee under the Indenture) and indentures supplemental thereto (collectively, the “INDENTURE”). Under the Indenture, one or more series of notes may be issued and, as used herein,
the term “Notes” refers to the Notes of this Series and any other outstanding series of Notes. Reference is hereby made to the Indenture for a more complete statement of the respective rights, limitations of rights, duties and
immunities thereunder of the Company, the Trustee and the Noteholders and of the terms upon which the Notes are and are to be authenticated and delivered. This Note has been issued in respect of the series designated on the first
page hereof, issued in the initial aggregate principal amount of $250,000,000. 
 The Notes will be secured by first mortgage bonds
(the “SENIOR NOTE FIRST MORTGAGE BONDS”) delivered by the Company to the Trustee for the benefit of the Holders of the Notes, issued under the Indenture of Mortgage and Deed of Trust, dated June 15, 1937, from the Company to The Bank
of New York Mellon, as successor trustee (the “MORTGAGE TRUSTEE”), as supplemented and modified (collectively, the “FIRST MORTGAGE”). Reference is made to the First Mortgage and the Indenture for a description of the rights
of the Trustee as holder of the Senior Note First Mortgage Bonds, the property mortgaged and pledged, the nature and extent of the security and the rights of the holders of first mortgage bonds, under the First Mortgage and the rights of the Company
and of the Mortgage Trustee in respect thereof, the duties and immunities of the Mortgage Trustee and the terms and conditions upon which the Senior Note First Mortgage Bonds are secured and the circumstances under which additional first mortgage
bonds may be issued. By its acquisition of an interest in this Note, each Holder of this Note irrevocably (a) consents to each of the amendments to the First Mortgage described in Article III of the Supplemental Indenture dated May 15,
2012 to the First Mortgage without any other or further action by any Holder of such Notes, and (b) designates the Trustee, and its successors, as its proxy with irrevocable instructions to vote and deliver written consents on behalf of such
Holder in favor of such amendments at any Noteholder meeting or meeting of bondholders, in lieu of any Noteholder meeting or meeting of bondholders, in response to any consent solicitation or otherwise. 

  
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 Each Note of this Series shall be dated and issued as of the date of its authentication by
the Trustee and shall bear an Original Issue Date. Each Note of this Series issued upon transfer, exchange or substitution of such Note shall bear the Original Issue Date of such transferred, exchanged or substituted Note, as the case may be. 

Interest on this Note will accrue from and including the Original Issue Date specified above to, but excluding October 15, 2015, and
thereafter, from and including each Interest Payment Date to, but excluding, the next succeeding Interest Payment Date, the Maturity Date or any redemption date, as the case may be. 

All or a portion of the Notes of this Series may be redeemed at the option of the Company at any time or from time to time. The
redemption price for the Notes of this Series to be redeemed on any redemption date prior to October 15, 2044 (six months prior to the Maturity Date) will be equal to the greater of the following amounts: (a) 100% of the principal
amount of the Notes of this Series being redeemed on the redemption date; or (b) the sum of the present values of the remaining scheduled payments of principal and interest on the Notes of this Series being redeemed on that redemption
date that would be payable if such Notes matured on October 15, 2044 (not including any portion of any payments of interest accrued to the redemption date) discounted to the redemption date on a semiannual basis (assuming a 360-day year
consisting of twelve 30-day months) at the Adjusted Treasury Rate (as defined below) plus 20 basis points, as determined by the Reference Treasury Dealer (as defined below), plus, in each case, accrued and unpaid interest thereon to the redemption
date. The redemption price for the Notes of this Series to be redeemed on any redemption date on or after October 15, 2044 will be equal to 100% of the principal amount of the Notes of this Series being redeemed on the redemption date plus
accrued and unpaid interest thereon to the redemption date. Notwithstanding the foregoing, installments of interest on Notes of this Series that are due and payable on Interest Payment Dates falling on or prior to a redemption date will be
payable on the Interest Payment Date to the Holder of this Note as of the close of business on the relevant Regular Record Date. 
 With
respect to a redemption occurring prior to October 15, 2044, the Company shall give the Trustee written notice of the redemption price promptly after the calculation thereof and the Trustee shall not be responsible for such calculation. 

The Company shall mail notice of any redemption at least 30 days but not more than 60 days before the redemption date to each Holder of
the Notes of this Series to be redeemed, and, if less than all Notes of this Series are to be redeemed, the particular Notes of this Series to be redeemed will be selected by the Trustee in such manner as it shall deem appropriate and fair;
provided, that as long as the Notes of this Series are represented by global certificates, beneficial interests in such global certificates will be selected for redemption by The Depository Trust Company in accordance with its standard procedures
therefor. Unless the Company defaults in payment of the redemption price, on and after the redemption date, interest will cease to accrue on the Notes of this Series or portions thereof called for redemption. 

Any notice of redemption at the Company’s option may state that such redemption will be conditional upon receipt by the Trustee, on or
prior to the redemption date, of money sufficient to pay the principal of and premium, if any, and interest on, the Notes of this Series or 

  
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portions thereof called for redemption, and that if such money has not been so received, such notice will be of no force and effect and the Company will not be required to redeem such Notes or
portions thereof. 
 “ADJUSTED TREASURY RATE” means, with respect to any redemption date, the rate per annum 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 such redemption date. 

“COMPARABLE TREASURY ISSUE” means the United States Treasury security selected by the Reference Treasury Dealer as having a maturity
comparable to the remaining term of the Notes of this Series to be redeemed (assuming, for this purpose, that the Notes matured on October 15, 2044) 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 such Notes of this Series. 

“COMPARABLE TREASURY PRICE” means, with respect to any redemption date, (A) the average of the Reference Treasury Dealer
Quotations for such redemption date, after excluding the highest and lowest of such Reference Treasury Dealer Quotations, or (B) if the Company obtains fewer than four such Reference Treasury Dealer Quotations, the average of all such
quotations, or (C) if only one Reference Treasury Dealer Quotation is received, such quotation. 
 “REFERENCE TREASURY
DEALER” means (A) Morgan Stanley & Co. LLC, RBC Capital Markets, LLC and a Primary Treasury Dealer (as defined below) selected by each of Mitsubishi UFJ Securities (USA), Inc. and Wells Fargo Securities, LLC, or, in each case, an
affiliate thereof, which are primary U.S. Government securities dealers in the United States (each, a “Primary Treasury Dealer”), and their respective successors; provided, however, that if any of the foregoing shall cease to be a Primary
Treasury Dealer, the Company shall substitute therefor another Primary Treasury Dealer; and (B) any other Primary Treasury Dealer(s) selected by the Company. 

“REFERENCE TREASURY DEALER QUOTATIONS” means, with respect to each Reference Treasury Dealer and any redemption date, the average,
as determined by the Company, 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 Company by such Reference Treasury Dealer at 5:00 p.m. (New
York City time) on the third Business Day preceding such redemption date. 
 Interest payments for this Note shall be computed and paid on
the basis of a 360-day year consisting of twelve 30-day months (and for any partial periods shall be calculated on the basis of the number of days elapsed in a 360-day year of twelve 30 day months). If any Interest Payment Date falls on a day
that is not a Business Day, the Interest Payment Date will be the next succeeding Business Day (and without any interest or other payment in respect of any such delay). If the Maturity Date of this Note or any redemption date falls on a day that is
not a Business Day, the payment of principal, premium, if any, and interest will be made on the next succeeding Business Day with the same force and effect as if made on such Maturity Date or redemption date, and no interest on such payment shall
accrue for the period from and after the Maturity Date or such redemption date. 

  
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 The Company, at its option, and subject to the terms and conditions provided in the Indenture,
will be discharged from any and all obligations in respect of the Notes of this Series (except for certain obligations including obligations to register the transfer or exchange of Notes of this Series, replace stolen, lost or mutilated Notes of
this Series, maintain paying agencies and hold monies for payment in trust, all as set forth in the Indenture) if the Company deposits with the Trustee money, U.S. Government Obligations which through the payment of interest thereon and principal
thereof in accordance with their terms will provide money, or a combination of money and U.S. Government Obligations, in any event in an amount sufficient, without reinvestment, to pay all the principal of and any premium and interest on the Notes
of this Series on the dates such payments are due in accordance with the terms of the Notes of this Series. 
 If an Event of Default shall
occur and be continuing with respect to the Notes, the principal of and interest on the Notes may be declared due and payable in the manner and with the effect provided in the Indenture and, upon such declaration, the Trustee shall demand the
redemption of the Senior Note First Mortgage Bonds to the extent provided in the Indenture. 
 The Indenture permits, with certain
exceptions as therein provided, the amendment thereof and the modifications of the rights and obligations of the Company and the rights of the Noteholders under the Indenture at any time by the Company and the Trustee with the consent of the Holders
of a majority in aggregate principal amount of the outstanding Notes. Any such consent or waiver by the Holder of this Note shall be conclusive and binding upon such Holder and upon all future Holders of this Note and of any Note issued upon the
registration of transfer hereof or in exchange therefor or in lieu thereof whether or not notation of such consent or waiver is made upon this Note. 

As set forth in and subject to the provisions of the Indenture, no Holder of any Notes will have any right to institute any proceeding with
respect to the Indenture or for any remedy thereunder unless such Holder shall have previously given to the Trustee written notice of a continuing Event of Default with respect to such Notes, the Holders of a majority in aggregate principal amount
of the outstanding Notes affected by such Event of Default shall have made written request and offered reasonable indemnity to the Trustee to institute such proceeding as Trustee and the Trustee shall have failed to institute such proceeding within
60 days; provided, however, that such limitations do not apply to a suit instituted by the Holder hereof for the enforcement of payment of the principal of and any premium or interest on this Note on or after the respective due dates expressed
herein. 
 No reference herein to the Indenture and to provisions of this Note 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 Note at the times, places and rates and the coin or currency prescribed in the Indenture. 

As provided in the Indenture and subject to certain limitations therein set forth, this Note may be transferred only as permitted by the
legend hereto and the provisions of the Indenture. 

  
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 The Indenture and the Notes shall be governed by, and construed in accordance with, the laws of
the State of New York without regard to conflicts of law principles thereof. 
 Unless the certificate of authentication hereon has been
executed by the Trustee, directly or through an Authenticating Agent by manual signature of an authorized officer, this Note shall not be entitled to any benefit under the Indenture or be valid or obligatory for any purpose. 

All terms used in this Note that are defined in the Indenture shall have the meanings assigned to them in the Indenture unless otherwise
indicated herein. 

  
 6 

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

 

			
	UNION ELECTRIC COMPANY
		
	By:		 /s/ Bruce A. Steinke

			Bruce A. Steinke
	Title:		Senior Vice President, Finance and Chief Accounting Officer
		
	Attest:		 /s/ Craig W. Stensland

			Craig W. Stensland
	Title:		Assistant Secretary

  

			
	TRUSTEE’S CERTIFICATE OF AUTHENTICATION
	
	Dated: April 6, 2015
	
	This Note is one of the Notes of the series herein designated, described or provided for in the within-mentioned Indenture.
	
	THE BANK OF NEW YORK MELLON, As Trustee
		
	 By:
		 /s/ Francine Kincaid

			Authorized Signatory

  
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 ABBREVIATIONS 

The following abbreviations, when used in the inscription on the face of this instrument, shall be construed as though they were written out
in full according to applicable laws or regulations: 
  

					
	TEN COM — as tenants in common				UNIF GIFT
					MIN ACT -              Custodian                 
					      (Cust)
                    (Minor)

			
	TEN ENT — as tenants by the entireties				Under Uniform Gifts to Minors
			
	JT TEN — as joint tenants with right of survivorship and not as tenants in common				  

					State

 Additional abbreviations may also be used 

though not in the above list. 
  

 
 FOR VALUE
RECEIVED the undersigned hereby sell(s), 
 assign(s) and transfer(s) unto 

PLEASE INSERT SOCIAL SECURITY OR OTHER 
 IDENTIFYING NUMBER OF
ASSIGNEE 
  
  

 
  
  

 
 Please print or typewrite name and
address 
 including postal zip code of assignee 
  

			
	  
 the within note and all rights thereunder, hereby
irrevocably constituting and appointing                      attorney to transfer said note on the books of the Company, with full power of
substitution in the premises.
		

  

			
		
	Dated:                     		  

			NOTICE: The signature to this assignment must correspond with the name as written upon the face of the within instrument in every particular, without alteration or enlargement or any change whatever.
		
			Signature(s) must be guaranteed by a financial institution that is a member of the Securities Transfer Agents Medallion Program (“STAMP”), the Stock Exchange Medallion Program (“SEMP”) or the New York Stock
Exchange, Inc. Medallion Signature Program (“MSP”)

  
 8EX-4.5

 Exhibit 4.5 

Executed in 25 Counterparts, No.      . 

SUPPLEMENTAL INDENTURE 
 DATED
MARCH 15, 2015 
 UNION ELECTRIC COMPANY 

TO 
 THE BANK OF NEW YORK MELLON,

 AS TRUSTEE 
  

 
 (SUPPLEMENTAL TO
THE INDENTURE OF MORTGAGE AND DEED OF TRUST DATED JUNE 15, 1937, AS AMENDED, EXECUTED BY UNION ELECTRIC COMPANY TO THE BANK OF NEW YORK MELLON, AS TRUSTEE) 
  

 
 First Mortgage
Bonds, Senior Notes 
 Series QQ 

This instrument was prepared by Gregory L. Nelson, Esq., Senior Vice President, General Counsel and Secretary of Union Electric Company,
1901 Chouteau Avenue, St. Louis, Missouri 63103, (314) 621-3222. 
 WHEN RECORDED MAIL TO: 

Gerald L. Waters 
 Union Electric Company 

1901 Chouteau Avenue 
 St. Louis, MO 63103 

 SUPPLEMENTAL INDENTURE, dated the 15th day of March, Two thousand and fifteen
(2015) made by and between UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the “Company”), party of the first part, and The Bank of New York Mellon, formerly The
Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen’s Trust Company), a bank existing under the laws of the State of New York (hereinafter called the “Trustee”), as Trustee under the
Indenture of Mortgage and Deed of Trust dated June 15, 1937, hereinafter mentioned, party of the second part: 
 WHEREAS, the
Company has heretofore executed and delivered to the Trustee its Indenture of Mortgage and Deed of Trust, dated June 15, 1937, as amended May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000,
August 15, 2002 and May 15, 2012 (said Indenture of Mortgage and Deed of Trust as so amended, being hereinafter referred to as the “Original Indenture”), to secure the payment of the principal of and the interest (and premium, if
any) on all bonds at any time issued and outstanding thereunder, and indentures supplemental thereto dated June 15, 1937, May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11,
1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957,
February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961,
August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968,
August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971,
December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977,
December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982,
December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992,
September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002,
March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003, February 1, 2004 (eight separate indentures supplemental thereto), May 1, 2004, September 1, 2004, January 1, 2005, July 1, 2005,
December 1, 2005, June 1, 2007, April 1, 2008, June 1, 2008, March 1, 2009, September 1, 2012 and April 1, 2014 respectively, have heretofore been entered into between the Company and the Trustee; and

 WHEREAS, the following Bonds have heretofore been issued by the Company under the Original Indenture and remain outstanding: 

(1) $44,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1993 (expected to mature in
2028), which are described in the Supplemental Indenture dated October 1, 1993, $5,000 of which are outstanding at the date of the execution hereof; 

(2) $184,000,000 principal amount of First Mortgage Bonds, Senior Notes Series BB, which are described in the Supplemental
Indenture dated March 5, 2003, all of which are outstanding at the date of the execution hereof; 
 (3) $114,000,000
principal amount of First Mortgage Bonds, Senior Notes Series CC, which are described in the Supplemental Indenture dated April 1, 2003, all of which are outstanding at the date of the execution hereof; 

(4) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series DD, which are described in the Supplemental
Indenture dated July 15, 2003, $198,657,000 of which are outstanding at the date of the execution hereof; 
 (5)
$60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004A (1998A Bonds), which are described in the Supplemental Indenture dated February 1, 2004, all of which are outstanding at the date of the execution
hereof; 

 (6) $50,000,000 principal amount of First Mortgage Bonds, Environmental
Improvement Series 2004B (1998B Bonds), which are described in the Supplemental Indenture dated February 1, 2004, all of which are outstanding at the date of the execution hereof; 

(7) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004C (1998C Bonds), which are
described in the Supplemental Indenture dated February 1, 2004, all of which are outstanding at the date of the execution hereof; 

(8) $47,500,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004H (1992 Bonds), which are
described in the Supplemental Indenture dated February 1, 2004, all of which are outstanding at the date of the execution hereof; 

(9) $300,000,000 principal amount of First Mortgage Bonds, Senior Notes Series GG, which are described in the Supplemental
Indenture dated September 1, 2004, $244,311,000 of which are outstanding at the date of the execution hereof; 
 (10)
$85,000,000 principal amount of First Mortgage Bonds, Senior Notes Series HH, which are described in the Supplemental Indenture dated January 1, 2005, all of which are outstanding at the date of the execution hereof; 

(11) $300,000,000 principal amount of First Mortgage Bonds, Senior Notes Series II, which are described in the
Supplemental Indenture dated July 1, 2005, all of which are outstanding at the date of the execution hereof; 
 (12)
$260,000,000 principal amount of First Mortgage Bonds, Senior Notes Series JJ, which are described in the Supplemental Indenture dated December 1, 2005, all of which are outstanding at the date of the execution hereof; 

(13) $425,000,000 principal amount of First Mortgage Bonds, Senior Notes, Series KK, which are described in the
Supplemental Indenture dated June 1, 2007, all of which are outstanding at the date of the execution hereof; 
 (14)
$250,000,000 principal amount of First Mortgage Bonds, Senior Notes, Series LL, which are described in the Supplemental Indenture dated April 1, 2008, $178,520,000 of which are outstanding at the date of the execution hereof; 

(15) $450,000,000 principal amount of First Mortgage Bonds, Senior Notes, Series MM, which are described in the
Supplemental Indenture dated June 1, 2008, $329,283,000 of which are outstanding at the date of the execution hereof; 

(16) $350,000,000 principal amount of First Mortgage Bonds, Senior Notes, Series NN, which are described in the
Supplemental Indenture dated March 1, 2009, all of which are outstanding at the date of the execution hereof; 
 (17)
$485,000,000 principal amount of First Mortgage Bonds, Senior Notes, Series OO, which are described in the Supplemental Indenture dated September 1, 2012, all of which are outstanding at the date of the execution hereof; and 

(18) $350,000,000 principal amount of First Mortgage Bonds, Senior Notes, Series PP, which are described in the
Supplemental Indenture dated April 1, 2014, all of which are outstanding at the date of the execution hereof; and 
 WHEREAS,
the Company on August 31, 1955 acquired all of the properties of Union Electric Power Company, the Subsidiary as defined in Article I of the Original Indenture, upon the dissolution of the Subsidiary; the Company, by Supplemental Indenture
dated August 31, 1955, conveyed all of the properties so acquired (other than 

  
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property of the character defined as excepted property in the granting clauses of the Original Indenture) to the Trustee upon the terms and trusts in the Original Indenture and the indentures
supplemental thereto set forth for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, all the shares of stock of the Subsidiary were released from the lien
of the Original Indenture; and the Company became entitled to change the general designation of the Bonds so as to omit the words “and Collateral Trust”; and 

WHEREAS, the Articles of Incorporation of the Company were duly amended on April 23, 1956, to change its corporate name from
“Union Electric Company of Missouri” to “Union Electric Company”; and 
 WHEREAS, the Articles of
Agreement of the Trustee were duly amended effective on January 4, 1982 to change its corporate name from “St. Louis Union Trust Company” to “Centerre Trust Company of St. Louis”, and further amended on December 9,
1988, to change its corporate name from “Centerre Trust Company of St. Louis” to “Boatmen’s Trust Company”; and 

WHEREAS, that on March 13, 1998, Boatmen’s Trust Company merged into NationsBank, National Association and effective
July 5, 1999, changed its name to Bank of America, National Association; and 
 WHEREAS, that on February 1, 2000,
The Bank of New York, as transferee of the corporate trust business of Bank of America, National Association (formerly known as Boatmen’s Trust Company), Trustee under the Original Indenture, became successor Trustee under the Original
Indenture; and 
 WHEREAS, that effective as of July 1, 2008, The Bank of New York changed its name to The Bank of
New York Mellon; and 
 WHEREAS, the Company is entitled at this time to have authenticated and delivered additional Bonds on
the basis of “property additions” upon compliance with and pursuant to the provisions of Section 4 of Article III of the Original Indenture or on the basis of “refundable Bonds” upon compliance with and pursuant to the
provisions of Section 5 of Article III of the Original Indenture; and 
 WHEREAS, the Company has entered into an
Indenture dated as of August 15, 2002 (the “Senior Note Indenture”) with The Bank of New York, now known as Bank of New York Mellon, as trustee (the “Senior Note Trustee”) providing for the issuance from time to time of
senior notes thereunder; and 
 WHEREAS, the Company desires by this Supplemental Indenture to provide for the creation of,
and the issuance to the Senior Note Trustee of, a new series of Bonds under the Original Indenture as security for $250,000,000 aggregate principal amount of the Company’s 3.65% Senior Secured Notes due 2045 (the “Senior Notes”) to be
issued under the Senior Note Indenture, to have the designation provided in Article I, Section 1 hereof (herein called the “New Bonds”), and the Original Indenture provides that certain terms and provisions, as determined by the
Board of Directors of the Company, of the Bonds of any particular series may be expressed in and provided by the execution of an appropriate supplemental indenture; and 

WHEREAS, the Original Indenture provides that the Company and the Trustee may enter into indentures supplemental to the Original
Indenture specifically to convey, transfer and assign to the Trustee and to subject to the lien of the Original Indenture additional properties acquired by the Company; and 

WHEREAS, the Company, in the exercise of the powers and authority conferred upon and reserved to it under the provisions of the
Original Indenture and pursuant to appropriate resolutions of the Board of Directors, has duly resolved and determined to make, execute and deliver to the Trustee a Supplemental Indenture in the form hereof for the purposes herein provided; and

 WHEREAS, all conditions and requirements necessary to make this Supplemental Indenture a valid, binding and legal instrument
have been done, performed and fulfilled and the execution and delivery hereof have been in all respects duly authorized; 

  
 3 

 NOW, THEREFORE, THIS INDENTURE WITNESSETH: 

That, in consideration of the premises and of the mutual covenants herein contained and of the acceptance of this trust by the Trustee and of
the sum of One Dollar duly paid by the Trustee to the Company at or before the time of the execution of this Supplemental Indenture, and of other valuable considerations, the receipt whereof is hereby acknowledged, and in order further to secure the
payment of the principal of and interest (and premium, if any) on all Bonds at any time issued and outstanding under the Original Indenture, according to their tenor and effect, and to secure the Senior Notes, the Company has executed and delivered
this Supplemental Indenture and has granted, bargained, sold, warranted, aliened, remised, released, conveyed, assigned, transferred, mortgaged, pledged, set over and confirmed and by these presents does grant, bargain, sell, warrant, alien, remise,
release, convey, assign, transfer, mortgage, pledge, set over and confirm unto The Bank of New York Mellon, as Trustee, and to its successors in trust under the Original Indenture forever, all and singular the following described properties (in
addition to all other properties heretofore subjected to the lien of the Original Indenture and not heretofore released from the lien thereof) - that is to say: 

FIRST. 
 ALL (except as in
the Original Indenture expressly excepted) power houses, plants, buildings and other structures, dams, dam sites, substations, heating plants, gas works, holders and tanks, together with all and singular the electric, heating, gas and mechanical
appliances appurtenant thereto of every nature whatsoever, now owned by the Company, including all and singular the machinery, engines, boilers, furnaces, generators, dynamos, turbines and motors, and all and every character of mechanical appliance
for generating or producing electricity, steam, gas and other agencies for light, heat, cold, or power or other purposes, and all transmission and distribution systems used for the transmission and distribution of electricity, steam, gas and other
agencies for light, heat, cold or power or any other purpose whatsoever, whether underground or overhead, surface or otherwise, now owned by the Company, including all poles, towers, posts, wires, cables, conduits, manholes, mains, pipes, tubes,
drains, furnaces, switchboards, transformers, conductors, insulators, supports, meters, lamps, fuses, junction boxes, regulator stations, and other electric, steam and gas fixtures and apparatus; all of the aforementioned property being located in
the City of St. Louis, the counties of Adair, Audrain, Benton, Bollinger, Boone, Butler, Caldwell, Callaway, Camden, Cape Girardeau, Clark, Clay, Clinton, Cole, Cooper, Crawford, Daviess, Dunklin, Franklin, Gasconade, Howard, Iron, Jefferson, Knox,
Lewis, Lincoln, Livingston, Macon, Madison, Maries, Marion, Miller, Mississippi, Moniteau, Montgomery, Morgan, New Madrid, Osage, Pemiscot, Perry, Pettis, Phelps, Pike, Pulaski, Ralls, Randolph, Ray, Reynolds, Ripley, St. Charles, St. Francois, Ste.
Genevieve, St. Louis, Saline, Schuyler, Scott, Stoddard, Warren, Washington, and Wayne, Missouri, the counties of Clay, Hancock, Henderson, Madison, Marion, Perry, Piatt and St. Clair, Illinois, and the counties of Des Moines, Henry, Johnson,
Lee, and Washington, Iowa, upon real estate owned by the Company, or occupied by it under rights to so occupy, which real estate is described in, or added through the provisions of, the Indenture of Mortgage and Deed of Trust dated June 15,
1937, the Supplemental Indentures dated May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950,
September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959,
June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965,
April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1,
1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975,
June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980,
August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985,
March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993,
May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003, February 1, 2004 (eight separate
supplemental indentures), May 1, 2004, September 1, 2004, January 1, 2005, July 1, 2005, December 1, 2005, June 1, 2007, April 1, 2008, June 1, 2008, March 1, 2009, May 15,
2012, September 1, 2012, April 1, 2014 and this Supplemental Indenture, or attached to or connected with such real estate or transmission or distribution systems of the Company leading from or into such real estate. 

  
 4 

 SECOND. 

ALSO, (except as in the Original Indenture expressly excepted) all franchises and all permits, ordinances, easements, privileges,
immunities and licenses, all rights to construct, maintain and operate overhead, surface and underground systems for the distribution and transmission of electricity, steam, gas or other agencies for the supply to itself or others of light, heat,
cold or power, all rights-of-way, all waters, water rights and flowage rights and all grants and consents, now owned or, subject to the provisions of Article XII of
the Original Indenture, which it may hereafter acquire. 
 ALSO, (except as in the Original Indenture expressly excepted) all
inventions, patent rights and licenses of every kind now owned by the Company or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire. 

THIRD. 
 ALSO,
subject to the provisions of Article XII of the Original Indenture, all other property, real, personal and mixed (except as therein or herein expressly excepted) of every nature and kind and wheresoever situated now or hereafter possessed by or
belonging to the Company, or to which it is now, or may at any time hereafter be, in any manner entitled at law or in equity. 

EXPRESSLY EXCEPTING AND EXCLUDING, HOWEVER, from this Supplemental Indenture and from the lien and operation hereof: 

(a) all property expressly excepted and excluded from the Original Indenture, and from the lien and operation thereof; and 

(b) when the amendment set forth in Section 2 of Article III of the Supplemental Indenture dated May 15, 2012 becomes effective, all
Excepted Property as defined in such Section. 
 TO HAVE AND TO HOLD all said properties, real, personal and mixed, mortgaged,
pledged and conveyed by the Company as aforesaid, or intended so to be, unto the Trustee and its successors and assigns forever; 

SUBJECT, HOWEVER, to the exceptions and reservations and matters hereinabove recited, to existing leases, to existing liens upon rights
of way for transmission or distribution line purposes, as defined in Article I of the Original Indenture, and any extensions thereof, and subject to existing easements for streets, alleys, highways, rights-of-way and railroad purposes over,
upon and across certain of the property hereinbefore described, and subject also to all the terms, conditions, agreements, covenants, exceptions and reservations expressed or provided in the deeds or other instruments respectively under and by
virtue of which the Company acquired the properties hereinabove described, and to undetermined liens and charges, if any, incidental to construction or other existing permitted liens as defined in Article I of the Original Indenture;

 IN TRUST, NEVERTHELESS, upon the terms and trusts in the Original Indenture and the indentures supplemental thereto, including
this Supplemental Indenture, set forth, for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, or any of them, without preference of any of said Bonds and
coupons of any particular series over the Bonds and coupons of any other series, by reason of priority in the time of the issue, sale or negotiation thereof, or by reason of the purpose of issue or otherwise howsoever, except as otherwise provided
in Section 2 of Article IV of the Original Indenture. 

  
 5 

 AND IT IS HEREBY COVENANTED, DECLARED AND AGREED, by and between the parties hereto, for
the benefit of those who shall hold the Bonds and coupons, or any of them to be issued under the Original Indenture, as follows: 

ARTICLE I 
 DESCRIPTION OF THE
NEW BONDS 
 Section 1. There is hereby created a new series of Bonds to be executed, authenticated and delivered under and secured
by the Original Indenture which shall, subject to the provisions of Section 1 of Article II of the Original Indenture, be designated as “First Mortgage Bonds, Senior Notes Series QQ” (the “New Bonds”) of the
Company. The New Bonds shall be executed, authenticated and delivered in accordance with the provisions of, and shall in all respects be subject to all of the terms, conditions and covenants of, the Original Indenture and shall be issued to,
and registered in the name of, the Senior Note Trustee under the Senior Note Indenture to secure any and all obligations of the Company under the Senior Notes and any other series of senior notes from time to time outstanding under the Senior Note
Indenture. 
 The New Bonds shall mature on April 15, 2045, and shall bear interest at the rate per annum set forth in the form of the
New Bond contained in Section 3 of this Article I, payable semi-annually on the 15th day of April and the 15th day of October in each year, commencing on October 15, 2015, and at maturity. The New Bonds shall be
payable as to principal and interest in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and shall be payable, in immediately available funds, at the office of the Senior
Note Trustee. 
 Section 2. The New Bonds shall not be assignable or transferable except as permitted or required by Section 4.04
of the Senior Note Indenture. Any such transfer shall be effected at the principal office or place of business of the Trustee under the Original Indenture. The New Bonds are exchangeable for the New Bonds of other denominations, as in the
Original Indenture provided, except that payment of a service charge therefor will not be required by the Company. 
 Notwithstanding the
provisions of Section 6 of Article II of the Original Indenture, the New Bonds shall be dated the date of authentication and shall bear interest from the interest payment date to which interest on the New Bonds has been paid next preceding
the date thereof, unless such date is an interest payment date to which interest has been paid, in which case they shall bear interest from the date thereof, or unless the date thereof is prior to October 15, 2015, in which case they shall bear
interest from April 6, 2015; provided, however, that, subject to the provisions of this Section with respect to failure by the Company to pay any interest on an interest payment date, the holder of any New Bond dated after a record date
(as hereinafter defined) for the payment of interest and prior to the date of payment of such interest shall not be entitled to payment of such interest and shall have no claim against the Company with respect thereto. 

The person in whose name any New Bond is registered at the close of business on any record date 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 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 on 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 the Company by notice mailed to the holders of the New Bonds not less
than ten days preceding such record date, which record date shall be not more than thirty 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 April 1 or October 1, as the case may be, next preceding such interest payment date, or, if such April 1 or October 1 shall be a legal holiday in the State of New York or in the State of
Missouri or a day on which banking institutions in the Borough of Manhattan, The City of New York, or the City of St. Louis, Missouri, are authorized by law to close, the next preceding day which shall not be a legal holiday or a day on which such
institutions are so authorized to close. 
 Upon any payment of the principal of, premium, if any, and interest on, all or any portion of
the Senior Notes, whether at maturity or prior to maturity by redemption or otherwise or upon provision for the payment thereof having been made in accordance with Section 5.01(a) of the Senior Note Indenture, the New Bonds in a principal
amount equal to the principal amount of such Senior Notes 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

  
 6 

 
payment shall be discharged to such extent and, in the case of the payment of principal (and premium, if any), such New Bonds shall be surrendered to the Company for cancellation as provided in
Section 4.08 of the Senior Note Indenture. The Trustee may at any time and all times conclusively assume that the obligation of the Company to make payments with respect to the principal of, premium, if any, and interest on the Senior Notes, 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 Senior Note Trustee signed by one of its officers
stating (i) the timely payment of principal, or premium, if any, or interest on, the Senior Notes has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Senior Note Trustee pursuant to
the Senior Note Indenture, and (iii) the amount of the arrearage. 
 Section 3. The New Bonds and the Trustee’s certificate
on the New Bonds shall be substantially in the following forms respectively: 
 [FORM OF FACE OF NEW BOND] 

 

					
	No.		$	                	  

 NOTWITHSTANDING ANY PROVISIONS HEREOF OR IN THE ORIGINAL INDENTURE, THIS BOND IS NOT ASSIGNABLE OR
TRANSFERABLE EXCEPT AS PERMITTED OR REQUIRED BY SECTION 4.04 OF THE INDENTURE DATED AS OF AUGUST 15, 2002, BETWEEN UNION ELECTRIC COMPANY AND THE BANK OF NEW YORK MELLON, AS TRUSTEE. 

UNION ELECTRIC COMPANY 

(Incorporated under the laws of the State of Missouri) 

First Mortgage Bonds, Senior Notes Series QQ 

UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the
“Company”, which term shall include any successor corporation as defined in the Amended Indenture referred to on the reverse hereof), for value received, hereby promises to pay to The Bank of New York Mellon, as trustee under the Senior
Note Indenture hereinafter referred to, or registered assigns, the sum of          Dollars, on the 15th day of April, 2045 in any coin or currency of the United States of America which at the time of
payment is legal tender for public and private debts, and to pay interest thereon, in like coin or currency, at the rate of THREE AND SIXTY-FIVE HUNDREDTHS per centum (3.65%) per annum, payable semi-annually, on April 15 and
October 15 in each year until maturity, commencing October 15, 2015, and at maturity or, if the Company shall default in the payment of the principal hereof, until the Company’s obligation with respect to the payment of such principal
shall be discharged as provided in the Amended Indenture referred to on the reverse hereof. Such interest shall be payable from the April 15 or October 15, as the case may be, next preceding the date hereof to which interest has not
been paid, unless the date hereof is a April 15 or October 15 to which interest has been paid, in which case from the date hereof, or unless the date hereof is prior to the first payment of interest, in which case from April 6,
2015. The interest so payable will be paid to the person in whose name this Bond, or the Bond in exchange or substitution for which this Bond shall have been issued, shall have been registered at the close of business on the April 1 or
October 1, as the case may be, next preceding the date of payment, subject to certain exceptions set forth in the Amended Indenture. The principal of, premium, if any, and interest on, this Bond are payable, in immediately available funds,
at the office of the Senior Note Trustee hereinafter referred to. 
 Under an Indenture dated as of August 15, 2002 (the “Senior
Note Indenture”) between the Company and The Bank of New York Mellon, formerly The Bank of New York, as trustee (the “Senior Note Trustee”), the Company will issue, concurrently with the issuance of this Bond, an issue of notes under
the Senior Note Indenture entitled “3.65% Senior Secured Notes due 2045” (the “Senior Notes”). Pursuant to Article IV of the Senior Note Indenture, this Bond is issued to the Senior Note Trustee to secure any and all
obligations of the Company under the Senior Notes and any other series of senior notes from time to time outstanding under the Senior Note Indenture. Payment of principal of, or premium, if any, or interest on, the Senior Notes shall constitute
payments on this Bond as further provided herein and in the Supplemental Indenture dated March 15, 2015 pursuant to which this Bond has been issued (the “Supplemental Indenture”). 

  
 7 

 Upon any payment of the principal of, premium, if any, and interest on, all or any portion of the
Senior Notes, whether at maturity or prior to maturity by redemption or otherwise or upon provision for the payment thereof having been made in accordance with Section 5.01(a) of the Senior Note Indenture, a principal amount of this Bond
equal to the principal amount of such Senior Notes 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 (and premium, if any), such bonds shall be surrendered to the Company for cancellation as provided in Section 4.08 of the Senior Note Indenture. The Trustee (as hereinafter defined) may at any
time and all times conclusively assume that the obligation of the Company to make payments with respect to the principal of, premium, if any, and interest on, the Senior Notes, 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 Senior Note Trustee signed by one of its officers stating (i) that timely payment of principal of, premium,
if any, or interest on, the Senior Notes has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Senior Note Trustee pursuant to the Senior Note Indenture, and (iii) the amount of the
arrearage. 
 For purposes of Section 4.09 of the Senior Note Indenture, this Bond shall be deemed to be the “Related
Series of Senior Note First Mortgage Bonds” in respect of the Senior Notes. 
 This Bond shall not be entitled to any benefit
under the Amended Indenture or any indenture supplemental thereto, or become valid or obligatory for any purpose, until The Bank of New York Mellon, the Trustee under the Amended Indenture, or a successor trustee thereto under the Amended Indenture,
or an agent therefor, shall have signed the form of certificate endorsed hereon. 
 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. 

  
 8 

 IN WITNESS WHEREOF, Union Electric Company has caused this Bond to be signed in its name by its
Chairman of the Board or President or a Vice President by manual signature or a facsimile thereof, and its corporate seal (or a facsimile thereof) to be hereto affixed and attested by its Secretary or an Assistant Secretary by manual signature or a
facsimile thereof. 
 Dated 
  

			
	UNION ELECTRIC COMPANY
		
	By		  

 

			
	[CORPORATE SEAL]
		
	Attest:		  

 [FORM OF TRUSTEE’S CERTIFICATE] 

This Bond is one of the Bonds, of the series designated therein, described in the within-mentioned Amended Indenture and Supplemental
Indenture of March 15, 2015. 
  

			
	THE BANK OF NEW YORK MELLON, as
	TRUSTEE
		
	By		  

			Authorized Officer

  
 9 

 [FORM OF REVERSE OF NEW BOND] 

This Bond is one of a duly authorized issue of Bonds of the Company (herein called the “Bonds”), in unlimited aggregate principal
amount, of the series hereinafter specified, all issued and to be issued under and equally secured by the Indenture of Mortgage and Deed of Trust, dated June 15, 1937, executed by the Company to The Bank of New York Mellon, formerly The Bank of
New York (successor trustee to Bank of America, National Association, formerly Boatmen’s Trust Company), as trustee (herein called the “Trustee”), as amended by indentures supplemental thereto dated May 1, 1941, April 1,
1971, February 1, 1974, July 7, 1980, February 1, 2000, August 15, 2002 and May 15, 2012, between the Company and the Trustee (said mortgage and deed of trust, as so amended, being herein called the “Amended
Indenture”), to which Amended Indenture and all indentures supplemental thereto reference is hereby made for a description of the properties mortgaged and pledged, the nature and extent of the security, the rights of the bearers or registered
owners of the Bonds and of the Trustee in respect thereto, and the terms and conditions upon which the Bonds are, and are to be, secured. To the extent permitted by, and as provided in, the Amended Indenture, modifications or alterations of the
Amended Indenture, or of any indenture supplemental thereto, and of the rights and obligations of the Company and of the holders of the Bonds may be made with the consent of the Company by an affirmative vote of not less than 60% in amount of the
Bonds entitled to vote then outstanding, at a meeting of Bondholders called and held as provided in the Amended Indenture, and by an affirmative vote of not less than 60% in amount of the Bonds of any series entitled to vote then outstanding and
affected by such modification or alteration, in case one or more but less than all of the series of Bonds then outstanding under the Amended Indenture are so affected. Additionally, the Company may amend the Amended Indenture, as supplemented,
by an appropriate written consent of not less than 60% in aggregate principal amount of the Bonds outstanding (and, if the rights of one or more, but less than all, series of Bonds then outstanding are to be affected by action taken pursuant to such
consent, then also by consent of the holders of at least 60% in principal amount of each series of Bonds so to be affected and outstanding hereunder) without a meeting of such Bondholders. No such modification or alteration shall be made which
will affect the terms of payment of the principal of, or interest or premium on, this Bond, which are unconditional. The Bonds may be issued in series, for various principal sums, may mature at different times, may bear interest at different
rates and may otherwise vary as in the Amended Indenture provided. This Bond is one of a series designated as the “First Mortgage Bonds, Senior Notes Series QQ” (herein called the “Bonds of this Series”) of the Company,
issued under and secured by the Amended Indenture and described in the indenture (hereinafter called the “New Supplemental Indenture”) dated March 15, 2015, between the Company and the Trustee, supplemental to the Amended Indenture.

 The Bonds of this Series are not entitled to the benefit of any improvement, maintenance or analogous fund. 

This Bond is not redeemable except on the date, in the principal amount and for the redemption price that correspond to the redemption date
for, the principal amount to be redeemed of, and the redemption price for, the Senior Notes, and except upon written demand of the Senior Note Trustee following the occurrence of an event of default under the Senior Note Indenture and the
acceleration of the Senior Notes, as provided in Section 8.01 of the Senior Note Indenture. 
 In case an event of default, as defined
in the Amended Indenture, shall occur, the principal of all the Bonds at any such time outstanding under the Amended Indenture may be declared or may become due and payable, upon the conditions and in the manner and with the effect provided in the
Amended Indenture. The Amended Indenture provides that such declaration may in certain events be waived by the holders of a majority in principal amount of the Bonds outstanding. 

This Bond shall not be assignable or transferable except as permitted or required by Section 4.04 of the Senior Note Indenture. This
Bond is exchangeable by the registered owner hereof, in person or by duly authorized attorney, on the books of the Company to be kept for that purpose at the office of the Company in the City of St. Louis, Missouri, upon surrender and
cancellation of this Bond and on presentation of a duly executed written instrument of transfer, and thereupon a new Bond or Bonds of the same series, of the same aggregate principal amount and in authorized denominations will be issued to the
transferee or transferees in exchange herefor, without payment of any charge other than stamp taxes and other governmental charges incident thereto; and this Bond with or without others of like series, may in like manner be exchanged for one or more
new Bonds of the same series of other authorized denominations but of the same aggregate principal amount; all subject to the terms and conditions set forth in the Amended Indenture. 

  
 10 

 No recourse shall be had for the payment of the principal of, premium, if any, or the interest
on, this Bond, or for any claim based hereon or on the Amended Indenture or any indenture supplemental thereto, against any incorporator, or against any stockholder, director or officer, past, present or future, of the Company, or of any predecessor
or successor corporation, either directly or through the Company or any such predecessor or successor corporation, whether for amounts unpaid on stock subscriptions or by virtue of any constitution, statute or rule of law, or by the enforcement
of any assessment or penalty or otherwise, all such liability, whether at common law, in equity, by any constitution, statute or otherwise, of incorporators, stockholders, directors or officers being released by every owner hereof by the acceptance
of this Bond and as part of the consideration for the issue hereof, and being likewise released by the terms of the Amended Indenture. 

[END OF FORM OF REVERSE OF NEW BOND] 

Section 4. Until New Bonds in definitive form are ready for delivery, the Company may execute, and upon its request in writing the
Trustee shall authenticate and deliver, in lieu thereof, New Bonds in temporary form, as provided in Section 9 of Article II of the Original Indenture. 

ARTICLE II 
 ISSUE OF THE NEW
BONDS 
 Section 1. The principal amount of the New Bonds which may be authenticated and delivered hereunder is limited to an
amount equal to the principal amount of the Senior Notes issued under the Senior Note Indenture and secured thereby and are further subject to the limitations regarding the principal amount of Bonds which may be issued under the Original Indenture
set forth therein. 
 Section 2. The New Bonds in the aggregate principal amount of Two Hundred Fifty Million Dollars ($250,000,000),
being the initial issue of the New Bonds, may forthwith at any time or from time to time be executed by the Company and delivered to the Trustee and shall be authenticated by the Trustee and delivered (either before or after the filing or recording
hereof) to or upon the order of the Company, upon compliance by the Company with the applicable provisions of Article III and Article XVIII of the Original Indenture. 

Section 3. For purposes of Section 4.09 of the Senior Note Indenture, the New Bonds shall be deemed to be the “Related
Series of Senior Notes First Mortgage Bonds” in respect of the Senior Notes. 
 ARTICLE III 

REDEMPTION OF THE NEW BONDS 

Section 1. The New Bonds are not redeemable except on the date, in the principal amount and for the redemption price that correspond to
the redemption date for, the principal amount to be redeemed of, and the redemption price for, the Senior Notes, and except as set forth in Section 2 of this Article III. 

In the event that the Company redeems any Senior Notes prior to maturity in accordance with the provisions of the Senior Note Indenture, the
Senior Note Trustee shall on the same date deliver to the Company the New Bonds in principal amount corresponding to the Senior Notes so redeemed, as provided in Section 4.08 of the Senior Note Indenture. The Company agrees to give the
Senior Note Trustee notice of any such redemption of the Senior Notes on or before the date fixed for any such redemption. There shall be no improvement, maintenance or analogous fund for the New Bonds. 

Section 2. Upon the occurrence of an event of default under the Senior Note Indenture and the acceleration of the Senior Notes, the New
Bonds shall be redeemable in whole upon receipt by the Trustee of a written demand (hereinafter called a “QQ Redemption Demand”) from the Senior Note Trustee stating that there has 

  
 11 

 
occurred under the Senior Note Indenture both an event of default and a declaration of acceleration of payment of principal, accrued interest and premium, if any, on the Senior Notes specifying
the last date to which interest on such Senior Notes has been paid (such date being hereinafter referred to as the “QQ Initial Interest Accrual Date”) and demanding redemption of the New Bonds. The Company waives any right it may have
to prior notice of such redemption under the Original Indenture. Upon surrender of the New Bonds by the Senior Note Trustee to the Trustee, the New Bonds shall be redeemed at a redemption price equal to the principal amount thereof plus accrued
interest thereon from the QQ Initial Interest Accrual Date to the date of the QQ Redemption Demand; provided, however, that in the event of a rescission or annulment of acceleration of the Senior Notes pursuant to the last paragraph of
Section 8.01(a) of the Senior Note Indenture, then any QQ Redemption Demand shall thereby be deemed to be rescinded by the Senior Note Trustee although no such rescission or annulment shall extend to or affect any subsequent default or
impair any right consequent thereon. 
 ARTICLE IV 

COVENANTS 
 The Company
hereby covenants, warrants and agrees; 
 Section 1. That the Company is lawfully seized and possessed of all of the mortgaged property
described in the granting clauses of this Supplemental Indenture to the extent shown on its books and records as of the date hereof; that it has good right and lawful authority to mortgage the same as provided in this Supplemental Indenture; and
that such mortgaged property will be, at the actual date of the issue of the New Bonds, free and clear of any deed of trust, mortgage, lien, charge or encumbrance thereon or affecting the title thereto prior to the lien of the Original Indenture,
except for permitted liens and as set forth in the granting clauses of the Original Indenture and this Supplemental Indenture. 

Section 2. That, so long as any of the New Bonds are outstanding, whenever any officers’ certificate is required to be filed or
deposited with the Trustee pursuant to Section 3(b) of Article III of the Original Indenture upon an application for the authentication of additional Bonds pursuant to Article III of the Original Indenture, such officers’
certificate shall include, in addition to the matters required to be stated therein by said Section 3(b), the statement with respect to the net earnings of the Company available for interest after property retirement appropriations required by
Section 2 of Article V of the Supplemental Indenture of July 1, 1956. 
 ARTICLE V 

THE TRUSTEE 
 The Trustee
hereby accepts the trusts hereby declared and provided, and agrees to perform the same upon the terms and conditions in the Original Indenture and in this Supplemental Indenture set forth, and upon the following terms and conditions: 

The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture
or the due execution hereof by the Company or for or in respect of the recitals contained herein, all of which recitals are made by the Company solely. 

ARTICLE VI 
 MISCELLANEOUS
PROVISIONS. 
 Section 1. Except as otherwise defined herein, all terms contained in this Supplemental Indenture shall, for all
purposes thereof, have the meanings given to such terms in Article I of the Original Indenture. 
 Section 2. This Supplemental
Indenture may be simultaneously executed in any number of counterparts, each of which when so executed shall be deemed to be an original; but such counterparts shall together constitute but one and the same instrument. 

  
 12 

 IN WITNESS WHEREOF, said Union Electric Company has caused this Supplemental Indenture to
be executed on its behalf by its Chairman of the Board or President or one of its Vice Presidents and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary or one of its Assistant
Secretaries; and said The Bank of New York Mellon, in evidence of its acceptance of the trust hereby created, has caused this Supplemental Indenture to be executed on its behalf by its President or one of its Vice Presidents, and its corporate seal
to be hereto affixed and said seal and this Supplemental Indenture to be attested by one of its Vice Presidents, its Secretary, or one of its Assistant Secretaries; all as of the 15th day of March, Two thousand and fifteen. 

 

							
	Attested:				 UNION ELECTRIC COMPANY,

      1901 Chouteau Avenue

      St. Louis, Missouri 63103

				
	 /s/ G. L. Waters
				By:		 /s/ Bruce A. Steinke

	G. L. Waters				Name:		Bruce A. Steinke
	Assistant Secretary				Title:		Senior Vice President, Finance and Chief Accounting Officer
	  
 Signed, sealed and delivered by

        UNION ELECTRIC COMPANY

        in the presence of:
						
				
	 /s/ Sue E. Whitman
						
				
	 /s/ Lynn M. Smith
						
	  
 As Witnesses
						

  
 13 

							
	Attested:				THE BANK OF NEW YORK MELLON,
				
	 /s/ Thomas Hacker
				By:		 /s/ Francine Kincaid

	Thomas Hacker				Name:		Francine Kincaid
	Vice President						Vice President
	  
 Signed, sealed and delivered by

        THE BANK OF NEW YORK MELLON

        in the presence of:
						
				
	 /s/ Arsala Kidwai
						
				
	 /s/ Stacey Poindexter
						
	  
 As Witnesses
						

  
 14 

					
	STATE OF MISSOURI		}		
			}		SS.:
	CITY OF ST. LOUIS		}		

 On this 31st day of March, 2015, before me appeared Bruce A. Steinke and G. L. Waters, to me personally known,
who, being by me duly sworn, did say that they are the Senior Vice President, Finance and Chief Accounting Officer and an Assistant Secretary of UNION ELECTRIC COMPANY, a corporation, and that the seal affixed to the foregoing instrument is
the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation by authority of its Board of Directors, and said Senior Vice President, Finance and Chief Accounting Officer and Assistant Secretary
acknowledged said instrument to be the free act and deed of said corporation. 
 IN TESTIMONY WHEREOF, I have hereto set my hand and
affixed my official seal at my office, in the City and State aforesaid, the day and year last above written. 
  

	
	 /s/ Carla J. Flinn

 Carla J. Flinn – Notary Public 

Notary Seal, State of 
 Missouri – St. Louis City 

Commission #14399906 
 My Commission Expires 4/20/2018 

  
 15 

					
	STATE OF NEW YORK		}		
			}		SS.:
	COUNTY OF NEW YORK		}		

 On this 26 day of March, 2015, before me appeared Francine Kincaid, to me personally known, who, being by me
duly sworn, did say that he is a Vice President of THE BANK OF NEW YORK MELLON, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in
behalf of said corporation, as the trustee thereunder by authority of its Board of Directors, and said Vice President, acknowledged said instrument to be the free act and deed of said corporation as the trustee under said instrument. 

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and
year last above written. 
  

	
	 /s/ Anna Yiu

 ANNA YIU 
 Notary Public
State of New York 
 Qualified in Queens County 
 Reg
#01Y15080477 
 Commission Expires 6/13/15 

  
 16

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