EX-4.2



 Exhibit 4.2 

WHEN RECORDED MAIL TO: 
 Ameren Illinois Company 

Craig W. Stensland 
 One Ameren Plaza (MC 1310) 

1901 Chouteau Avenue 
 St. Louis, MO 63103 

AMEREN ILLINOIS COMPANY 

(SUCCESSOR TO ILLINOIS POWER COMPANY) 

TO 
 THE BANK OF NEW
YORK MELLON TRUST COMPANY, N.A. 
 AS SUCCESSOR TRUSTEE TO 

HARRIS TRUST AND SAVINGS BANK 
  

 
 SUPPLEMENTAL
INDENTURE 
 DATED AS OF NOVEMBER 1, 2017 

TO 
 GENERAL MORTGAGE
INDENTURE AND DEED OF TRUST 
 DATED AS OF NOVEMBER 1, 1992 

 
  

This instrument was prepared by Gregory L. Nelson, Esq., Senior Vice President, General Counsel and Secretary of Ameren Illinois Company c/o Ameren
Corporation, One Ameren Plaza, 1901 Chouteau Avenue, St. Louis, Missouri 63103. 
  

 
  







 SUPPLEMENTAL INDENTURE dated as of November 1, 2017 (this “Supplemental
Indenture”), made by and between AMEREN ILLINOIS COMPANY (formerly named Central Illinois Public Service Company (“CIPS”) and successor to Illinois Power Company (“IP”) pursuant to the Merger, as defined
below), a corporation organized and existing under the laws of the State of Illinois (hereinafter sometimes called the “Company”), party of the first part, and THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., a national banking
association organized and existing under the laws of the United States, as successor trustee to Harris Trust and Savings Bank, as Trustee (the “Trustee”) under the General Mortgage Indenture and Deed of Trust dated as of
November 1, 1992, hereinafter mentioned, party of the second part; 
 WHEREAS, the Company has heretofore executed and delivered
its General Mortgage Indenture and Deed of Trust dated as of November 1, 1992 as from time to time amended and supplemented (the “Indenture”), to the Trustee, for the security of the Bonds issued and to be issued thereunder
(the “Bonds”); and 
 WHEREAS, as of 12:01 a.m. Central Time (the “Effective Time”) on
October 1, 2010, pursuant to the Agreement and Plan of Merger dated as of April 13, 2010 among CIPS, IP and Central Illinois Light Company (“CILCO”), IP and CILCO were merged with and into the Company (the
“Merger”) whereby the Company is the surviving corporation; and 
 WHEREAS, pursuant to Sections 13.01 and 14.01(a)
of the Indenture, the Company and the Trustee executed the Supplemental Indenture dated as of October 1, 2010 whereby, among other things, the Company (a) assumed the due and punctual payment of the principal of and premium, if any, and
interest, if any, on all of the Bonds then Outstanding and the performance and observance of every covenant and condition of the Indenture to be performed or observed by IP and (b) subjected to the Lien of the Indenture all equipment and
fixtures (other than Excepted Property, which is expressly excepted and excluded from the Lien of the Indenture) that were owned by CIPS immediately prior to the Effective Time and were of the same kind and character as the Mortgaged Property
immediately prior to the Effective Time; and 
 WHEREAS, pursuant to Sections 13.02 and 14.01(a)(i) of the Indenture, the Company has
succeeded to, and has been substituted for, and may exercise every right and power of, IP under the Indenture with the same effect as if the Company had been named the “Company” in the Indenture; and 

WHEREAS, pursuant to Section 14.01(a) of the Indenture, the Company and the Trustee executed 59 Supplemental Indentures dated
as of January 15, 2011 subjecting to the Lien of the Indenture certain real property that was owned by CIPS immediately prior to the Merger; and 

WHEREAS, pursuant to Section 14.01(a) of the Indenture, the Company and the Trustee executed a Supplemental Indenture dated
as of December 1, 2013 subjecting to the Lien of the Indenture certain franchises, permits, licenses, easements and rights of way; and 

WHEREAS, pursuant to the terms and provisions of the Indenture there were created and authorized by supplemental indentures thereto
bearing the following dates, respectively, the Bonds of the series issued thereunder and respectively identified opposite such dates: 
  

					
	 DATE OF
 SUPPLEMENTAL

INDENTURE
	  	 IDENTIFICATION OF SERIES
	  	 CALLED

			
	February 15, 1993	  	8% Series due 2023 (redeemed)	  	Bonds of the 2023 Series
			
	March 15, 1993	  	6 1/8% Series due 2000 (paid at maturity)	  	Bonds of the 2000 Series
			
	March 15, 1993	  	6 3/4% Series due 2005 (paid at maturity)	  	Bonds of the 2005 Series
			
	July 15, 1993	  	7 1/2% Series due 2025 (redeemed)	  	Bonds of the 2025 Series









					
	 DATE OF
 SUPPLEMENTAL

INDENTURE
	  	 IDENTIFICATION OF SERIES
	  	 CALLED

			
	August 1, 1993	  	6 1/2% Series due 2003 (paid at maturity)	  	Bonds of the 2003 Series
			
	October 15, 1993	  	5 5/8% Series due 2000 (paid at maturity)	  	Bonds of the Second 2000 Series
			
	November 1, 1993	  	Pollution Control Series M (redeemed)	  	Bonds of the Pollution Control Series M
			
	November 1, 1993	  	Pollution Control Series N (redeemed)	  	Bonds of the Pollution Control Series N
			
	November 1, 1993	  	Pollution Control Series O (redeemed)	  	Bonds of the Pollution Control Series O
			
	April 1, 1997	  	Pollution Control Series P (retired)	  	Bonds of the Pollution Control Series P
			
	April 1, 1997	  	Pollution Control Series Q (retired)	  	Bonds of the Pollution Control Series Q
			
	April 1, 1997	  	Pollution Control Series R (retired)	  	Bonds of the Pollution Control Series R
			
	March 1, 1998	  	Pollution Control Series S (redeemed)	  	Bonds of the Pollution Control Series S
			
	March 1, 1998	  	Pollution Control Series T (redeemed)	  	Bonds of the Pollution Control Series T
			
	July 15, 1998	  	6 1/4% Series due 2002 (paid at maturity)	  	Bonds of the 2002 Series
			
	September 15, 1998	  	6% Series due 2003 (paid at maturity)	  	Bonds of the Second 2003 Series
			
	June 15, 1999	  	7.50% Series due 2009 (paid at maturity)	  	Bonds of the 2009 Series
			
	July 15, 1999	  	Pollution Control Series U	  	Bonds of the Pollution Control Series U
			
	July 15, 1999	  	Pollution Control Series V (redeemed)	  	Bonds of the Pollution Control Series V
			
	May 1, 2001	  	Pollution Control Series W (retired)	  	Bonds of the Pollution Control Series W
			
	May 1, 2001	  	Pollution Control Series X (retired)	  	Bonds of the Pollution Control Series X
			
	July 1, 2002	  	10 5/8% Series due 2007 (not issued)	  	Bonds of the 2007 Series
			
	July 1, 2002	  	10 5/8% Series due 2012 (not issued)	  	Bonds of the 2012 Series
			
	December 15, 2002	  	11.50% Series due 2010 (redeemed)	  	Bonds of the 2010 Series
			
	June 1, 2006	  	Mortgage Bonds, Senior Notes Series AA (retired)	  	Bonds of Series AA


  
 2 









					
	 DATE OF
 SUPPLEMENTAL

INDENTURE
	  	 IDENTIFICATION OF SERIES
	  	 CALLED

			
	August 1, 2006	  	Mortgage Bonds, 2006 Credit Agreement Series Bonds (retired)	  	2006 Credit Agreement Series Bonds
			
	March 1, 2007	  	Mortgage Bonds, 2007 Credit Agreement Series Bonds (retired)	  	2007 Credit Agreement Series Bonds
			
	November 15, 2007	  	Mortgage Bonds, Senior Notes Series BB	  	Bonds of Series BB
			
	April 1, 2008	  	Mortgage Bonds, Senior Notes Series CC	  	Bonds of Series CC
			
	October 1, 2008	  	Mortgage Bonds, Senior Notes Series DD	  	Bonds of Series DD
			
	June 15, 2009	  	Mortgage Bonds, 2009 Credit Agreement Series Bonds (retired)	  	2009 Credit Agreement Series Bonds
			
	October 1, 2010	  	Mortgage Bonds, Senior Notes Series CIPS-AA	  	Series CIPS-AA Mortgage Bonds
			
	October 1, 2010	  	Mortgage Bonds, Senior Notes Series CIPS-BB (retired)	  	Series CIPS-BB Mortgage Bonds
			
	October 1, 2010	  	Mortgage Bonds, Senior Notes Series CIPS-CC	  	Series CIPS-CC Mortgage Bonds
			
	August 1, 2012	  	First Mortgage Bonds, Senior Notes Series EE	  	Bonds of Series EE
			
	December 1, 2013	  	First Mortgage Bonds, Senior Notes Series FF	  	Bonds of Series FF
			
	June 1, 2014	  	First Mortgage Bonds, Senior Notes Series GG	  	Bonds of Series GG
			
	December 1, 2014	  	First Mortgage Bonds, Senior Notes Series HH	  	Bonds of Series HH
			
	December 1, 2015	  	First Mortgage Bonds, Senior Notes Series II	  	Bonds of Series II

 and 

WHEREAS, a supplemental indenture with respect to the Bonds of the 2007 Series and the Bonds of the 2012 Series listed above
was executed and filed but such Bonds of the 2007 Series and Bonds of the 2012 Series were never issued and a release with respect to such supplemental indenture was subsequently executed and filed; and 

WHEREAS, pursuant to Section 14.01(a)(xi) of the Indenture, the Company and the Trustee executed a Supplemental Indenture dated as
of October 25, 2017 amending the Indenture and reserving rights to amend the Indenture; and 
 WHEREAS, the Company desires to
create a new series of Bonds to be issued under the Indenture; and 
 WHEREAS, the Company, in the exercise of the powers and
authority conferred upon and reserved to it under the provisions of the Indenture, and pursuant to appropriate resolutions of the Board of Directors, has duly resolved and determined to make, execute and deliver to the Trustee this Supplemental
Indenture in the form hereof for the purposes herein provided; and 

  
 3 








 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; 

NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE WITNESSETH: 

THAT the Company, in consideration of the purchase and ownership from time to time of the Bonds and the service by the Trustee, and its
successors, under the Indenture and of One Dollar to it duly paid by the Trustee at or before the ensealing and delivery of these presents, the receipt of which is hereby acknowledged, hereby covenants and agrees to and with the Trustee and its
successors in trust under the Indenture, for the benefit of those who shall hold Bonds, as follows: 
 ARTICLE I 

DESCRIPTION OF THE BONDS OF THE 2047 SERIES 

Section 1.    The Company hereby creates a new series of Bonds to be known as “3.70% First Mortgage Bonds due
2047” (the “Bonds of the 2047 Series”). The Bonds of the 2047 Series 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 Indenture, as supplemented and modified. 
 The Bonds of the 2047 Series shall be dated as provided in Section 3.03 of
Article Three of the Indenture. The Bonds of the 2047 Series shall mature on December 1, 2047, shall accrue interest as set forth in the form of such Bonds below and shall bear interest at the rate of three and seventy hundredths
percent (3.70%) per annum. Interest on the Bonds of the 2047 Series is payable semi-annually in arrears on June 1 and December 1 of each year, commencing on June 1, 2018, until the principal sum is paid in full. Payments of
principal, premium, if any, and interest of or on the Bonds of the 2047 Series shall be payable 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. 

Section 2.    The Bonds of the 2047 Series and the Trustee’s Certificate of Authentication shall be
substantially in the following forms respectively: 
 [FORM OF BONDS OF THE 2047 SERIES]

 

			
	REGISTERED	 	REGISTERED

 [DTC Legend 

THIS BOND IS A GLOBAL BOND 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 BONDS REPRESENTED HEREBY AS PROVIDED IN THE INDENTURE REFERRED TO BELOW, THIS BOND 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 BOND 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 

  
 4 








 
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.] 
 AMEREN ILLINOIS COMPANY 

(Incorporated under the laws of the State of Illinois) 

Illinois Commerce Commission 

Identification No.: Ill. C.C. No.     

3.70% FIRST MORTGAGE BOND DUE 2047 
  

			
	CUSIP:	  	NUMBER:
	ISIN:	  	
		
	ORIGINAL ISSUE DATE:                	  	PRINCIPAL AMOUNT: $                
	INTEREST RATE: 3.70%	  	MATURITY DATE: December 1, 2047

 AMEREN ILLINOIS COMPANY, a corporation organized and existing under the laws of the State of Illinois (the
“Company”), which term shall include any Successor Corporation as defined in the Indenture hereinafter referred to, for value received, hereby promises to pay to
                    , or registered assigns, the principal sum of
                 ($            ) on the Maturity Date set forth above 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 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 June 1 and December 1 of each year, commencing on June 1, 2018, 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 Bond 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 acceleration), will, as provided in the Indenture hereinafter referred to, be paid to the Person in whose name this Bond is registered at
the close of business on the Regular Record Date for such interest, which shall be the May 15 or November 15, 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 Bond, 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 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 Bond is registered at the close of business on a Special Record Date for the
payment of such defaulted interest to be fixed by the Trustee, notice whereof shall be given to Holders not more than fifteen days nor fewer than ten days prior to such Special Record Date. 

This Bond is one of a duly authorized issue of Bonds of the Company (the “Bonds”) in unlimited aggregate principal amount
except as provided in the Indenture, of the series hereinafter specified, all issued and to be issued under and equally secured by the General Mortgage Indenture and Deed of Trust (as amended and supplemented, the “Indenture”),
dated as of November 1, 1992, executed by the Company (as successor to Illinois Power Company) to The Bank of New York Mellon Trust Company, N.A., as successor trustee to Harris Trust and Savings Bank (the “Trustee”), to which
Indenture reference is hereby made for a description of the properties mortgaged and pledged, the nature and extent of the security, the rights of registered owners of the Bonds and of the Trustee in respect thereof, and the terms and conditions
upon which the Bonds are, and are to be, secured. 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 provided in the Indenture. This
Bond is one of a series designated as the Bonds of the 2047 

  
 5 








 
Series of the Company, unlimited in aggregate principal amount except as provided in the Indenture, issued under and secured by the Indenture and described in the Supplemental Indenture dated as
of November 1, 2017 (the “Supplemental Indenture of November 1, 2017”), between the Company and the Trustee, supplemental to the Indenture. 

Each Bond 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 Bond of this Series issued upon transfer, exchange or substitution of such Bond shall bear the Original Issue Date of such transferred, exchanged or substituted Bond, as the case may be. 

The Bonds of this Series shall be issued in minimum denominations of $2,000 and integral multiples of $1,000 in excess thereof. 

Interest on this Bond will accrue from and including the Original Issue Date specified above to, but excluding, June 1, 2018, 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 Bonds 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 Bonds of this Series to be redeemed on any redemption date prior to June 1, 2047 (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
Bonds of this Series being redeemed on that redemption date; or (b) the sum of the present values of the remaining scheduled payments of principal and interest on the Bonds of this Series being redeemed on that redemption date that would be
payable if such Bonds matured on June 1, 2047 , six months prior to the Maturity Date (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 15 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 Bonds of this Series to be redeemed on any redemption date on or after June 1, 2047 (six months prior to the
Maturity Date) will be equal to 100% of the principal amount of the Bonds of this Series being redeemed on that redemption date plus accrued and unpaid interest thereon to the redemption date. 

The redemption price shall be payable to the Person to whom principal shall be payable except that installments of interest on Bonds 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 Bond as of the close of business on the relevant Regular Record Date pursuant to
the Indenture. 
 With respect to a redemption occurring prior to June 1, 2047, 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 10 days but not more than 60 days before the redemption date to each Holder of the Bonds of this Series to be redeemed, and, if less than all Bonds of this Series are to be redeemed, the particular
Bonds 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 Bonds of this Series are represented by global certificates registered in the name of The
Depository Trust Company (“DTC”), or its nominee, beneficial interests in such global certificates will be selected for redemption by DTC in accordance with its standard procedures therefor. 

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 date fixed for such redemption, of money sufficient to pay the principal of, premium, if any, and interest on, the Bonds of this Series or 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 Bonds or portions thereof. Unless the Company defaults in payment of the redemption price, on and after the redemption date, interest will cease to accrue on
the Bonds of this Series or portions thereof called for redemption. 

  
 6 








 “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. 
 “Business Day” means, with respect to Bonds of this series, any weekday that is not a day on which
banking institutions or trust companies in the Borough of Manhattan, the City and State of New York, or in the city where the corporate trust office of the Trustee is located, are obligated or authorized by law or executive order to close. 

“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 Bonds of this Series to be redeemed (assuming, for this purpose, that the Bonds of this Series matured on June 1, 2047, six months prior to the Maturity Date) 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 Bonds 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) J.P. Morgan Securities LLC, Mizuho Securities USA LLC and a Primary Treasury Dealer (as defined below) selected by MUFG Securities Americas Inc., 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 will
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 Bond 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 due on such Interest Payment Date will be paid on the next succeeding Business Day (and
without any interest or other payment in respect of any such delay). If the Maturity Date of this Bond 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. 

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 Bonds of this Series (except for certain obligations including obligations to register the transfer or exchange of Bonds of this Series, replace stolen, lost or mutilated Bonds 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, 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 Government Obligations, in any event in an amount sufficient, without reinvestment, to pay all the principal of and any premium and interest on the Bonds of this Series on the dates such payments are due in
accordance with the terms of the Bonds of this Series. 

  
 7 








 In case an Event of Default, as defined in the Indenture, shall occur and be continuing, the
principal of all Bonds at any such time outstanding under the Indenture may be declared or may become due and payable, upon the conditions and in the manner and with the effect provided in the Indenture. The Indenture provides that such
declaration may be rescinded under certain circumstances. 
 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 Holders 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 Bonds of all series directly affected by such amendment or modifications, considered as one class. Each initial and future Holder of this Bond, by its acquisition of an interest in this Bond, irrevocably (a) consents
to the amendments set forth in Article I of the Supplemental Indenture dated as of October 25, 2017, supplemental to the Indenture, without any other or further action by any Holder of this Bond, 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 meeting of Holders, in lieu of any meeting of Holders, in any consent solicitation or otherwise.
Any such consent or waiver by the Holder of this Bond shall be conclusive and binding upon such Holder and upon all future Holders of this Bond and of any Bond 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 Bond. 
 As set forth in and subject to the provisions of the
Indenture, no Holder of any Bonds 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 Bonds, the Holders of a majority in aggregate principal amount of the outstanding Bonds 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 after its receipt of such notice; 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 Bond on or after the respective due dates expressed herein. 
 No reference herein to the Indenture
and to provisions of this Bond 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 Bond 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
Bond may be transferred only as permitted by the legend hereto and the provisions of the Indenture. 
 This Bond shall be governed by and
construed in accordance with the laws of the State of Illinois, except to the extent that the law of any other jurisdiction shall be mandatorily applicable. 

This Bond shall not be entitled to any benefit under the Indenture or any indenture supplemental thereto, or become valid or obligatory for
any purpose, until the form of certificate endorsed hereon shall have been signed by or on behalf of The Bank of New York Mellon Trust Company, N.A., as successor trustee to Harris Trust and Savings Bank, the Trustee under the Indenture, or a
successor trustee thereto under the Indenture (the “Trustee”). 
 All terms used in this Bond that are defined in the
Indenture shall have the meanings assigned to them in the Indenture unless otherwise indicated herein. 

  
 8 








 IN WITNESS WHEREOF, Ameren Illinois Company has caused this Bond to be signed (manually or by
facsimile signature) in its name by an Authorized Executive Officer, as defined in the aforesaid Indenture, and attested (manually or by facsimile signature) by an Authorized Executive Officer, as defined in such Indenture on the date hereof. 

 

							
	Dated:	 		 		 	
			
		 		 	AMEREN ILLINOIS COMPANY
				
		 		 	By:	 	  

		 		 		 	AUTHORIZED EXECUTIVE OFFICER

  

			
	ATTEST:
		
	By:	 	  

		 	AUTHORIZED EXECUTIVE OFFICER

 [FORM OF TRUSTEE’S CERTIFICATE OF AUTHENTICATION] 

This is one of the Bonds of the series designated therein referred to in the within mentioned Indenture and the Supplemental Indenture dated
as of November 1, 2017. 
 THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A. 

as successor trustee to 
 Harris
Trust and Savings Bank, 
 TRUSTEE, 
  

			
	By:	 	  

		 	AUTHORIZED SIGNATORY

 ARTICLE II 

REDEMPTION AND CONSENT TO AMENDMENTS 

Section 1.    The Bonds of the 2047 Series are redeemable as set forth in the form of such Bonds in Article I hereof.
If the Company elects to redeem any Bonds of the 2047 Series, it shall notify the Trustee of the redemption date and the principal amount of such Bonds to be redeemed not less than 15 days nor more than 90 days before such redemption date. 

Section 2.    Each initial and future Holder of the Bonds of the 2047 Series, by its acquisition of an interest in
such Bonds, irrevocably (a) consents to the amendments set forth in Article I of the Supplemental Indenture dated as of October 25, 2017, supplemental to the Indenture, without any other or further action by any Holder of such Bonds, 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 meeting of Holders, in lieu of any meeting of Holders,
in any consent solicitation or otherwise. 

  
 9 








 ARTICLE III 

ISSUE OF THE BONDS OF THE 2047 SERIES 

Section 1.    The Company hereby exercises the right to obtain the authentication of $500,000,000 principal amount of
additional Bonds pursuant to the terms of the Indenture, all of which shall be Bonds of the 2047 Series. 

Section 2.    Such Bonds of the 2047 Series may be authenticated and delivered prior to the filing for recordation of
this Supplemental Indenture. 
 Section 3.    After the authentication of such Bonds of the 2047 Series, without
the consent of any existing Holder of the Bonds of the 2047 Series, the Company may thereafter obtain from time to time the authentication of additional Bonds of the 2047 Series pursuant to the terms of the Indenture by Company Order referring to
this Supplemental Indenture having the same terms and conditions as the Outstanding Bonds of the 2047 Series in all respects (including the same CUSIP number), except for the date of original issuance, the offering price and, if applicable, the
initial interest accrual date and the initial Interest Payment Date. 
 ARTICLE IV 

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 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. In general, each and every term and condition contained in Article Eleven of the
Indenture shall apply to this Supplemental Indenture with the same force and effect as if the same were herein set forth in full, with such omissions, variations and modifications thereof as may be appropriate to make the same conform to this
Supplemental Indenture. 
 ARTICLE V 

MISCELLANEOUS PROVISIONS 

Except as otherwise defined herein, capitalized terms defined in the Indenture are used herein as therein defined. 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. 

The Indenture, as supplemented and amended by this Supplemental Indenture and all other indentures supplemental thereto, is in all respects
ratified and confirmed, and the Indenture, this Supplemental Indenture and all indentures supplemental thereto shall be read, taken and construed as one and the same instrument. 

  
 10 








 IN WITNESS WHEREOF, said Ameren Illinois Company has caused this Supplemental Indenture to be
executed on its behalf by an Authorized Executive Officer as defined in the Indenture, and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by an Authorized Executive Officer as defined in the
Indenture; and said The Bank of New York Mellon Trust Company, N.A., as successor trustee to Harris Trust and Savings Bank, in evidence of its acceptance of the trust hereby created, has caused this Supplemental Indenture to be executed on its
behalf by one of its Vice Presidents and this Supplemental Indenture to be attested by its Secretary or one of its Vice Presidents; all as of November 1, 2017. 

AMEREN ILLINOIS COMPANY 
 (CORPORATE SEAL)


			
	By:	 	 /s/ Ryan J. Martin

	Name:	 	Ryan J. Martin
	Title:	 	Vice President and Treasurer


  

			
	 ATTEST:
	  	

  

			
	By:	 	 /s/ Craig W. Stensland

	Name:	 	Craig W. Stensland
	Title:	 	Assistant Secretary


  
 11 








 THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A. 

successor trustee to 
 Harris Trust
and Savings Bank, 
 TRUSTEE, 
  

			
	By:	 	 /s/ Lawrence M. Kusch

	Name:	 	Lawrence M. Kusch
	Title:	 	Vice President


  

			
	ATTEST:	  	

  

			
	By:	 	 /s/ Emily Gigerich

	Name:	 	Emily Gigerich
	Title:	 	Vice President


  
 12 









					
	STATE OF MISSOURI	 	 )	  	
		 		  	ss.
	CITY OF ST. LOUIS	 	  )	  	

 BE IT REMEMBERED, that on this 16th day of November,
2017, before me, the undersigned, a Notary Public within and for the City and State aforesaid, personally came Ryan J. Martin, Vice President and Treasurer and Craig W. Stensland, Assistant Secretary, of Ameren Illinois Company, a corporation duly
organized, incorporated and existing under the laws of the State of Illinois, who are personally known to me to be such officers, and who are personally known to me to be the same persons who executed as such officers the within instrument of
writing, and such persons duly acknowledged that they signed, sealed and delivered the said instrument as their free and voluntary act as such officers and as the free and voluntary act of said Ameren Illinois Company for the uses and purposes
therein set forth. 
 IN WITNESS WHEREOF, I have hereunto subscribed my name and affixed my official seal on the day and year last above
written. 
  

	
	 /s/ Jessica Poat

	NOTARY PUBLIC


  

	
	  

JESSICA POAT

	Notary Public – Notary Seal
	State of Missouri
	Commissioned for Franklin County
	My Commission Expires: December 07, 2019
	
Commission Number: 11211966
  




  
 13 









					
	 STATE OF ILLINOIS
	 	)	  	
		 		  	 ss.

	 COUNTY OF COOK
	 	)	  	

 BE IT REMEMBERED, that on this 17th day of November,
2017, before me, the undersigned, a Notary Public within and for the County and State aforesaid, personally came Lawrence M. Kusch, Vice President and Emily Gigerich, Vice President, of The Bank of New York Mellon Trust Company, N.A., a national
banking association duly organized, incorporated and existing under the laws of the United States, who are personally known to me or proved to me on the basis of satisfactory evidence to be the same persons who executed as such officers the within
instrument of writing, and such persons duly acknowledged that they signed and delivered the said instrument as their free and voluntary act as such Vice President and Vice President, and as the free and voluntary act of said The Bank of New York
Mellon Trust Company, N.A. for the uses and purposes therein set forth. 
 IN WITNESS WHEREOF, I have hereunto subscribed my name and
affixed my official seal on the day and year last above written. 
  

					
	“OFFICIAL SEAL”	  		  	 /s/ Carrie M. Beecher

	CARRIE M. BEECHER	  		  	NOTARY PUBLIC
	NOTARY PUBLIC – STATE OF ILLINOIS	  		  	
	MY COMMISSION EXPIRES	  		  	
		  		  	
	Official Seal	  		  	
	Carrie M. Beecher	  		  	
	Notary Public – State of Illinois	  		  	
	My Commission Expires: 03/29/2021	  		  	


  
 14