SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                ----------------

                                    FORM 8-A


                FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
                     PURSUANT TO SECTION 12(b) OR (g) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


                               AMEREN CORPORATION
- -------------------------------------------------------------------------------
             (Exact name of registrant as specified in its charter)


           Missouri                                      43-1723446
- -------------------------------------------------------------------------------
(State of incorporation or organization)        (IRS EmployerIdentification No.)


 1901 Chouteau Avenue, St. Louis, Missouri                    63103
- -------------------------------------------------------------------------------
Address of principal executive offices)                     (Zip Code)


Securities to be registered pursuant to Section 12(b) of the Act:


Title of each class                           Name of each exchange on which
to be so registered                           each class is to be registered
- -------------------                           ------------------------------

Preferred Share Purchase Rights               New York Stock Exchange





Securities to be registered pursuant to Section 12(g) of the Act:


                                      None
- -------------------------------------------------------------------------------
                                (Title of Class)








                 INFORMATION REQUIRED IN REGISTRATION STATEMENT

Item 1.           Description of Securities To Be Registered.

Introduction
- ------------

                  On  October  9,  1998,   the  Board  of  Directors  of  Ameren
Corporation (the "Company")  declared a dividend of one preferred share purchase
right (a "Right") for each outstanding share of common stock, par value $.01 per
share,  of the Company  (the  "Common  Shares").  The dividend is payable on the
tenth day following  approval by the Securities  and Exchange  Commission of the
issuance of the Rights under the Public Utility  Holding Company Act of 1935, as
amended (such date,  the "Record  Date") to the  stockholders  of record on that
date. The description and terms of the Rights are set forth in an Agreement (the
"Agreement") between the Company and First Chicago Trust Company of New York, as
Rights Agent (the "Rights Agent").

Purchase Price
- --------------

                  Each Right entitles the registered holder to purchase from the
Company one one-hundredth of a share of Series A Junior Participating  Preferred
Stock of the Company,  par value $.01 per share (the "Preferred  Shares"),  at a
price of $180 per one one-hundredth of a Preferred Share (the "Purchase Price"),
subject to adjustment.

Flip-In
- -------

                  In the  event  that  any  person  or group  of  affiliated  or
associated  persons  acquires  beneficial  ownership  of  15%  or  more  of  the
outstanding Common Shares (an "Acquiring Person"), each holder of a Right, other
than Rights beneficially owned by the Acquiring Person (which will thereafter be
void),  will  thereafter  have the right to receive upon exercise that number of
Common  Shares  having a market  value of two  times the  exercise  price of the
Right.

Flip-Over
- ---------

                  If the  Company  is  acquired  in a merger  or other  business
combination  transaction  or 50% or more of its  consolidated  assets or earning
power are sold  after a person or group has  become an  Acquiring  Person,  each
holder of a Right (other than Rights  beneficially  owned by  Acquiring  Person,
which will be void) will  thereafter  have the right to receive  that  number of
shares  of  common  stock  of the  acquiring  company  which at the time of such
transaction  will have a market  value of two times  the  exercise  price of the
Right.

                                      -1-


Distribution Date
- -----------------

                  The distribution date is the earlier of

                  (i) 10 days following a public  announcement  that a person or
group of affiliated or associated persons have acquired beneficial  ownership of
15% or more of the outstanding Common Shares; or

                  (ii) 10 business days (or such later date as may be determined
by action of the Board of  Directors  of the  Company  prior to such time as any
person or group of affiliated persons becomes an Acquiring Person) following the
commencement  of, or  announcement  of an  intention  to make, a tender offer or
exchange  offer  the  consummation  of  which  would  result  in the  beneficial
ownership by a person or group of 15% or more of the outstanding Common Shares.

Transfer and Detachment
- -----------------------

                  Until the  Distribution  Date,  the Rights will be  evidenced,
with  respect  to any of the Common  Share  certificates  outstanding  as of the
Record  Date,  by such Common Share  certificate  with a copy of this Summary of
Rights attached thereto.  Until the Distribution Date (or earlier  redemption or
expiration of the Rights), the Rights will be transferred with and only with the
Common Shares, and transfer of those certificates will also constitute  transfer
of these Rights.

                  As  soon  as  practicable  following  the  Distribution  Date,
separate  certificates  evidencing  the Rights  ("Right  Certificates")  will be
mailed to holders of record of the Common  Shares as of the close of business on
the Distribution Date and such separate Right Certificates alone will thereafter
evidence the Rights.

Exercisability
- --------------
                  The Rights are not exercisable  until the  Distribution  Date.
The Rights will expire on October 9, 2008 (the "Final Expiration Date"),  unless
the Final  Expiration Date is extended or unless the Rights are earlier redeemed
or exchanged by the Company, in each case, as described below.

Adjustments
- -----------
                  The Purchase Price payable, and the number of Preferred Shares
or other  securities  or  property  issuable,  upon  exercise  of the Rights are
subject  to  adjustment  from time to time to prevent  dilution  in the event of
stock dividends, stock splits, reclassifications,  or certain distributions with
respect to the Preferred Shares. The number of outstanding Rights and the number
of one  one-hundredths of a Preferred Share issuable upon exercise of each Right
are also subject to adjustment if, prior to the  Distribution  Date,  there is a
stock  split of the  Common  Shares or a stock  dividend  on the  Common  Shares
payable in Common Shares or subdivisions,  consolidations or combinations of the
Common Shares. With certain exceptions, no adjustment in the Purchase Price will
be required until cumulative adjustments require an adjustment of at least 1% in
such Purchase Price. No fractional  Preferred  Shares will be issued (other than
fractions  which are  integral  multiples  of one  one-hundredth  of a Preferred
Share,  which may, at the  election of the Company,  be evidenced by  depositary
receipts) and, in lieu thereof,  an adjustment in cash will be made based on the
market price of the  Preferred  Shares on the last trading day prior to the date
of exercise.
                                      -2-


Preferred Shares
- ----------------

                  Preferred Shares  purchasable upon exercise of the Rights will
not  be  redeemable.  Each  Preferred  Share  will  be  entitled  to  a  minimum
preferential  quarterly dividend payment of $1 per share but will be entitled to
an aggregate  dividend of 100 times the dividend  declared per Common Share.  In
the event of liquidation,  the holders of the Preferred  Shares will be entitled
to a  minimum  preferential  liquidation  payment  of $100 per share but will be
entitled to an aggregate payment of 100 times the payment made per Common Share.
Each  Preferred  Share  will have 100  votes,  voting  together  with the Common
Shares. Finally, in the event of any merger,  consolidation or other transaction
in which Common Shares are exchanged,  each Preferred  Share will be entitled to
receive  100 times the  amount  received  per  Common  Share.  These  rights are
protected by customary antidilution provisions.

                  The value of the one  one-hundredth  interest  in a  Preferred
Share  purchasable upon exercise of each Right should,  because of the nature of
the Preferred Shares' dividend,  liquidation and voting rights,  approximate the
value of one Common Share.

Exchange
- --------

                  At any time  after any person or group  becomes  an  Acquiring
Person,  and prior to the  acquisition by such person or group of 50% or more of
the  outstanding  Common  Shares,  the Board of  Directors  of the  Company  may
exchange the Rights (other than Rights owned by the Acquiring Person, which will
have  become  void),  in whole or in part,  at an  exchange  ratio of one Common
Share, or one one-hundredth of a Preferred Share (subject to adjustment).

Redemption
- ----------

                  At any time prior to any person or group becoming an Acquiring
Person,  the Board of  Directors  of the Company may redeem the Rights in whole,
but not in part,  at a price of $.01 per Right  (the  "Redemption  Price").  The
redemption  of the Rights may be made  effective at such time on such basis with
such  conditions as the Board of Directors in its sole discretion may establish.
Immediately upon any redemption of the Rights,  the right to exercise the Rights
will  terminate  and the only right of the  holders of Rights will be to receive
the Redemption Price.

Amendments
- ----------
                  The  terms  of the  Rights  may be  amended  by the  Board  of
Directors  of the  Company  without  the  consent of the  holders of the Rights,
including an amendment to lower certain  thresholds  described above to not less
than the  greater  of (i) the sum of .001%  and the  largest  percentage  of the
outstanding  Common Shares then known to the Company to be beneficially owned by
any person or group of  affiliated or  associated  persons and (ii) 10%,  except
that from

                                      -3-



and after such time as any person or  group of affiliated or  associated persons
becomes an Acquiring Person no such amendment may adversely affect the interests
of the holders of the Rights.

Rights and Holders
- ------------------

                  Until a Right is exercised,  the holder thereof, as such, will
have no rights as a stockholder of the Company,  including,  without limitation,
the right to vote or to receive dividends.

Further Information
- -------------------

                  A copy of the  Agreement  is filed as  Exhibit 1 hereto and is
incorporated  herein by reference.  The  foregoing  summary  description  of the
Rights does not  purport to be  complete  and is  qualified  in its  entirety by
reference to the Agreement.

Item 2.  Exhibits.

                  1    Agreement, dated as of  October 9, 1998,  between  Ameren
                       Corporation and First Chicago Trust Company of  New York,
                       as Rights Agent, which  includes the form of  Certificate
                       of  Designation  of  the Preferred  Shares as  Exhibit A,
                       the  form  of  Right  Certificate as  Exhibit B  and  the
                       Summary of Rights as Exhibit C (incorporated by reference
                       to  Exhibit 4 to  Ameren Corporation's  Current Report on
                       Form 8-K, dated October 9, 1998).


                                      -4-




                                    SIGNATURE


                  Pursuant to the  requirements  of Section 12 of the Securities
Exchange Act of 1934, the registrant has duly caused this registration statement
to be signed on its behalf by the undersigned, thereunto duly authorized.

Dated:  November 23, 1998


                                              AMEREN CORPORATION


                                              By:  /S/ Steven R. Sullivan
                                                  ------------------------- 
                                              Name: Steven R. Sullivan
                                              Title: Vice President, General
                                                     Counsel and Secretary  





                                      -5-





                                  EXHIBIT LIST


 
                  1    Agreement, dated as of  October 9, 1998,  between  Ameren
                       Corporation and First Chicago Trust  Company of New York,
                       as Rights  Agent, which  includes the form of Certificate
                       of Designation of the Preferred  Shares as Exhibit A, the
                       form of Right Certificate as Exhibit B and the Summary of
                       Rights  as   Exhibit C  (incorporated  by  reference   to
                       Exhibit 4 to Ameren Corporation's  Current Report on Form
                       8-K, dated October 9, 1998).









                                      -6-