(As filed May 21, 2001)
                                                                File No. 70-8945

                             Washington, D.C. 20549

                        (Post-Effective Amendment No. 3)
                           APPLICATION OR DECLARATION
                                    FORM U-1
                 The Public Utility Holding Company Act of 1935


                               AMEREN CORPORATION
                              1901 Chouteau Avenue
                            St. Louis, Missouri 63103

               (Name of company or companies filing this statement
                   and address of principal executive offices)


                               AMEREN CORPORATION

                 (Name of top registered holding company parent
                         of each applicant or declarant)


                       Steven R. Sullivan, Vice President,
                          General Counsel and Secretary
                             Ameren Services Company
                              1901 Chouteau Avenue
                            St. Louis, Missouri 63103

                     (Name and address of agent for service)

              The Commission is requested to mail signed copies of
                   all orders, notices and communications to:

     Ronald Gieseke, Esq.                    William T. Baker, Jr., Esq.
     Ameren Services Company                 Thelen Reid & Priest LLP
     1901 Chouteau Avenue                    40 West 57th Street
     St. Louis, Missouri 63103               New York, New York 10019-4097

     Post-Effective Amendment No. 2, as filed in this proceeding on May 1, 2001,
is hereby amended and restated in its entirety to read as follows:


     Ameren Corporation ("Ameren"), whose principal business address is at 1901
Chouteau Avenue, St. Louis, Missouri 63103, is a registered holding company
under the Public Utility Holding Company Act of 1935, as amended (the "Act").
Ameren owns all of the issued and outstanding common stock of Union Electric
Company ("AmerenUE") and Central Illinois Public Service Company ("AmerenCIPS"),
each of which is an electric and gas utility company. Together, AmerenUE and
AmerenCIPS provide retail and wholesale electric service to approximately 1.5
million customers and retail natural gas service to approximately 300,000
customers in a 24,500 square-mile area of Missouri and Illinois.

     By order dated December 30, 1997 in this proceeding (Holding Co. Act
Release No. 26809) (the "Merger Order"), the Commission authorized Ameren to
acquire AmerenUE and CIPSCO Incorporated, which was then the parent company of
AmerenCIPS, to organize a service company subsidiary, and to issue and sell
common stock pursuant to certain stock plans. In addition, the Commission
authorized Ameren to retain the direct and indirect non-utility subsidiaries and
investments of AmerenUE and CIPSCO Incorporated, subject to certain exceptions.
Specifically, the Commission conditioned its approval for the transaction on the
commitment of Ameren to reduce the voting interest or investment of Union
Electric Development Corporation ("UEDC"), a subsidiary of Union Electric, of
CIPSCO Investment Company ("CIPSCO Investment"), a subsidiary of CIPSCO
Incorporated, and of CIPSCO Venture Company ("CIPSCO Venture"), an indirect
subsidiary of CIPSCO Incorporated, in certain limited liability companies, which
are described as follows:

     St. Louis Equity Funds & Housing Missouri, Inc. - At the time of the
merger, UEDC had invested or committed to invest in varying percentages (not
greater than 23%) in ten separate investment funds (called the "St. Louis
Funds") that were formed to make investments, as a limited partner, in
individual low income housing projects in the St. Louis area. These projects
qualify for federal tax credits. Four of the ten St. Louis Funds in existence at
the time of the merger were organized as limited liability companies; the other
six are limited partnerships in which UEDC is a limited partner. In most cases,
the St. Louis Fund is the sole limited partner in an individual project
partnership. In every case, the general partner is an unaffiliated third party.
The four St. Louis Funds that were formed as limited liability companies are
so-called "manager-managed" limited liability companies, meaning that, subject
to certain limitations, the manager has full, complete and exclusive discretion
in the management and control of the business and affairs of the fund. The
manager is a not-for-profit company that is not in any way affiliated with

     Effingham Development Building II Limited Liability Company - CIPSCO
Venture holds a 40% membership interest in this entity, which owns a 267,000
square foot manufacturing facility located in the Effingham Industrial Park that


is leased to an industrial customer. This investment was intended to promote
industrial development within AmerenCIPS' service territory. Agracel Inc., an
unaffiliated third party, is the managing member.

     Mattoon Enterprise Park, LLC - CIPSCO Venture owns a 20% interest in this
limited liability company, which purchased 231 acres of farmland that was used
in the development of an industrial park within the boundaries of the City of
Mattoon. As was the case with the Effingham Industrial Park, this investment was
made to promote industrial development activity in AmerenCIPS' service territory
in order to, among other things, increase industrial load. CIPSCO Venture also
owns a one-third interest in a limited liability company, MACC, LLC, which
purchased land from Mattoon Enterprise Park, LLC and developed an industrial
facility for lease to two industrial tenants in the park. (This transaction
closed subsequent to the date of the Merger Order). Agracel Inc. is the managing
member of both entities.

     Ameren's aggregate investment in all of these limited liability companies
is approximately $1.9 million, or less than .02% of Ameren's consolidated assets
as of December 31, 2000.

     Under Section 9(c)(3) of the Act, the Commission has authorized registered
holding companies to acquire or retain the securities of companies organized to
engage in local economic development activities.1  The Commission has
interpreted Section 9(c)(3) of the Act as preventing the creation of an
"affiliate" relationship between a registered holding company and any such
entity. Rule 40(a)(5), which exempts acquisitions of this type, is by its
terms inapplicable if the acquiring company would become an "affiliate"
(i.e., owner of 5% of more of the voting securities) of the issuer.

     Likewise, the Commission has authorized registered holding companies to
acquire or retain interests in low income housing properties that qualify for
federal tax credits. Recently, in Exelon Corporation, Holding Co. Act Release
No. 27256 (Oct. 19, 2000), the Commission articulated that such interests are
retainable if they are "passive," are made for the purpose of obtaining the tax
credits, and are "self-liquidating," i.e., the assets wind down as the tax
credits expire. Ameren's investments in low-income housing properties all meet
the standards articulated in Exelon Corporation.

     In the Merger Order, the Commission indicated that membership interests in
a limited liability company may be considered "voting securities."2 Accordingly,
because Ameren's membership interest in each of the limited liability companies
that are named above exceeds 5%, the Commission conditioned its approval of the
merger upon Ameren's commitment to reduce its membership interest in each
company to below 5% within three years of the date of the Commission's order.

1    See e.g., cases cited in footnotes 11 and 12 of Appendix A to the Merger

2    Merger Order, Appendix A, n. 17.


     By supplemental order dated December 13, 2000 (Holding Co. Act Release No.
27299), the Commission granted Ameren an extension until June 30, 2001 to comply
with its commitment to sell down its limited liability company interests. For
the reasons set forth below, Ameren is now requesting that the Commission
relieve Ameren of its commitment to sell down these limited liability company
interests and make further findings permitting Ameren to retain these interests

     Since the date of the Merger Order, the Commission has, in at least two
cases, permitted new registered holding companies to retain membership interests
greater than 5% in limited liability companies formed to develop, own and
operate low-income housing projects.3  In each case, the limited liability
companies were managed by an unaffiliated manager, and the role of the
registered holding company affiliate was "passive." Although the Commission did
not specifically address whether the membership interests involved in either of
these cases could be considered "voting securities," the fact that the interests
were described as "passive" and that the new registered holding companies were
authorized to retain them suggests that the Commission no longer regards a
membership interest in a limited liability company as a "voting security" in all
cases. This view is further supported by the Commission's holding in Alliant
Energy Corporation, et al., Holding Co. Act Release No. 27331 (Dec. 29, 2000).
There, the Commission recognized the similarities between the manager in a
"manager-managed" limited liability company and the general partner of a limited
partnership, in that both typically have the exclusive right to manage the
business and operations of the venture.

     As in those previous cases, each of the limited liability companies in
which Ameren has an indirect interest is managed by a third-party manager that
has full authority and discretion in the management and control of the business
of each of the entities. Ameren's rights as a non-managing member in each of the
limited liability companies is substantially the same as its rights as a limited
partner in the other investment vehicles organized as limited partnerships that
it was authorized to retain.

     For the foregoing reasons, the Commission is requested to issue a further
supplemental order before June 30, 2001, permitting Ameren to retain its
indirect interest in each of the above-described limited liability companies.

3    See NiSource Inc., Holding Co. Act Release No. 27263 (Oct. 30, 2000), and
     --- -------------
     CP&L Energy, Inc., Holding Co. Act Release No. 27284 (Nov. 27, 2000). CP&L
     Energy (now Progress Energy) indirectly holds membership interests in about
     20 low-income housing ventures organized as limited liability companies. In
     most cases, it holds a 99% interest as the sole non-managing member.
     Likewise, CP&L Energy was authorized to retain membership interests of 49%
     and 33-1/3% in two limited liability companies that were organized to build
     and lease or sell buildings in industrial parks as part of its economic
     development activities.



     Section 9(c)(3) of the Act is applicable to the proposed transaction.


     The Commission is requested to publish a notice under Rule 23 with respect
to the filing of this Post-Effective Amendment as soon as practicable. Ameren
requests that the Commission's order be issued as soon as the rules allow, and
that there should not be a 30-day waiting period between issuance of the
Commission's order and the date on which the order is to become effective.
Ameren hereby waives a recommended decision by a hearing officer or any other
responsible officer of the Commission and consents to the Division of Investment
Management assisting in the preparation of the Commission's decision and/or
order, unless such Division opposes the matters proposed herein.


     Pursuant to the requirements of the Public Utility Holding Company Act of
1935, as amended, the undersigned company has duly caused this Post-Effective
Amendment filed herein to be signed on its behalf by the undersigned thereunto
duly authorized.

                                        AMEREN CORPORATION

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

Date:  May 21, 2001