UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549


                                    FORM 10-Q

[X]  QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
       ACT OF 1934

     For Quarterly Period Ended September 30, 1999

[ ]  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
       EXCHANGE ACT OF 1934

     For The Transition Period From                  to

                         Commission file number 1-14756.

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

            Missouri                                            43-1723446
(State or other jurisdiction of                              (I.R.S. Employer
incorporation or organization)                               Identification No.)


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


                         Registrant's telephone number,
                       including area code: (314) 621-3222


         Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the  Securities  Exchange  Act of
1934  during  the  preceding  12 months  (or for such  shorter  period  that the
registrant was required to file such reports),  and (2) has been subject to such
filing requirements for the past 90 days.


                               Yes  X.     No   .


Shares outstanding of each of registrant's classes of common stock as of October
    31, 1999: Common Stock, $ .01 par value - 137,215,462







                               Ameren Corporation

                                      Index

                                                                   Page No.

Part I        Consolidated Financial Information (Unaudited)

              Management's Discussion and Analysis                     2

              Quantitative and Qualitative Disclosure
              About Market Risk                                        8

              Consolidated Balance Sheet
              - September 30, 1999 and December 31, 1998              10

              Consolidated Statement of Income
              - Three months, nine months and 12 months ended
                 September 30, 1999 and 1998                          11

              Consolidated Statement of Cash Flows
              - Nine months ended September 30, 1999 and 1998         12

              Notes to Consolidated Financial Statements              13


Part II       Other Information                                       16








             PART I. CONSOLIDATED FINANCIAL INFORMATION (UNAUDITED)

MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF
OPERATIONS

OVERVIEW

Ameren  Corporation  (Ameren or the Registrant) is a holding company  registered
under the Public Utility Holding Company Act of 1935 (PUHCA).  In December 1997,
Union Electric Company (AmerenUE) and CIPSCO  Incorporated  (CIPSCO) combined to
form Ameren,  with AmerenUE and CIPSCO's  subsidiaries,  Central Illinois Public
Service  Company  (AmerenCIPS)  and CIPSCO  Investment  Company  (CIC), becoming
wholly-owned  subsidiaries  of Ameren (the  Merger).  As a result of the Merger,
Ameren has a 60 percent ownership interest in Electric Energy, Inc. (EEI), which
is consolidated for financial reporting  purposes.  In 1998, Ameren formed a new
energy  marketing  subsidiary,  AmerenEnergy,  Inc., which primarily serves as a
power marketing agent for the operating companies and provides a range of energy
and risk management services to targeted customers.

The  Merger  was  accounted  for  as  a  pooling  of  interests;  therefore  the
consolidated   financial   statements  are  presented  as  if  the  Merger  were
consummated as of the beginning of the earliest period presented.  However,  the
consolidated  financial statements are not necessarily indicative of the results
of operations, financial position or cash flows that would have occurred had the
Merger been consummated for the periods for which it is given effect,  nor is it
necessarily  indicative of the future results of operations,  financial position
or cash flows.

The following  discussion and analysis  should be read in  conjunction  with the
Notes  to  Consolidated  Financial  Statements  beginning  on page  13,  and the
Management's  Discussion  and  Analysis of  Financial  Condition  and Results of
Operations (MD&A), the Audited  Consolidated  Financial Statements and the Notes
to Consolidated  Financial  Statements appearing in the Registrant's 1998 Annual
Report to stockholders  (which is incorporated by reference in the  Registrant's
1998 Form 10-K).

References to the Registrant are to Ameren on a consolidated basis;  however, in
certain  circumstances,  the subsidiaries are separately referred to in order to
distinguish between their different business activities.

RESULTS OF OPERATIONS

Earnings
Third quarter 1999 earnings of $250 million,  or $1.82 per share,  increased $13
million, or 9 cents per share, from 1998's third quarter earnings.  Earnings for
the nine months ended  September 30, 1999,  totaled $391  million,  or $2.85 per
share,  compared to the  year-ago  earnings of $360  million or $2.63 per share.
Earnings for the 12 months ended September 30, 1999, were $417 million, or $3.04
per share,  compared  to $355  million,  or $2.59 per share,  for the  preceding
12-month  period.  Excluding  the  extraordinary  charge  recorded in the fourth
quarter  of 1997 to  write  off the  generation-related  regulatory  assets  and
liabilities of the Registrant's Illinois retail electric business,  earnings for
the 12-month period ended  September 30, 1998,  were $407 million,  or $2.97 per
share.

Earnings and earnings per share  fluctuated due to many  conditions,  primarily:
weather  variations,  credits to electric  customers,  electric rate reductions,
competitive market forces, sales growth,  fluctuating operating costs (including
Callaway Nuclear Plant refueling outages),  merger-related expenses,  changes in
interest expense,  changes in income and property taxes, a charge for a targeted
employee separation plan and an extraordinary charge as noted above.

The  significant  items  affecting  revenues,  costs  and  earnings  during  the
three-month,  nine-month and 12-month periods ended September 30, 1999 and 1998
are detailed on the following pages.

                                      -2-





Electric Operations

Electric Operating Revenues    Variations for periods ended September 30, 1999
                                   from comparable prior-year periods
- -------------------------------------------------------------------------
(Millions of Dollars)           Three Months  Nine Months  Twelve Months
- -------------------------------------------------------------------------
Rate variations                    $ (7)         $(24)         $(37)
Credit to customers                 (10)           13            13
Effect of abnormal weather          (16)          (50)          (76)
Growth and other                     28            33            30
Interchange sales                    87           159           189
EEI                                 (11)           13            (5)
- -------------------------------------------------------------------------
                                   $ 71          $144          $114
- -------------------------------------------------------------------------


The $71 million  increase in third  quarter  electric  revenues  compared to the
year-ago  quarter was  primarily  driven by increased  interchange  sales due to
strong marketing  efforts.  Interchange sales increased 44 percent for the third
quarter of 1999 compared to the year-ago quarter. These increases were partially
offset  by a 1 percent  decline  in native  sales  due to milder  weather,  rate
decreases  in both  Missouri and  Illinois,  and the  estimated  credit that the
Registrant expects to pay its Illinois electric customers for the initial period
of a sharing  mechanism  provided by deregulation  legislation (see Note 5 under
Notes  to   Consolidated   Financial   Statements   for  further   information).
Weather-sensitive  residential sales decreased 3 percent, while industrial sales
rose 2 percent, and commercial sales were flat.

Electric  revenues  for the first nine  months of 1999  increased  $144  million
compared to the  prior-year  period,  primarily due to a 10 percent  increase in
total  kilowatthour  sales.  This increase was primarily  driven by a 79 percent
increase in interchange  sales due to strong marketing  efforts and a 17 percent
increase in EEI sales.  Also contributing to the revenue increase was a decrease
in the credit to Missouri electric customers,  partially offset by the credit to
Illinois  electric  customers (see Note 5 under Notes to Consolidated  Financial
Statements  for further  information).  Partially  offsetting  these  increases,
weather-sensitive  residential  and  commercial  sales were down 3 percent and 2
percent,  respectively,  and industrial  sales declined 1 percent.  In addition,
revenues  were lower due to rate  decreases in both  Missouri and Illinois  (see
Note  5  under  Notes  to   Consolidated   Financial   Statements   for  further
information).

Electric  revenues for the 12 months ended  September 30, 1999,  increased  $114
million  compared to the prior  12-month  period.  The  increase in revenues was
primarily driven by increased interchange sales due to strong marketing efforts.
Also contributing to the revenue increase was a decrease in the estimated credit
to Missouri  electric  customers,  partially  offset by the estimated  credit to
Illinois  electric  customers.  These  increases were  partially  offset by rate
decreases in both Missouri and Illinois. (See Note 5 under Notes to Consolidated
Financial Statements for further  information.) In addition,  revenues decreased
due  to  a  decline   in   native   sales   resulting   from   milder   weather.
Weather-sensitive  residential  and commercial  sales  decreased 4 percent and 2
percent, respectively, while industrial sales fell 1 percent.

Fuel and Purchased Power         Variations for periods ended September 30, 1999
                                          from comparable prior-year periods
- --------------------------------------------------------------------------------
(Millions of Dollars)                 Three Months  Nine Months  Twelve Months
- --------------------------------------------------------------------------------
Fuel:
  Variation in generation                 $(8)         $11           $27
  Price                                     -          (22)          (47)
  Generation efficiencies and other         1            -            (2)
Purchased power variation                  53           84            63
EEI variation                               2           25            19
- --------------------------------------------------------------------------------
                                          $48          $98           $60
- --------------------------------------------------------------------------------


The $48  million  increase  in third  quarter  fuel and  purchased  power  costs
compared  to the  year-ago  quarter  was driven by  increased  purchased  power,
resulting from higher sales volume, partially offset by decreased generation.

Fuel and  purchased  power costs for the nine and 12 months ended  September 30,
1999, increased $98 million and $60 million, respectively, versus the comparable
prior-year  periods  primarily due to increased  generation and purchased power,
resulting from higher sales volume, and increased fuel and purchased power costs
at EEI, partially offset by lower fuel prices.

                                      -3-



Gas Operations
Gas revenues for the 12-month  period ended  September  30, 1999,  decreased $18
million  compared  to the same  year-ago  period  primarily  due to a 19 percent
decline in total sales resulting primarily from milder winter weather, partially
offset by an Illinois gas rate increase  effective  February 1999 and a Missouri
gas rate increase effective February 1998.

Gas costs for the 12 months  ended  September  30, 1999,  decreased  $22 million
compared to the year-ago  period  primarily due to lower sales and a decrease in
gas prices.

Other Operating Expenses
Other operating expense variations  reflected  recurring factors such as growth,
inflation, labor and benefit increases.

Other operations expenses decreased $7 million and $6 million, respectively, for
the three and nine months ended  September 30, 1999,  compared to the comparable
prior-year  periods  primarily  due to the 1998  one-time  pretax  charge of $25
million  for the  targeted  employee  separation  plan  and  reduced  workforce,
partially  offset by current  year  expenses  associated  with  deregulation  in
Illinois and the Year 2000 project.

Maintenance expenses for the three, nine and 12 months ended September 30, 1999,
increased $14 million,  $28 million and $25 million,  respectively,  compared to
the year-ago  periods  primarily due to increased  power plant  maintenance  and
tree-trimming activity.  These increases were partially offset by the absence of
a refueling at the Callaway Nuclear Plant until fourth quarter 1999. There was a
Callaway Nuclear Plant refueling in second quarter 1998.

Taxes
Income taxes increased $9 million,  $18 million and $37 million,  for the three,
nine and 12 months ended September 30, 1999, respectively,  due to higher pretax
income.

Other Income and Deductions
The variation in miscellaneous,  net for the 12-month period ended September 30,
1999,  compared to the  year-ago  period,  was  primarily  due to an increase in
miscellaneous  expense  resulting  from the reversal of the Missouri  portion of
merger-related costs which were recorded as a regulatory asset upon Merger close
in December 1997,  under  conditions of the Missouri  Public Service  Commission
order  approving the Merger.  This  increase was  partially  offset by increased
interest  income  and  gains on the sale of  property  in the  current  12-month
period.

Balance Sheet
The $254 million  increase in cash and cash  equivalents  was  primarily  due to
higher revenues  attributable to interchange  sales in August and September 1999
compared to November and December 1998.

The $91 million  increase in trade accounts  receivable and unbilled revenue was
due  primarily  to higher  revenues  in August and  September  1999  compared to
November and December 1998.

Changes in accounts and wages payable and taxes accrued resulted from the timing
of various payments to taxing authorities and suppliers.

The $109 million increase in other current  liabilities was primarily due to the
timing of when  credits will be paid to electric  customers in the  Registrant's
Missouri and Illinois jurisdictions,  as well as an estimated rate reduction for
Missouri electric  customers  retroactive to September 1, 1998 (See Note 5 under
Notes  to  Consolidated  Financial  Statements  for  further  information).  The
remaining variance is a result of the timing of various payments to suppliers.

LIQUIDITY AND CAPITAL RESOURCES

Cash provided by operating  activities  totaled $854 million for the nine months
ended September 30, 1999, compared to $642 million during the same 1998 period.

Cash flows used in  investing  activities  totaled $327 million and $202 million
for  the  nine  months  ended   September  30,  1999  and  1998,   respectively.
Construction  expenditures  for the nine months ended  September  30, 1999,  for
constructing  new or improving  existing  facilities  were $342  million,  which
included  expenditures  associated  with  the  purchase  of  combustion  turbine
generators  (see Note 6 under Notes to  Consolidated  Financial  Statements  for
further information).  In addition,  the Registrant expended $20 million for the
acquisition of nuclear fuel. Capital  requirements for the remainder of 1999 are
expected to be principally for construction  expenditures and the acquisition of
nuclear fuel.

Cash flows used in financing activities totaled $273 million for the nine months
ended September 30, 1999,  compared to $354 million during the same 1998 period.
The  Registrant's  principal  financing  activities for the period  included the

                                      -4-



redemption  of $119  million  of debt and the  payment of  dividends,  partially
offset by the issuance of $58 million of long-term debt. On August 27, 1999, the
Registrant's  Board of Directors declared a quarterly dividend of 63.5 cents per
common share that was paid to shareholders  on September 30, 1999.  Common stock
dividends paid for the 12 months ended September 30, 1999,  resulted in a payout
rate  of 84  percent  of  the  Registrant's  earnings  to  common  stockholders.
Dividends  paid to the  Registrant's  common  shareholders  relative to net cash
provided by operating activities for the same period were 34 percent.

The Registrant  plans to continue  utilizing  short-term  debt to support normal
operations and other temporary requirements. The Registrant and its subsidiaries
are authorized by the Securities and Exchange  Commission under PUHCA to have up
to  an  aggregate  $2.8  billion  of  short-term   unsecured  debt   instruments
outstanding  at any one  time.  Short-term  borrowings  consist  of  bank  loans
(maturities  generally on an overnight basis) and commercial  paper  (maturities
generally  within 10 to 45 days).  At September  30, 1999,  the  Registrant  had
committed bank lines of credit aggregating $191 million (all of which was unused
and available at such date) which make  available  interim  financing at various
rates of interest based on LIBOR,  the bank certificate of deposit rate or other
options.  The lines of credit are renewable annually at various dates throughout
the year.  The  Registrant  also has a bank  credit  agreement  due 2002,  which
permits the borrowing of up to $200 million on a short-term  basis.  This credit
agreement  is  available  for  the  Registrant's  own use and for the use of its
subsidiaries.  There was $68  million  outstanding  under this  agreement  as of
September 30, 1999. The Registrant had no outstanding  short-term  borrowings as
of September 30, 1999.

Additionally,  AmerenUE has a bank credit  agreement  due 2000 which permits the
borrowing  of up to $300 million on a long-term  basis,  all of which was unused
and available at September 30, 1999.

AmerenUE also has a lease  agreement  that provides for the financing of nuclear
fuel. At September 30, 1999, the maximum amount that could be financed under the
agreement  was $120  million.  Cash used in  financing  activities  for the nine
months  ended  September  30,  1999,  included  redemptions  under the lease for
nuclear fuel of $11 million,  offset by $60 million of  issuances.  At September
30, 1999, $116 million was financed under the lease.

The Registrant,  in the ordinary course of business,  explores  opportunities to
reduce its cost in order to remain  competitive in the marketplace.  Areas where
the Company focuses its review include,  but are not limited to, labor costs and
fuel  supply  costs.   In  the  labor  area,  the  Registrant  is  currently  in
negotiations with many of the Registrant's major collective  bargaining units in
an effort to manage its labor costs and practices effectively in the future. The
Registrant  also explores  alternatives  to  effectively  manage the size of its
workforce. These alternatives include utilizing hiring freezes,  outsourcing and
offering employee separation  packages.  In the fuel supply area, the Registrant
explores  alternatives  to  effectively  manage its overall  fuel  costs.  These
alternatives  include  diversifying  fuel  sources  for use at the  Registrant's
fossil plants (e.g.  utilizing  low sulfur versus high sulfur coal),  as well as
restructuring or terminating existing contracts with suppliers.

Certain of these reduction  alternatives could result in additional  investments
being made at the Registrant's  power plants in order to utilize different types
of coal, or could require nonrecurring  payments of employee separation benefits
or  nonrecurring  payments to restructure or terminate an existing fuel contract
with a supplier.  Management  is unable to predict  which (if any),  and to what
extent,  these  alternatives  to  reduce  its  overall  cost  structure  will be
executed,  as well as determine the impact of these actions on the  Registrant's
future financial position, results of operations or cash flows.

RATE MATTERS

In March 1999,  AmerenUE and AmerenCIPS  filed delivery service tariffs with the
Illinois  Commerce  Commission  (ICC) to  comply  with the  requirements  of the
Electric  Service  Customer  Choice and Rate Relief Law of 1997.  These  tariffs
would be used by electric  customers who choose to purchase  their power from an
alternate  supplier.  On August 25, 1999, the ICC issued an order  approving the
delivery services  tariffs,  with an allowed rate of return on equity of 10.45%.
AmerenUE  and  AmerenCIPS  filed a joint  petition  for  rehearing of that order
requesting the ICC to alter its  conclusions  on a number of issues.  On October
13,  1999,  the ICC  granted a  rehearing  on certain  issues.  An order on this
reopened proceeding is expected in early 2000.

In August 1999,  the Registrant  filed a transmission  system rate case with the
Federal Energy Regulatory  Commission (FERC). This filing was primarily designed
to implement  rates,  terms and  conditions for  transmission  service for those
retail customers in Illinois which choose other suppliers.  On October 14, 1999,
the FERC issued an order suspending the proposed rates until March 25, 2000. The
Registrant filed in response an emergency  request for rehearing which requested
that the  portion of the filing  which  related to retail  access in Illinois be
placed into  effect as of October 1, 1999 to  coincide  with the start of retail
competition  in  Illinois.  An order from the FERC to this  request is  expected
shortly.  An initial decision as to the Registrant's  overall filing is expected
in early 2001.

See  Note 5  under  Notes  to  Consolidated  Financial  Statements  for  further
discussion of Rate Matters.

                                      -5-



ELECTRIC INDUSTRY RESTRUCTURING

In December 1997, the Governor of Illinois signed the Electric  Service Customer
Choice and Rate  Relief Law of 1997 (the Law)  providing  for  electric  utility
restructuring  in Illinois.  This  legislation  introduces  competition into the
supply of electric energy in Illinois.

One of the major  provisions of the Law includes the phasing-in  through 2002 of
retail direct access,  which allows customers to choose their electric supplier.
The  phase-in  of retail  direct  access  began on October  1, 1999,  with large
commercial and industrial  customers  principally  comprising the initial group.
The  customers  in  this  group  represent   approximately  10  percent  of  the
Registrant's total sales.  Retail direct access will be offered to the remaining
commercial  and  industrial  customers on December 31, 2000,  and to residential
customers on May 1, 2002.

In conjunction with another provision of the Law, in July 1999, AmerenCIPS filed
a  notice  with the ICC  that it  intends  to  transfer  AmerenCIPS'  generating
facilities  (all in Illinois) to a new  unregulated  subsidiary  of Ameren.  The
formation  of  the  new  generating  subsidiary,  as  well  as the  transfer  of
AmerenCIPS' generating assets and liabilities (at historical net book value) and
certain  power  sales  contracts,  will be  subject to  regulatory  proceedings.
Regulatory  approval  was  received  from the ICC on  October  13,  1999.  Other
regulatory approvals are required from the Federal Energy Regulatory  Commission
and the  Missouri  Public  Service  Commission.  In addition  to the  AmerenCIPS
facilities,  the generating  subsidiary  will include  substantially  all of the
combustion turbine generators which the Registrant has committed to acquire (see
Note 6 under Notes to  Consolidated  Financial  Statements and the  Registrant's
report on Form 8-K dated  September 21, 1999 for further  information).  The new
subsidiary  is  expected  to be  operational  sometime  in 2000,  subject to the
outcome of these regulatory proceedings.

Once the  transfer is  completed,  a power  supply  agreement  would be in place
between the new generating company and a nonregulated  marketing  subsidiary for
all generation.  The marketing  subsidiary  would have a power supply  agreement
with  AmerenCIPS  to supply  them  sufficient  generation  to meet  native  load
requirements  over the term of the agreement.  Power will continue to be jointly
dispatched between AmerenUE, AmerenCIPS and the new generating subsidiary.

The proposed  transfer of generating assets and liabilities had no effect on the
Registrant's financial statements as of September 30, 1999.

YEAR 2000 ISSUE

The Year  2000  Issue  relates  to how  dates are  stored  and used in  computer
systems,  applications, and embedded systems. As the century date change occurs,
certain date-sensitive systems need to be able to recognize the year as 2000 and
not as 1900. This inability to recognize and properly treat the year as 2000 may
cause these systems to process  critical  financial and operational  information
incorrectly.   The  Registrant's  primary  concern  is  the  potential  for  any
interruption in providing electric and gas service to customers,  as well as the
potential inability to process critical financial and operational information on
a timely basis,  including  billing its customers,  if appropriate steps are not
taken to address this issue.  Management  has  developed a Year 2000 plan (Plan)
and Ameren's  Board of Directors  has been briefed about the Year 2000 Issue and
how it may affect the Registrant.

The  Registrant's  Plan to resolve the Year 2000 Issue  involves  three  phases:
assessment, planning, and implementation/testing.  Implementation of the Plan is
directly  supervised  by each area's  responsible  Vice  President.  A Year 2000
Project  Director  coordinates the  implementation  of the Plan among functional
teams who are addressing  issues specific to a particular  area, such as nuclear
and  non-nuclear   generation   facilities,   energy  management  systems,   gas
distribution,   etc.  Ameren  has  also  engaged  certain  outside  consultants,
technicians and other external  resources to aid in formulating and implementing
the Plan.

The  Registrant  has completed its assessment  phase,  which included  analyzing
date-sensitive  electronic hardware,  software applications and embedded systems
and has developed a compliance plan to address issues that were identified. Many
of the major  corporate  computer  systems  at  Ameren  are  relatively  new and
therefore are either Year 2000  compliant or only require  minor  modifications.
Also,   several  of  the  operating   hardware  and  embedded   systems   (i.e.,
microprocessor  chips) use analog  rather than digital  technology  and thus are
unaffected  by the  two-digit  date  issue.  In  addition,  the  Registrant  has
contacted hundreds of vendors and suppliers to verify compliance.

The  Registrant  has also  completed  its planning  phase.  Items that have been
identified  for  remediation  have been  prioritized  into groups based on their
significance to Company operations.

                                      -6-



The implementation/testing  phase for all mission critical systems was completed
by  September  30,  1999.  The   implementation/testing   phase  for  all  other
components/applications is approximately 98 percent complete as of September 30,
1999.

With  respect  to  third  parties,   for  areas  that  interface  directly  with
significant  vendors, the Registrant has inventoried vendors and major suppliers
and is currently  assessing their Year 2000 readiness through surveys,  websites
and personal contact. The Registrant plans to follow up with major suppliers and
vendors and verify Year 2000 compliance,  where appropriate.  The Registrant has
also queried its health  insurance  providers.  To date,  the  Registrant is not
aware of any problems  that would  materially  impact its  financial  condition,
results of operations  or liquidity.  However,  the  Registrant  has no means of
ensuring that these parties will be Year 2000 compliant.  The inability of those
parties to complete their Year 2000 resolution  process could materially  impact
the Registrant.

The  Registrant  has also  addressed the impact of electric  power grid problems
that may occur outside of its own electric system.  The Registrant has conducted
Year 2000  electric  power grid impact  planning  through the  system's  various
electric  interconnection  affiliations  and is  working  with the  Mid-American
Interchange  Network (MAIN) and the North American Electric  Reliability Council
(NERC) to plan Year 2000 operational  preparedness and restoration scenarios. As
of September 30, 1999, the Registrant had completed its assessment, planning and
implementation/testing  phases for mission critical items as identified by NERC.
As a result, the Registrant has been added to the "Ready" list being compiled by
NERC as it assesses  readiness  of the  regional  and  national  electric  grid.
Through the Electric Power Research  Institute (EPRI),  an industry-wide  effort
has been established to deal with Year 2000 problems  affecting  digital systems
and equipment used by the nation's electric power companies.  Under this effort,
participating  utilities are working together to assess specific vendors' system
problems and test plans.  The assessment is being shared with EPRI  participants
to facilitate Year 2000 problem solving.

In addressing  the Year 2000 Issue,  the  Registrant  will incur  internal labor
costs as well as external  consulting  and other expenses to prepare for the new
century.  The Registrant  estimates that its external costs (consulting fees and
related costs) for addressing the Year 2000 Issue will range from $10 million to
$15 million. As of September 30, 1999, the Registrant has expended approximately
$8 million. The Registrant's plans to complete Year 2000 modifications are based
on management's best estimates, which are derived utilizing numerous assumptions
of future events including the continued availability of certain resources,  and
other factors.  However,  there can be no guarantee that these estimates will be
achieved and actual results could differ  materially from those plans.  Specific
factors that might cause such material  differences include, but are not limited
to, the availability and cost of personnel  trained in this area, the ability to
locate and correct all relevant computer codes, and similar uncertainties.

The  Registrant  believes  that,  with  appropriate  modifications  to  existing
computer  systems/components,  updates  by vendors  and  trading  partners,  and
conversion to new software and hardware in the ordinary course of business,  the
Year  2000  Issue  will  not  pose  significant  operational  problems  for  the
Registrant.  However,  if such  conversions  are not  completed  in a proper and
timely  manner by all  affected  parties,  the Year 2000 Issue  could  result in
material adverse operational and financial  consequences to the Registrant,  and
there can be no assurance that the Registrant's efforts, or those of vendors and
trading partners,  interconnection  affiliates, NERC or EPRI to address the Year
2000 Issue will be  successful.  The  Registrant is in the process of developing
contingency plans to address potential risks,  including risks of vendor/trading
partners  noncompliance,  as well as  noncompliance  of any of the  Registrant's
material  operating systems.  The first operational  contingency plan addressing
power grid issues was completed  during the first  quarter of 1999.  Contingency
plans related to the business  areas were  completed in July 1999. At this time,
the  Registrant  is unable to predict the ultimate  impact,  if any, of the Year
2000 Issue on the  Registrant's  financial  condition,  results of operations or
liquidity; however, the impact could be material.

ACCOUNTING MATTERS

In June 1998, the Financial  Accounting  Standards Board (FASB) issued Statement
of  Financial  Accounting  Standards  (SFAS)  133,  "Accounting  for  Derivative
Instruments  and  Hedging  Activities."  SFAS  133  establishes  accounting  and
reporting  standards for derivative  instruments and for hedging  activities and
requires  recognition  of all  derivatives on the balance sheet measured at fair
value.  In June 1999,  the FASB  issued  SFAS 137,  "Accounting  for  Derivative
Instruments  and  Hedging  Activities--Deferral  of the  Effective  Date of FASB
Statement No. 133," which  delayed the effective  date of SFAS 133 to all fiscal
quarters of all fiscal years beginning after June 15, 2000. Earlier  application
is still  encouraged.  At this time,  the  Registrant is unable to determine the
impact of SFAS 133 on its  financial  position  or  results of  operations  upon
adoption;  however,  SFAS 133 could increase the volatility of the  Registrant's
future earnings.

                                      -7-



QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

Market risk  represents the risk of changes in value of a financial  instrument,
derivative  or  non-derivative,  caused by  fluctuations  in interest  rates and
equity prices.  The following  discussion of the  Registrant's  risk  management
activities  includes   "forward-looking"   statements  that  involve  risks  and
uncertainties.  Actual results could differ  materially  from those projected in
the  "forward-looking"  statements.  The  Registrant  handles  market  risks  in
accordance with  established  policies,  which may include entering into various
derivative  transactions.  In the normal course of business, the Registrant also
faces  risks  that are  either  non-financial  or  non-quantifiable.  Such risks
principally  include  credit risk and legal risk and are not  represented in the
following analysis.

Interest Rate Risk
The  Registrant  is exposed to market risk  through  changes in interest  rates,
principally  at its  subsidiaries,  through its issuance of both  long-term  and
short-term  variable-rate  debt,  fixed-rate debt,  commercial paper and auction
market  preferred  stock.  The Registrant  manages its interest rate exposure by
controlling  the  amount  of  these   instruments  it  holds  within  its  total
capitalization  portfolio  and by  monitoring  the effects of market  changes in
interest rates.

If  interest  rates  increase  1  percent  in  2000 as  compared  to  1999,  the
Registrant's interest expense would increase by approximately $6 million and net
income  would  decrease  by  approximately  $4  million.  This  amount  has been
determined using the assumptions that the Registrant's outstanding variable rate
debt,  commercial  paper and auction market  preferred stock as of September 30,
1999, continued to be outstanding throughout 2000, and that the average interest
rates for these  instruments  increased 1 percent over 1999.  The model does not
consider  the effects of the reduced  level of overall  economic  activity  that
would  exist in such an  environment.  In the event of a  significant  change in
interest  rates,  management  would likely take actions to further  mitigate its
exposure to this market risk.  However,  due to the  uncertainty of the specific
actions that would be taken and their possible effects, the sensitivity analysis
assumes no change in the Registrant's financial structure.

Commodity Price Risk
The  Registrant  is exposed to changes in market prices for natural gas and fuel
and  purchased  power.  With regard to its natural  gas  utility  business,  the
Registrant's  exposure to changing  market prices is in large part  mitigated by
the fact that the  Registrant  has a Purchased  Gas  Adjustment  Clause (PGA) in
place in both its  Missouri  and  Illinois  jurisdictions.  The PGA  allows  the
Registrant to pass on to its customers its prudently  incurred  costs of natural
gas.  With  approval  of  the  Missouri  Public  Service  Commission,   AmerenUE
participated in an experimental  program to control the volatility of gas prices
paid by its  Missouri  customers  in the  1998-1999  winter  months  through the
purchase of financial instruments. This program concluded in April 1999.

Since  the  Registrant  does not  have a  provision  similar  to the PGA for its
electric operations, the Registrant has entered into several long-term contracts
with various  suppliers to purchase coal and nuclear fuel to manage its exposure
to fuel prices.  With regard to the Registrant's  exposure to commodity risk for
purchased  power,  the  Registrant has  established a subsidiary,  AmerenEnergy,
Inc.,  whose primary  responsibility  includes  managing market risks associated
with the  changing  market  prices  for  purchased  power  for the  Registrant's
operating subsidiaries, AmerenUE and AmerenCIPS.

AmerenEnergy  utilizes  several  techniques  to  mitigate  its  market  risk for
purchased  power,  including  utilizing  derivative  financial  instruments.   A
derivative  is a contract  whose value is dependent on or derived from the value
of some underlying asset. The derivative financial instruments that AmerenEnergy
is allowed to utilize (which include  forward  contracts and futures  contracts)
are  dictated by a risk  management  policy,  which has been  reviewed  with the
Auditing  Committee of Ameren's  Board of  Directors.  Compliance  with the risk
management policy is the responsibility of a risk management steering committee,
consisting of Ameren  officers and an  independent  risk  management  officer at
AmerenEnergy.

As of September  30, 1999,  the fair value of derivative  financial  instruments
exposed to commodity price risk was immaterial.

Equity Price Risk
The  Registrant  maintains  trust funds,  as required by the Nuclear  Regulatory
Commission  and  Missouri  and Illinois  state laws,  to fund  certain  costs of
nuclear  decommissioning.  As of September  30, 1999,  these funds were invested
primarily in domestic equity securities,  fixed-rate,  fixed-income  securities,
and cash  and  cash  equivalents.  By  maintaining  a  portfolio  that  includes
long-term equity investments,  the Registrant is seeking to maximize the returns
to be  utilized  to fund  nuclear  decommissioning  costs.  However,  the equity
securities  included  in  the  Registrant's   portfolio  are  exposed  to  price
fluctuations in equity markets, and the fixed-rate,  fixed-income securities are
exposed to changes in interest  rates.  The  Registrant  actively  monitors  its
portfolio by benchmarking  the  performance of its  investments  against certain
indices

                                      -8-



and by maintaining,  and periodically  reviewing,  established target allocation
percentages  of the  assets of its  trusts to various  investment  options.  The
Registrant's exposure to equity price market risk is in large part mitigated due
to  the  fact  that  the   Registrant  is  currently   allowed  to  recover  its
decommissioning costs in its rates.

SAFE HARBOR STATEMENT

Statements made in this Form 10-Q which are not based on historical  facts,  are
"forward-looking"  and, accordingly,  involve risks and uncertainties that could
cause actual results to differ  materially from those  discussed.  Although such
"forward-looking"  statements  have  been  made in good  faith  and are based on
reasonable assumptions,  there is no assurance that the expected results will be
achieved.  These statements include (without limitation) statements as to future
expectations,   beliefs,  plans,  strategies,  objectives,  events,  conditions,
financial  performance  and the Year 2000 Issue.  In  connection  with the "Safe
Harbor" provisions of the Private Securities  Litigation Reform Act of 1995, the
Registrant is providing this cautionary  statement to identify important factors
that could cause actual results to differ materially from those anticipated. The
following factors,  in addition to those discussed  elsewhere in this report and
in the 1998 Annual Report to Stockholders (which is incorporated by reference in
the Registrant's  1998 Form 10-K) and in subsequent  securities  filings,  could
cause results to differ materially from management  expectations as suggested by
such "forward-looking" statements: the effects of regulatory actions; changes in
laws and other  governmental  actions;  the impact on the  Registrant of current
regulations  related to the phasing-in of the  opportunity for some customers to
choose  alternative  energy  suppliers  in  Illinois;  the effects of  increased
competition  in the future due to, among other things,  deregulation  of certain
aspects  of the  Registrant's  business  at both the state and  Federal  levels;
future market prices for fuel and purchased power, electricity, and natural gas,
including the use of financial instruments; average rates for electricity in the
Midwest;  business and economic conditions;  interest rates; weather conditions;
fuel  prices  and  availability;  generation  plant  performance;  the impact of
current  environmental  regulations on utilities and the  expectation  that more
stringent  requirements  will be introduced over time,  which could  potentially
have a negative financial effect; monetary and fiscal policies; future wages and
employee benefits costs; and legal and administrative proceedings.

                                      -9-




                               AMEREN CORPORATION
                           CONSOLIDATED BALANCE SHEET
                                    UNAUDITED
                      (Thousands of Dollars, Except Shares)




                                                                  September 30, December 31,
ASSETS                                                                1999          1998
- ------                                                            ------------- -------------
                                                                         
Property and plant, at original cost:
   Electric                                                        $11,950,939   $11,761,306
   Gas                                                                 484,735       469,216
   Other                                                                46,919        44,646
                                                                   -----------   -----------
                                                                    12,482,593    12,275,168
   Less accumulated depreciation and amortization                    5,839,489     5,602,816
                                                                   -----------   -----------
                                                                     6,643,104     6,672,352
Construction work in progress:
   Nuclear fuel in process                                             134,394       108,294
   Other                                                               219,040       147,393
                                                                   -----------   -----------
         Total property and plant, net                               6,996,538     6,928,039
                                                                   -----------   -----------
Investments and other assets:
   Investments                                                          62,865        86,694
   Nuclear decommissioning trust fund                                  172,477       161,877
   Other                                                                77,009        78,091
                                                                   -----------   -----------
         Total investments and other assets                            312,351       326,662
                                                                   -----------   -----------
Current assets:
   Cash and cash equivalents                                           331,114        76,863
   Accounts receivable - trade (less allowance for doubtful
         accounts of $10,537 and $8,393, respectively)                 318,679       198,193
   Unbilled revenue                                                    121,201       150,481
   Other accounts and notes receivable                                  68,274        76,919
   Materials and supplies, at average cost -
      Fossil fuel                                                      122,094       112,908
      Other                                                            135,770       132,884
   Other                                                                53,323        22,912
                                                                   -----------   -----------
         Total current assets                                        1,150,455       771,160
                                                                   -----------   -----------
Regulatory assets:
   Deferred income taxes                                               628,532       633,529
   Other                                                               170,809       188,049
                                                                   -----------   -----------
         Total regulatory assets                                       799,341       821,578
                                                                   -----------   -----------
Total Assets                                                       $ 9,258,685   $ 8,847,439
                                                                   ===========   ===========

CAPITAL AND LIABILITIES
Capitalization:
   Common stock, $.01 par value, authorized 400,000,000 shares -
     outstanding 137,215,462 shares                                $     1,372   $     1,372
   Other paid-in capital, principally premium on
     common stock                                                    1,582,501     1,582,548
   Retained earnings                                                 1,601,612     1,472,200
                                                                   -----------   -----------
         Total common stockholders' equity                           3,185,485     3,056,120
   Preferred stock not subject to mandatory redemption                 235,197       235,197
   Long-term debt                                                    2,301,586     2,289,424
                                                                   -----------   -----------
         Total capitalization                                        5,722,268     5,580,741
                                                                   -----------   -----------
Minority interest in consolidated subsidiary                             3,534         3,534
Current liabilities:
   Current maturity of long-term debt                                  237,156       201,713
   Short-term debt                                                        --          58,528
   Accounts and wages payable                                          262,566       297,185
   Accumulated deferred income taxes                                    69,663        66,299
   Taxes accrued                                                       302,930       114,106
   Other                                                               326,022       216,889
                                                                   -----------   -----------
         Total current liabilities                                   1,198,337       954,720
                                                                   -----------   -----------
Accumulated deferred income taxes                                    1,510,741     1,521,417
Accumulated deferred investment tax credits                            172,811       178,832
Regulatory liability                                                   184,519       198,937
Other deferred credits and liabilities                                 466,475       409,258
                                                                   -----------   -----------
Total Capital and Liabilities                                      $ 9,258,685   $ 8,847,439
                                                                   ===========   ===========


See Notes to Consolidated Financial Statements.

                                      -10-



                               AMEREN CORPORATION
                        CONSOLIDATED STATEMENT OF INCOME
                                    UNAUDITED
           (Thousands of Dollars, Except Shares and Per Share Amounts)





                                             Three Months Ended           Nine Months Ended       Twelve Months Ended
                                                September 30,               September 30,             September 30,
                                          ------------------------    -----------------------   -----------------------
                                              1999         1998           1999         1998         1999         1998
                                              ----         ----           ----         ----         ----        ----
                                                                                         
 OPERATING REVENUES:
    Electric                              $1,160,693   $1,090,069     $2,620,792   $2,476,977   $3,238,026   $3,124,203
    Gas                                       29,675       25,718        161,600      157,333      220,948      239,249
    Other                                      3,094        1,331          6,856        5,395        8,777        8,175
                                        ------------   ----------     ----------   ----------   ----------    ---------
       Total operating revenues            1,193,462    1,117,118      2,789,248    2,639,705    3,467,751    3,371,627

 OPERATING EXPENSES:
    Operations
       Fuel and purchased power              295,625      248,086        718,493      620,170      878,446      818,318
       Gas                                    16,481       12,993         89,840       88,282      120,404      142,052
       Other                                 180,202      187,453        483,661      489,344      641,474      640,491
                                        ------------   ----------     ----------   ----------   ----------    ---------
                                             492,308      448,532      1,291,994    1,197,796    1,640,324    1,600,861
    Maintenance                               80,976       66,978        252,115      224,406      339,720      314,852
    Depreciation and amortization             90,140       86,160        266,782      259,075      356,110      346,208
    Income taxes                             162,985      153,581        259,996      242,290      285,379      248,734
    Other taxes                               70,326       78,215        191,435      213,896      250,313      273,702
                                        ------------   ----------     ----------   ----------   ----------    ---------
       Total operating expenses              896,735      833,466      2,262,322    2,137,463    2,871,846    2,784,357

 OPERATING INCOME                            296,727      283,652        526,926      502,242      595,905      587,270

 OTHER INCOME AND DEDUCTIONS:
    Allowance for equity funds used
       during construction                     1,141        1,148          6,029        3,415        7,615        5,264
    Miscellaneous, net                        (2,784)        (491)        (6,718)      (5,277)      (4,050)        (480)
                                        ------------   ----------     ----------   ----------   ----------    ----------
      Total other income and deductions       (1,643)         657           (689)      (1,862)       3,565        4,784

 INCOME BEFORE INTEREST
    CHARGES AND PREFERRED
    DIVIDENDS                                295,084      284,309        526,237      500,380      599,470      592,054

 INTEREST CHARGES AND
    PREFERRED DIVIDENDS:
    Interest                                  43,396       46,071        131,444      136,298      176,726      180,404
    Allowance for borrowed funds
       used during construction               (1,292)      (1,559)        (5,359)      (5,548)      (6,837)      (7,567)
    Preferred dividends of subsidiaries        3,161        3,140          9,455        9,414       12,603       12,551
                                         -----------   ----------     ----------  -----------  -----------    ---------
      Net interest charges and preferred
         dividends                            45,265       47,652        135,540      140,164      182,492      185,388

 INCOME BEFORE
    EXTRAORDINARY CHARGE                     249,819      236,657        390,697      360,216      416,978      406,666
                                         -----------   ----------     ----------  -----------  -----------    ---------

 EXTRAORDINARY CHARGE
  (NET OF INCOME TAXES)                         -            -              -            -            -         (51,820)
                                         -----------   ----------     ----------  -----------  -----------    ---------

 NET INCOME                               $  249,819   $  236,657      $ 390,697   $  360,216   $  416,978   $  354,846
                                          ==========   ==========      =========   ==========   ==========   ==========

 EARNINGS PER COMMON SHARE -
    BASIC AND DILUTED (Based on
       average shares outstanding)
     Income before extraordinary charge        $1.82        $1.73          $2.85        $2.63        $3.04        $2.97
     Extraordinary charge                          -            -              -            -            -        (0.38)
                                              ------        -----          -----        -----        -----        -----
     Net income                                $1.82        $1.73          $2.85        $2.63        $3.04        $2.59
                                               =====        =====          =====        =====        =====        =====

 AVERAGE COMMON SHARES
  OUTSTANDING                            137,215,462  137,215,462    137,215,462  137,215,462  137,215,462  137,215,462
                                         ===========  ===========    ===========  ===========  ===========  ===========




See Notes to Consolidated Financial Statements.

                                      -11-




                               AMEREN CORPORATION
                      CONSOLIDATED STATEMENT OF CASH FLOWS
                                    UNAUDITED
                             (Thousands of Dollars)






                                                                    Nine Months Ended
                                                                       September 30,
                                                               --------------------------
                                                                  1999            1998
                                                                  ----            ----
                                                                        
Cash Flows From Operating:
   Net income                                                  $ 390,697        $360,216
   Adjustments to reconcile net income to net cash
      provided by operating activities:
        Depreciation and amortization                            259,447         251,609
        Amortization of nuclear fuel                              30,823          26,837
        Allowance for funds used during construction             (11,388)         (8,963)
        Deferred income taxes, net                               (16,493)        (15,203)
        Deferred investment tax credits, net                      (6,021)         (8,859)
        Changes in assets and liabilities:
           Receivables, net                                      (82,561)       (103,856)
           Materials and supplies                                (12,072)        (10,872)
           Accounts and wages payable                            (34,619)        (90,175)
           Taxes accrued                                         188,824         155,293
           Pension and postretirement benefits                    33,192          18,397
           Credit to customers                                    42,510          30,416
           Other, net                                             71,519          37,074
                                                             -----------     -----------
Net cash provided by operating activities                        853,858         641,914

Cash Flows From Investing:
   Construction expenditures                                    (342,352)       (215,252)
   Allowance for funds used during construction                   11,388           8,963
   Nuclear fuel expenditures                                     (19,662)         (7,523)
   Other                                                          23,829          11,388
                                                             -----------     -----------
Net cash used in investing activities                           (326,797)       (202,424)

Cash Flows From Financing:
   Dividends on common stock                                    (261,395)       (261,395)
   Environmental bond redemption fund                                  -        (160,000)
   Redemptions -
      Nuclear fuel lease                                         (11,332)        (53,670)
      Short-term debt                                            (58,528)        (30,063)
      Long-term debt                                             (60,000)        (45,000)
   Issuances -
      Nuclear fuel lease                                          60,045           9,917
      Long-term debt                                              58,400         186,200
                                                               ---------       ---------
Net cash used in financing activities                           (272,810)       (354,011)
                                                               ---------       ---------

Net increase in cash and cash equivalents                        254,251          85,479
Cash and cash equivalents at beginning of year                    76,863          42,425
                                                               ---------       ---------
Cash and cash equivalents at end of period                     $ 331,114       $ 127,904
                                                               =========       =========

Cash paid during the periods:
    Interest (net of amount capitalized)                        $111,005        $118,075
    Income taxes, net                                           $153,260        $164,556




See Notes to Consolidated Financial Statements

                                      -12-



AMEREN CORPORATION
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 1999

Note 1 - Ameren  Corporation  (Ameren) is a holding company registered under the
Public Utility  Holding  Company Act of 1935 (PUHCA).  In December  1997,  Union
Electric Company  (AmerenUE) and CIPSCO  Incorporated  (CIPSCO) combined to form
Ameren, with AmerenUE and CIPSCO's subsidiaries, Central Illinois Public Service
Company (AmerenCIPS) and CIPSCO Investment Company (CIC),  becoming wholly-owned
subsidiaries of Ameren (the Merger).  The  accompanying  consolidated  financial
statements (the financial statements) reflect the accounting for the Merger as a
pooling of interests and are  presented as if the companies  were combined as of
the  earliest  period  presented.  However,  the  financial  information  is not
necessarily indicative of the results of operations,  financial position or cash
flows that would have occurred had the Merger been  consummated  for the periods
for which it is given effect, nor is it necessarily indicative of future results
of operations, financial position or cash flows. The outstanding preferred stock
of AmerenUE and AmerenCIPS were not affected by the Merger.

The  accompanying  financial  statements  include the accounts of Ameren and its
consolidated  subsidiaries  (collectively the Registrant).  All subsidiaries for
which the  Registrant  owns directly or  indirectly  more than 50 percent of the
voting  stock  are  included  as  consolidated  subsidiaries.  Ameren's  primary
operating  companies,  AmerenUE and AmerenCIPS,  are engaged  principally in the
generation,  transmission,  distribution  and sale of  electric  energy  and the
purchase,  distribution,  transportation  and sale of natural gas. The operating
companies  serve 1.5 million  electric  and 300,000  natural gas  customers in a
44,500-square-mile area of Missouri and Illinois. The Registrant's non-regulated
subsidiaries include CIC, an investing  subsidiary,  and AmerenEnergy,  Inc., an
energy  marketing  subsidiary.  The Registrant also has a 60 percent interest in
Electric Energy,  Inc. (EEI).  EEI owns and operates an electric  generation and
transmission  facility in Illinois that supplies  electric power  primarily to a
uranium  enrichment  plant  located  in  Paducah,   Kentucky.   All  significant
intercompany   balances  and   transactions   have  been   eliminated  from  the
consolidated financial statements.

Note 2 - Financial statement note disclosures, normally included in consolidated
financial  statements  prepared in conformity with generally accepted accounting
principles,  have  been  omitted  in this Form  10-Q  pursuant  to the Rules and
Regulations of the Securities and Exchange  Commission.  However, in the opinion
of the Registrant,  the disclosures  contained in this Form 10-Q are adequate to
make the  information  presented  not  misleading.  See  Notes  to  Consolidated
Financial  Statements  included in the 1998 Annual Report to Stockholders (which
is incorporated by reference in the Registrant's 1998 Form 10-K) for information
relevant to the consolidated  financial  statements contained in this Form 10-Q,
including  information  as  to  the  significant   accounting  policies  of  the
Registrant.

Note 3 - In the  opinion of the  Registrant,  the interim  financial  statements
filed as part of this Form 10-Q  reflect  all  adjustments,  consisting  only of
normal recurring adjustments,  necessary for a fair statement of the results for
the periods presented.  The Registrant's  consolidated financial statements were
prepared to permit the  information  required  in the  Financial  Data  Schedule
(FDS),  Exhibit 27, to be directly extracted from the filed statements.  The FDS
amounts  correspond  to or are  calculable  from  the  amounts  reported  in the
consolidated financial statements or notes thereto.

Note 4 - Due to the  effect of  weather  on sales and  other  factors  which are
characteristic of public utility  operations,  financial results for the periods
ended September 30, 1999 and 1998, are not necessarily  indicative of trends for
any three-month, nine-month or twelve-month period.

Note 5 - In July 1995, the Missouri Public Service  Commission  (MoPSC) approved
an  agreement  involving  AmerenUE's  Missouri  electric  rates.  The  Agreement
included a three-year  experimental  alternative  regulation  plan that provides
that  earnings in excess of a 12.61  percent  regulatory  return on equity (ROE)
will be shared equally between  customers and shareholders and earnings above 14
percent ROE will be credited to customers.  The formula for computing the credit
uses twelve-month results ending June 30, rather than calendar year earnings.

The  Registrant  recorded an estimated $43 million  credit for the final year of
the  original  experimental  alternative  regulation  plan.  The MoPSC staff has
proposed adjustments to the Registrant's  estimated $43 million credit, which if
ultimately  accepted,  could increase the  Registrant's  estimated  credit up to
approximately $5 million.  Hearings were held on this matter in June 1999, and a
final order from the MoPSC is expected by the end of 1999.

                                      -13-



A new three-year  experimental  alternative  regulation plan was included in the
joint  agreement  approved by the MoPSC in its February 1997 order approving the
Merger. Like the original plan, the new plan requires that earnings over a 12.61
percent ROE up to a 14 percent ROE will be shared equally between  customers and
stockholders.  The new three-year  plan will also return to customers 90 percent
of all earnings above a 14 percent ROE up to a 16 percent ROE.  Earnings above a
16 percent ROE will be credited entirely to customers. As of September 30, 1999,
the  Registrant  had recorded an estimated $20 million credit for the first year
of this plan. This credit was reflected as a reduction in electric revenues.

The joint  agreement  approved by the MoPSC in its February 1997 order approving
the Merger also provided for a Missouri  electric rate decrease,  retroactive to
September  1, 1998,  based on the  weather-adjusted  average  annual  credits to
customers under the original experimental alternative regulation plan. The MoPSC
staff proposed  adjustments to the  Registrant's  methodology of calculating the
weather-adjusted  credits. During the second quarter of 1999, the Registrant and
the MoPSC staff  reached a settlement on the  methodology  for  calculating  the
weather-adjusted credits. This proposed settlement is subject to approval by the
MoPSC. In addition, the results of the regulatory proceeding associated with the
final year of the original experimental  alternative regulation plan will impact
the final Missouri electric rate decrease as well. The Registrant estimates that
its  Missouri  electric  rate  decrease  should  approximate  $15 million to $20
million on an annualized  basis. A final order from the MoPSC is expected by the
end of 1999.

In conjunction  with the Electric Service Customer Choice and Rate Relief Law of
1997  (the  Law),  a 5  percent  residential  electric  rate  decrease  for  the
Registrant's Illinois electric customers was effective August 1, 1998. This rate
decrease is expected to decrease electric  revenues $14 million annually,  based
on  estimated  levels of sales  and  assuming  normal  weather  conditions.  The
Registrant  may be subject to  additional 5 percent  residential  electric  rate
decreases  in each of 2000 and 2002,  to the extent its rates exceed the Midwest
utility  average at that time. The  Registrant's  rates are currently  below the
Midwest utility average.

The Law also contains a provision requiring one-half of excess earnings from the
Illinois  jurisdiction  for the years 1998  through  2004 to be  refunded to the
Registrant's  customers.  Excess  earnings  are  defined  as the  portion of the
two-year average annual rate of return on common equity in excess of 1.5 percent
of the two-year average of an Index, as defined in the Law. The Index is defined
as the sum of the  average  for the  twelve  months  ended  September  30 of the
average  monthly  yields of the  30-year  U.S.  Treasury  bonds plus  prescribed
percentages  ranging from 4 percent to 5 percent.  In July 1999,  Senate Bill 24
was passed which increased the prescribed  percentages to 7 percent beginning in
2000.  Filings must be made with the Illinois  Commerce  Commission on or before
March  31 of each  year  2000  through  2005.  As of  September  30,  1999,  the
Registrant  recorded an estimated $10 million credit it expects to return to its
customers under the Law for the two year period ended December 31, 1999.

Note 6 - The Registrant has committed to purchase  combustion turbine generators
(CTs).  The CTs will add over 2000  megawatts  to the  Registrant's  net peaking
capacity and are expected to cost approximately  $940 million.  CTs with a total
capacity of approximately 530 megawatts are planned to be installed in 2000, 560
megawatts in 2001, 590 megawatts in 2002, and 325 megawatts in 2003.  Except for
approximately 120 megawatts,  the new capacity is expected to be operated by the
Registrant's proposed new unregulated generating subsidiary.

Note 7 - Statement of Position (SOP) 98-1, "Accounting for the Costs of Computer
Software  Developed or Obtained for Internal Use" became effective on January 1,
1999.  SOP 98-1  provides  guidance  on  accounting  for the  costs of  computer
software  developed or obtained for internal use. Under SOP 98-1,  certain costs
may be capitalized and amortized over some future period.  SOP 98-1 did not have
a  material  impact  on  the  Registrant's  financial  position  or  results  of
operations upon adoption.

The  Emerging  Issues Task Force of the  Financial  Accounting  Standards  Board
(EITF)  Issue  98-10,   "Accounting  for  Energy  Trading  and  Risk  Management
Activities" became effective on January 1, 1999. EITF 98-10 provides guidance on
the  accounting  for energy  contracts  entered into for the purchase or sale of
electricity,  natural  gas,  capacity  and  transportation.  The EITF  reached a
consensus in EITF 98-10 that sales and purchase  activities being performed need
to be classified as either  trading or  non-trading.  Furthermore,  transactions
that are determined to be trading  activities would be recognized on the balance
sheet measured at fair value,  with gains and losses included in earnings.  EITF
98-10  includes  factors  or  indicators  to  consider  when  determining  if  a
transaction is a trading or non-trading activity. Currently, AmerenEnergy, Inc.,
an energy marketing subsidiary of Ameren, enters into contracts for the sale and
purchase of energy on behalf of AmerenUE and AmerenCIPS.  These transactions are
considered  non-trading  activities  and are  accounted for using the accrual or
settlement method, which represents

                                      -14-



industry practice.  Should any of AmerenEnergy's future activities be considered
material trading  activities  based on the indicators  provided in EITF 98-10, a
change in  accounting  practice  would be  required.  EITF  98-10 did not have a
material impact on the Registrant's  financial position or results of operations
upon adoption.

Note 8 -  Segment  information  for the  three  month,  nine  month and 12 month
periods ended September 30, 1999 and 1998 is as follows:




- ---------------------------------------------------------------------------------------------------------
                                           Regulated                        Reconciling
(in millions)                              Utilities        All Other          Items *           Total
- ---------------------------------------------------------------------------------------------------------

                                                                                  
Three months ended September 30, 1999:

Revenues                                     $1,185           $  62             $(54)           $ 1,193
Net Income                                      248               2               --                250
- ---------------------------------------------------------------------------------------------------------

Three months ended September 30, 1998:

Revenues                                     $1,093           $  62             $(38)            $1,117
Net Income                                      242              (5)              --                237
- ---------------------------------------------------------------------------------------------------------

Nine months ended September 30, 1999:

Revenues                                     $2,742            $182            $(135)           $ 2,789
Net Income                                      387               4               --                391
- ---------------------------------------------------------------------------------------------------------


Nine months ended September 30, 1998:

Revenues                                     $2,575            $143             $(78)           $ 2,640
Net Income                                      360              --               --                360
- ---------------------------------------------------------------------------------------------------------


12 months ended September 30, 1999:

Revenues                                     $3,397            $230            $(159)           $ 3,468
Net Income                                      408               9               --                417
- ---------------------------------------------------------------------------------------------------------


12 months ended September 30, 1998:

Revenues                                     $3,267            $200              (95)           $ 3,372
Net Income                                      352               3               --                355
- ---------------------------------------------------------------------------------------------------------


* Elimination of intercompany revenues.



Note 9 - Certain  reclassifications were made to prior-year financial statements
to conform to current-period presentation.

                                      -15-





                           PART II. OTHER INFORMATION


ITEM 6. EXHIBITS AND REPORTS ON FORM 8-K

        (a) Exhibits.

            Exhibit 27 - Financial Data Schedule.

        (b) Reports on Form 8-K. The Registrant filed a report on Form 8-K dated
September 21,  1999,  reporting  on  the  Registrant's  commitment  to  purchase
additional combustion turbine generators to add to its peaking capacity.



                                   SIGNATURES

         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  Registrant  has duly  caused  this report to be signed on its behalf by the
undersigned thereunto duly authorized.

                                                    AMEREN CORPORATION
                                                        (Registrant)


                                                 By   /s/ Donald E. Brandt
                                                    ------------------------
                                                         Donald E. Brandt
                                                 Senior Vice President, Finance
                                                 (Principal Financial Officer)


Date:  November 15, 1999



                                      -16-