1. Citi Power, Gas & Utilities Conference June 5-6, 2008investing for our future.1

2. Cautionary Statements Regulation G Statement Ameren has presented certain information in this presentation on a diluted cents per share basis. These diluted per share amounts reflect certain factors that directly impact Amerens total earnings per share. The core earnings per share (non-GAAP) and core earnings per share guidance (non-GAAP) exclude one or more of the following: costs related to severe January 2007 storms, abnormal weather, the earnings impact of the settlement agreement among parties in Illinois for comprehensive electric rate relief and customer assistance, the reversal of accruals made in 2006 for low-income energy assistance and energy efficiency program funding commitments in Illinois, a March 2007 FERC order, which retroactively adjusted prior years regional transmission organization costs, and net mark-to-market gains or losses from nonqualifying hedges. Ameren uses core earnings internally for financial planning and for analysis of performance. Ameren also uses core earnings as primary performance measurements when communicating with analysts and investors regarding our earnings results and outlook, as the company believes it allows it to more accurately compare the companys ongoing performance across periods. In providing consolidated and segment core earnings guidance (non-GAAP), there could be differences between core earnings (non-GAAP) and earnings prepared in accordance with GAAP for certain items, such as the 2007 Illinois electric settlement and net mark-to market gains or losses from nonqualifying hedges. Except for the Illinois settlement, Ameren is not able to estimate the impact, if any, on future GAAP earnings of these items. Forward-looking Statements Amerens earnings guidance assumes normal weather and is subject to, among other things, regulatory decisions and legislative actions, plant operations, energy market and economic conditions, severe storms, unusual or otherwise unexpected gains or losses and other risks and uncertainties outlined in Amerens Forward-looking Statements in its news releases and in the Forward-looking Statements and Risk Factors sections in its periodic filings with the Securities and Exchange Commission.investing for our future. 2 3. Ameren Introduction Regional electric and gas utility Missouri regulated generation, transmission and delivery businessCILCO Illinois regulated transmission and delivery businesses CIPS UE Non-rate-regulatedIP generation business NYSE-listed under AEE Market cap. ~ $9.5 billion Component of the S&P 500 investing for our future. 3 4. Investment Highlights Focused on the Basics - the generation of electricity, and the delivery of electricity and natural gas Strong EPS growth prospects Strong, sustainable dividend Current yield of ~5.5% Focused on future dividend growth Commitment to conservative financial management Attractive, risk-adjusted long-term total return potential Strong underlying value/straight-forward strategy to deliver shareholder valueinvesting for our future. 4 5. Amerens Business Plan Achieve operational excellence in allMeaningful aspects of our businessinvestment in serving Improve our customer service, customers satisfaction and image Demonstrate environmentalFair leadershipreturnHigh quality onservice Improve regulatory frameworks and investment returns Optimize non-rate-regulated High generation business customersatisfaction Maximize the value of our shareholders investment investing for our future. 5 6. Financial Outlook Near-term regulatory lag Rising cost environment (O&M and capital) Fuel Reliability projects Environmental projects Depreciation Finance costs No significant rate adjustments until late 2008 and early 2009 Significant longer-term earnings growth opportunities investing for our future. 6 7. Financial Outlook Opportunities Regulated Businesses Significant longer-term earnings growth Regulated rates reflecting more current costs Rate cases filed in Illinois and Missouri Increasing rate base investment Earning fair returns in regulated operationsinvesting for our future. 7 8. Current Regulated Returns Support Earnings Growth Missouri Regulated Operations(a)2007 Core (non-GAAP) ROE = 9%Estimated 2008 Core (non-GAAP) ROE = 7% Allowed return in last rate case was 10.2%. Every 1% equalsapproximately $50 million of revenues Illinois Regulated Operations(b) 2007 Core (non-GAAP) ROE = 5% Estimated 2008 Core (non-GAAP) ROE = 4% Allowed return in last rate case was 10%. Every 1% equalsapproximately $27 million of revenuesBased on actual and projected financial results excluding non-GAAP items(a) Based on actual and projected financial results excluding non-GAAP items and(b) impact of goodwill associated with CILCORP and Illinois Power acquisitionsinvesting for our future. 8 9. Regulated Investment Plans Support Earnings GrowthRate Base Growth ($ in Millions)(Issued and effective as of January 17, 2008) $9,000MissouriRate Base$8,000 $7,000Missouri $6,000Electric(a)$5,900$5,000Gas(b)218$4,000 Subtotal $6,118$3,000 $2,000 $1,000Illinois(b) $0Distribution $2,1202006200720082009 201020112012 Transmission245$4,500Illinois $4,000Gas 928$3,500Subtotal $3,293$3,000 $2,500 TOTAL$9,411$2,000 $1,500 At June 30, 2008 (est.) as submitted in current (a) $1,000 rate case filing$500 At December 31, 2007 (b) At December 31, 2006, as submitted in current (c)$0 rate case filings 2006200720082009 201020112012investing for our future. 9 10. Illinois Rate Filings Illinois electric and gas delivery service rate cases filed November 2,2007 Decision by end of September 2008 Current requested revenue increase is $220 million 11% ROE; 50% to 53% equity Requested rider rate-making mechanisms for electric infrastructureinvestment and gas decoupling Withdrew request for bad debt expense rider in rebuttal testimony ICC staff revenue increase recommendation of $87 million 10.7% ROE recommended. Modifications to capital structure Recommended disallowances include certain A&G costs, plant additions,and post-test year reliability expenditures Rider mechanism recommendationsinvesting for our future. 10 11. Missouri Rate Case Filing Electric rate case filed on April 4, 2008 Decision by March 2009 Requested electric revenue increase of $251 million 10.9% ROE; 51% equity Increase driven by higher costs and increased investment Utilized test year ended March 31, 2008 Requested implementation of fuel and purchased powercost recovery mechanism Did not pursue environmental cost recovery mechanism Expect changes to recently adopted rules to be considered by MoPSC investing for our future. 11 12. Financial Outlook OpportunitiesNon-rate-regulated Generation Position non-rate-regulated business for earnings growth Improving plant performance Effective marketing, trading and hedging Environmental compliance Areas significantly impacting future earnings results include futurepower, capacity and fuel pricesinvesting for our future. 12 13. Q1 2008 Earnings Reconciliation $0.592007 GAAP Earnings per Share0.092007 severe storm-related costs0.05FERC order MISO charges (0.05)Illinois contribution plan termination0.02Net mark-to-market losses $ 0.702007 Core Earnings per Share (Non-GAAP)0.06Missouri rate cases (margin and expense) (0.05)Illinois rate redesign0.16Other electric and gas margins0.03Weather (estimate) (0.09)Fuel prices (0.02)Plant operations and maintenance (0.06)Distribution system reliability (0.01)Other labor and employee benefits (0.01)Bad debt expenses (0.01)Depreciation and amortization (0.01)Other taxes (0.05)Other, net $ 0.642008 Core Earnings per Share (Non-GAAP) (0.03)Illinois electric rate relief settlement0.05Net mark-to-market gains $ 0.662008 GAAP Earnings per Shareinvesting for our future. 13 14. 2008 Earnings Guidance(Issued and effective as of May 2, 2008) 2007 GAAP Earnings per Share$2.982007 severe storm-related costs0.09Illinois electric rate relief settlement, net0.21FERC order MISO charges0.062007 Core Earnings per Share (non-GAAP) $3.34Missouri 2007 rate cases (margin and expense)0.09Other electric and gas margins 0.77Weather (estimate)(0.08)Fuel prices (0.40)Callaway refueling and maintenance outage0.06Plant operations and maintenance(0.19)Distribution system reliability (0.22)Other labor and employee benefits (0.06)Depreciation and amortization (0.06)Dilution and financing, net (0.13)Other taxes (0.05)Other, net(0.07)2008 Core EPS Guidance Range (non-GAAP) $2.80 $3.20Illinois electric rate relief settlement (0.12)2008 GAAP EPS Guidance Range$2.68 $3.08investing for our future. 14 15. 2008 Core EPS Segment Guidance(Issued and effective as of May 2, 2008)Expected Segment Contribution to Earnings per Share Missouri Regulated $1.20 $1.30 Illinois Regulated0.30 0.40 Non-Rate-Regulated Generation 1.30 1.50 2008 Core EPS Guidance Range (Non-GAAP)(a) $2.80 $3.20(a) The 12 cents per share earnings impact of the settlement agreement among parties in Illinois for comprehensive electric rate relief and customer assistance and net mark-to market gains or losses from nonqualifying hedges are excluded from non-GAAP guidance. investing for our future. 15 16. Financial Objectives Targeting 4% to 6% average non-GAAP EPS growth fromnormalized 2007 base to 2010 Driven primarily by regulated business growth Goal of ~$4 per share by 2011 and higher in 2012 Overall percentage of earnings contribution by regulated businesssegments forecasted to increase and approximate current annualdividend by the end of 2010 Focused on providing a strong, sustainable dividend Current yield of ~5.5% Cash flows do not support near-term change Focus on future dividend growth Targeting long-term total annual shareholder return of ~10% Bottom line: strong underlying value Straight-forward strategy to deliver valueinvesting for our future. 16 17. Long-Range EPS Targets>$4.00~$3.70Non-GAAPNon-GAAP$3.34 $2.80 - $3.20 Weather-Normalized$3.24GAAP$2.98GAAP$2.68 - $3.082007 20082009 2010 2011 2012 GAAP Non-GAAPinvesting for our future. 17 18. Appendix investing for our future. 18 19. Ameren Segmentsinvesting for our future.19 20. Missouri Regulated2007 Electric Revenue Mix 1.2 million electric and127,000 gas customers18% Diverse electric revenue mix44% 10,000 MW generation38% Low-cost 7,000 MW baseloadcoal-fired and nuclear fleetResidential CommercialIndustrial 24,000 square milesAverage Residential Electricity 2,900 miles of electricPrices (2006)0.1919transmission lines0.1717150.15 32,000 miles of electric130.13distribution lines110.11 3,300 employees90.09 San FranciscoNew York City 7 Los Angeles Residential rates approximately 40% 0.07 PhiladelphiaClevelandWash DCSt.Louis*HoustonChicago 5BostonSeattleAtlantaDetroit0.05DallasMiamibelow national average 30.03 Source: Bureau of Labor statistics Assumes UEs 2007 rate increase was in effect in 2006 investing for our future. 20 21. Ameren Illinois Utilities2007 Margin Mix Regulated transmission anddistribution company 29%Electric Owns no generationGas 71% 1.2 million electric and830,000 gas customers 44,000 square miles 4,490 miles of electric transmission lines 45,000 miles of electric distribution linesCILCO 17,900 miles of natural gas mains 2,300 employees CIPS Current bundled electric rates approximateIPnational averageinvesting for our future. 21 22. Non-Rate-Regulated Generation Operate power plants Edwards CTGs Three legal entities 745 MW1,140 MWCoal 1960 Gas 2000-01 Market power and HutsonvilleDuck Creek related products150 MW 330 MW Coal 1953Coal 1976 6,300 MW generation Low-cost 4,500 MW baseloadcoal-fired fleetCoffeen Meredosia900 MW445 MW 1,100 employeesCoal 1965 Coal/Oil 1948 Newton1,210 MWGrand Tower CTG Coal 1977510 MW Gas 2001Joppa 80% 1,000 MWCoal 1953investing for our future. 22 23. Referencesinvesting for our future.23 24. Fuel CostsForecasted numbers are issued and effective as of January 17, 2008 Fuel Costs per MWh(a) Fuel costs expected to continueto increase Estimates include all fuel costs $23$21$19(coal, nuclear, natural gas, $17$15$14 diesel, emission allowances andtransportation) 2008 20092010 Regulated costs are assumed toEstimated Costs Hedgedbe recoverable through a costrecovery mechanism beginningin 200994% 98%86% 72%54%16% 2008 20092010(a)Includes contracted and estimated cost increase Regulated MissouriNon-Rate-Regulatedinvesting for our future. 24 25. Non-rate-regulated GenerationPositioned for Earnings GrowthForecasted numbers are issued and effective as of January 17, 2008Baseload GenerationBaseload Capacity and(Megawatthours)Availability Factors40,000 100%Net Capacity Factor Forecasted35,000Equivalent Availability Factor Actual 90%30,00025,000 80% 20,000 70%15,00010,000 60%5,000050% 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 20072008 2009 2010investing for our future. 25 26. Solid Market FundamentalsForecasted numbers are issued and effective as of January 17, 2008 Generation hedging policy designedHedged Power Salesto reduce risk, but allow for market (excludes capacity-only revenues) 86%upsideTar get Energy prices60%Ran ATC forward curve for 2008 to 2010ge 45%ranged from $48/MWh to $54/MWh$54at time of January 17, 2008$52 $50MWh MWhguidance MWh Fundamentals support energy20082009 2010prices strengthening Hedged Capacity Sales Expect continued development andtightening of MISO capacity market 28% Targeting to sell ~75%18%of capacity through 2010 37%10%22% MISO prices are well below PJM10% 200820092010Embedded in Full Requirements Contract Capacity Only investing for our future. 26 27. 2008 Illinois Electric Rate Redesign Illinois electricrate redesign will10result inquarterlychanges inearnings pershare, but noannual change 55Q1 Q2 Q3Q4investing for our future. 27 28. Ameren CalendarIllinois Evidentiary hearings June 9-13, 2008 Briefs July 2008 Proposed delivery service orderAugust 2008 (estimate) Final delivery service order issuedSeptember 2008Missouri Submit actual data for forecasted data June 4, 2008 Supplemental direct testimony regardingupdated dataJune 16, 2008 MoPSC Staff and intervenor testimony filed August 28, 2008 Rebuttal testimony filed by all partiesOctober 14, 2008 Surrebuttal testimony filed by all parties November 5, 2008 Hearings November 17-25 &December 1-5, 2008BriefsJanuary 8, 2009Rate order issued February 2009New rates effective March 2009Investor Relations Q2 2008 quiet period Begins July 7, 2008 Q3 2008 quiet period Begins October 7, 2008 investing for our future. 28 29. Major Regulatory Proceedings Illinois Web site www.icc.illinois.gov/e-docket Case # 07-0527 Interim procurement plan Case # 07-0585, 07-0586, 07-0587 Electric delivery services rate cases Case # 07-0588, 07-0589, 07-0590 Gas delivery services rate cases Missouri Web site www.efis.psc.mo.gov/mpsc/DocketSheet.html Case # ER-2008-0318 Electric rate caseinvesting for our future. 29 30. Investor Relations Contacts Bruce Steinke314-554-2574 Vice President & Controller bsteinke@ameren.com Manager Investor Relations Theresa Nistendirk 314-206-0693 Managing Supervisortnistendirk@ameren.com Investor Relations investing for our future. 30