2007 Illinois Electric Settlement Agreement – A comprehensive settlement of issues in Illinois arising out of the end of ten years of frozen electric rates, effective January 2, 2007. The settlement, which became effective in 2007, was designed to avoid new rate rollback and freeze legislation and legislation that would impose a tax on electric generation in Illinois. The settlement addressed the issue of power procurement, and it included a comprehensive rate relief and customer assistance program.

2010 Credit Agreements – The 2010 Genco Credit Agreement, the 2010 Illinois Credit Agreement, and the 2010 Missouri Credit Agreement, collectively.

2010 Genco Credit Agreement – Ameren’s and Genco’s $500 million multiyear senior unsecured revolving credit facility, which expires on September 10, 2013.

2010 Illinois Credit Agreement – Ameren’s and Ameren Illinois’ $800 million multiyear senior unsecured credit agreement, which expires on September 10, 2013.

2010 Missouri Credit Agreement – Ameren’s and Ameren Missouri’s $800 million multiyear senior unsecured revolving credit facility, which expires on September 10, 2013.

AER – Ameren Energy Resources Company, LLC, an Ameren Corporation subsidiary that consists of non-rate-regulated operations, including Genco, AERG, Marketing Company and Medina Valley. The Medina Valley energy center was sold in February 2012. On October 1, 2010, AERG stock was distributed to Ameren, which then contributed it to AER, thereby making AERG a subsidiary of AER.

AERG – AmerenEnergy Resources Generating Company, a CILCO subsidiary until October 1, 2010, that operates a merchant electric generation business in Illinois. On October 1, 2010, AERG stock was distributed to Ameren and subsequently contributed by Ameren to AER, which resulted in AERG becoming a subsidiary of AER.

AFS – Ameren Energy Fuels and Services Company, an AER subsidiary that procured fuel and natural gas and managed the related risks for the Ameren Companies prior to January 1, 2011. Effective January 1, 2011, the functions previously performed by AFS were assumed by the Ameren Missouri, Ameren Illinois and Merchant Generation business segments.

Ameren – Ameren Corporation and its subsidiaries on a consolidated basis. In references to financing activities, acquisition activities, or liquidity arrangements, Ameren is defined as Ameren Corporation, the parent.

Ameren Companies – The individual registrants within the Ameren consolidated group.

Ameren Illinois or AIC – Ameren Illinois Company, an Ameren Corporation subsidiary that operates a rate-regulated electric and natural gas transmission and distribution business in Illinois, doing business as Ameren

Illinois. This business consists of the combined rate-regulated electric and natural gas transmission and distribution businesses operated by CIPS, CILCO and IP before the Ameren Illinois Merger. References to Ameren Illinois prior to the Ameren Illinois Merger refer collectively to the rate-regulated electric and natural gas transmission and distribution businesses of CIPS, CILCO and IP. Immediately after the Ameren Illinois Merger, Ameren Illinois distributed the common stock of AERG to Ameren Corporation. AERG’s operating results and cash flows were presented as discontinued operations in Ameren Illinois’ financial statements.

Ameren Illinois Merger – On October 1, 2010, CILCO and IP merged with and into CIPS, with the surviving corporation renamed Ameren Illinois Company.

Ameren Illinois Regulated Segment – A financial reporting segment consisting of Ameren Illinois’ rate-regulated businesses.

Ameren Missouri or AMO – Union Electric Company, an Ameren Corporation subsidiary that operates a rate-regulated electric generation, transmission and distribution business, and a rate-regulated natural gas transmission and distribution business in Missouri, doing business as Ameren Missouri. Ameren Missouri is also defined as a financial reporting segment consisting of Union Electric Company’s rate-regulated businesses.

Ameren Services – Ameren Services Company, an Ameren Corporation subsidiary that provides support services to Ameren and its subsidiaries.

AMIL – The MISO balancing authority area operated by Ameren, which includes the load of Ameren Illinois and the generating assets of Genco (excluding EEI and Genco’s Elgin CT facility) and AERG.

AMMO – The MISO balancing authority area operated by Ameren, which includes the load and generating assets of Ameren Missouri.

ARO – Asset retirement obligations.

ATX – Ameren Transmission Company, an Ameren Corporation subsidiary dedicated to electric transmission infrastructure investment.

ATXI – Ameren Transmission Company of Illinois, an Ameren Corporation subsidiary that is engaged in the construction and operation of electric transmission assets in Illinois.

Baseload – The minimum amount of electric power delivered or required over a given period of time at a steady rate.

Btu – British thermal unit, a standard unit for measuring the quantity of heat energy required to raise the temperature of one pound of water by one degree Fahrenheit.

CAIR – Clean Air Interstate Rule.

Capacity factor – A percentage measure that indicates how much of an electric power generating unit’s capacity was used during a specific period.

CCR – Coal combustion residuals.

CILCO – Central Illinois Light Company, a former Ameren Corporation subsidiary that operated a rate-regulated electric transmission and distribution business, a merchant electric generation business through AERG, and a rate-regulated natural gas transmission and distribution business, all in Illinois, before the Ameren Illinois Merger. CILCO owned all of the common stock of AERG and included AERG within its consolidated financial statements. Immediately after the Ameren Illinois Merger in 2010, Ameren Illinois distributed the common stock of AERG to Ameren Corporation. AERG was treated as a discontinued operation within Ameren Illinois’ financial statements.

CILCORP – CILCORP Inc., a former Ameren Corporation subsidiary that operated as a holding company for CILCO and its merchant generation subsidiary. On March 4, 2010, CILCORP merged with and into Ameren.

CIPS – Central Illinois Public Service Company, an Ameren Corporation subsidiary, renamed Ameren Illinois Company at the effective date of the Ameren Illinois Merger, that operates a rate-regulated electric and natural gas transmission and distribution business, all in Illinois.

CO₂ – Carbon dioxide.

COLA – Combined nuclear plant construction and operating license application.

Cole County Circuit Court – Circuit Court of Cole County, Missouri.

Cooling degree-days – The summation of positive differences between the mean daily temperature and a 65-degree Fahrenheit base. This statistic is useful for estimating electricity demand by residential and commercial customers for summer cooling.

CSAPR – Cross-State Air Pollution Rule.

CT – Combustion turbine electric generation equipment used primarily for peaking capacity.

DOE – Department of Energy, a United States government agency.

DRPlus – Ameren Corporation’s dividend reinvestment and direct stock purchase plan.

Dth (dekatherm) – One million Btus of natural gas.

EEI – Electric Energy, Inc., an 80%-owned Genco subsidiary that operates merchant electric generation facilities and FERC-regulated transmission facilities in Illinois. Effective January 1, 2010, in an internal reorganization, AER contributed its 80% ownership interest in EEI to its subsidiary, Genco. The remaining 20% ownership interest is owned by Kentucky Utilities Company, a nonaffiliated entity.

EPA – Environmental Protection Agency, a U.S. government agency.

Equivalent availability factor – A measure that indicates the percentage of time an electric power generating unit was available for service during a period.

ERISA – Employee Retirement Income Security Act of 1974, as amended.

Exchange Act – Securities Exchange Act of 1934, as amended.

FAC – A fuel and purchased power cost recovery mechanism that allows Ameren Missouri to recover,

through customer rates, 95% of changes in fuel (coal, coal transportation, natural gas for generation, and nuclear), emission allowances and purchased power costs, net of off-system revenues, including MISO costs and revenues, greater or less than the amount set in base rates, without a traditional rate proceeding.

FASB – Financial Accounting Standards Board, a rulemaking organization that establishes financial accounting and reporting standards in the United States.

FERC – The Federal Energy Regulatory Commission, a United States government agency.

Fitch – Fitch Ratings, a credit rating agency.

FTRs – Financial transmission rights, financial instruments that entitle the holder to pay or receive compensation for certain congestion-related transmission charges between two designated points.

Fuelco – Fuelco LLC, a limited liability company that provides nuclear fuel management and services to its members. The members are Ameren Missouri, Luminant, and Pacific Gas and Electric Company.

GAAP – Generally accepted accounting principles in the United States of America.

Genco – Ameren Energy Generating Company, an AER subsidiary that operates a merchant electric generation business in Illinois and holds an 80% ownership interest in EEI.

Gigawatthour – One thousand megawatthours.

Heating degree-days – The summation of negative differences between the mean daily temperature and a 65- degree Fahrenheit base. This statistic is useful as an indicator of demand for electricity and natural gas for winter space heating by residential and commercial customers.

IBEW – International Brotherhood of Electrical Workers, a labor union.

ICC – Illinois Commerce Commission, a state agency that regulates Illinois utility businesses, including ATXI and Ameren Illinois.

IEIMA – Illinois Energy Infrastructure Modernization Act, an Illinois law that established a performance-based formula process for determining electric delivery service rates. Ameren Illinois elected to participate in this regulatory framework in 2012, which will require it to make incremental capital expenditures to modernize its electric distribution system over a ten-year period beginning in 2012, to meet performance standards, and to create jobs in Illinois, among other things.

Illinois Customer Choice Law – Illinois Electric Service Customer Choice and Rate Relief Law of 1997, which was designed to introduce competition into the retail supply of electric energy in Illinois.

Illinois EPA – Illinois Environmental Protection Agency, a state government agency.

IP – Illinois Power Company, a former Ameren Corporation subsidiary that operated a rate-regulated electric and natural gas transmission and distribution business, all in Illinois, before the Ameren Illinois Merger.

IPA – Illinois Power Agency, a state government agency that has broad authority to assist in the procurement of electric power for residential and nonresidential customers.

ISRS – Infrastructure system replacement surcharge, which is a cost recovery mechanism that allows Ameren Missouri to recover gas infrastructure replacement costs from utility customers without a traditional rate proceeding.

IUOE – International Union of Operating Engineers, a labor union.

Kilowatthour – A measure of electricity consumption equivalent to the use of 1,000 watts of power over one hour.

LIUNA – Laborers’ International Union of North America, a labor union.

Marketing Company – Ameren Energy Marketing Company, an AER subsidiary that markets power for Genco, AERG, EEI and Medina Valley.

MATS – Mercury and Air Toxics Standards, issued by the EPA on December 21, 2011, which limit mercury, acid gases and other toxic pollution from power plants.

Medina Valley – AmerenEnergy Medina Valley Cogen LLC, an AER subsidiary, which owns a 40-megawatt natural gas-fired electric energy center. This energy center was sold in February 2012.

MEEIA – Missouri Energy Efficiency Investment Act, a Missouri law that allows electric utilities to recover costs related to MoPSC-approved energy efficiency programs.

Megawatthour – One thousand kilowatthours.

Merchant Generation – A financial reporting segment consisting primarily of the operations or activities of AER, including Genco, AERG, Medina Valley and Marketing Company.

MGP – Manufactured gas plant.

MIEC – Missouri Industrial Energy Consumers.

MISO – Midwest Independent Transmission System Operator, Inc., an RTO.

MISO Energy and Operating Reserves Market – A market that uses market-based pricing, which takes into account transmission congestion and line losses, to compensate market participants for power and ancillary services.

Missouri Environmental Authority – Environmental Improvement and Energy Resources Authority of the state of Missouri, a governmental body authorized to finance environmental projects by issuing tax-exempt bonds and notes.

Mmbtu – One million Btus.

Money pool – Borrowing agreements among Ameren and its subsidiaries to coordinate and provide for certain short-term cash and working capital requirements. Separate money pools maintained for rate-regulated and non-rate-regulated businesses are referred to as the utility money pool and the non-state-regulated subsidiary money pool, respectively.

Moody’s – Moody’s Investors Service Inc., a credit rating agency.

MoOPC – Missouri Office of Public Counsel.

MoPSC – Missouri Public Service Commission, a state agency that regulates Missouri utility businesses including Ameren Missouri.

MPS – Multi-Pollutant Standard, an agreement, as amended, reached in 2006 among Genco, AERG, EEI and the Illinois EPA, which was codified in Illinois environmental regulations.

MTM – Mark-to-market.

MW – Megawatt.

Native load – End-use retail customers whom we are obligated to serve by statute, franchise, contract, or other regulatory requirement.

NERC – North American Electric Reliability Corporation.

NO₂ – Nitrogen dioxide.

NO_x – Nitrogen oxide.

Noranda – Noranda Aluminum, Inc.

NPNS – Normal purchases and normal sales.

NRC – Nuclear Regulatory Commission, a United States government agency.

NSPS – New Source Performance Standards, a provision under the Clean Air Act.

NSR – New Source Review provisions of the Clean Air Act, which include Nonattainment New Source Review and Prevention of Significant Deterioration regulations.

NWPA – Nuclear Waste Policy Act of 1982, as amended.

NYMEX – New York Mercantile Exchange.

NYSE – New York Stock Exchange, Inc.

OATT – Open Access Transmission Tariff.

OCI – Other comprehensive income (loss) as defined by GAAP.

Off-system revenues – Revenues from other than native load sales, including wholesale sales beginning with the effective date of the MoPSC’s 2011 electric rate order.

OTC – Over-the-counter.

PGA – Purchased Gas Adjustment tariffs, which permit prudently incurred natural gas costs to be recovered directly from utility customers without a traditional rate proceeding.

PJM – PJM Interconnection LLC.

PUHCA 2005 – The Public Utility Holding Company Act of 2005, enacted as part of the Energy Policy Act of 2005, effective February 8, 2006.

Regulatory lag – The effect of adjustments to retail electric and natural gas rates being based on historic cost and revenue levels. Rate increase requests can take up to 11 months to be acted upon by the MoPSC and the ICC. As a result, revenue increases authorized by regulators will lag behind changing costs and revenues when based on historical periods.

RFP – Request for proposal.

RTO – Regional Transmission Organization.

S&P – Standard & Poor’s Ratings Services, a credit rating agency.

SEC – Securities and Exchange Commission, a United States government agency.

SERC – SERC Reliability Corporation, one of the regional electric reliability councils organized for coordinating the planning and operation of the nation’s bulk power supply.

SO₂ – Sulfur dioxide.

UA – United Association of Plumbers and Pipefitters, a labor union.

UGSOA – United Government Security Officers of America, a labor union.

FORWARD-LOOKING STATEMENTS

Statements in this report not based on historical facts are considered “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, and financial performance. In connection with the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995, we are 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 under Risk Factors and elsewhere in this report and in our other filings with the SEC, could cause actual results to differ materially from management expectations suggested in such forward-looking statements:

Ameren, headquartered in St. Louis, Missouri, is a public utility holding company under PUHCA 2005 administered by FERC. Ameren was formed in 1997 by the merger of Ameren Missouri and CIPSCO Inc. Ameren acquired CILCORP in 2003 and IP in 2004. Ameren’s primary assets are the common stock of its subsidiaries, including Ameren Missouri, Ameren Illinois and AER. Ameren’s subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. These subsidiaries operate, as the case may be, rate-regulated electric generation, transmission, and distribution businesses, rate-regulated natural gas transmission and distribution businesses, and merchant generation businesses in Missouri and Illinois. Dividends on Ameren’s common stock and the payment of other expenses by Ameren depend on distributions made to it by its subsidiaries. Below is a summary description of Ameren Missouri, Ameren Illinois and AER. A more detailed description can be found in Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of this report.

The following table presents our total employees at December 31, 2011:

As of January 1, 2012, the IBEW, the IUOE, the LIUNA, and the UA labor unions collectively represented about 58% of Ameren’s total employees. They represented 63% of the employees at Ameren Missouri, 65% at Ameren Illinois, and 67% at Genco. The collective bargaining agreements have three- to five-year terms, and expire between 2012 and 2016. Several collective bargaining agreements between Ameren subsidiaries and the IBEW, covering approximately 3,500 employees, expire during 2012. Additionally, employees providing security at the Callaway energy center elected to organize under the UGSOA in August 2011.

Negotiations for a collective bargaining agreement with these employees began in December 2011 and are ongoing.

For additional information about the development of our businesses, our business operations, and factors affecting our operations and financial position, see Management’s Discussion and Analysis of Financial

Condition and Results of Operations under Part II, Item 7, of this report and Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of this report.

BUSINESS SEGMENTS

Ameren has three reportable segments: Ameren Missouri, Ameren Illinois, and Merchant Generation. See Note 18 – Segment Information under Part II, Item 8, of this report for additional information on reporting segments.

RATES AND REGULATION

Rates

The rates that Ameren Missouri and Ameren Illinois are allowed to charge for their utility services significantly influence the results of operations, financial position, and liquidity of these companies and Ameren. The electric and natural gas utility industry is highly regulated. The utility rates charged to Ameren Missouri and Ameren Illinois customers are determined, in large part, by governmental entities, including the MoPSC, the ICC, and FERC. Decisions by these entities are influenced by many factors, including the cost of providing service, the prudency of expenditures, the quality of service, regulatory staff knowledge and experience, economic conditions, public policy, and social and political views. Decisions made by these governmental entities regarding rates are largely outside of Ameren Missouri’s and Ameren Illinois’ control. These decisions, as well as the regulatory lag involved in filing and getting new rates approved, could have a material impact on the results of operations, financial position, and liquidity of Ameren, Ameren Missouri and Ameren Illinois. Rate orders are also subject to appeal, which creates additional uncertainty as to the rates Ameren Missouri and Ameren Illinois are ultimately allowed to charge for their services. Beginning in 2012, the effect of regulatory lag on Ameren Illinois’ electric distribution business is expected to be mitigated through the use of the formula ratemaking regulatory framework established under the IEIMA.

The ICC regulates rates and other matters for Ameren Illinois and ATXI. The MoPSC regulates rates and other matters for Ameren Missouri. The FERC regulates Ameren Missouri, Ameren Illinois, Genco and ATXI as to their ability to charge market-based rates for the sale and transmission of energy in interstate commerce and various other matters discussed below under General Regulatory Matters.

About 49% of Ameren’s electric and 16% of its natural gas operating revenues were subject to regulation by the MoPSC in the year ended December 31, 2011. About 30% of Ameren’s electric and 84% of its natural gas operating

revenues were subject to regulation by the ICC in the year ended December 31, 2011. Wholesale revenues for Ameren Missouri, Ameren Illinois, Genco and AERG are subject to FERC regulation, but not subject to direct MoPSC or ICC regulation.

Ameren Missouri

Electric

About 99% of Ameren Missouri’s electric operating revenues were subject to regulation by the MoPSC in the year ended December 31, 2011 with the remainder subject to FERC regulation.

In July 2011, the MoPSC issued an order approving an increase for Ameren Missouri in annual revenues for electric service of $173 million, including $52 million related to an increase in normalized net fuel costs above the net fuel costs included in base rates previously authorized by the MoPSC in its May 2010 electric rate order. The revenue increase was based on a 10.2% return on equity, a capital structure composed of 52.2% common equity, and a rate base of $6.6 billion. The rate changes became effective on July 31, 2011. The MoPSC order approved the continued use of Ameren Missouri’s vegetation management and infrastructure cost tracker, pension and postretirement benefit cost tracker, and FAC at the current 95% sharing level. The MoPSC order shortened the FAC recovery and refund period from 12 months to eight months. Additionally, the MoPSC order provided for a tracking mechanism for uncertain income tax positions.

In February 2012, Ameren Missouri filed a request with the MoPSC to increase its annual revenues for electric service by $376 million. Included in this requested increase was a $103 million increase in normalized net fuel costs above the net fuel costs included in base rates previously authorized by the MoPSC in its July 2011 electric rate order. Absent initiation of this general rate proceeding, 95% of this amount would have been reflected in rate adjustments implemented under Ameren Missouri’s FAC. The request also included recovery of the costs associated with energy efficiency programs under the MEEIA, including energy efficiency investments, a storm cost tracking mechanism, plant-in-service accounting treatment, and recovery of other costs incurred to provide systemwide reliability improvements for customers, among other items. The electric rate increase request was based on a 10.75% return on equity, a capital structure composed of 52% common equity, an aggregate electric rate base of $6.8 billion, and a test year ended September 30, 2011, with certain pro forma adjustments expected through the anticipated true-up date of July 31, 2012. A decision by the MoPSC in this proceeding is expected in December 2012.

FERC regulates the rates charged and the terms and conditions for electric transmission services. Each RTO separately files a regional transmission tariff for approval by FERC. All transmission service within that RTO is then

subjected to that tariff. As a member of MISO, Ameren Missouri’s transmission rate is calculated in accordance with the MISO OATT. The transmission rate is updated in

June of each year; it is based on Ameren Missouri’s filings with FERC. This rate is not directly charged to Missouri retail customers, because in Missouri the MoPSC includes transmission-related costs in setting bundled retail rates.

Natural Gas

All of Ameren Missouri’s natural gas operating revenues were subject to regulation by the MoPSC in the year ended December 31, 2011. In January 2011, the MoPSC approved a stipulation and agreement that allowed Ameren Missouri to increase annual natural gas revenues by $9 million. The new rates became effective on February 20, 2011. As part of the stipulation and agreement, Ameren Missouri agreed not to file a separate natural gas rate increase request before December 31, 2012; however, Ameren Missouri can file a combined natural gas and electric rate case before that date. Further, this agreement does not prevent Ameren Missouri from filing to recover infrastructure replacement costs through an ISRS during this moratorium. The return on equity to be used by Ameren Missouri for purposes of the ISRS tariff filing is 10%.

If certain criteria are met, Ameren Missouri’s natural gas rates may be adjusted without a traditional rate proceeding. PGA clauses permit prudently incurred natural gas costs to be passed directly to the consumer. The ISRS also permits prudently incurred natural gas infrastructure replacement costs to be passed directly to the consumer.

For additional information on Missouri rate matters, including Ameren Missouri’s pending electric rate case, and Ameren Missouri’s 2009, 2010 and 2011 electric rate orders and related court appeals and regulatory proceedings, see Results of Operations and Outlook in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, Quantitative and Qualitative Disclosures About Market Risk under Part II, Item 7A, and Note 2 – Rate and Regulatory Matters, and Note 15 – Commitments and Contingencies under Part II, Item 8, of this report.

Ameren Illinois

Electric

About 99% of Ameren Illinois’ electric operating revenues were subject to regulation by the ICC in the year ended December 31, 2011 with the remainder subject to FERC regulation.

Under the Illinois Customer Choice Law, all electric customers in Illinois may choose their own electric energy provider. However, Ameren Illinois is required to serve as the provider of last resort (POLR) for electric customers within its territory who have not chosen an alternative retail

electric supplier. Ameren Illinois’ obligation to provide POLR electric service varies by customer size. Ameren Illinois is not required to offer fixed-priced electric service to customers with electric demands of 400 kilowatts or greater, as the market for service to this group of customers has been declared competitive. Power and related procurement costs incurred by Ameren Illinois are passed directly to its customers through a cost recovery mechanism.

In October 2011, the IEIMA was enacted into law and became effective immediately. Certain amendments to the IEIMA became effective on December 30, 2011. On January 3, 2012, Ameren Illinois elected to participate in the performance-based formula ratemaking process established pursuant to the IEIMA by filing initial performance-based formula rates with the ICC. The initial filing, based on 2010 recoverable costs and expected net plant additions for 2011 and 2012, will result in new electric delivery service rates in October 2012. Pending ICC approval, the initial filing will result in a decrease in Ameren Illinois revenues for electric delivery service of $19 million, on an annualized basis. Ameren Illinois anticipates making an update filing by May 1, 2012, based on 2011 costs and expected net plant additions for 2012, that would result in new electric delivery service rates on January 1, 2013.

By choosing to opt-in, Ameren Illinois will participate in a performance-based formula process for determining rates that will provide for the recovery of actual costs of electric delivery service that are prudently incurred, reflect the utility’s actual regulated capital structure and include a formula for calculating the return on equity component of the cost of capital. The equity component of the formula rate will be equal to the average for the applicable calendar year of the monthly average yields of 30-year United States treasury bonds plus 590 basis points for 2012 and 580 basis points thereafter. Ameren Illinois’ actual return on equity relating to electric delivery service will be subject to a collar adjustment on earnings in excess of 50 basis points above or below its allowed return. Beginning in 2012, the law provides for an annual reconciliation of revenues to costs prudently and reasonably incurred. This annual revenue reconciliation along with the collar adjustment, if necessary, will be collected from or refunded to customers in a subsequent year.

Ameren Illinois will also be subject to five performance standards under the IEIMA whereby the failure to achieve the standards will result in a reduction in its allowed return on equity calculated under the formula. The performance standards include improvements in service reliability to reduce both the frequency and duration of outages, improvements in customer satisfaction scores, reduction in the number of estimated bills, and a reduction in uncollectible accounts expense. The IEIMA provides for return on equity penalties totaling up to 30 basis points in 2013 through 2015, 34 basis points in 2016 through 2018 and 38 basis points in 2019 through 2022 if the performance standards are not met. The formula ratemaking process is effective until the end of 2017, but could be extended by the Illinois General Assembly

for an additional five years. The formula ratemaking process

would also terminate if the average residential rate increases by more than 2.5% annually from June 2011 through May 2014.

Between 2012 and 2021, Ameren Illinois will be required to invest $625 million in capital expenditures

incremental to Ameren Illinois’ average electric delivery capital expenditures for calendar years 2008 through 2010 to modernize its distribution system. Such investments are

expected to encourage economic development and create an estimated 450 additional jobs within Illinois. Ameren Illinois is subject to monetary penalties if 450 additional jobs are not created during the peak program year. Also, Ameren Illinois will be required to contribute $1 million annually for certain nonrecoverable customer assistance programs, up to a total of $10 million through 2021, for as long as Ameren Illinois participates in the formula ratemaking process. Ameren Illinois will also be required to make a one-time $7.5 million nonrecoverable donation to the Illinois Science and Energy Innovation Trust in 2012, as well as an approximate $1 million annual donation to the same trust for as long as it participates in the formula ratemaking process.

Ameren Illinois has a tariff rider to recover the costs of asbestos-related litigation claims, subject to the following terms: 90% of cash expenditures in excess of the amount included in base electric rates are to be recovered from a trust fund that was established when Ameren acquired IP. At December 31, 2011, the trust fund balance was $23 million, including accumulated interest. If cash expenditures are less than the amount in base rates, Ameren Illinois will contribute 90% of the difference to the fund. Once the trust fund is depleted, 90% of allowed cash expenditures in excess of base rates will be recovered through charges assessed to customers under the tariff rider. Following the Ameren Illinois Merger, this rider is applicable only for claims that occurred within IP’s historical service territory. Similarly, the rider will permit recovery only from customers within IP’s historical service territory.

As a member of MISO, Ameren Illinois’ transmission rate is calculated in accordance with the MISO OATT. The transmission rate is updated in June of each year based on Ameren Illinois’ filings with FERC. This rate is charged directly to wholesale customers and alternative retail electric suppliers. Retail customers who have not chosen an alternative retail electric supplier pay the transmission rate through a rider mechanism.

Natural Gas

All of Ameren Illinois’ natural gas operating revenues were subject to regulation by the ICC in the year ended December 31, 2011.

In January 2012, the ICC issued a rate order that approved an increase in Ameren Illinois’ annual revenues for natural gas delivery service of $32 million. The revenue increase was based on a 9.06% return on equity, a capital structure composed of 53.3% common equity, and a rate

base of approximately $1 billion. The rate order was based on a 2012 future test year. The rate changes became effective on January 20, 2012. In February 2012, the ICC denied rehearing requests by Ameren Illinois and an intervenor related to the granted return on equity.

If certain criteria are met, Ameren Illinois’ natural gas rates may be adjusted without a traditional rate proceeding. PGA clauses permit prudently incurred natural gas costs to be passed directly to the consumer. Also, Ameren Illinois has approval from the ICC to use cost recovery mechanisms for energy efficiency programs and bad debt expense not recovered in base rates.

For additional information on Illinois rate matters, including the IEIMA and the ICC’s January 2012 natural gas rate order, see Results of Operations and Outlook in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, Quantitative and Qualitative Disclosures About Market Risk under Part II, Item 7A, and Note 2 – Rate and Regulatory Matters, and Note 15 – Commitments and Contingencies under Part II, Item 8, of this report.

Merchant Generation

Merchant Generation revenues are determined by market conditions and contractual arrangements. We expect the Merchant Generation fleet of assets to have 5,503 megawatts of capacity available for the 2012 peak summer electrical demand. This capacity reflects the closure of the four units at Genco’s Meredosia and Hutsonville energy centers and the sale of the Columbia CT during 2011, as well as the sale of the Medina Valley energy center in early 2012. As discussed below, Genco and AERG sell all of their power and capacity to Marketing Company through power supply agreements. Marketing Company attempts to optimize the value of those assets and to mitigate risks through a variety of hedging techniques, including wholesale sales of capacity and energy, retail sales in the non-rate-regulated Illinois market, spot market sales primarily in MISO and PJM, and financial transactions, including options and other derivatives. Marketing Company enters into long-term and short-term contracts. Marketing Company’s counterparties include cooperatives, municipalities, residential, commercial and industrial customers, power marketers, MISO, PJM and investor-owned utilities, including Ameren Illinois. For additional information on Marketing Company’s hedging activities and Marketing Company’s sales to Ameren Illinois, see Outlook in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7 and Note 7 – Derivative Financial Instruments and Note 14 – Related Party Transactions under Part II, Item 8, of this report.

General Regulatory Matters

Ameren Missouri and Ameren Illinois must receive FERC approval to enter into various transactions, including to issue short-term debt securities and to conduct certain

acquisitions, mergers, and consolidations involving electric utility holding companies having a value in excess of $10 million. In addition, these Ameren utilities must receive authorization from the applicable state public utility regulatory agency to issue stock and long-term debt securities (with maturities of more than 12 months) and to conduct mergers, affiliate transactions, and various other

activities. Genco and AERG are subject to FERC’s jurisdiction when they issue any securities and when they enter into certain other transactions, including those listed above.

Ameren Missouri, Ameren Illinois, ATXI, Genco and AERG are also subject to mandatory reliability standards, including cybersecurity standards, adopted by FERC to ensure the reliability of the bulk power electric system. These standards are developed and enforced by NERC pursuant to authority given to it by the FERC. If the Ameren Companies were found not to be in compliance with any of these mandatory reliability standards they may incur substantial monetary penalties and other sanctions.

Under PUHCA 2005, FERC and any state public utility regulatory agencies may access books and records of Ameren and its subsidiaries that are determined to be relevant to costs incurred by Ameren’s rate-regulated subsidiaries with respect to jurisdictional rates. PUHCA 2005 also permits the MoPSC and the ICC to request that FERC review cost allocations by Ameren Services to other Ameren companies.

Operation of Ameren Missouri’s Callaway energy center is subject to regulation by the NRC. Its facility operating license expires on June 11, 2024. In December 2011, Ameren Missouri submitted a license extension application with the NRC to extend the plant’s operating license to 2044. There is no date by which the NRC must act on this relicensing request. Ameren Missouri’s Osage hydroelectric energy center and Ameren Missouri’s Taum Sauk pumped-storage hydroelectric energy center, as licensed projects under the Federal Power Act, are subject to FERC regulations affecting, among other things, the general operation and maintenance of the projects. The license for Ameren Missouri’s Osage hydroelectric energy center expires on March 30, 2047. In June 2008, Ameren Missouri filed a relicensing application with FERC to operate its Taum Sauk pumped-storage hydroelectric energy center for another 40 years. The existing FERC license expired on June 30, 2010. On July 2, 2010, Ameren Missouri received a license extension that allows Taum Sauk to continue operations until FERC issues a new license. FERC is reviewing the relicensing application. A FERC order is expected in 2012 or 2013. Ameren Missouri cannot predict the ultimate outcome of the order. Ameren Missouri’s Keokuk energy center and its dam, in the Mississippi River between Hamilton, Illinois, and Keokuk, Iowa, are operated under authority granted by an Act of Congress in 1905.

For additional information on regulatory matters, see Note 2 – Rate and Regulatory Matters and Note 15 – Commitments and Contingencies under Part II, Item 8, of this report, which include a discussion about the December 2005 breach of the upper reservoir at Ameren Missouri’s Taum Sauk pumped-storage hydroelectric energy center.

Environmental Matters

Certain of our operations are subject to federal, state, and local environmental statutes or regulations relating to the safety and health of personnel, the public, and the environment. These environmental statutes and regulations include requirements for identification, generation, storage, handling, transportation, disposal, recordkeeping, labeling, reporting, and emergency response in connection with hazardous and toxic materials; safety and health standards; and environmental protection requirements, including standards and limitations relating to the discharge of air and water pollutants and the management of waste and byproduct materials. Failure to comply with those statutes or regulations could have material adverse effects on us. We could be subject to criminal or civil penalties by regulatory agencies or we could be ordered by the courts to pay private parties. Except as indicated in this report, we believe that we are in material compliance with existing statutes and regulations.

In addition to existing laws and regulations, including the Illinois MPS, which govern our facilities, the EPA is developing numerous new environmental regulations that will have a significant impact on the electric utility industry. These regulations could be particularly burdensome for certain companies, including Ameren, Ameren Missouri and Genco, that operate coal-fired energy centers. Significant new rules proposed or promulgated since the beginning of 2010 include the regulation of greenhouse gas emissions; revised national ambient air quality standards for SO₂ and NO₂ emissions; the CSAPR, which requires further reduction of SO₂ and NO_x emissions from power plants; a regulation governing management of CCR and coal ash impoundments; the MATS, which reduces emissions of mercury, metals, and acid gases from power plants; revised NSPS for particulate matter, SO₂, and NO_x emissions from new sources; and new regulations under the Clean Water Act that could require significant capital expenditures such as new water intake structures or cooling towers at our energy centers. The EPA also plans to propose an additional rule, applicable to new and existing electric generating units, governing NSPS and emission guidelines for greenhouse gas emissions. These new regulations may be litigated, so the timing of their implementation is uncertain, as evidenced by the stay of the CSAPR by the United States Court of Appeals for the District of Columbia on December 30, 2011. Although many details of these future regulations are unknown, the combined effects of the new and proposed environmental regulations may result in significant capital expenditures and/or increased operating costs over the next five to ten years for Ameren, Ameren Missouri and Genco. Actions required to ensure that our

facilities and operations are in compliance with environmental laws and regulations could be prohibitively expensive. If they are, these regulations could require us to

close or to significantly alter the operation of our energy

centers, which could have an adverse effect on our results of operations, financial position, and liquidity, including the impairment of plant assets. Failure to comply with environmental laws and regulations might also result in the imposition of fines, penalties, and injunctive measures.

For additional discussion of environmental matters, including NO_x, SO₂, and mercury emission reduction requirements, global climate change, remediation efforts, and a discussion of the EPA’s allegations of violations of the Clean Air Act and Missouri law in connection with projects at certain coal-fired energy centers, see Liquidity and Capital Resources in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, and Note 15 – Commitments and Contingencies under Part II, Item 8, of this report.

TRANSMISSION AND SUPPLY OF ELECTRIC POWER

Ameren owns an integrated transmission system that comprises the transmission assets of Ameren Missouri, Ameren Illinois and ATXI. Ameren also operates two balancing authority areas, AMMO (which includes Ameren Missouri), and AMIL (which includes Ameren Illinois, ATXI, Genco excluding EEI and Genco’s Elgin CT facility, and AERG). During 2011, the peak demand was 8,831 megawatts in AMMO and 9,605 megawatts in AMIL. The Ameren transmission system directly connects with 15 other balancing authority areas for the exchange of electric energy.

Ameren Missouri, Ameren Illinois and ATXI are transmission-owning members of MISO. Transmission service on the Ameren transmission systems is provided pursuant to the terms of the MISO OATT on file with FERC. EEI operates its own balancing authority area and its own transmission facilities in southern Illinois. The EEI transmission system is directly connected to MISO, the Tennessee Valley Authority, and Louisville Gas and Electric Company. EEI’s generating units are dispatched separately from those of Ameren Missouri, Genco and AERG.

FERC, in its order issued in May 2011, approved transmission rate incentives for the Illinois Rivers project and the Big Muddy project, which will be developed by ATXI or ATX. In December 2011, MISO approved the Illinois Rivers project as well as the Spoon River and Mark Twain projects. The total investment in these three MISO-approved projects is expected to be more than $1.2 billion through 2019, with potential investment of approximately $750 million from 2012 to 2016. All four projects are in Missouri and Illinois. Construction will begin first on the Illinois Rivers project. The Big Muddy project is currently being evaluated for inclusion in MISO’s 2012 expansion plan.

The Ameren Companies and EEI are members of SERC. SERC is responsible for the bulk electric power supply

system in all or portions of Missouri, Illinois, Arkansas, Kentucky, Tennessee, North Carolina, South Carolina, Georgia, Mississippi, Alabama, Louisiana, Virginia, Florida, Oklahoma, Iowa, and Texas. As a result of the Energy Policy Act of 2005, owners and operators of the bulk electric power system are subject to mandatory reliability standards promulgated by NERC and its regional entities, such as SERC, which are enforced by FERC. The Ameren Companies must follow these standards, which are in place to ensure the reliability of the bulk electric power system.

See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for additional information.

Ameren Missouri

Ameren Missouri’s electric supply is obtained primarily from its own generation. Factors that could cause Ameren Missouri to purchase power include, among other things, absence of sufficient owned generation, energy center outages, the fulfillment of renewable energy portfolio requirements, the failure of suppliers to meet their power supply obligations, extreme weather conditions, and the availability of power at a cost lower than the cost of generating it.

Ameren Missouri continues to evaluate its longer-term needs for new baseload and peaking electric generation capacity. Ameren Missouri’s integrated resource plan filed with the MoPSC in February 2011 included the expectation that new baseload generation capacity would be required between 2020 and 2030. Because of the significant time required to plan, acquire permits for, and build a baseload power plant, Ameren Missouri continues to study future plant alternatives, as well as energy efficiency programs that could help defer new plant construction. To prepare for the long-term need for baseload capacity, and to prepare for potentially more stringent environmental regulation of coal-fired energy centers, which could lead to the retirement of current baseload assets, Ameren Missouri is taking steps to preserve options to meet future demand. These steps include seeking improvements in regulatory treatment of energy efficiency investments, evaluating potential sites for natural gas-fired generation, and pursuing an early site permit for an additional unit at its existing nuclear plant site. Ameren Missouri’s pursuit of an early site permit is dependent upon enactment of a legislative framework ensuring cost recovery.

See also Outlook in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, and Note 2 – Rate and Regulatory Matters and Note 15 – Commitments and Contingencies under Part II, Item 8, of this report.

Ameren Illinois

Any electric supply purchased by Ameren Illinois for its retail customers comes either through an annual procurement process conducted by the IPA or through

markets operated by MISO. The power and related

procurement costs incurred by Ameren Illinois are passed directly to its customers through a cost recovery mechanism.

The IPA administers a RFP process that procures Ameren Illinois’ expected supply obligation. Since the start of this process, the ICC has approved the outcomes of multiple electric power procurement RFPs for energy, capacity, and renewable energy credits covering different time periods.

A portion of the electric power supply required for Ameren Illinois to satisfy its distribution customers’ requirements is purchased in the RFP process administered by the IPA from Marketing Company on behalf of Genco and AERG. In addition, as part of the 2007 Illinois Electric Settlement Agreement, Ameren Illinois entered into financial contracts with Marketing Company (for the benefit of Genco and AERG) to lock in energy prices for 400 to 1,000 megawatts annually of its round-the-clock power requirements during the period June 1, 2008, through December 31, 2012, at the market prices relevant at that time. These financial contracts do not include capacity, are not load-following products, and do not involve the physical delivery of energy.

See Note 2 – Rate and Regulatory Matters, Note 14 – Related Party Transactions and Note 15 – Commitments and Contingencies under Part II, Item 8, of this report for additional information on power procurement in Illinois.

Merchant Generation

Genco and AERG have entered into power supply agreements with Marketing Company whereby Genco and AERG sell, and Marketing Company purchases, all of the capacity and energy available from Genco’s and AERG’s generation energy centers and the associated energy. These power supply agreements continue through December 31, 2022, and from year to year thereafter unless either party elects to terminate the agreement by providing the other party with no less than six months’ advance written notice. EEI and Marketing Company have entered into a power supply agreement for EEI to sell all of its capacity and energy to Marketing Company. This agreement expires on May 31, 2016. All of Genco’s, AERG’s and EEI’s energy centers compete for the sale of energy and capacity in the competitive energy markets through Marketing Company. See Note 14 – Related Party Transactions under Part II, Item 8, of this report for additional information.

Coal

Ameren, Ameren Missouri and Genco have agreements in place to purchase a portion of their coal needs and to transport it to electric generating energy centers through 2019. Ameren, Ameren Missouri and Genco expect to enter into additional contracts to purchase coal from time to time. Coal supply agreements typically have an initial term of up to five years, with about 20% of the contracts expiring annually. Ameren Missouri has an ongoing need for coal to serve its native load customers and pursues a price hedging strategy consistent with this requirement. Merchant Generation’s forward coal requirements are dependent on the volume of power sales that have been contracted. Merchant Generation strives to achieve increased margin certainty by aligning its fuel purchases with its power sales. Ameren burned 39 million tons (Ameren Missouri – 22 million, Genco – 13 million) of coal in 2011. See Part II, Item 7A – Quantitative and Qualitative Disclosures About Market Risk of this report for additional information about coal supply contracts.

About 98% of Ameren’s coal (Ameren Missouri – 97%, Genco – 99%) is purchased from the Powder River Basin in Wyoming. The remaining coal is typically purchased from the Illinois Basin. Ameren, Ameren Missouri and Genco have a goal to maintain coal inventory consistent with their risk management policies. Inventory may be adjusted because of changes in burn or uncertainties of supply due to potential work stoppages, delays in coal deliveries, equipment breakdowns, and other factors. In the past, deliveries from the Powder River Basin have occasionally been restricted because of rail maintenance, weather, and

derailments. As of December 31, 2011, coal inventories for Ameren Missouri were at targeted levels and were at or above targeted levels for Genco. Disruptions in coal deliveries could cause Ameren, Ameren Missouri and Genco to pursue a strategy that could include reducing sales of power during low-margin periods, buying higher-cost fuels to generate required electricity, and purchasing power from other sources.

Nuclear

The steps in the process to provide nuclear fuel generally involve the mining and milling of uranium ore to produce uranium concentrates, the conversion of uranium concentrates to uranium hexafluoride gas, the enrichment of that gas, and the fabrication of the enriched uranium hexafluoride gas into usable fuel assemblies. Ameren Missouri has entered into uranium, uranium conversion, enrichment, and fabrication contracts to procure the fuel supply for its Callaway nuclear plant.

Fuel assemblies for the 2013 spring refueling at Ameren Missouri’s Callaway energy center are scheduled for manufacture and delivery to the plant during 2012. Ameren Missouri also has agreements or inventories to

price-hedge approximately 92%, 82%, and 47% of

Callaway’s 2013, 2014 and 2016 refueling requirements, respectively. Ameren Missouri has uranium (concentrate

and hexafluoride) inventories and supply contracts

sufficient to meet all of its uranium and conversion

requirements through at least 2014. Ameren Missouri has enriched uranium inventories and enrichment supply

contracts sufficient to satisfy enrichment requirements through 2013. Fuel fabrication services are under contract through 2014. Ameren Missouri expects to enter into additional contracts to purchase nuclear fuel. As a member of Fuelco, Ameren Missouri can join with other member companies to increase its purchasing power, enhance diversification and pursue opportunities for volume discounts. The Callaway nuclear plant normally requires refueling at 18-month intervals. The last refueling was completed in November 2011. There is no refueling scheduled for 2012 and 2015. The nuclear fuel markets are competitive, and prices can be volatile; however, we do not anticipate any significant problems in meeting our future supply requirements.

Natural Gas Supply for Generation

To maintain gas deliveries to gas-fired generating units throughout the year, especially during the summer peak demand, Ameren’s portfolio of natural gas supply resources includes firm transportation capacity and firm no-notice storage capacity leased from interstate pipelines. Ameren Missouri and Genco primarily use the interstate pipeline systems of Panhandle Eastern Pipe Line Company, Trunkline Gas Company, Natural Gas Pipeline Company of America, and Mississippi River Transmission Corporation to transport natural gas to generating units. In addition to physical transactions, Ameren uses financial instruments, including some in the NYMEX futures market and some in the OTC financial markets, to hedge the price paid for natural gas.

Ameren Missouri’s and Genco’s natural gas procurement strategy is designed to ensure reliable and immediate delivery of natural gas to their generating units. This is accomplished by optimizing transportation and storage options and minimizing cost and price risk through various supply and price-hedging agreements that allow access to multiple gas pools, supply basins, and storage services. As of December 31, 2011, Ameren Missouri had price-hedged about 12% and Genco had price-hedged 32% of its expected natural gas supply requirements for generation in 2012.

Renewable Energy

Illinois and Missouri have enacted laws requiring electric utilities to include renewable energy resources in their portfolios. Illinois requires renewable energy resources to equal or exceed 2% of the total electricity that each electric utility supplies to its eligible retail customers as of June 1, 2008, increasing to 15% by June 1, 2015, and to 25% by June 1, 2025. Ameren Illinois has procured renewable energy credits under the IPA-administered procurement process to meet the renewable energy portfolio requirement through May 2012. In December 2010, Ameren Illinois entered into a 20-year agreement with renewable energy suppliers and will begin receiving renewable energy credits under the agreement starting in June 2012, to help supplement these requirements. Approximately 50% of the 2012 renewable energy requirement will be met through this agreement. In 2011,

Ameren Illinois procured approximately 6% of its total electricity from renewable energy resources.

In Missouri, utilities are required to purchase or generate from renewable energy sources electricity equaling at least 2% of native load sales, with that percentage increasing to at least 15% by 2021, subject to a 1% limit on customer rate impacts. At least 2% of each renewable energy portfolio requirement must be derived from solar energy. Ameren Missouri expects to satisfy the nonsolar requirement through 2017 with existing renewable generation in its current fleet along with a 15-year 102 MW power purchase agreement with a wind farm operator in Iowa that became effective in 2009 and the landfill gas project discussed below. Currently, Ameren Missouri expects to meet the solar energy requirement through the purchase of solar-generated renewable energy credits; however, Ameren Missouri is studying other options for compliance. In 2011, Ameren Missouri purchased or generated approximately 3% of its native load sales from renewable energy resources.

In September 2009, Ameren Missouri announced an agreement with a landfill owner to install CTs at a landfill site in Maryland Heights, Missouri, which is expected to generate approximately 15 megawatts of electricity by burning methane gas collected from the landfill. The CTs (known as the Maryland Heights energy center) are expected to begin generating power in 2012. Ameren Missouri signed a 20-year supply agreement with the landfill owner to purchase methane gas.

Energy Efficiency

Ameren’s rate-regulated utilities have implemented energy efficiency programs to educate and help their customers become more efficient users of energy. The MEEIA, enacted in 2009, established a regulatory framework that, among other things, allows electric utilities to recover costs related to MoPSC-approved energy efficiency programs. The law requires the MoPSC to ensure that a utility’s financial incentives are aligned with helping customers use energy more efficiently, to provide timely cost recovery, and to provide earnings opportunities associated with cost-effective energy efficiency programs. Missouri does not have a law mandating energy efficiency standards.

In January 2012, Ameren Missouri made its initial filing with the MoPSC under the MEEIA. This filing proposes a three-year plan that includes a portfolio of energy efficiency programs along with a cost recovery mechanism. If the proposal is approved, beginning in January 2013, Ameren Missouri plans to invest $145 million over three years for the proposed energy efficiency programs. A decision by the MoPSC in this proceeding is anticipated in the second quarter of 2012. Ameren Missouri anticipates that the impacts of the MoPSC’s decision in this MEEIA filing will be included in rates set under its pending electric service rate case that was filed on February 3, 2012, which has an anticipated true-up date of July 31, 2012. Ameren Missouri’s pending electric rate case includes an annual revenue increase of

$81 million relating to its planned portfolio of energy efficiency programs included in its MEEIA filing. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for additional information.

Illinois has enacted a law requiring Ameren Illinois to offer energy efficiency programs. The law also allows recovery mechanisms of the programs’ costs. The ICC has issued orders approving Ameren Illinois’ electric and natural gas energy efficiency plans as well as cost recovery mechanisms by which program costs can be recovered from customers. In addition, over a ten-year period, Ameren Illinois will invest an estimated $625 million to upgrade and modernize its transmission and distribution infrastructure in accordance with the IEIMA. As part of these upgrades, Ameren Illinois expects to invest $360 million to install smart meters, which could enable customers to improve efficiency.

NATURAL GAS SUPPLY FOR DISTRIBUTION

Ameren Missouri and Ameren Illinois are responsible for the purchase and delivery of natural gas to their gas utility customers. Ameren Missouri and Ameren Illinois develop and manage a portfolio of gas supply resources. These include firm gas supply under term agreements with producers, interstate and intrastate firm transportation capacity, firm storage capacity leased from interstate pipelines, and on-system storage facilities to maintain gas deliveries to customers throughout the year and especially during peak demand. Ameren Missouri and Ameren Illinois primarily use the Panhandle Eastern Pipe Line Company, the Trunkline Gas Company, the Natural Gas Pipeline Company of America, the Mississippi River Transmission Corporation, the Northern Border Pipeline Company, and the Texas Eastern Transmission Corporation interstate pipeline systems to transport natural gas to their systems. In addition to physical transactions, financial instruments, including those entered into in the NYMEX futures market and in the OTC financial markets, are used to hedge the price paid for natural gas. See Part II, Item 7A – Quantitative and Qualitative Disclosures About Market Risk of this report for additional information about natural gas supply contracts. Natural gas purchase costs are passed on to customers of Ameren Missouri and Ameren Illinois under PGA clauses, subject to prudency reviews by the MoPSC and the ICC. As of December 31, 2011, Ameren Missouri had price-hedged 90%, and Ameren Illinois had price-hedged 87%, of its expected natural gas supply requirements for distribution in 2012.

For additional information on our fuel and purchased power supply, see Results of Operations, Liquidity and Capital Resources and Effects of Inflation and Changing Prices in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, of this report. Also see Quantitative and Qualitative Disclosures About Market Risk under Part II, Item 7A, of this report, Note 1 – Summary of Significant Accounting

Policies, Note 7 – Derivative Financial Instruments, Note 10 – Callaway Energy Center, Note 14 – Related Party Transactions, and Note 15 – Commitments and Contingencies under Part II, Item 8 of this report.

INDUSTRY ISSUES

We are facing issues common to the electric and natural gas utility industry and the merchant electric generation industry. These issues include:

We are monitoring these issues. Except as otherwise noted in this report, we are unable to predict what impact, if any, these issues will have on our results of operations, financial position, or liquidity. For additional information, see Risk Factors under Part I, Item 1A, and Outlook in

Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, and Note 2 – Rate and Regulatory Matters and Note 15 – Commitments and Contingencies under Part II, Item 8, of this report.