Key Stats
Market Cap: $28 billion (2025)
Annual Revenue: $7.62 billion (2024)
Employees: 8,981
Electric Customers: 2.4 million
Natural Gas Customers: 900,000
Ameren Corporation is an American utility holding company headquartered in St. Louis, Missouri. The company provides electric and natural gas services to customers across Missouri and Illinois through its operating subsidiaries.
Ameren operates through four segments: Ameren Missouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Transmission. The company generates electricity through coal, nuclear, natural gas, and renewable energy sources including hydroelectric, wind, and solar.
Ameren serves a 64,000-square-mile region and ranks among the largest investor-owned utilities in the United States. The company trades on the New York Stock Exchange under the ticker symbol AEE.
Ameren Corp History
Ameren Corporation traces its origins to the early 1900s when predecessor companies first brought electricity to Missouri and Illinois. The company formed through a series of mergers that consolidated regional utilities into a single holding company.
Union Electric Company organized in St. Louis through merger of local utilities
Union Electric powered the Palace of Electricity at the St. Louis World’s Fair
Bagnell Dam completed on the Osage River, creating Lake of the Ozarks
Central Illinois Public Service and Union Electric formed Midwest Power Pool
Taum Sauk pumped storage plant completed as world’s largest at the time
Callaway Energy Center nuclear plant began commercial operations
Ameren Corporation formed through merger of Union Electric and CIPSCO
Acquired CILCORP and Illinois Power, expanding Illinois operations
All Illinois utilities consolidated into Ameren Illinois Company
Ameren Corp Co-founders
Ameren Corporation formed through the 1997 merger of Union Electric Company and CIPSCO Inc. rather than through a traditional founding. The executives who led these companies through the merger shaped Ameren’s early direction.
Charles Mueller
First Chairman and CEO of Ameren Corporation, led the company from formation in 1997 until his retirement in 2003.
Gary Rainwater
Succeeded Mueller as Chairman and CEO in 2003, previously served as President and COO during the merger integration.
Warner Baxter
Joined Ameren in 1995, served as CEO from 2014 to 2021, now Executive Chairman overseeing strategic matters.
Martin J. Lyons Jr.
Current Chairman, President and CEO since January 2022, previously served as CFO and Ameren Missouri President.
Ameren Corp Revenue
Ameren Corp generated $7.62 billion in annual revenue during 2024. The company has maintained steady revenue growth over the past decade through infrastructure investments and rate base expansion.
The Ameren Missouri segment contributes the largest share of revenue, accounting for approximately 52% of total company revenue. Regulatory approvals for infrastructure investments continue to support revenue growth across all operating segments.
Ameren Corp Annual Revenue (2015-2024)
Ameren Corp Marketcap
Ameren Corp maintains a market capitalization of approximately $28 billion as of 2025. The company’s market value has grown significantly over the past decade, reflecting investor confidence in its regulated utility business model.
Ameren ranks among the largest investor-owned utilities in the United States by market capitalization. Similar to other major utilities like Duke Energy, the company benefits from stable cash flows and consistent dividend payments.
Ameren Corp Market Capitalization (2015-2024)
Ameren Corp Acquisitions
Ameren Corporation has grown significantly through strategic acquisitions since its formation in 1997. The company has focused on consolidating regional utilities in Missouri and Illinois to create operational efficiencies and expand its service territory.
The foundational merger between Union Electric Company and CIPSCO Inc. created Ameren Corporation on December 31, 1997. Union Electric brought assets of nearly $600 million along with $1.8 billion in long-term debt. CIPSCO contributed approximately $210 million in assets. Both companies had traded on the New York Stock Exchange before combining under the new Ameren name with ticker symbol AEE.
In 2003, Ameren acquired CILCORP Inc. and its subsidiary Central Illinois Light Company from AES Corporation. CILCORP had previously traded on the NYSE and was a member of the S&P Small Cap 600 index. The utility had paid dividends since 1921. Following the acquisition, the company operated as AmerenCILCO.
The 2004 acquisition of Illinois Power Company from Dynegy Inc. marked another major expansion for Ameren. Illinois Power had traded on the NYSE under ticker symbol IPC and paid dividends since 1947. This acquisition reunited all three partners from the 1952 Midwest Power Pool system under single ownership. The subsidiary operated as AmerenIP until 2010.
In 2010, Ameren consolidated all its Illinois utility operations into Ameren Illinois Company. This merger combined AmerenCIPS, AmerenCILCO, and AmerenIP into a single operating entity. The consolidation streamlined operations and regulatory processes across the Illinois service territory. Other utilities like FirstEnergy Corp. have followed similar consolidation strategies in recent years.
Recent acquisitions have focused on renewable energy assets. In 2024, Ameren acquired a 150-megawatt solar project in Cass County, Illinois from Savion. The company continues to invest in wind, solar, and battery storage projects to meet clean energy commitments.
Ameren Corp Competitors
Ameren Corp operates in the regulated utility sector alongside several major competitors. The company faces competition primarily from other investor-owned utilities serving the Midwest and surrounding regions.
Many of these competitors have similar business models focused on regulated electric and gas distribution. Companies like WEC Energy Group and Dominion Energy operate across multiple states with diversified energy portfolios.
| Company | Headquarters | Primary Service Area |
|---|---|---|
| Duke Energy | Charlotte, NC | Southeast and Midwest |
| Xcel Energy | Minneapolis, MN | Upper Midwest and Southwest |
| WEC Energy Group | Milwaukee, WI | Wisconsin, Illinois, Michigan |
| FirstEnergy | Akron, OH | Ohio, Pennsylvania, Mid-Atlantic |
| American Electric Power | Columbus, OH | Midwest and South Central |
| Eversource Energy | Hartford, CT | New England |
| CenterPoint Energy | Houston, TX | Texas, Indiana, Ohio |
| NextEra Energy | Juno Beach, FL | Florida and nationwide renewables |
| CMS Energy | Jackson, MI | Michigan |
| PPL Corporation | Allentown, PA | Pennsylvania, Kentucky, Rhode Island |
FAQs
When was Ameren Corporation founded?
Ameren Corporation formed on December 31, 1997, through the merger of Union Electric Company and CIPSCO Inc. Union Electric traced its origins to 1902 in St. Louis.
Where is Ameren Corp headquartered?
Ameren Corporation is headquartered at One Ameren Plaza in St. Louis, Missouri. The company operates across Missouri and Illinois serving customers in a 64,000-square-mile region.
How many customers does Ameren serve?
Ameren serves approximately 2.4 million electric customers and 900,000 natural gas customers. The company operates through Ameren Missouri and Ameren Illinois subsidiaries.
What is Ameren Corp stock ticker symbol?
Ameren Corporation trades on the New York Stock Exchange under the ticker symbol AEE. The company joined the NYSE when it formed through the 1997 merger.
Who is the CEO of Ameren Corporation?
Martin J. Lyons Jr. serves as Chairman, President and CEO of Ameren Corporation. He assumed the CEO role on January 1, 2022, after previously serving as CFO. You can learn more about utility company leadership by exploring profiles of Edison International and other major utilities.
