Careers at Ameren


Ameren’s mission is to power the quality of life.

Business segments

Ameren is a power company.  The firm operates two reportable business segments:

  • Ameren Missouri – Operates energy centers and delivers electric and natural gas services in Missouri. Includes Ameren Missouri Energy Management & Trading and Ameren Missouri Wholesale.
  • Ameren Illinois – Provides electric and natural gas services in Illinois.


1902 saw a merger between three utilities:  Missouri Edison Electric Company, Citizens Electric Lighting and Power Company, and Imperial Electric Light, Heat, and Power Company. The resulting firm was Union Electric, which was incorporated in 1922 as Union Electric Light and Power Company. In 1931 Union Electric bought Keokuk Dam, providing power over a longer distance than ever before.

During World War I Union Electric grew by serving rural areas and acquiring many small light and power companies in Illinois and Missouri. In 1937 it changed its name to Union Electric Company of Missouri, with its Illinois and Iowa operations becoming subsidiaires. In 1945 the Iowa and Illinois divisions were merged into one subsidiary called Union Electric Power Company.

By the 1950s Union Electric was the third largest distributor of natural gas in Missouri. In 1963 it finished building one of the largest pumped storage plants, the Taum Sauk Plant. In 1995 it merged with CIPSCO. A new firm, Ameren Corporation, was then created to serve as a holding company for Union Electric’s operations. Ameren ranked 11th in the U.S. in terms of generating capacity.

Business model of Ameren

Customer Segments

Ameren has a segmented market business model, with customer groups that have slight differences. The company targets its offerings at residential and commercial customers.

Value Proposition

Ameren offers one primary value proposition: brand/status.

The company has established a strong brand due to its success. It provides power to 2.4 million electric customers and over 900,000 natural gas customers in a 64,000-square-mile area. In 2015 the company became the first major energy firm to open an Innovation Center at the Research Park, University of Illinois at Urbana-Champaign.

Lastly, it has won many honors, including recognition as one of the Top 100 Military-Friendly Employers by G.I. Jobs and the Top Utility in the Nation for Diversity by DiversityInc.


Ameren’s main channel is its direct sales team. The company promotes its offering through its website, social media pages, and participation in conferences.

Customer Relationships

Ameren’s customer relationship is primarily of a self-service nature. Customers utilize its products and services while having limited interaction with employees. The company’s website provides useful resources such as a video library and energy saving tips. It also offers an online account through which customers can make payments. That said, there is a personal assistance component in the form of phone and e-mail support.

Key Activities

Ameren’s business model entails generating and delivering its energy products for customers, and providing associated services.

Key Partners

Ameren’s key partners are the suppliers that provide it with the equipment, materials, and services it needs to manage its operations. These range from pens and paper to parts and wire to professional services. The company also has business partners in the following areas:

  • Account & Data Management  – Includes Agents, Brokers, and Consultants, as well as Multi-Account Managers
  • Construction & Facilities – Includes Energy Efficiency Contractors
  • Property Management – Includes Property Managers

Key Resources

Ameren’s main resources are its physical resources, which include the energy centers it operates across Missouri and Illinois. They offer a combined capability of 10,226,000 net kilowatts.

Cost Structure

Ameren has a cost-driven structure, aiming to minimize expenses through significant automation. Its biggest cost driver is operations/maintenance, a fixed cost. Other major drivers are in the areas of cost of fuel and cost of purchased power, both variable expenses.

Revenue Streams

Ameren has one revenue stream: revenues it generates from sales of its electric and gas products to customers.

Our team

Warner Baxter,
President, Chairman, and CEO

info: Warner Baxter earned a Bachelor of Science in Accounting at the University of Missouri–St. Louis. He previously held several leadership roles at Ameren, including Chief Financial Officer and President of Ameren Missouri. He also served as a Senior Manager at PwC.

Martin J. Lyons,
EVP and Chief Financial Officer

info: Martin J. Lyons earned a Bachelor of Science in Accounting at Saint Louis University and an MBA at Washington University in St. Louis. He previously held various leadership roles at Ameren, including Chief Accounting Officer and Controller.

Latres Poisan,
SVP, General Counsel, and Secretary

info: earned B.A. and J.D. degrees at Vanderbilt University and an LL.M. degree in Taxation at Georgetown University. He previously held several leadership roles at Ameren, including VP, Tax and Deputy General Counsel.

Mary P. Heger,
SVP and Chief Information Officer of Ameren Services

info: Mary P. Heger earned a Bachelor’s degree in Management at Maryville University in St. Louis and an MBA at Washington University in St. Louis. She previously served as VP of Information Technology and Ameren Services Center.