Ameren's Executive Leadership

Thomas R. Voss
Ameren Corporation
Chairman of the Board
President and Chief Executive Officer
Thomas R. Voss was elected to the position of chairman of the board of directors of Ameren Corporation on April 27, 2010. He was elected president and chief executive officer of Ameren in May 2009 – titles he retained with his promotion to the position of board chairman. (more)
Warner Baxter
Ameren Missouri Chairman, President and
Chief Executive Officer
Warner Baxter became chairman, president and chief executive officer of AmerenUE (now Ameren Missouri) on May 1, 2009, after serving as executive vice president and chief financial officer and as president and CEO of Ameren Services – positions he had held since 2003 and 2006 respectively. (more)
Richard J. Mark
Ameren Illinois Chairman, President and Chief Executive Officer
Richard J. Mark is chairman, president and chief executive officer of Ameren’s Illinois rate-regulated business segment. In this position, he is responsible for the gas and electric delivery business, customer service, gas support and community affairs for Ameren Illinois Company. (more)
Daniel F. Cole
Ameren Services Chairman, President and
Chief Executive Officer
Daniel F. Cole on May 1, 2009, became chairman, president and chief executive officer of Ameren Services, an Ameren subsidiary providing administrative and technical support services to Ameren and its operating companies, subsidiaries and affiliates. (more)
Maureen A. Borkowski
President and Chief Executive Officer
Ameren Transmission Company 
Maureen A. Borkowski is president and chief executive officer of Ameren Transmission Company (ATX) – a subsidiary dedicated to electric transmission infrastructure investment. addition to leading the development of new transmission, she is also responsible (more)
Adam C. Heflin
Ameren Missouri Senior Vice President and
Chief Nuclear Officer
Adam C. Heflin is senior vice president and chief nuclear officer of Ameren Missouri. In this position he is responsible for all of Ameren Missouri’s nuclear operations. Mr. Heflin joined the company in 2005 as site vice president, Callaway Energy Center, (more)
  Mary P. Heger
Ameren Vice President and Chief Information Officer, Information Technology and Ameren Services Center
Mary P. Heger is vice president of Ameren Services Center and Information Technology of Ameren Services, where she directs the staff responsible for all information technology operations, including information security and planning, development and business services operations. (more)
  Mark C. Lindgren
Ameren Vice President and Chief Human Resources Officer
Mark C. Lindgren is vice president of Human Resources for Ameren where he directs the staff responsible for all Human Resources, including benefits, compensation, employee relations, hiring, leadership and organizational development. (more)
Martin J. Lyons
Ameren Executive Vice President and
Chief Financial Officer
Martin J. Lyons is executive vice president and chief financial officer for Ameren Corporation. In his current position, Lyons is responsible for corporate planning, risk management, financial accounting and reporting, tax planning and compliance, treasury and investor relations functions. (more)
Michael Moehn
Ameren Missouri Senior Vice President 
Customer Operations  
Michael Moehn is senior vice president, Customer Operations, Ameren Missouri. In this position, he is responsible for electric and gas distribution and Customer Service operations to more than 1.2 million customers. (more)
Charles D. Naslund
Ameren Missouri Senior Vice President
Environmental and Generation Projects
Charles D. Naslund is senior vice president, Generation and Environmental Projects for Ameren Missouri – a position he assumed on March 2, 2010, after serving as chairman, president and chief executive officer, Ameren Energy Resources. (more)
Gregory L. Nelson
Ameren Senior Vice President 
General Counsel and Secretary
Gregory L. Nelson is senior vice president, general counsel and secretary of Ameren, where he is responsible for the legal, federal legislative, security and economic development functions for the corporation. (more)
Steven R. Sullivan
Chairman and President,
Ameren Energy Resources
Ameren Energy Generating Company
Ameren Energy Marketing
Steven R. Sullivan is chairman, president and chief executive officer, Ameren Energy Resources, and chairman and president, Ameren Energy Generating Company. Ameren Energy Resources is an integrated energy commodity company. (more)