Chief executive Thomas Kloet will retire from the company effective Aug. 31.
Kloet became CEO of TMX Group Inc., the predecessor of TMX Group Ltd., in June 2008 and continued in the role after the company was acquired by the consortium of 13 financial institutions and pension funds known as the Maple Group Acquisition Corp. in 2012.
"The board of directors wishes to thank Tom for his leadership and many contributions to the organization, and we wish him the very best in his retirement," said Chuck Winograd, chairman of TMX Group Ltd.
"Tom leaves behind a strong management team who will continue to execute on the organization's growth strategy."
Kloet helped oversee the expansion of TMX Group with new offices in London, New York, Sydney and Beijing under his watch and a more than doubling of its number of international companies listed.
He also attempted a billion-dollar merger with the London Stock Exchange that was thwarted by the Maple Group after a prolonged takeover battle.
The company said the TMX board has formed a search committee to find Kloet's replacement and the work would begin immediately.
TMX Group's businesses include the Toronto Stock Exchange and TSX Venture Exchange as well as the Canadian Depository for Securities, Montreal Exchange, Canadian Derivatives Clearing Corp., NGX and the BOX Options Exchange.