Constellation Software President Mark Leonard Steps Down for Health Reasons — Update

By Robb M. Stewart

Constellation Software founder and President Mark Leonard has resigned for what the Canadian tech company said were unspecified health reasons.

The Toronto-based company said its board appointed Mark Miller, currently chief operating officer, to succeed Leonard as president. The company doesn't have a chief executive.

Miller's other roles at Constellation will remain unchanged, and Leonard will remain a board director, Constellation said.

The company's shares fell sharply on news of Leonard's departure, widening the decline seen this year, though recovered some ground. Just before midday, the stock was down 5.8%, for a drop of 12% year-to-date.

Chairman John Billowits in a statement said that since Leonard's original inception of Constellation in 1995, he had inspired countless company leaders and employees to build a global software company.

Leonard, who had worked in venture capital for 11 years, built Constellation into a big technology company and one of the largest companies in Canada by market value through a string of acquisitions of software companies. He holds a 1.9% stake in the company, worth roughly $1.21 billion, data compiled by FactSet shows.

News of Leonard's decision to step down came days after he early in the week held a call with investors to discuss the affect of artificial intelligence on Constellation's business, following a request from one of the company's largest shareholders for a question-and-answer session about AI. Leonard struck a cautious tone on the technology during the call, describing AI as still in its infancy and just as likely to empower clients as it is to boost Constellation's business.

Constellation owns hundreds of vertical-market software businesses that serve specialized industries ranging from municipal utilities and healthcare providers to schools and government agencies. Because AI tools are widely available, Leonard said Constellation's edge lies in its deep knowledge of customer workflows and its long-standing client relationships, not in owning the technology itself.

Miller has been with CSI for more than two decades, though had recently spent the majority of his time as the executive chairman of Volaris Operating Group and Trapeze Operating Group, according to Constellation's website. Miller also is on the boards of Medgate and pVelocity, two privately held software companies that are headquartered in Toronto.

Write to Robb M. Stewart at robb.stewart@wsj.com

(END) Dow Jones Newswires

September 25, 2025 12:18 ET (16:18 GMT)