Michael Foust, CEO of Digital Realty Trust, the world's largest data center developer and provider of wholesale data center space, has stepped down, replaced in the interim by the company's CFO William Stein.

The company did not provide a specific reason for Foust's departure. Dennis Singleton, chairman of the board, said in a statement that Foust and the board had agreed that it was “an appropriate time to find the next leader to help guide Digital Realty to the next level and scale of operational sophistication.”

Foust will stay on the company's board until the next shareholder meeting in April. He will not stand for re-election.

Singleton praised Foust's contribution to building the company and expanding its portfolio. “Under his leadership, Digital Realty has dramatically expanded the size of its asset base, from a US$1bn collection of properties at the IPO in 2004 to a global platform with a $12bn enterprise value,” he said.

He also pointed out that the company's share price had more than quadrupled since the IPO. The share price was $51.77, down almost 2%, in after-hours trading Monday, following the announcement of Foust's departure.

The chairman said the board was confident in Stein's ability to lead the company before it finds a permanent replacement for Foust. “Bill has been a member of the senior management team since prior to our IPO in 2004, and has been responsible for creating and maintaining the fortress balance sheet that has provided us a significant competitive advantage with respect to both access to and cost of capital,” he said.

Foust was one of the founders of Digital Realty and was its only CEO since inception in 2004. The company was spun out of Global Innovation Partners, a private-equity firm that has since been renamed into GI Partners.

He and partner Rick Magnuson founded Global Innovation, and Digital Realty was spun out through an initial public offering as a real estate investment trust, operating GI's data center real estate portfolio.

Magnuson still leads GI as executive managing director. Other key members of Digital Realty's founding team have started data center businesses on their own.

Jim Trout, who was senior VP of portfolio and technical operations at Digital Realty, founded Santa, Clara, California-based Vantage Data Centers, a direct competitor to Digital Realty. Chris Crosby, who ran sales and technical services at Digital Realty when the company was formed, started Compass Datacenters, a developer and provider of data centers in second-tier US markets.