Bats Global Markets, one of the country’s three big stock-exchange operators, is preparing to replace its chief executive as it lays the groundwork for restarting an IPO, according to people familiar with the matter.

Chris Concannon, a former executive at the high-speed trading firm Virtu Financial who joined Bats as president last December, is expected to be appointed as CEO as early as this summer, the people said. Joseph Ratterman, the long-time CEO, would become chairman of the company's board, they said.