Groupon board votes to replace cofounder in CEO role
Williams came to Groupon in 2011 after running worldwide marketing and advertising for Amazon.
In an interview with Re/Code, Lefkofsky said he had been talking to them about handing over the job, and Williams emerged as the successor in the past six to 12 months.
The Groupon cofounder took over as CEO in 2013 after the board fired another cofounder, Andrew Mason, from the role.
Lefkofsky will return to his role as Chairman of the Board.
Despite Groupon's struggles, revenue grew 32 percent during Lefkofsky's tenure, according to the company's statement.
Today's earnings show that that growth has stalled. Revenue was $713.6 million in the third quarter of 2015, down slightly from the $714.3 million in the same quarter in 2014.
Groupon's shares were up 5 percent during regular trading, but trading was halted a couple minutes after the release crossed.