SAN FRANCISCO (MarketWatch) -- Groupon Inc. GRPN, -1.85% said Thursday that it has replaced Chief Executive Andrew Mason. The Chicago-based online daily deal company said executive chairman Eric Lefkofsky and vice chairman Ted Leonsis will have been appointed to the newly created Office of the Chief Executive, and the company will begin searching for a new, full-time CEO. Mason's departure comes one day after Groupon reported a fourth-quarter loss and gave a weaker-than-expected first-quarter revenue forecast. Groupon shares rose 7.5% in after-hours trading following the announcement of Mason's departure.