By Gerry Shih and Alexei Oreskovic SAN FRANCISCO (Reuters) – Twitter Inc, whose stock has surged 150 percent since it went public in November, has a lot to live up to when it reports quarterly earnings for the first time on Wednesday. A growing number of naysayers warn that Twitters stock is greatly overpriced, and that even mediocre inaugural results could deflate its soaring valuation, now several times that of its closest social media peer, Facebook Inc. But a clutch of earnings from the giants of the Internet sector last week suggest the companys mobile advertising business model is rooted in solid – and fertile – ground. Facebook last week posted its strongest quarterly revenue growth in two years, even though 53 percent of its advertising revenue came from mobile users, once its Achilles heel. Facebook shares shot up 14 percent the day after the news.