SAN FRANCISCO (MarketWatch) - Shares of Facebook Inc. were up 1.6% at $31.27 on Wednesday ahead of the social networking company's fourth-quarter results. Analysts polled by FactSet on average expect the Menlo Park, Calif.-based company to report a profit of 15 cent a share, on revenue of $1.51 billion. Market Pulse Stories are Rapid-fire, short news bursts on stocks and markets as they move. Visit MarketWatch.com for more information on this news.