Stocks rose as corporate earnings reports got off to a good start. Fresh off the fiscal cliff rally, stocks are facing their first big challenge of 2013 as companies report quarterly earnings. Analysts had been cutting their outlook for earnings growth but now expect an overall 3.2% gain, according to S&P Capital IQ data. Early signs encouraged: Alcoa swung to a profit, though its Wednesday stock performance was lackluster. Helen of Troy, though, added 2.7% on net income that rose 15 percent. Boeing was the Dow’s big gainer, up 3.5% after two days of sharp declines due to problems with its 787 Dreamliner. Boeing said it has ‘extreme confidence’ in the plane.