General Motors Corp. (GM) opened at 30.43. So far today, the stock has hit a low of 30.00 and a high of 30.51. GM is now trading at 30.03, down 1.01 (-3.25%). The stock hit its 52 week high of 38.66 in June and set its 52 week low of 28.49 in November. The stock has been very volatile for the past year. Auto makers' shares have been dropping today on investors' concerns about the U.S. economy after the Labor Department reported this morning that em...