shares of general motors co gm on friday are poised to end at their highest since march 8 up for the 9th straight session the stock is up nearly 10 over that period gm has gained 18 this year compared with an advance of about 15 for the sp 500 index spx gm earlier this week reported a 19 jump in its secondquarter us auto sales and said all of its four brands saw doubledigit growth