Stock prices are skidding at the open Friday as bond yields inch up and lingering credit worries are dragging down financial stocks. The blue-chip Dow average fell more than 50 points in the first few minutes, with the TSX composite down by a like amount. Both have recovered slightly. Blackstone Group LP opened at $45 (U.S.) after pricing its big IPO at $31. But it has traded down to $40. Leading the TSX lower are commodity stocks and the financial group.