Bombardier shares hit a three-year low on the Toronto Stock Exchange amid several downgrades from credit ratings agencies. Bombardier stock closed down six per cent, or 20 cents per share, to $2.99 on heavy trading of more than 43 million shares. It was the lowest close since March 2009. The Standard and Poor's ratings agency downgraded Bombardier's long-term corporate rating one notch Wednesday, following its peers in lowering the plane and train maker's status after a weak earnings report. -
