TORONTO — The Toronto stock market gained ground on a volatile day as oil prices rose and the U.S. central bank said it would leave its overnight interest rate unchanged. The S&P/TSX composite index added 46.45 points to end the day at 12,377.77, after rising 188 points on Tuesday. In New York, the Dow Jones Industrial average plummeted 222.77 points to close at 15,944.46, the broader S&P 500 index dropped 20.68 points to 1,882.95, and the …
