|From Theglobeandmail.com: October was actually nowhere near the worst decline for the main Canadian and U.S. indexes. The S&P/TSX composite fell about 17 per cent in the month, far less than the decline of almost 23 per cent in October, 1987. The Dow dropped about 14 per cent in the month, again far less than its record fall of just under 23 per cent, also in October, 1987.
What made this autumn so remarkable were the back-to-back declines in September and October. While September, 1987, wasn't a great month, both the U.S. and Canadian markets fell by less than 3 per cent. September of this year was much worse, so the combined two-month decline in 2008 was devastating..... Full Article: Source