Apologies to T.S. Eliot, but October has historically been the cruelest month — in the market. Since 1929, the Roman Calendar’s eighth month has seen some of the market’s most brutal sell-offs. That was true in 1987, when global markets fell like dominoes, starting in Hong Kong mid-month and ending with the Dow Jones industrial average. The Dow swooned 23% and the S&P 500 20% on the 19th, commonly called Black Monday.