Is this going to be another October to remember for Wall Street? As I have explained previously, the month of October has historically been the worst month by far for the U.S. stock market, and it has also been the month when our most famous stock market crashes have taken place. The stock market crash that started the Great Depression in 1929 happened in October. The largest single day percentage decline in stock market history happened in October 1987. And most of us still remember what happened in October 2008.