Stock Speculation Before the Great Depression, there were limited regulations that governed the stock market. Investors were able to speculate wildly and buy stocks on margin or using borrowed money. This rampant speculation led to erroneously high stock prices. In October 1929, the stock market crashed, paving the way into America's Great Depression of the 1930s. Banking failures were at the heart of America’s worst depression, but it had multiple underlying causes: a recession (caused by income inequality, market saturation, and installment buying), weak agriculture (caused by drought and over-investment), the Stock Market Crash (fueled by on margin investing),