The major event that led to the beginning of the Great Depression in 1929 was the stock market crash that occurred in October of that year. Known as Black Tuesday, this crash saw millions of shares sold at a rapid pace, resulting in a significant loss of wealth and confidence in the economy. The crash did not solely precipitate the depression, but it exposed underlying economic weaknesses, including excessive speculation, overproduction, and bank failures. The crisis led to widespread unemployment, business bankruptcies, and a profound decline in global trade, setting the stage for a decade-long economic downturn.