The event that led to the start of the Great Depression in 1929 was the stock market crash that occurred in October of that year. On October 24, known as Black Thursday, the stock market experienced a massive sell-off, with panic selling leading to a drastic drop in stock prices. This crash eroded investor confidence and triggered a chain reaction of failures in financial institutions, reduced consumer spending, and soaring unemployment. The Great Depression that followed was marked by severe economic hardship worldwide, lasting through the 1930s and profoundly impacting the global economy, leading to significant changes in economic policies and regulations.