The year that saw the largest single-day stock market crash, triggering the Great Depression, was 1929, specifically on October 29, known as Black Tuesday. This catastrophic event, marked by panic selling and plummeting stock prices, led to widespread economic instability. It resulted in a prolonged economic downturn, affecting markets, businesses, and the overall economy. The crash is often considered a major factor that contributed to the Great Depression, fundamentally reshaping economic policies and practices in the United States and globally.