The cause of the 1929 Wall Street Crash was a combination of speculative investments, excessive borrowing, and an overheated stock market. Throughout the 1920s, known as the "Roaring Twenties," there was rampant speculation, where many investors purchased stocks on margin, meaning they borrowed money to buy shares. This created an economic bubble, as stock prices soared well beyond their actual value. When confidence began to wane, and investors started selling off their shares, prices plummeted. On October 29, 1929, known as Black Tuesday, the market crashed dramatically, triggering a chain reaction that led to the Great Depression and widespread economic turmoil worldwide.