The three major reasons that led to the stock market crash were overextended credit, uncontrolled spending, and overproduction.
The stock market crash of 1929 was considered the worst economic event in world history. This event began on Thursday, October 24, 1929, with skittish investors trading a record 12.9 million shares. On October 28, dubbed “Black Monday,” the Dow Jones Industrial Average fell nearly 13 percent. The market fell another 12 percent the next day, “Black Tuesday.”