The stock market crash was the bursting of a speculative bubble. Speculation inflated the value of many company's stocks far above what their assets were conceivably worth. Additionally, the stock bubble encouraged banks to take money out of low-risk securities and put them into high-risk securities. It was much like what happened in 2008, only worse. Or do you think that tariffs caused the 2008 real estate market collapse too?
But a stock market crash isn't a 12 year depression.
The U.S. had a stock market crash, but the policies of Hoover, then FDR prolonged a short term event into a much worse long term event.
Why do you think that FDR was so desperate to get into a war in Europe? His policies weren't working in getting us out of depression.