What was a major financial cause of the 1929 stock market crash?

Institutions and financiers stepped in with bids above the market price to stem the panic, and the losses on that day were modest with stocks bouncing back the next two days.

However, this bounce turned out to be illusory, as the following Monday, now known as Black Monday, the market finished down 13% with the losses exacerbated by margin calls. The next day, bids completely vanished, and the market fell another 12%. From there, the market trended lower until hitting bottom in 1932.

There was a rapid growth in bank credit and loans in the us in 1929