Black Thursday was on October 24th 1929. On Black thursday the stock market dropped a total of 11%. This happened do to all the extravagant spending that happened through out the twenties.
This is the heart of the crash. This is also the day that the great depression started. The date was Tuesday October 29th 1929. On Black Tuesday 16,410,030 stocks were exchanged, causing the loss of billions of dollars.