Contractionary Issues
From Dickinson College Wiki
The Contractionary Theory:
http://www.shambhala.org/business/goldocean/depsupply.gif
With significantly less money to go around, businessmen could not get new loans and could not even get their old loans renewed, forcing many to stop investing. This interpretation blames the Federal Reserve, especially the New York branch, which was owned and controlled by Wall Street bankers. The Fed was not controlled by President Herbert Hoover or the U.S. Treasury; it was primarily controlled by member banks and businessmen and it was to these groups that the Fed listened most attentively regarding policies to follow.
In Conclusion:
What happens to the quantity of money directly effects what happens to national income and to stock prices.