The deflation spiral http://en.wikipedia.org/wiki/Great_Depression
The Great Depression was triggered by a sudden, total collapse in the stock market. The stock market turned upward in early 1930, returning to early 1929 levels by April, though still almost 30 percent below the peak of September 1929. Together, government and business actually spent more in the first half of 1930 than in the corresponding period of the previous year. But consumers, many of whom had suffered severe losses in the stock market the previous year, cut back their expenditures by ten percent, and a severe drought ravaged the agricultural heartland of the USA beginning in the summer of 1930.
In early 1930, credit was ample and available at low rates, but people were reluctant to add new debt by borrowing. By May 1930, auto sales had declined to below the levels of 1928. Prices in general began to decline, but wages held steady in 1930, then began to drop in 1931. Conditions were worse in farming areas, where commodity prices plunged, and in mining and logging areas, where unemployment was high and there were few other jobs. The decline in the US economy was the factor that pulled down most other countries at first, then internal weaknesses or strengths in each country made conditions worse or better. Frantic attempts to shore up the economies of individual nations through protectionist policies, such as the 1930 U.S. Smoot-Hawley Tariff Act and retaliatory tariffs in other countries, exacerbated the collapse in global trade. By late in 1930, a steady decline set in which reached bottom by March 1933.
Fisher argued that the predominant factor leading to the Great Depression was overindebtedness and deflation. Fisher tied loose credit to over-indebtedness, which fueled speculation and asset bubbles. He then outlined 9 factors interacting with one another under conditions of debt and deflation to create the mechanics of boom to bust. The chain of events proceeded as follows:
Debt liquidation and distress selling
Contraction of the money supply as bank loans are paid off
A fall in the level of asset prices
A still greater fall in the net worths of business, precipitating bankruptcies
A fall in profits
A reduction in output, in trade and in employment.
Pessimism and loss of confidence
Hoarding of money
A fall in nominal interest rates and a rise in deflation adjusted interest rates.
Crowd gathering on Wall Street after the 1929 crash.During the Crash of 1929 preceding the Great Depression, margin requirements were only 10?citation needed] Brokerage firms, in other words, would lend $9 for every $1 an investor had deposited. When the market fell, brokers called in these loans, which could not be paid back. Banks began to fail as debtors defaulted on debt and depositors attempted to withdraw their deposits en masse, triggering multiple bank runs. Government guarantees and Federal Reserve banking regulations to prevent such panics were ineffective or not used. Bank failures led to the loss of billions of dollars in assets. Outstanding debts became heavier, because prices and incomes fell by 20–50?ut the debts remained at the same dollar amount. After the panic of 1929, and during the first 10 months of 1930, 744 US banks failed. (In all, 9,000 banks failed during the 1930s). By April 1933, around $7 billion in deposits had been frozen in failed banks or those left unlicensed after the March Bank Holiday.
Bank failures snowballed as desperate bankers called in loans which the borrowers did not have time or money to repay. With future profits looking poor, capital investment and construction slowed or completely ceased. In the face of bad loans and worsening future prospects, the surviving banks became even more conservative in their lending. Banks built up their capital reserves and made fewer loans, which intensified deflationary pressures. A vicious cycle developed and the downward spiral accelerated.The liquidation of debt could not keep up with the fall of prices which it caused. The mass effect of the stampede to liquidate increased the value of each dollar owed, relative to the value of declining asset holdings. The very effort of individuals to lessen their burden of debt effectively increased it. Paradoxically, the more the debtors paid, the more they owed. This self-aggravating process turned a 1930 recession into a 1933 great depression..http://en.wikipedia.org/wiki/Great_Depression#Causes