Financial shocks take many forms. Some, such as in 1987 and 1998, involve a sharp increase in risk premia that precipitate a fall in asset prices and that in turn leads to what economists and engineers call "positive feedback" dynamics. As firms and investors move to hedge against future losses and to raise money to meet margin calls, the brake becomes the accelerator: markets come under additional pressure, pushing asset prices lower. Volatility increases. Liquidity in markets for more risky assets falls.
In systems where credit is more market-based and more credit risk is in leveraged financial institutions outside the banking system, a sharp rise in asset-price volatility and the concomitant reduction in market liquidity, can potentially have greater negative effects on credit markets. If losses in these institutions force them to withdraw from credit markets, credit availability will decline, unless or until other institutions in a stronger financial position are willing to step in. The greater connection between asset-price volatility, market liquidity and the credit mechanism is the necessary consequence of a system in which credit risk is dispersed outside the banking system, including among leveraged funds. This does not make the system less stable, though, only different. For if risk is spread more broadly, shocks should be absorbed with less trauma. Moreover, the system as a whole may be less vulnerable to distortions introduced by the moral hazard associated with the access that banks have to the safety net.