Twenty years ago it was commonly believed that deposit insurance had  put an end to banking instability. But now quite the opposite seems to be   the case, particularly as the idea of insuring bank debt has spread from   the United States to other countries and to international protection   through International Monetary Fund largesse.       
The history of banking crises worldwide during the last 20 years reveals  how damaging safety nets can be. Though some see the recent experience as   proof of banks' inherent instability, the last 20 years, when contrasted to   earlier eras, stands out as a uniquely unstable and costly era, with events   that have shown the flaws in bank safety nets.       
  
Losses to U.S. depositors during the Depression (the negative net worth  of banks) were 4% of domestic gross domestic product. Though enormous by   historical standards, such losses are now commonplace. Since 1982 there   have been some 90 banking crises worldwide that have produced losses   comparable to, or in excess of, the U.S. experience during the Great   Depression. In about 20 of those cases, losses have exceeded 10% of GDP,   and in half of those 20 cases, losses have reached more than 20% of GDP.           
At the same time, the recent volatility of aggregate demand and supply  shocks has been small in comparison with those of other eras (including the   1830s, 1850s, 1890s, and 1930s). The last 15 years have seen positive and   relatively stable growth in demand worldwide and an absence of oil price   shocks or other supply-side disturbances. What, then, has produced the   unprecedented wave of banking loss?         
  
A mountain of academic research links the expansion of government bank  safety nets to the new banking "mega-crises" worldwide. The details of   crises vary, but the essential pattern (which fits the U.S. S&L debacle of   the 1980s, the Mexican collapse of 1994, the recent banking crises of   Thailand, Korea, and Indonesia, and the demise of Japanese banks in the   1990s) is the same: When banks know they can count on government bailouts,   they and their creditors have strong incentives to assume higher asset risk   and leverage, especially in response to adverse shocks that reduce bank   capital.               
The upside profits from taking such risk belong to protected banks'  stockholders. The increased downside risk of bank debt is absorbed by   taxpayers, not bank stockholders or debtholders. That protection explains   why bank debtholders are willing accomplices in excessive risk taking. And   government supervisors of banks throughout the world repeatedly have turned   a blind eye to bank losses and risks, because they lack the skills and the   incentives to discipline banks.           
Policymakers refer to the need to modernize the "architecture" of the  financial system to deal with new banking system risks, but they often   mistake the sources of those new risks. Rather than expand the scope of   safety nets, they should consider a "back-to-the future" approach.     
  
From the perspective of the 1980s and 1990s, late 19th century capital  markets and banking systems offer an enviable blueprint-one based on   credible market discipline, not ever-expanding safety nets. Banks knew that   excessive risk taking would be penalized by the marketplace, just as   productive investment opportunities would be rewarded by inflows of funds.   That system was not perfect, but from the perspective of the 1990s it looks   better every year.           
Of course, deposit insurance, for better or worse, is here to stay.
What is needed is a way to introduce market discipline into the deposit  insurance system. The key ingredient here is a mandatory requirement that   banks raise a minimum portion of their funding in the form of credibly   uninsured debt, subordinated to insured bank debt.     
Doing so would force banks to satisfy market perceptions that their risk  is sufficiently low, or suffer market-induced contraction of their risky   assets. Such an approach would stabilize banking systems' responses to   adverse shocks, and protect taxpayers. Plans to impose such a requirement   have been proposed by the Federal Reserve banks of Chicago and Atlanta   since 1988.         
  
Now the Senate Banking Committee is considering the possibility of  adding a subordinated debt requirement to existing bank capital   requirements.   
Not only would such a requirement strengthen the banking system and  protect American taxpayers, it would open the way to significant   deregulation of banking services, by removing the potential for abuse of   deposit insurance.     
The recent consolidation wave and expansion of powers in American  banking has redressed structural inefficiencies, but concerns about the   abuse of deposit insurance remains an important impediment to further   deregulation.     
Concerns that expanding bank powers might unwittingly increase the  safety net "subsidy"-a recurrent theme of Fed Chairman Alan Greenspan's   congressional testimony-must be addressed, and market discipline is the way   to do it.     
Today, the path forward in banking deregulation requires that we borrow  a page from the past by restoring credible market discipline as a core   principle of sound banking.