The 1990s witnessed a series of major international financial crises, for example in Mexico in 1995, Southeast Asia in 1997-8, Russia in 1998 and Brazil in 1998-9. These episodes have revived interest among economists in the study of financial system fragility. Theoretical research has analyzed various problems, such as bank runs, currency attacks and international contagion. Although many approaches have been taken, two main perspectives have emerged. One part of the literature has emphasized the relation between financial crises and weak fundamentals of the economy.