Causes of the Great Depression
Second, there are the monetarists, who believe that the Great Depression started as an ordinary recession, but that significant policy mistakes by monetary authorities (especially the Federal Reserve) caused a shrinking of the money supply which greatly exacerbated the economic situation, causing a recession to descend into the Great Depression. Related to this explanation are those who point to debt deflation causing those who borrow to owe ever more in real terms.
Comparisons between the Great Recession and the Great Depression
Nobel Prize–winning economist Paul Krugman predicted a series of depressions in his "The Return of Depression Economics" (1999), based on "failures on the demand side of the economy." On January 5, 2009, he wrote that "preventing depressions isn't that easy after all" and that "the economy is still in free fall." In March 2009, Krugman explained that a major difference in this situation is that the causes of this financial crisis were from the shadow banking system. "The crisis hasn't involved problems with deregulated institutions that took new risks... Instead, it involved risks taken by institutions that were never regulated in the first place."