Task: Question Generation
Input (English): Countering Krugman, Peter J. Wallison wrote: "It is not true that every bubble—even a large bubble—has the potential to cause a financial crisis when it deflates." Wallison notes that other developed countries had "large bubbles during the 1997–2007 period" but "the losses associated with mortgage delinquencies and defaults when these bubbles deflated were far lower than the losses suffered in the United States when the 1997–2007 [bubble] deflated." According to Wallison, the reason the U.S. residential housing bubble (as opposed to other types of bubbles) led to financial crisis was that it was supported by a huge number of substandard loans – generally with low or no downpayments.
Output (English): According to Peter J. Wallison, why did the U.S. residential housing bubble led to financial crisis?