I want to know the answer to the following question:
What type downpayments do substandard loans generally have?
All the background I'm provided with is that "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.". Is that enough to answer the question?