Here is a very interesting paper showing real analysis of the data to illustrate that the deteriorating condition of loans should have been caught by those financing such loans years before the mortgage crisis erupted. Understanding the Subprime Mortgage Crisis by Yuliya Demyanyk, Federal Reserve Bank of Cleveland and Otto Van Hemert, New York University.
In many respects, the subprime market experienced a classic lending boom-bust scenario with rapid market growth, loosening underwriting standards, deteriorating loan performance, and decreasing risk premiums.30 Argentina in 1980, Chile in 1982, Sweden, Norway, and Finland in 1992, Mexico in 1994, Thailand, Indonesia, and Korea in 1997 all experienced the culmination of a boom-bust scenario, albeit in different economic settings.
Were problems in the subprime mortgage market apparent before the actual crisis erupted in 2007? Our answer is yes, at least by the end of 2005. Using the data available only at the end of 2005, we show that the monotonic degradation of the subprime market was already apparent. Loan quality had been worsening for five years in a row at that point. Rapid appreciation in housing prices masked the deterioration in the subprime mortgage market and thus the true riskiness of subprime mortgage loans. When housing prices stopped climbing, the risk in the market became apparent.