The researchers found that rising home prices up to 2003 could be explained by economic fundamentals, such as low unemployment rates, expanding household incomes and population growth. These factors fueled housing demand and, in turn, increased U.S. home prices. During this time, Fannie Mae and Freddie Mac actively issued and purchased conventional, conforming mortgage-backed securities.
But in 2003, political, regulatory and economic factors – including accounting irregularities that led to their senior officers’ resignations and the capping of their retained loan portfolios – forced the two entities to significantly slow their lending volume. Private funding in the form of asset-backed securities and residential mortgage-backed securities replaced conventional, conforming mortgage-backed securities as the prevalent source of mortgage capital.
The new credit environment allowed looser underwriting standards and increased tolerance for riskier, high-yield loan products. Such products included adjustable-rate mortgages with low initial “teaser” rates, Alt-A loans that did not require income verification and nonowner-occupied investor products. This borrowing climate provided previously marginal borrowers with additional access to credit. The credit market shift led to a record increase in total mortgage volume and pushed up home prices with momentum characteristic of a bubble.
The researchers also determined that interest rates did not significantly affect house prices. The finding defied conventional wisdom that ties interest rates directly to the monthly cost of housing and assumes an effect on purchase prices.
“These findings help us understand that the government can have a major role in affecting the mortgage and housing markets,” Vandell said. “It’s important policymakers consider this influence when they attempt to shape the markets in the future.”