Financial crisis of 2007%E2%80%9308:

Lower interest rates encouraged borrowing. From 2000 to 2003, the Federal Reserve lowered the federal funds rate target from 6.5% to 1.0%. This was done to soften the effects of the collapse of the dot-com bubble and the September 2001 terrorist attacks, as well as to combat a perceived risk of deflation. As early as 2002 it was apparent that credit was fueling housing instead of business investment as some economists went so far as to advocate that the Fed "needs to create a housing bubble to replace the Nasdaq bubble". Moreover, empirical studies using data from advanced countries show that excessive credit growth contributed greatly to the severity of the crisis.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". What contributed greatly to the severity of the financial crisis of 2007?
excessive credit growth