Extract the answer to the question from the following context. Question: What is a house loan called? Context: Others have pointed out that there were not enough of these loans made to cause a crisis of this magnitude. In an article in Portfolio Magazine, Michael Lewis spoke with one trader who noted that "There weren't enough Americans with [bad] credit taking out [bad loans] to satisfy investors' appetite for the end product." Essentially, investment banks and hedge funds used financial innovation to enable large wagers to be made, far beyond the actual value of the underlying mortgage loans, using derivatives called credit default swaps, collateralized debt obligations and synthetic CDOs.
A:
mortgage