"The goal of Lippmann's group on that winter evening in 2005: to design a new financial product that would standardize mortgage-backed securities, including those based on high-yield subprime loans, paving the way for their rapid growth."
"The trouble was that most creditworthy borrowers had already refinanced their houses at 2003's record-low mortgage rates. To meet demand for mortgage-backed securities, Wall Street had to find a new source of loans. Those still available mainly involved subprime borrowers, who paid higher rates because they were seen as credit risks."