In a research note titled "Mortgage Credit Quality Problems Go Well Beyond Subprime", Goldman Sachs suggests (short excerpt):
According to our (very rough) estimates, the credit quality of so-called “teaser-rate” debt—prime ARMs with very low initial interest rates—is deteriorating at pace that is similar to that of subprime ARMs. Since teaser-rate ARMs typically have a longer reset schedule than subprime ARMs, this suggest that the teaser-rate problem could ultimately well exceed the subprime problem.