According to Bloomberg, issuers charged with reviving the U.S. mortgage securities market are creating debt with features not witnessed since the pre-financial crisis. In effect, the instruments are increasing risk levels for investors.

The expanding ways in which investors in the various slices of deals will share cash flows from the underlying loans raise additional “analytical challenges,” Moody’s said today in a report. The structures are creating debt -- with names including super-senior support bonds, exchangeable securities, principal-only notes and pool interest-only bonds -- in which investors in some pieces can have greater losses even with the same levels of loan defaults and repayments.