Investors at risk as Wall Street repackages debt. Again

In what may be a scary revelation for many investors, it appears that Wall Street is back to its old tricks again in repackaging old mortgage debt into new investment vehicles. For those who have forgotten the events of the last few years, the now-infamous CDOs, or "collateralized debt obligations," were a combination of both solid and risky mortgages squashed together into one instrument. Deemed the safest of all investments thanks to their AAA rating, they were ushered into the marketplace where unsuspecting investors bought them in droves.

Of course, we all know how it played out. After a few years, the bottom fell out of the real-estate market, and the investments -- which relied on portfolios of properties that were expected to continually increase in value -- crumbled too. In the process, they also took down Lehman Bros., dozens of mortgage lenders and the nation's economy.