Lehman Brothers Holdings Inc. (fka LEHMQ)

[QaB2i]

Lehman's collapse is likely to force some unwinds in the roughly $600 billion market of synthetic collateralized debt obligations (CDOs), which pose one of the biggest deleveraging threats hanging over the market, analysts said.

Synthetic CDOs are pools of credit default swaps (CDS) on 50, 100 or more typically investment-grade U.S. and European corporate credits. These portfolios are divided into tranches, or slices, by degree of risk and sold to investors.