That, or those who have historically tried to use their assets to manipulate the markets found out about Civil Asset Forfeiture.
They can buy the junk bonds back which they sold to pension funds and retirement accounts. Then, when they are prosecuted and destroyed, all that bad debt evaporates with them. It's an option I didn't consider in my collapse scenarios years ago. In theory, you can "stealth collapse" the market by making the CIA shells hold the bag. These wouldn't be publicly traded entities (most of them, anyway), and not tracked by most of the indexes.