It seems it might be a bad idea to trade *the same* debt *more than once*. Or more than some fixed number of times, maybe. Each time you make a leveraged trade, real information about what is traded is lost, and not fully replaced by the information inherent in the price of the trade.
Leverage is good, it makes new things possible by trading time for money. It is less obvious whether trading based on assets already leveraged -- "mortgaged, having liens, borrowed against" is any good.
