This is the key figure re: the buyout boom. Bolding is mine. My guess is that someone is mispricing risk here...
The debt markets are a potentially bigger threat, though not clearly an immediate one. Investors have a huge appetite for corporate debt, in part because default rates are historically low, and are willing to accept relatively skimpy returns for it. In recent weeks, the additional interest that even the riskiest corporate bonds pay over Treasurys has fallen to a record low. This so-called spread, which is a proxy for investors' appetite for risk, is currently around 2.5 percentage points, according to Merrill Lynch data. It was at 3 percentage points at the start of this year, while in 2002 it stood at more than 10 percentage points.
From WSJ ($)