Junk Bonds Officially Enter Bubble Territory

 | Sep 21, 2016 12:07AM ET

Marty Fridson, of Standard & Poor’s Global Market Intelligence, reported yesterday that on September 8 the difference between the yield on junk bonds and the company’s estimation of fair value stretched to two-standard deviations of its long-term average. To understand just what this means, Fridson writes:

“a divergence of just one standard deviation qualifies as extreme overvaluation in our analysis.”

Two-standard deviations is far more rare than even this measure of “extreme overvaluation.” In fact, it’s the mathematical threshold Jeremy Grantham uses to define a financial “bubble.”