All "asset" classes are near-record expensive: bonds, stocks, gold, housing, college education, health insurance policies . . ..
Cliff Asness, here:
So, the bottom line is, as measured by real bond yield, U.S. Treasury bonds are really frickin’ expensive. Measured by the slope of the yield curve they are really frickin’ expensive. But, measured by the average of these two simple variables, they are 60+ year just about record-low frickin’ expensive. This result is not caused by, but is certainly exacerbated by, the (perhaps) surprisingly uncorrelated nature of slope and real bond yield, thus making both so low and at the same time considerably more surprising.