Real t-bill and bond yields have been falling for decades and are incredibly low right now, even negative (see chart below). With an eye to historical real returns of 2%, folks like Martin Feldstein think that bonds are currently mis-priced and warn that a bond bubble is ready to burst. Investors need to be careful about comparing real interest rates over different time periods. Today's bond is a sleek electronic entry that trades at lightning speed. Your grandfather's bond was a clunky piece of paper transferred by foot. It's very possible that a modern bond doesn't need to provide investors with the same 2% real coupon that it provided in times past because it provides a compensating return in the form of a higher liquidity yield. [By now, faithful readers of this blog will know that I'm just repeating the same argument I made about equity yields .] Here's a way to think about a bond's liquidity yield. Bonds are not merely impassive stores-of-value, they ...