During the past year, yields on long-term U.S. Treasury securities have fallen to historically low levels. In a recent speech at the Federal Reserve Bank of San Francisco, Federal Reserve Chairman Bernanke said these low yields partly reflect cyclical factors, including the slow pace of economic recovery, modest inflation rates, and accommodative monetary policy (Bernanke 2013). However, in addition to cyclical variation, yields have registered a longer-run decline. Indeed, from 1990 to 2012, 10-year U.S. Treasury yields fell fairly steadily from just over 8% to around 2%.