Just six months ago, money market traders expected the Federal Reserve to raise interest rates by the end of 2013. Now, they see borrowing costs staying at record lows for about three more years as the economic outlook worsens.

Bond market measures from overnight index swaps, which indicate no increase in the federal funds rate until mid-2015, to a 62 percent decline in a measure of volatility in government bonds signal that rates will stay near zero for longer. The gap between two- and five-year Treasury yields, which decreases when traders expect benchmark rates to remain subdued, is more than 50 percent narrower than its average since 2008.

Investor expectations for sluggish growth and low inflation remain intact even though the collapse of Lehman Brothers Holdings Inc., which triggered the worst financial crisis since the Great Depression, happened four years ago. While the economy expanded in the second quarter, the unemployment rate remained above 8 percent for the 43rd-straight month in August.