Treasuries headed for the best annual performance since 2011 as global turmoil and low inflation supported prices even while the economy improved.

U.S. government debt fell for a fifth day, the longest skid in three months, amid concern investors are underestimating when the Federal Reserve will raise borrowing costs next year.

U.S. inflation-indexed bonds are outperforming Treasuries this year, recovering from unprecedented losses in 2013, even as consumer prices have stayed in check through the sluggish U.S. economic recovery of the past five years.