Deutsche Bank AG was one of the few firms surveyed by Bloomberg in January to correctly predict the worst rout in the U.S. Treasury market since 2009. Now, Germany's largest lender says it's time to buy.

"The economy isn't growing as strongly as we'd hoped," Dominic Konstam, the New York-based global head of interest-rate research at Deutsche Bank, said in a telephone interview on Oct. 28, one day before a measure of U.S. consumer confidence plunged by the most in more than two years.

Given up for dead less than six months ago by Bill Gross, who oversees the world's biggest bond fund at Pacific Investment Management Co. (Pimco), the three-decade bull market in debt is showing renewed strength as indicators such as retail sales and jobs growth falter. Last week, a Citigroup Inc. index showed that U.S. economic data began to fall short of analysts' estimates for the first time in three months.