Treasury Department auctions $13 billion of 30-year bonds at a high yield of 2.681%

Bond prices traded flat on Thursday after the U.S. government's auction of 30-year Treasury bonds, the third of three debt auctions this week.

The Treasury Department auctioned $13 billion in 30-year bonds at a high yield of 2.681 percent, the highest yield since December. The bid-to-cover ratio, an indicator of demand, was 2.18 and much lower than the 2.45 recent average.

The 30-year Treasury, which this week has benefited most from relative-value investment flows caused by Europe's massive bond-buying program, turned flat after the announcement. It was last yielding 2.682 percent after touching a low of 2.634 percent.

Other maturity Treasurys also pared earlier price gains, with the benchmark 10-year yield modestly higher at 2.115 percent.

Treasury prices rallied earlier after the government reported unexpectedly soft U.S. retail sales during February.

The Commerce Department reported shortly after the start of New York trading that U.S. retail sales had unexpectedly fallen for a third straight month in February.

Retail sales dropped 0.6 percent last month, after declining 0.8 percent in January, and were slowed by harsh weather in much of the country. It was the first time since 2012 that sales had dropped for three consecutive months.

"There's been good buying since we got very, very disappointing retail sales," said Justin Lederer, an analyst at Cantor Fitzgerald in New York.

The persistent weakness in retail sales stoked speculation over the timing of interest rate hikes by Federal Reserve policymakers. They meet next week and may move towards ending an era of near-zero U.S. rates by removing the word "patient" from a post-meeting comment.

"Today is not necessarily a game changer for the Fed. I think they take out 'patient' next week and we are still looking at mid-2015 liftoff," Lederer said. "But if we keep getting weak data prints, we could get delays in liftoff."

Three-year and other shorter maturities most affected by changes in Fed interest-rate policies were up more modestly on Thursday, as they have been all week.

Since Monday, when the European Central Bank began a 1.1 trillion euro bond-buying program to battle economic sluggishness, Treasurys have been rallying as foreign investors scoop up much higher-yielding U.S. debt securities.

European bond yields have plumbed record lows this week. The 10-year German bund last yielded 0.237 percent, or about 184 basis points under the 10-year Treasury.