“The negative rate announcement by the BOJ sent investors into dollar assets, pushing up prices of Treasurys. But the yields are still trading within a fundamentally-based range of 1.75%-2.5%,” Guy LeBas, chief fixed income strategist at Janney Montgomerry Scott, told Dow Jones Business News.

However, gains in Treasuries were capped Friday after data showed U.S. economic growth slowed in the fourth quarter. Gross domestic product expanded at a 0.7% annual pace in the past three months, compared to the 2% growth over the third quarter.

U.S. government bonds have been enjoying strong January performances for three consecutive years. Treasuries gained 1.8% this month through Thursday after returning 3% in January 2015 and 1.8% in January 2014, according to Bloomberg.

Year-to-date, IEF gained 2.8% and TLT increased 4.7%.

iShares 7-10 Year Treasury Bond ETF

Max Chen contributed to this article.