The 30-year sale was the final leg of this week's $64 billion quarterly refunding.
The ratio of bids to the amount offered was 2.41, which was the lowest since August but above its 12-month average of 2.35.
Fund managers, foreign central banks and other indirect bidders bought 60.25 percent of the latest 30-year issue, up from 56.39 percent at the prior auction in October.
Small bond dealers and other direct bidders bought 10.16 percent, less than October's 15.52 percent which was the most since December 2014.
Primary dealers or the top 22 Wall Street firms that do business directly with the Federal Reserve, purchased 29.58 percent, more than October's 28.10 percent and their biggest share since August.