Investors viewed U.S. Treasurys as a safe investment Monday as Europe tries to resolve its debt crisis.
Over the weekend, the Group of 20 nations ignored Europe's plea for aid and failed to reach agreement on making more money available from the International Monetary Fund for troubled countries. The G-20 countries say Europe should increase its own bailout fund.
The need for the European Union to raise more funds heightened Monday, when ratings agency Standard & Poor's lowered its credit outlook for the current fund, the European Financial Stability Facility, to negative.
The price of the benchmark 10-year Treasury note rose 43.75 cents Monday for every $100 invested. The yield on the benchmark note fell to 1.93 percent from 1.98 percent late Friday.
In other trading, the 30-year bond rose $1.06, pushing its yield down to 3.04 percent from 3.11 percent. The yield on the two-year note inched down to 0.30 percent, from 0.31 percent. The three-month T-bill paid a yield of 0.09 percent, flat from Friday.