Average US 30-year mortgage rate rises to year-high 4.21 pct

An increase in a key interest rate is expected by the Federal Reserve next week, propelled by signs of strength in the economy.

The benchmark rate stood at 3.68 percent a year ago and averaged 3.65 percent through 2016, the lowest level in records dating to 1971.

Fed Chair Janet Yellen has signaled that the central bank likely will decide at its policymakers' meeting next week to resume raising its key interest rate, reflecting a strengthening job market and inflation edging toward the Fed's 2 percent target.

Investors' views of expanding economic growth and rising inflation drove prices of long-term Treasury bonds lower over the past week.