U.S. consumer prices rose more than expected in January, adding to fears that inflationary pressures could lead the Federal Reserve to tighten monetary policy at a faster pace.

The Consumer Price Index, or CPI, increased 0.5 percent in January, above expectations for a gain of 0.3 percent, according to data from the Department of Labor. The year-over-year increase was 2.1 percent, above expectations for a 1.9 percent gain.

Core CPI, which excludes volatile food and energy components, rose 0.3 percent from the previous month, above forecasts of 0.2 percent. It is up 1.8 percent on a year-over-year basis. Economists had expected 1.7 percent.

Markets reacted immediately. Before the release of CPI, stock market futures indicated the market would open higher. With the news, stocks are set to open higher. Bond yields rose.

Investors have been focused on the question of inflation in recent weeks. Many believe that higher inflation could prompt the Federal Reserve to raise interest rates at a faster pace, which could slow the economy.