Fed Chairman Ben Bernanke warned on Wednesday the economy remained at risk, but he also cautioned that inflation had risen and was being watched closely by the central bank. (See: "Ben Bernanke: No Surprises") The personal consumption expenditures price index, which excludes food and energy, was left unrevised at an annual 2.7% rate in the fourth quarter, matching forecasts and following 2.0% in the previous three months.