The U.S. Commerce Department released personal spending and income figures on Monday. Personal spending was flat in December, missing expectations for a 0.1% gain, after a 0.5% increase in November. November's figure was revised up from a 0.3% rise.

Consumer spending makes more than two-thirds of U.S. economic activity. Consumer spending grew 2.2% in the fourth quarter, after a 3.0% increase in the third quarter.

In 2015 as whole, the U.S. consumer spending climbed 3.4%, after a 4.2% growth in 2014.

This data suggests that American consumers were cautious.

The saving rate climbed was 5.5% in December, up from 5.6% in November.

Personal income increased 0.3% in December, exceeding expectations for 0.2% rise, after a 0.3% gain in November.

In 2015 as whole, personal income rose 4.5%, after a 4.4% increase in 2014. It was the largest rise since 2012.

Wages and salaries were up 0.2% in December, after a 0.5% gain in November.

The personal consumption expenditures (PCE) price index excluding food and energy was flat in December, missing forecasts of a 0.1% increase, after a 0.1% gain in November. November's figure was revised up from a flat reading.

On a yearly basis, the PCE price index excluding food and index remained unchanged at 1.4% in December. November's figure was revised up from a 1.3% gain.

The PCE index is below the Fed's 2% inflation target. The PCE index is the Fed's preferred measure of inflation.