U.S. retail sales recorded their biggest drop in more than nine years in December as receipts fell across the board, suggesting a sharp slowdown in economic activity at the end of 2018.

The economy's outlook was further dimmed by other data on Thursday showing an unexpected increase in the number of Americans filing claims for unemployment benefits last week. That pushed the four-week moving average of claims to a one-year high, an indication that job growth was moderating.

There was also little sign of inflation in the economy, with producer prices dropping in January for a second straight month. Moderate inflation and softening domestic demand support the Federal Reserve's pledge to be "patient" before raising interest rates further this year.