The Institute for Supply Management (ISM) reported on Tuesday its non-manufacturing index (NMI) came in at 55.0 in December, which was 1.1 percentage points higher than the November reading of 53.9 percent. This represents continued growth in the non-manufacturing sector, at a slightly faster rate.

Economists forecast the index to increase to 54.5 last month. A reading above 50 signals expansion, while a reading below 50 indicates contraction.

Of the 18 manufacturing industries, 11 reported growth last month, the ISM said, adding that the respondents are positive about the potential resolution on tariffs.

According to the report, the ISM's non-manufacturing business activity measure increased to 57.2 percent, 5.6 percentage points higher than the November reading of 51.6 percent. That reflected growth for the 125th consecutive month, at a faster rate in December. Meanwhile, the New orders gauge decreased to 54.9 percent, down 2.2 percentage points from the reading of 57.1 percent in November. The Employment indicator fell 0.3 percentage point in December to 55.2 percent from the November reading of 55.5 percent. The Prices Index reading of 58.5 percent was the same as the November figure, indicating that prices increased in December for the 31st consecutive month.