The figures, released Thursday, come after the Commerce Department announced weak December retail sales data that had been delayed by nearly a month because of the government shutdown. The trade group and other analysts are questioning whether the shutdown and resulting delay in collecting the data had made the results less reliable.
The numbers, which include online sales but exclude automobile dealers, gas stations and restaurants, fell short of the trade group's forecast for the November and December period combined to increase anywhere from 4.3 percent to 4.8 percent. The National Retail Federation had forecast that online sales would increase 11 percent to 15 percent, but that sector increased 11.5 percent for the November and December period.
The overall holiday figure marked the weakest growth since 2012 when holiday sales rose 2.6 percent, the trade group said. "The combination of financial market volatility, the government shutdown and trade tensions created a trifecta of anxiety and uncertainty impacting spending and might also have misaligned the seasonal adjustment factors used in reporting data," said Jack Kleinhenz, chief economist at the trade group, in a statement.
Kleinhenz said the sales figures tell an "incomplete story" and the group will be in a better position to judge the reliability of the results when the government revises its 2018 data in coming months.
This story has been corrected to show that sales were weakest since 2012, not 2013.