Early sales data released Monday and over the weekend suggested a strong start to the US holiday shopping season but analysts said it was too soon to declare victory overall.
As of 1500 GMT, US shoppers had already doled out $531 million in online sales on "Cyber Monday," according to Adobe Analytics.
Cyber Monday, the retail industry's big e-commerce push that comes just days after "Black Friday" opens the holiday shopping season, was expected to yield a total of $7.8 billion, up 18.3 percent from last year and in line to become the biggest e-commerce day in US history.
Online sales on Black Friday itself were also up to $6.2 billion, an increase from last year of 23.6 percent.
Analysts have projected US retail sales will grow between four and five percent in 2018 from the year-ago levels, thanks to a strong labor market that has bolstered consumer confidence.
But analysts at Credit Suisse warned it was still too soon for retailers to uncork the champagne. Key "watch outs" include the possibility that retailers will be forced to deepen discounts, elevated costs to the industry from e-commerce investment and higher inventory levels of some goods that could be problematic.
This year's holiday-shopping season is longer than usual due to an early Thanksgiving.
"There is a lot of time ahead with a longer period until Christmas," Credit Suisse said.
The bank said investors had already been expecting higher sales and that they would need "some improvement in underlying profitability" to push shares up.
Explore further: 'Cyber Monday' sales rise after weekend disappointment