"If you're spending $400 on a generator, that could hurt discretionary purchases," said Brian Sozzi, chief equities analyst at NBG Productions.
Flickinger now estimates that holiday sales in November and December will rise 2.1 percent over last year instead of the 3.2 percent he had originally predicted.
A better idea of Hurricane Sandy's effect will come Thursday, when some major retailers like Target Corp. and Macy's will report sales figures for October.
The storm is affecting small retailers as well as large ones. For many small businesses, opening depended on whether employees lived close by or could work remotely. Businesses vulnerable to wind and water damage and power outages were forced to close. The storm also ruined business trips, meetings and presentations.
At Angelo's Civita Farnese, a restaurant in Providence, R.I., the lunchtime crowd didn't surface as usual on Monday. By 12:30 p.m., barely 10 customers were inside, and owner Bob Antignano had no hope of seeing the 200 to 250 he usually serves for lunch.
"It's a wasted day and it looks like tomorrow probably will be as well," Antignano said.
The loss of two days' revenue will wipe out his profit for the month. He will face losses if the restaurant lost power. He would have to close, and the food in his walk-in refrigerator and freezers could spoil.
The cost to insurers is expected to rival the insured damage from Hurricane Irene last year. Damage from Irene cost insurers roughly $5 billion, according to Sterne, Agee & Leach Research. Because the storm is hitting a highly populous region, with "one of the highest concentrations of wealth in the world," the damages are likely to run into the billions, say analysts at Morgan Stanley.
CoreLogic, a private data provider, estimates that there are 284,000 homes worth about $88 billion in the hurricane's path.