Post-Christmas sales will be in full swing today — and for some retailers every transaction will be crucial, due to sales numbers during the Thanksgiving to Christmas shopping season. 

“The sense I’m getting is that brick-and-mortar retailers are not going to beat expectations,” said Arun Sundararajan, a New York University business school professor. Online shopping is cutting into sales, Sundararajan said.

Bryan Eisenberg, co-founder of the retail consultancy Buyer Legends, is keeping an eye on stores that did not get a big share of shoppers’ attention early on.

“I expect to see really, really big sales for them to kind of do a Hail Mary,” Eisenberg said.

That’s because after Christmas is a final chance to capture holiday dollars. About half of us are expected to return unwanted gifts.  

“And while you’re in store, they’re hoping to capture sales,” Eisenberg said. “We know this is the quarter they have to make it.”

The National Retail Federation expects U.S. consumers will spend some $730 billion this holiday season — up about 4% from last year.