Move over Black Friday.

The biggest shopping day in terms of holiday sales is expected to be Friday, Dec. 23, while the biggest day in terms of store traffic is expected to be Saturday, Dec. 17, according to RetailNext Inc. It's the first time in many years that Black Friday failed to top either of the lists. 

"As retailers have continued the trend to open more stores on Thanksgiving Day, it has pilfered away both sales and traffic from Black Friday," said Shelley E. Kohan, VP of retail…