Market Is Open on Friday and Monday - No Holiday

From the NYSE:

New Years' Day (January 1) in 2011 falls on a Saturday. The rules of the applicable exchanges state that when a holiday falls on a Saturday, we observe the preceding Friday unless the Friday is the end of a monthly or yearly accounting period. In this case, Friday, December 31, 2010 is the end of both a monthly and yearly accounting period; therefore the exchanges will be open that day and the following Monday.

The next market holiday is on January 17.