Most businesses and government offices are closed so that folks can get a day off for Saturday's New Year's holiday. Why not the exchanges? Something about Friday being the end of a monthly and yearly accounting period, but Henry Blodget doesn't get it:
What's wrong with THURSDAY? Months often end on Saturdays or Sundays, so in those months the stock exchange isn't open on the final day of the period. So what's so special about months in which there's a holiday?
As you might imagine, trading is super slow today, as it's been all week. Dow is hovering around the line.