The Stock market will be open a full day on December 30, 2011 and close at 4pm EST, regular time. The stock market will be closed on December 31, 2011 & January 1, 2012 due to the weekend.
The Stock Market and Dow Jones will be closed on 1/2/11 January 2, 2012 for the New Years Holiday. The stock market will be open a full day on 1/3/11.