NEW YORK (Reuters) - Stocks extended gains on Wednesday after the Institute of Supply Management said activity in the service sector grew for a second consecutive month.

* The Dow Jones industrial average <.DJI> gained 109.96 points, or 1.13 percent, to 9,881.87. The Standard & Poor's 500 Index <.SPX> climbed 11.29 points, or 1.08 percent, to 1,056.70. The Nasdaq Composite Index <.IXIC> rose 14.36 points, or 0.70 percent, to 2,071.68.

(Reporting by Chuck Mikolajczak; editing by Jeffrey Benkoe)