Stocks tumble on Dow Chemical and techs

NEW YORK (Reuters) - Stocks extended declines on Monday as the collapse of a joint venture between Kuwait and Dow Chemical threatened to unravel one of the larger merger deals of the year and overshadowed gains in energy shares.

* Dow tumbled more than 20 percent after Kuwait decided to end a $17.4 billion petrochemical joint venture, igniting worries the largest U.S. chemical company would not be able to buy rival Rohm & Haas . Shares of Rohm & Haas slid more than 17 percent.

* The drop in the Nasdaq outpaced the other major indexes, dragged by large-cap tech companies including Research in Motion , which fell 5.4 percent to $38.65, while Google shed 2.1 percent to $294.04.

* The Dow Jones industrial average <.DJI> was down 129.99 points, or 1.53 percent, at 8,385.56. The Standard & Poor's 500 Index <.SPX> was down 14.10 points, or 1.62 percent, at 858.70. The Nasdaq Composite Index <.IXIC> was down 34.94 points, or 2.28 percent, at 1,495.30.

(Reporting by Chuck Mikolajczak; Editing by Tom Hals)