Stocks extended gains on Monday with the Dow industrials up nearly 1 percent as higher oil prices boosted energy shares.

Nasdaq gains were limited after a brokerage downgrade on Biogen Idec pressured the biotech sector.

The Dow Jones industrial average <.DJI> rose 79.88 points, or 0.95 percent, to 8,518.27. The Standard & Poor's 500 Index <.SPX> added 7.02 points, or 0.76 percent, to 925.92. The Nasdaq Composite Index <.IXIC> increased 6.06 points, or 0.33 percent, to 1,844.28.