The Nasdaq turned positive on Monday as shares of biotechnology companies advanced, but the drag from retreating commodity prices kept both the Dow and the S&P 500 in negative territory.

* The rise in biotechnology companies followed a brokerage's raised recommendation on Celgene Corp , up almost 5 percent at $55.02.

* A weaker-than-expected reading in a forward-looking measure of the U.S. economy also curbed the broader market.

* The Dow Jones industrial average <.DJI> was down 35.22 points, or 0.36 percent, at 9,784.98. The Standard & Poor's 500 Index <.SPX> was down 3.72 points, or 0.35 percent, at 1,064.58. The Nasdaq Composite Index <.IXIC> was up 4.12 points, or 0.19 percent, at 2,137.00.

(Reporting by Ellis Mnyandu; Editing by Jan Paschal)