US STOCKS-Dow, S&P 500 fall on Fed nervousness; Nasdaq inches up

The Dow and S&P 500 fell on Tuesday following a rally in the previous session, hit by declines in commodity-related shares and nervousness ahead of a Federal Reserve meeting. The Nasdaq was up slightly, boosted by shares of Apple (Swiss: AAPL.SW - news) , up 1.7 percent at $127.03, and Facebook (NasdaqGS: FB - news) , up 1.7 percent at $79.36. Among S&P 500 sectors, materials were the weakest with a 1.2 percent decline, led by Dupont, down 3.1 percent at $74.68. "People are waiting for the Fed t