US STOCKS-Dow, S&P 500 fall on Fed nervousness; Nasdaq inches up
* American Airlines shares up; oil prices fall
* Investors wait for Fed comment on rate hikes
* Indexes: Dow down 0.8 pct, S&P down 0.4 pct, Nasdaq up 0.04 pct (Updates to afternoon)
By Caroline Valetkevitch
March 17 (Reuters) - 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 , up 1.7 percent at $127.03, and Facebook, 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. The energy sector was down 0.9 percent as oil prices fell further, pressured by concerns over a growing supply glut.
Investors were anxious as the Federal Open Market Committee kicked off its meeting, to be followed by a statement from Chair Janet Yellen Wednesday afternoon. Investors hope the statement brings insight into the timing of an interest rate hike.
"People are waiting for the Fed to provide some degree of clarity going forward," said Michael O'Rourke, chief market strategist at JonesTrading in Greenwich, Connecticut. Continuación...