Mixed Day on Wall Street

Updated from 3:03 p.m. EDT

Blue chips closed lower Thursday as traders fretted ahead of a speech from the Federal Reserve chairman, but tech shares managed to survive a rocky session and eke out a gain.

The Dow Jones Industrial Average fell 50.56 points, or 0.38%, to 13,238.73, with only six of the index's 30 components finishing with gains. The S&P 500 slipped 6.12 points, or 0.42%, at 1457.64.

The Nasdaq Composite tacked on 2.14 points, or 0.08%, at 2565.30. The index was boosted by a 1.6% rise in shares of tech giant Apple (AAPL Quote), which is expected to introduce an update to its iPod MP3 player line of products at a conference next week.

As has been the case for much of the pre-holiday week, volume was on the light side. On the New York Stock Exchange, roughly 2.65 billion shares changed hands, with decliners topping advancers by a 10-to-7 margin. Only 1.74 billion shares traded on the Nasdaq, with losers topping winners 3 to 2.

"We're in the kind of environment where the market is changing directions on a short-term basis based on very little news," said Edgar Peters, chief market analyst with Pan Agora. "There is a limit to how far we can go down, so we're showing some resilience."

On Wednesday, the major averages rebounded from a Tuesday selloff after news that Federal Reserve Chairman Ben Bernanke had sent a letter to New York Sen. Chuck Schumer saying the central bank would "act as needed" if the economy appeared to be in trouble due to the shakiness of the credit markets.

The Dow jumped 247.44 points, or 1.9%, to 13,289.29, and the S&P 500 added 31.40 points, or 2.19%, to 1463.76. The Nasdaq rose 62.52 points, or 2.5%, to 2563.16. The rally in the major averages erased most of Tuesday's large drop.