Blue chips traded lower on Friday, but technology stocks clung to modest gains after the Nasdaq market extended its trading hours because of system glitches that halted trading at the nation's second largest stock market for a second day in a row.

The Nasdaq, which suffered a similar outage on Thursday afternoon, said it would keep trading until 5 p.m. EDT (2100 GMT) to make up for the halt. The cause of the problem, which affected the prices quoted for stocks on the last trading day of the second quarter, was not immediately available.

The high-tech sector had lead the market higher earlier in the session as investors bet there may be a light at the end of the tunnel for a sector badly bruised by slowing US economic growth. The Nasdaq Composite Index was up 43 points, or 2.06 percent, at 2,169., according to the latest data.

The Standard & Poor's 500 Index traded up at 2 points, or 0.18 percent, at 1,228.