Stocks mostly fell on Wednesday in a sixth day of losses as investors worried about the bleak economic outlook and technical market indicators pointed to more weakness ahead.

The S&P 500 has taken out successive lows in the recent downdraft, falling around 6 percent since a peak in early May, with some technical analysts looking for a pullback to the March lows in the index at around 1,250, around 3 percent below its close on Tuesday.

We're midstream in a correction, said Nick Kalivas, an analyst at MF Global in Chicago. The data flow has not been helpful.

On Wednesday, signs of weakness came from Ciena Corp , which reported a wider-than-expected loss and forecast third-quarter revenue below Wall Street's expectations, and from McDonald's Corp , which reported modest same-store sales in the United States.

Ciena's shares fell 12.5 percent to $21.18, and McDonald's fell 0.8 percent to $80.50.

The Dow Jones industrial average <.DJI> dropped 17.71 points, or 0.15 percent, to 12,053.10. The Standard & Poor's 500 Index <.SPX> fell 3.37 points, or 0.26 percent, to 1,281.57. The Nasdaq Composite Index <.IXIC> lost 16.41 points, or 0.61 percent, to 2,685.15.

Stocks reversed tentative gains late in the last session after Federal Reserve Chairman Ben Bernanke acknowledged the economy has slowed but offered no hint the U.S. central bank is considering any more stimulus to accelerate growth.

Limiting losses, the energy sector rose sharply after talks at the oil cartel OPEC in Vienna broke down without an agreement, sending the S&P 500 energy index <.GSPE> up 1 percent.

U.S. light crude jumped over 1 percent after the OPEC talks broke down meeting. In the longer-term investors are worried about the affect of higher oil prices on the consumer.

(Editing by Padraic Cassidy)