US stocks mostly gained on Wednesday, but the moves were slim before the US Federal Reserve's expected announcement of a new stimulus plan at the end of its two-day monetary policy meeting. The S&P 500 was up for a sixth straight day, its longest winning streak since August, although gains have been less than 0.5 percent per day, on average, in part due to uncertainty over the "fiscal cliff" negotiations.

Shares of Aetna, the third-largest US health insurer, jumped 4.3 percent to $46.39 a day after the company gave a higher forecast for profit and revenue growth next year. The Dow Jones industrial average edged up 7.44 points, or 0.06 percent, to 13,255.88. The Standard & Poor's 500 Index rose 2.95 points, or 0.21 percent, to 1,430.79. But the Nasdaq Composite Index slipped 2.98 points, or 0.10 percent, at 3,019.32. A slide in Wal-Mart Stores shares accounted for the biggest point drag on the Dow at midday. Wal-Mart's stock fell 2.3 percent to $69.26 after India's government announced an inquiry into the company's lobbying practices.

Copyright Reuters, 2012