The S&P 500 rebounded slightly Wednesday after the stock average closed Tuesday at the lowest level since Aug. 20, the latest in a string of negative trading sessions this September.The major index traded ticked up 0.2%. The Dow Jones Industrial Average traded near the flatline. The Nasdaq Composite inched 0.2% higher.Some bullish economic news released before the bell Wednesday helped sooth investor sentiment. The NY Fed's Empire Index, a measure of manufacturing in the region came in at 34.3 f