In this Friday, May 31, 2013, photo, traders use their handheld devices as they work on the floor of the New York Stock Exchange. Uncertainty about the U.S. Federal Reserve's next course of action and a sharp, sudden plunge on Wall Street sent global stock markets lower Monday June 3, 2013. AP Photo/Richard Drew NEW YORK (AP) - Stock indexes are ending higher on Wall Street as traders hope that the Federal Reserve won't move quickly to pull back on its economic stimulus. The Standard & Poor's 500 index ended up nine points at 1,640 Monday, an increase of 0.6 percent. It wavered between gains and losses in early trading, then turned higher in the last hour. The Dow Jones industrial average ended up 138 points at 15,254, a gain of 0.9 percent. Merck had one of the biggest gains in the Dow after reporting encouraging clinical results in a skin-cancer treatment. The Nasdaq composite index rose nine points, or 0.3 percent, to 3,465. More stocks fell than rose on the New York Stock Exchange. Volume was heavier than usual at 3.9 billion shares.