US stocks briefly pared gains on Thursday after data showed factory activity in the US Mid-Atlantic region grew much more slowly than expected in May. The Dow Jones industrial average was up 41.21 points, or 0.33 percent, at 12,601.39. The Standard & Poor's 500 Index was up 2.97 points, or 0.22 percent, at 1,343.65. The Nasdaq Composite Index was up 6.14 points, or 0.22 percent, at 2,821.14.