U.S. stocks added to gains in early afternoon trading on Thursday after a 30-year U.S. Treasury bond auction was well received.

The Dow Jones industrial average <.DJI> rose 35.97 points, or 0.38 percent, to 9,397.58. The Standard & Poor's 500 Index <.SPX> gained 6.44 points, or 0.64 percent, to 1,012.25. The Nasdaq Composite Index <.IXIC> added 12.60 points, or 0.63 percent, to 2,011.32.

(Editing by Leslie Adler)