U.S. stocks cut initial gains on Thursday, briefly sending the Dow industrials into negative territory as investors pulled out of defensive shares, including pharmaceuticals.

* Investors remain on edge as the second-quarter earnings season gets under way and search for fresh catalysts to propel the market higher.

* The Dow Jones industrial average <.DJI> added 15.87 points, or 0.19 percent, to 8,194.28. The Standard & Poor's 500 Index <.SPX> rose 3.26 points, or 0.37 percent, to 882.82. The Nasdaq Composite Index <.IXIC> gained 7.13 points, or 0.41 percent, to 1,754.30.

(Reporting by Leah Schnurr; editing by Jeffrey Benkoe)