The Dow and the S&P 500 fell on Thursday, but the Nasdaq composite index cut its losses to briefly turn positive in midday trading.

Vertex Pharmaceuticals Inc was the top gainer on the Nasdaq 100 <.NDX>, climbing 9 percent to $43.86 after IMS Health said it was revising estimates of the number of prescriptions written in late September for Vertex's hepatitis C drug.

The Dow and S&P remained solidly lower after three days of gains as earnings from JPMorgan and soft economic data from China reinforced worries about a slowing global economy.

The Dow Jones industrial average <.DJI> was down 95.06 points, or 0.83 percent, at 11,423.79. The Standard & Poor's 500 Index <.SPX> was down 11.51 points, or 0.95 percent, at 1,195.74. The Nasdaq Composite Index <.IXIC> was down 0.33 points, or 0.01 percent, at 2,604.40.

(Reporting by Ryan Vlastelica; Editing by Kenneth Barry)