Stocks opened higher on Thursday amid optimism over Greece's austerity plan, putting the market on track for a fourth day of gains.

The Dow Jones industrial average <.DJI> was up 42.57 points, or 0.35 percent, at 12,303.99. The Standard & Poor's 500 Index <.SPX> rose 4.25 points, or 0.33 percent, at 1,311.66. The Nasdaq Composite Index <.IXIC> added 10.95 points, or 0.40 percent, at 2,751.44.

(Reporting by Caroline Valetkevitch)