Stocks are rising in midday trading on Wall Street, shaking off a sluggish start. A surge in Home Depot's stock is sending the Dow Jones industrial average higher.

The market opened lower Tuesday after European leaders postponed the latest aid package for Greece. The Dow turned positive in the first hour of trading and continued to rise through the morning.

The Dow was up 50 points at 12,865 at noon Eastern. About a third of the gain was attributable to Home Depot, which soared 4 percent after the company delivered a strong earnings report.

The Standard & Poor's 500 index rose six points to 1,386. The Nasdaq composite index was flat at 2,904.

Microsoft fell 3 percent following the sudden departure of the head of its Windows division.