U.S. stocks rose, after the first weekly gain since April in the Standard & Poor’s 500 Index, amid data showing stabilization in the housing market and after Greek opinion polls eased concern the country will leave the euro.

Equities rose as the S&P/Case-Shiller index of property values fell 2.6 percent from a year earlier after a 3.5 percent drop in February. Greek opinion polls showed voters warming to parties supporting the European Union’s bailout agreement as political leaders at home and abroad warned of economic catastrophe should the single currency fragment.

Facebook lost 8.1 percent to $29.33. The company’s options trading began today. The stock fell below the prior low of $30.94 set on May 22. Facebook has slumped 23 percent from its initial public offering price of $38.

Vertex Pharmaceuticals Inc. tumbled 15 percent, the most on a closing basis since 2007, to $55.40. The company revised results reported three weeks ago from a study of two cystic fibrosis drugs, saying the combination showed less of a benefit.