BOSTON ( TheStreet) -- The S&P 500 Index has risen more than 4% in 2011, a faster pace than last year. But, recent geopolitical uncertainty has held back gains.The benchmark for U.S. stocks has fallen from a high of 1,343 reached Feb. 18. Unrest in the Middle East and the subsequent spike in the price of crude oil spooked investors about consumers' tolerance for higher gasoline prices. Then, the earthquake and ensuing nuclear calamity prompted a sell-off. Shares rebounded in the past week, but there are other risks looming -- a host of geopolitical concerns and the threat of slower economic and profit growth. 10 Worst-Performing S&P 500 Stocks of 2011 Amid this backdrop of uncertainty, the following 10 S&P 500 components have delivered outstanding 2011 gains, rising at least 32% and as much as 43%. Below is a look at what propelled their share prices. 10. CBS Corp. ( CBS) is a diversified media company, with television broadcasting, publishing and billboard advertising businesses. The company's stock has jumped 30% in 2011 on strong quarterly results and expectations for higher advertising demand, and rates, as the recovery accelerates. CBS has lucrative broadcasting deals, including the rights to AFC NFL games and to the NCAA Men's College Basketball Championship. Its stock, still reasonably valued, costs 13-times forward earnings, a discount of more than 50% to the media industry average. CBS recently inked a deal with Netflix ( NFLX), which will stream its content online, and was named a Morgan Stanley ( MS) Best Idea. The company is predicted to buy back billions of dollars worth of shares in 2011 and 2012.