BOSTON ( TheStreet) -- The sovereign debt crisis in Europe and the muddled outlook for the economies of the U.S. and China have squelched investor optimism, pushing down the S&P 500 Index by 5% in the second quarter.That's an abrupt reversal from the first quarter, when the benchmark jumped 12%. On balance for 2012, the S&P 500 is up 6.2%. Market activity at first blush appears to be relatively democratic, as the gain for this year includes increases in nine of the 10 sectors, with 304 stocks advancing and 195 decreasing. But the S&P 500's 6.2% increase in 2012 would be only 4.9% if it were not for iPhone and iPad maker Apple's ( AAPL) 44% surge. Apple is the index's largest component. That performance appears to have set a record for a company's impact on the index, said Howard Silverblatt, Standard & Poor's senior index analyst. On a positive note, violent market swings have been few, with only one day up more than 2% and two days down over 2% in the second quarter -- but both of those days were in June, he added. Financials have been the most volatile sector this year, gaining 22% in the first quarter, then losing 9.2% in the second, resulting in a gain of 10.3% this year. "Large caps have led markets higher this year and should continue to do so," said Citigroup analyst Tobias Levkovic. The S&P 500's rise this year is ahead of the S&P 600 small-cap index's 4% advance and the S&P 400 mid-cap index's 3% advance. And the S&P 100 has appreciated more than 6%, as its member companies have benefited from being industry leaders, which give investors more confidence in them. They also offer more generous dividend yields, now approaching 2.4%, which is about a 35% income premium to the 10-year Treasury's yield. Hence, they are attracting more yield-hungry investors. The top 10 performers on the S&P 500 for the second quarter are in a hodge-podge of industries, ranging from paint company Sherwin Williams ( SHW) to heart-valve device maker Edwards Lifesciences Corp. ( EW).
The closest thing to a trend is the performance of the two largest online travel booking firms, which have seen tremendous growth in demand. They are Expedia ( EXPE) and TripAdvisor ( TRIP). Here are the 10 top-performing S&P stocks in the second quarter in inverse order of their returns in the period: