NEW YORK ( TheStreet) -- The top 10 performers on the benchmark S&P 500 so far this year include some of the worst stocks of 2011. Sears ( SHLD), Bank of America ( BAC) and Netflix ( NFLX) are among those with the biggest increases in 2012, in contrast to last year, when they plunged between 55% and 61%. The benchmark is up 12%, driven by an improvement in the U.S. economy and increased efforts to solve Europe's debt crisis. In addition, the potential for new monetary stimulus is still on the table based on Fed Chairman Ben Bernanke's speech last week. With such a solid run in the first quarter of 2012, which came after a 11.4% increase in the S&P 500 in the last quarter of 2011, many investors are nervous that a pullback is in the cards. Sam Stovall, chief equity strategist at S&P Capital IQ, says the opposite is more likely. "Since 1945, in the eight times the S&P 500 was up 10% or more in Q1, it gained another 3.3%, on average, in Q2," he says. The 10 best-performing components of the S&P 500 so far this year have gained between 50% and 117%, topped by Sears. Unlike that department-store chain, high-fliers such as Priceline.com ( PCLN) and Salesforce.com ( CRM) rose last year -- and keep moving up. In the reverse order of performance, here are the S&P 500's 10 best-performing stocks in 2012: 10. Pulte Group ( PHM) Performance: up 50.2% (up 26.0% from year-end 2010) Company profile: Homebuilder with a presence in 28 states, mostly in the East, Gulf Coast, Central and West regions of the U.S. Investor takeaway: PulteGroup has benefitted from the improvement in the housing market, which seems to be bouncing along the bottom. Expectations for a solid spring selling season as the economy improves have also played a factor in the more recent performance of the stock. Selling, general and administrative costs at the company are lower than they are at other homebuilders. The company significantly reduced debt in the fourth quarter and now has about $1.2 billion in cash as a cushion.