"Investors believe that the economic trajectory is improving," said Stovall. Stocks "do not reflect the true valuations based on where the economy will be at the end of the year."

Among stocks making big moves:

â¿¿ Zynga rose 46 cents, or 15 percent, to $3.53 after the online game maker said two casino games would debut in the United Kingdom Wednesday.

â¿¿ Abercrombie & Fitch rose $1.74, or 3.8 percent, to $47.20, making it the biggest percentage gainer in the S&P 500. The company said late Tuesday that it planned to expand internationally and place greater emphasis on cost control.

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