Shares of children's publisher Scholastic Corp shot up 13.9 percent to $36.68 and hit a nine-year high after it raised its full-year profit forecast.

The stock of Winnebago Industries Inc, up 16 percent at $10.32, was also a top percentage gainer after the motor home maker reported a second-quarter loss but said it shipped 1,001 motor homes in the quarter, up 10 percent from last year. Backlog at the end of the quarter rose 4 percent to 1,004 motor homes.

Coal companies also were among top performers including Arch Coal, up 7.7 percent at $12.32, and Patriot Coal , up 5.7 percent at $6.67.

Stocks in general have benefited from recent stronger-than-expected economic data, which on Thursday boosted the S&P 500 above the 1,400 level for the first time since June 2008.

Among Thursday's data, a U.S. Labor Department report showed new claims for unemployment benefits fell back to a four-year low last week, while producer prices, excluding food and energy, were contained.

"As the stock market recognizes economic improvement it often times rewards smaller companies with larger returns, and that's what's happening today," said Lawrence Creatura, portfolio manager at Federated Clover Investment Advisors in Rochester, New York.

"Often their earnings growth rates are higher, and investors are attracted by that."

The S&P MidCap 400 index was up 0.8 percent while the S&P SmallCap 600 index was up 0.9 percent, both outperforming the benchmark S&P 500, which was up 0.5 percent.

The mid-cap index traded at its highest since July 2011, and is now up 13.9 percent since the end of 2011. The S&P 500 is up 11.5 percent since the end of 2011 while the small-cap index is also up 11.5 percent in that period.

• A Permanent Economic Emergency