The S&P 400 index was on track for gains of 2.1 percent for the week, its best weekly increase since the start of February, while the S&P small-cap 600 index was on track for 1.8 percent in gains.

The mid-cap index was last at 1,001.29, down 0.03 percent, having crossed 1,000 on Wednesday. On Thursday, the Standard & Poor's 500 index surpassed the key 1,4000 point.

Analysts said hitting the 1,000 point for the mid-cap index could trigger some selling in the short term but the market should regain its footing to move higher after that.

"It's another concern out there that may keep people on the sidelines or another reason for the shorts to hold out. But the fact that you do have a significant short position in the market and sideline money has bullish implications," said Todd Salamone, vice president of research at Schaeffer's Investment Research.

The S&P SmallCap 600 index was down 0.2 percent on the day while the S&P 500 was up 0.2 percent.

Among the day's decliners, Adtran shares were down 5 percent at $30.67 after Credit Suisse and Barclays cut their price targets on the stock.

Shares of Synovus Financial were down 3.7 percent at $2.06 after Credit Suisse cut its rating on the stock and the company announced changes to its board of directors.

Getty Realty shares tumbled 11.5 percent to $14.13 after it reported results late Thursday.

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