US STOCKS-Rite Aid, Pier 1 slide; futures rise on Fed support

* Futures up: Dow 52 pts, S&P 7.5 pts, Nasdaq 15.5 pts (Adds Rite Aid, Pier 1 details, updates trading)

By Rodrigo Campos

NEW YORK, Sept 18 (Reuters) - Shares (Frankfurt: DI6.F - news) of Rite Aid Corp were falling early Thursday, in the highest volume so far on the New York Stock Exchange, after it cut its full-year profit forecast for a second time this year and lowered the top end of its sales forecast.

Shares of the third-largest U.S. drugstore chain were last down 6.2 percent at $6.23 after advancing 31.2 percent so far this year to Wednesday's close.

Another large mover in premarket trading was Pier 1 Imports (NYSE: PIR - news) , down 11.8 percent to $13.70 a day after it slashed its full-year earnings forecast to $0.95-$1.05 per share from $1.14-$1.22 and reported a weaker-than-expected profit for the second quarter.

U.S. stock index futures were rising in light volume on Thursday, setting up the S&P 500 to test resistance at its record high, a day after the Federal Reserve renewed its commitment to keeping rates low.

The Fed said Wednesday it will keep interest rates near zero for a "considerable time," a language supportive of equities and other risky assets. It also indicated it could raise borrowing costs faster than previously forecast when it starts moving, boosting the U.S. dollar.

Data on monthly housing starts and building permits, as well as weekly applications for unemployment insurance, is due at 8:30 a.m. EDT (1230 GMT). The Philly Fed business index is due at 10:00 a.m. (1400 GMT).

Futures snapshot at 7:53 a.m. EDT (1153 GMT):

* S&P 500 e-minis were up 7.5 points, or 0.37 percent, with 46,858 contracts changing hands. At their session high, S&P futures came within 0.25 point of a record peak.

* Nasdaq 100 e-minis were gaining 15.5 points, or 0.38 percent, in volume of 2,616 contracts.

* Dow e-minis were up 52 points, or 0.3 percent, with 5,057 contracts changing hands. (Editing by Bernadette Baum)