U.S. stock index futures edged lower on Friday as investors locked in profit following steep gains in the previous session and as a strong quarter for equities draws to a close.
* Equities have advanced about 6.2 percent over the past three months, much of it linked to expectations for measures by central banks around the world to boost their economies.
* After those expectations were met, stocks have struggled for direction and trading has been thin, as investors looked to new catalysts amid lackluster data and lowered corporate earnings outlooks. Advance Micro Devices , which cut its outlook in July, has slumped 40 percent to be the S&P's worst performer this quarter.
* While the S&P climbed 1 percent on Thursday, its best daily gain since the Federal Reserved announced a new program of monetary easing September 13, the gain came on a plan for economic reform in Spain that was viewed as going beyond what the European Commission had asked of the country to help it tackle its debt.
* In company news, Nike Inc reported first-quarter earnings late Thursday that beat expectations, though it warned of slowing orders in China, the latest company to caution on how economic weakness in the Asian giant was impacting its business.
* U.S. shares of Research in Motion rocketed 18 percent to $8.45 in premarket trading after the BlackBerry maker reported a smaller-than-expected quarterly loss.
* S&P 500 futures fell 5.4 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures lost 52 points and Nasdaq 100 futures sank 8.5 points.
* The S&P is down 0.9 percent this week so far, for a second straight week in the red, though Thursday's rally sharply narrowed losses from five straight days of declines. The Dow is down 0.7 percent for the week and the Nasdaq is down 1.4 percent.
* There may be volatility on Friday as investors "window dress," or undergo a last-minute push to reposition portfolios ahead of the quarter's end. MetroPCS and Sprint Nextel are the S&P's two biggest gainers in the quarter, with the former almost doubling in value.
* In economic data, investors are looking ahead to August personal income and consumption data at 8:30 a.m. ET (1230 GMT). The Institute of Supply Management Chicago's September manufacturing activity index will be released later, as will the final September read of the Thomson Reuters-University of Michigan consumer sentiment index.
* Income and spending are seen rising modestly while the ISM index is seen holding steady at 53 and the sentiment index is seen moving to 79 from 79.2 in the preliminary report.
* The S&P snapped a five-day losing streak on Thursday, rallying on Spain's economic reform plan. The news overshadowed a weak read on gross domestic product and durable goods, though jobless claims were strong in the week.
(Editing by Bernadette Baum)