U.S. stock index futures pointed to a lower open on Friday as investors locked in gains at the end of a strong quarter for equities and amid uncertainty ahead of the result of stress tests on Spanish banks.
A plan for economic reform in Spain had sparked a rally Thursday, though the bank stress-test results and a review of Spain's credit rating by Moody's, both due later in the day, could compound the nation's challenges in dealing with its debt.
Investors are also worried about anti-austerity protests across Europe, which could make political maneuvering more difficult.
Trading was light as investors were reluctant to make big moves following Thursday's gains and on the last day of the quarter, when money managers reposition their portfolios. The S&P has advanced 6.2 percent over the past three months.
"People are concerned by the protests (in Europe), which throws fear into people's mind that we could see some kind of easy resolution," said Wayne Kaufman, chief market analyst at John Thomas Financial in New York. "Some people are locking in gains today, especially after an oversold bounce."
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. Shares fell 3.9 percent to $92.25.
U.S. shares of Research in Motion rocketed 16 percent to $8.28 in premarket trading after the BlackBerry maker reported a smaller-than-expected quarterly loss.
S&P 500 futures fell 7.6 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 79 points and Nasdaq 100 futures sank 11.5 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 narrowed the 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.
Wall Street's gains in the quarter were largely 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.
U.S. consumer spending rose in August by the most in six months as households stretched to pay for higher gasoline prices, according to a Commerce Department report. Futures were little changed by the data.
The Institute of Supply Management Chicago's September manufacturing activity index will be released later in the day, as will the final September read of the Thomson Reuters-University of Michigan consumer sentiment index. 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.
Recent data "showed an economy that is threatening to stall out," Kaufman said. "The economy is just not doing what it should be doing at this stage in a recovery."
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.
The S&P snapped a five-day losing streak on Thursday, climbing 1 percent in its best daily gain since the Federal Reserved announced a new program of monetary easing September 13. The rally came on Spain's reform plan and overshadowed a weak read on gross domestic product and durable goods.
(Editing by Bernadette Baum)