* S&P 500 down for four of the past five sessions
* U.S. shares of BlackBerry soar, panel to explore options
* Tesla Motors falls before the open after downgrade
* Futures down: Dow 56 pts, S&P 7.7 pts, Nasdaq 9.5 pts
NEW YORK, Aug 12 (Reuters) - U.S. stock index futures pointed to a lower open on Monday after shares recorded the biggest weekly decline since mid-June last week and investors found few reasons to buy.
The S&P 500 has fallen in four of the past five sessions, receding from record levels on uncertainty about the Federal Reserve's timing for exiting its stimulus policy. Mixed economic data and the winding down of the earnings season have offered few catalysts for traders.
Many traders are away on holiday in August, contributing to low volume and volatile markets.
Several Fed officials have said the central bank could cut back on its bond-buying as early as next month if the economy continues to improve. But many investors fear the economy will stall without the Fed's continued support, which has helped fuel the S&P's gain of nearly 19 percent in 2013.
"This is a back-and-fill after the remarkable move we've seen this year, and that's healthy," said Chris Bertelsen, chief investment officer of Global Financial Private Capital in Sarasota, Florida.
"There's a lot of hand-wringing about the Fed, and that's being exaggerated in a period with little else to trade off of."
U.S. shares of smartphone maker BlackBerry jumped 7.3 percent to $10.47 in premarket trading after the company said it had set up a committee to explore strategic alternatives that could include joint ventures, partnerships or a sale of the company.
Economic indicators this week include July retail sales on Tuesday and consumer sentiment on Friday. Investors will study the data for insight into the economy as well as for what they could mean for the Fed's exit from stimulus efforts.
Chinese shares rose to a two-month high as the South China Morning Post reported that authorities in Beijing were offering to provide stimulus to key cities and provinces to bolster a slowing economy.
"It looks like a bottom is being" formed for China's slowing economic growth, said Bertelsen, who helps oversee $2.1 billion. "I take heart at that. Investors have been very negative about China, so this is very positive."
S&P 500 futures fell 7.7 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 56 points, and Nasdaq 100 futures slid 9.5 points.
Shares of Apple Inc will be in focus after technology blog AllThingsD reported the company was expected to present a redesigned iPhone in September. Shares added 0.8 percent to $458.05 in premarket action.
Vical Inc shares plummeted 62 percent to $1.38 in premarket trading after the company said it would stop developing its cancer therapy Allovectin after a late-stage trial failed to show that the treatment was significantly better than chemotherapy.
Rockwell Collins Inc agreed to buy Arinc Inc, an aerospace communications firm, for $1.39 billion from Carlyle Group LP.
Tesla Motors Inc dipped 2.7 percent to $148.86 before the market's open after Lazard downgraded the stock.
Food company Sysco Corp shares fell 2.1 percent to $34.29 before the bell after reporting its fourth-quarter results.
Earnings season is winding down, with 446 companies in the S&P 500 having reported. Of those, 68 percent have exceeded analysts' expectations, slightly above the 67 percent beat rate over the past four quarters, Thomson Reuters data showed.
U.S. stocks fell on Friday, posting their biggest weekly decline since mid-June, as investors focused on the timing of the Federal Reserve action.