Futures lower after stocks log worst week since June; BlackBerry soars

U.S. stock index futures signaled a lower open on Monday, after stocks posted their biggest weekly decline since mid-June last week, following weaker-than-expected gross domestic product data from Japan and as investors looked for reasons to buy.

BlackBerry said its board of directors has formed a special committee to explore strategic alternatives, including going private. Shares soared more than 7 percent in pre-market trading after being temporarily halted following the news. Shares of the troubled smartphone maker have fallen nearly 20 percent this year. Its market value has fallen to $4.8 billion, from $84 billion at its peak in 2008.

"Given the importance and strength of our technology, and the evolving industry and competitive landscape, we believe that now is the right time to explore strategic alternatives," Timothy Dattels, chairman of BlackBerry's Special Committee of the Board, said in a statement.

Separately, Apple is expected to unveil its next-generation iPhone on Sept. 10 ahead of the holiday sales period. Meanwhile, rival Samsung is scheduled to take the wraps off a new Galaxy phone in Berlin, a week ahead of Apple's event, according to sources.

The Japanese Nikkei fell to a six-week low after second-quarter GDP came in at an annualized rate of 2.6 percent, lower than market forecasts of a 3.6 percent gain. However, Japanese officials said the data highlighted the success of "Abenomics", as it marked a third straight quarter of expansion.

Meanwhile, the Shanghai Composite rallied to a 7-week high after a key measure of China's money supply showed a 14.5 percent increase in July on the previous year, and new bank loans grew better than expected.

The data, released late Friday, was the latest sign of a rebound in China's economy, following last week's upbeat industrial production numbers.

(Read more: China data blitz points to stabilizing economy)

Meanwhile, the U.S. Treasury will release details of its budget deficit for July at 2 p.m. ET. Plus, the Federal Reserve will purchase between $1.25 billion and $1.75 billion of 23-30 year Treasury notes.

"We look for the U.S. federal government to have posted a budget deficit of $96 billion in July, which would bring the deficit to $606 billion for the first 10 months of the fiscal year," said Barclays analysts Rahul Bajoria and Laurent Fransolet in a research note.

Among earnings, Sysco slipped after the food distributor posted earnings that fell short of expectations.

General Motors is gradually pulling out of South Korea amid mounting labor costs and militant unionism, according to sources.

In Europe, Greece posted a second-quarter GDP contraction of 4.6 percent year on year, narrowly better than the 5 percent decline analysts had forecast.

—By CNBC's JeeYeon Park (Follow JeeYeon on Twitter: @JeeYeonParkCNBC)

On Tap This Week:

MONDAY: Treasury budget
TUESDAY: Retail sales, import/export prices, business inventories, Fed's Lockhart speaks, Samsung holiday mobile preview; Earnings from Flower Foods, Cree
WEDNESDAY: MBA mortgage applications, producer price index, oil inventories, Fed's Bullard speaks; Earnings from Deere, Macy's, Cisco, NetApp, NetEase
THURSDAY: Fed's Bullard speaks, consumer price index, jobless claims, Empire state mfg survey, Treasury int'l capital, industrial production, housing market index, Philadelphia Fed survey, e-commerce retail sales, natural gas inventories, Fed balance sheet/money supply, Ford analysts mtg; Earnings from Wal-Mart, Kohl's, Applied Materials, Nordstrom
FRIDAY: Housing starts, productivity & costs, consumer sentiment

What's Trending on CNBC.com: