Futures turn narrowly mixed after S&P 500 logs 6-day rally

U.S. stock index futures hovered around the flatline Wednesday, after the S&P 500 posted its sixth-straight gain and as President Barack Obama pledged to explore Russia's diplomatic plan to remove chemical weapons from Syria.

President Obama addressed the nation in a televised speech from the White House on Tuesday evening, saying he would work with allies to force Syria to hand over its chemical weapons. His comments came after Damascus accepted Moscow's proposal to hand over its weapon stockpile in a bid to avoid a U.S.-led attack. Obama voiced skepticism the strategy would work, however, and urged war-weary Americans to support the use of military force if necessary.

Apple tumbled nearly 4 percent a day after the tech giant unveiled two new iPhones. Meanwhile, at least two brokerages lifted their price targets on the company's stock.

(Read more: Would you buy the new low cost iPhone?)

Morgan Stanley edged higher after UBS upgraded the bank to a "buy" rating with a $33 price target, citing its increasingly wealth management-driven business model. Meanwhile, the brokerage downgraded BlackRock to a "neutral" rating, with a $280 target.

Verizon Communications officially launched a massive bond sale, offering $49 billion worth of debt in the biggest-ever corporate issue on record. The deal tops Apple's previous record of a $17-billion offering back in May. The telecoms giant will use the proceeds to replace a bridge loan used to finance its acquisition of Vodafone's stake in Verizon Wireless.

On the economic front, mortgage applications tumbled last week as rates hit their highest for the year, with refinancing activity dropping to its lowest in more than four years, according to the Mortgage Bankers Association.

Wholesale trade data for July is expected at 10 a.m. And the Energy Department is slated to issue its weekly oil and gasoline inventories report at 10:30 a.m.

The government is scheduled to auction $21 billion in 10-year notes with the results available shortly after 1pm ET.

Barclays analysts noted that recent auction performance had weakened amid heightened volatility.

"The bid-cover ratio has declined sharply, and none of the auctions has come through since March of this year. Consistent with this, domestic investment fund participation has declined sharply, offset partially by an increase in foreign demand," said Ajay Rajadhyaksha and Dean Maki in a note on Wednesday.

Investors will also be looking ahead to next week's Federal Open Market Committee meeting amid expectations that the central bank could announce a tapering of its bond-buying program.

On Tap This Week:

WEDNESDAY: Wholesale trade, oil inventories, 10-yr note auction; Earnings from Men's Warehouse
THURSDAY: Jobless claims, import & export sales, natural gas inventories, 30-yr bond auction, Treasury budget, Fed's balance sheet/money supply, Dell shareholder vote; Earnings from Kroger, Lululemon, Ulta Salon
FRIDAY: PPI, retail sales, consumer sentiment, business inventories, Wal-Mart holiday layaway begins

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