U.S. stock index futures struggled to find direction ahead of the open Tuesday as euphoria over China's pledge to allow the yuan to appreciate faded.
European shares were lower across the board, snapping a 9-session winning streak. Asian indexes ended lower as investors considered the potential negative impacts of a stronger yuan, such as less competitive exports.
The yuan slipped on Tuesday, after Chinese state-owned bank snapped up dollars in what some analysts said may be another way for the Chinese central bank to keep the currency's appreciation in check.
Walgreen reported profit of 47 cents a share that missed Wall Street expectations, sending shares 4.4 percent lower in premarket trading.
On the economic front, the National Association of Realtors will release May existing home sales data at 10 am New York time. Economists are forecasting an increase of 5.0 percent to an annual rate of 6.06 million units from April's 5.77 million annual rate.
The Treasury will sell $40 billion in 2-year notes later, with the results available shortly after 1 pm New York time. It will follow up by selling $38 billion in 5-year notes Wednesday and $30 billion in 7-year notes Thursday.
The Federal Reserve's Open Market Committee begins its two-day policy meeting Tuesday, issuing its latest pronouncement on interest rates and the economy Wednesday at around 2:15 pm.
Earthlink filed a petition with the FCC to block the planned merger of Comcast and NBC Universal (NBC is the parent company of CNBC; both are owned by GE ). Earthlink says the deal would be anti-competitive.
In Europe, a German newspaper reported that the country's borrowing needs are likely to be much lower than forecast for this year and next. The UK is set to announce significant spending cuts and tax hikes in an effort to enact a massive fiscal tightening. And a report from Moody's says Spain's banks are healthier than financial market participants generally believe.