US stock index futures pointed to a slightly higher open on Tuesday as investors continued to scrutinise a bailout plan for Spanish banks and prepare for critical weekend elections in Greece.

While the euro zone plan to lend Spain up to $125 billion did ease some concerns about the region's debt crisis, the June 17 elections in Greece are still viewed as a major headwind that could result in that country leaving the euro currency.

“There's no clear driver for markets until we get some clarity on Greece and the deal in Spain,” said David Carter, chief investment officer at Lenox Wealth Advisors in New York.

“We'll just drift higher and lower with no real conviction.”

Volatility was expected to persist, with trading volumes light. On Monday, the first trading day after the Spain aid package was announced, shares rallied early in the session before steadily losing ground, ending 1 percent lower.

US equities have been closely correlated to developments in Europe's financial crisis on concerns about how it might impact global growth prospects.

In the United States, recent US economic indicators, notably the May payroll report, have pointed to anaemic growth, while data from China has also been sluggish. The S&P 500 is down 7 percent in the second quarter.

S&P 500 futures rose 8 points and were above 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 added 38 points and Nasdaq 100 futures rose 11.25 points.

Michael Kors Holdings Ltd surged 13 percent to $43.15 in premarket trading after posting stronger fourth-quarter profit growth and giving a strong full-year outlook.

JPMorgan Chase & Co has hired an ex-Goldman Sachs energy trader to expand its customer flow business in Asia amid tightening regulation over proprietary trading, a source close to the matter said.

According to a report in the Wall Street Journal, some JPMorgan executives and directors were alerted to risky practices by a team of London-based traders two years before botched bets cost the bank over $2 billion.

Bank of America Corp rose 0.8 percent to $7.34 before the bell while US Steel Corp rose 0.6 percent to $18.

May US import prices fell 1 percent from April, as expected, according to Labor Department data. Export prices fell 0.4 percent, compared with the expectation for a drop of 1 percent. Data on the May federal budget will be released later Tuesday. - Reuters