* Alcoa to start earnings season after the close
* Finance minister summit eyed
* Futures off: Dow 6 pts, S&P 0.2 pt, Nasdaq 8 pts
By Chuck Mikolajczak
NEW YORK, Oct 9 (Reuters) - U.S. stock index futures edged lower on Tuesday, indicating the benchmark S&P index may fall for a third straight session after a warning from the IMF about global growth prospects.
* The International Monetary Fund cut its projected global output for 2012 to 3.3 percent from 3.5 percent in its latest world economic outlook, warning that a lack of action by policymakers in the U.S. and Europe to fix their economic problems could extend the current slump.
* The IMF warnings comes on the heels of a growth forecast cut for East Asia by the World Bank on concerns China's slowdown could last longer than expected.
* Investors were also eyeing a euro zone finance ministers' meeting and a visit by German Chancellor Angela Merkel to Greece for any signs of progress in dealing with the region's debt crisis.
* On Monday, the euro zone finance ministers and the International Monetary Fund held a "thorough and robust" debate on Greece, but failed to make significant progress in deciding how best to get the country back on track with its bailout program.
* S&P 500 futures slipped 0.2 point and were slightly 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 shed 6 points, and Nasdaq 100 futures dipped 8 points.
* Earnings season gets underway in the United States when Dow component Alcoa Inc reports quarterly earnings. Analysts expect Alcoa's third-quarter results to show it broke even, down from a profit of 15 cents per share a year earlier, according to Thomson Reuters data.
* Analysts forecast third-quarter earnings of Wall Street's S&P 500 companies would fall 2.3 percent from the year-ago quarter, according to Thomson Reuters data, which would be the first drop in U.S. quarterly earnings in three years. According to the data, 91 companies in the S&P 500 have issued negative outlooks versus 21 positive pre-announcements, for a ratio of 4.3, the weakest showing since the third quarter of 2001.
* Recent earnings warnings from large multinationals such as FedEx Corp, Caterpillar Inc and Hewlett-Packard Co which have cited weakness in Europe and China have left investors cautious about the prospects for corporate profits.
* Edwards Lifesciences Corp cut its revenue forecast for the third quarter, as sales of the medical device maker's unique heart valve that was expected to drive results fell short of estimates.
* European shares gave up early gains and turned negative as concerns over slowing global growth and its impact on corporate earnings weighed, although charts signaled a bounce back.
* Asian shares rose but gains were moderated by concerns over global growth prospects, especially in China, and expected weak U.S. corporate earnings.