US STOCKS-Futures edge lower, investors seek earnings clarity
* Dow holds above 17,000 on Monday despite decline
* Alcoa to report after market close, revenue seen down
* Groupon rallies in premarket after analyst upgrade
* Futures down: Dow 20 pts, S&P 3 pts, Nasdaq 3.5 pts
By Ryan Vlastelica
NEW YORK, July 8 (Reuters) - U.S. stock index futures edged lower on Tuesday, suggesting a second day of weakness as investors continued to hold off from making big bets going into the start of corporate earnings season.
* Alcoa Inc, among the first high-profile names to report, will release its results after the market closes on Tuesday. The aluminum maker is seen posting profit growth of more than 50 percent, according to Thomson Reuters data, along with a 3.6 percent decline in revenue.
* Recent U.S. economic data has been strong, following a dismal start to the year, and market participants are looking to corporate earnings for confirmation that the economy snapped back in the second quarter. Many analysts are especially looking for an acceleration in revenue growth.
* Profits are seen growing 6.2 percent in the second quarter, according to Thomson Reuters data, a rate that is down from the 8.4 percent growth that had been forecast at the start of April. Revenue is seen up 3 percent. Continuación...