US STOCKS-Futures edge up after selloff; Yellen testimony on tap
* Twitter bounces in premarket after Tuesday drop
* Whole Foods tumbles after earnings, outlook
* Yellen congressional testimony due
* Futures up: Dow 37 pts, S&P 3.9 pts, Nasdaq 6.75 pts
By Chuck Mikolajczak
NEW YORK, May 7 (Reuters) - U.S. stock index futures edged up on Wednesday, following the biggest drop in the S&P 500 since mid-April, as earnings season began to wind down and ahead of congressional testimony from Federal Reserve Chair Janet Yellen.
* U.S. stocks fell on Tuesday, closing at session lows as the S&P 500 suffered its biggest percentage decline since April 11. AIG dragged on financial shares after disappointing earnings and a slide in Twitter hurt other names in the technology and internet space. Twitter shares rebounded in premarket trading Wednesday, adding 1.5 percent to $32.32.
* Over 20 S&P 500 companies are scheduled to report earnings on Wednesday. Whole Foods Market Inc tumbled 16.8 percent to $39.90 in premarket trading after the organic grocer posted second-quarter results and cut its 2014 outlook on Tuesday.
* Testimony from Fed Chair Yellen to the Joint Economic Committee, scheduled for 10:00 a.m. (1400 GMT), will be closely monitored. While Yellen is largely expected to maintain a dovish policy stance, investors will be searching for clues on how soon interest rates will be raised, which many expect to see beginning in 2015. Continuación...