* Whole Foods tumbles after earnings, outlook
* Yellen congressional testimony due
* Futures up: Dow 47 pts, S&P 4 pts, Nasdaq 9.5 pts (Adds data, updates prices)
By Chuck Mikolajczak
NEW YORK, May 7 (Reuters) - U.S. stocks were set to bounce at the open on Wednesday, on the heels of the biggest drop in the S&P 500 since mid-April, as earnings season winds down and ahead of congressional testimony from Federal Reserve Chair Janet Yellen.
* Developments in Ukraine helped sentiment, as Russian President Vladimir Putin said Wednesday he was ready to discuss a way out of the crisis with the head of the Organization for Security and Co-operation in Europe (OSCE).
* 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 look for clues on how soon interest rates will be raised, with many expecting hikes beginning in 2015.
* 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.
* Over 20 S&P 500 companies are scheduled to report earnings on Wednesday. Whole Foods Market Inc tumbled 18 percent to $39.31 in premarket trading after the organic grocer posted second-quarter results and cut its 2014 outlook on Tuesday.
* S&P 500 e-mini futures rose 4 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 e-mini futures gained 47 points and Nasdaq 100 e-mini futures added 9.5 points.
* According to Thomson Reuters data through Tuesday morning, of 397 companies in the S&P 500 that have reported earnings, 67.5 percent beat expectations, above the 63 percent average since 1994 and 66 percent beat rate for the past four quarters.
* Profits are expected to rise 4.6 percent this quarter, down from 6.5 percent growth estimated at the start of the year, but above the low of 0.6 percent in mid-April, according to Thomson Reuters data.
* U.S. nonfarm productivity fell at its fastest pace in a year in the first quarter due to severe weather, leading to the largest gain in unit labor costs in more than a year. Productivity fell at a 1.7 percent annual rate in the quarter, the Labor Department said.
* Mondelez International Inc jumped 9.5 percent to $38.70 before the opening bell after the company posted first-quarter earnings and said it reached a deal with Dutch coffee and tea company D.E Master Blenders 1753 BV to combine coffee businesses.
* Electronic Arts surged 16.9 percent in premarket trading after the video game publisher posted quarterly profit and revenue that beat expectations late Tuesday. (Reporting by Chuck Mikolajczak; Editing by Bernadette Baum)