U.S. Federal Reserve

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Czech Republic's Lucie Safarova serves a ball to Italy's Sara Errani during the Fed Cup semifinals in Ostrava, Czech Republic, Saturday, April 19, 2014. (AP Photo/Petr David Josek)

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Italy's Sara Errani returns a ball to Czech Republic's Lucie Safarova during the Fed Cup semifinals in Ostrava, Czech Republic, Saturday, April 19, 2014. (AP Photo/Petr David Josek)

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Czech Republic's Lucie Safarova returns a ball to Italy's Sara Errani during the Fed Cup semifinals in Ostrava, Czech Republic, Saturday, April 19, 2014. (AP Photo/Petr David Josek)

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Federal Reserve Chairwoman Janet Yellen listen to questions after addressing a luncheon at the Economic Club of New York, Wednesday April 16, 2014. Yellen said Wednesday that the U.S. job market still needs help from the Fed and that the central bank must remain intent on adjusting its policy to respond to unforeseen challenges. (AP Photo/Bebeto Matthews)

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This handout photo provided by the International Monetary Fund (IMF) shows IMF Managing Director Christine Lagarde, left, talking with Federal Reserve Chair Janet Yellen prior to the G20 meeting at the IMF/World Bank Spring Meetings, Friday, April 11, 2014, at IMF Headquarters in Washington. (AP Photo/Stephen Jaffe, IMF)