Dollar slides after Yellen speech; S&P at 2016 high

By Rodrigo Campos NEW YORK (Reuters) - The U.S. dollar dropped sharply and stocks on Wall Street ended at 2016 highs after Federal Reserve Chair Janet Yellen said the Fed should proceed "cautiously" in deciding when to raise interest rates. "Given the risks to the outlook, I consider it appropriate for the Committee to proceed cautiously in adjusting policy," Yellen said in remarks to the Economic Club of New York. Yellen's comments, her first since the Fed held rates steady two weeks ago, appea