U.S. stocks fell on Thursday after the health of Portugal's top listed bank was questioned, bringing back to markets the specter of a weakened Europe. With U.S. stocks near record highs, the slide in Europe translated into broad selling on Wall Street. Many market participants have called for a pullback, with the steady S&P 500 yet to see a daily decline of 1 percent or more since April 10. Espirito Santo Financial Group (ESF.LS), the largest shareholder in Portugal's Banco Espirito Santo (BES.LS), suspended trading in its shares and bonds, citing "material difficulties" at parent company ESI. Shares of the bank fell ... (full story)