U.S. stocks dropped on Thursday as concerns about the financial health of Portugal’s top listed bank gave investors a reason to cash in recent gains. With the Dow and the S&P 500 near record highs, the slide in Europe triggered by financial shares quickly translated into broad selling on Wall Street. Espirito Santo Financial Group, the largest shareholder in Portugal’s Banco Espirito Santo, suspended trading in its shares and bonds, citing “material difficulties” at parent company ESI. Portugal’s benchmark stock index fell 4.2 percent and Italy’s FTSE MIB slid 1.9 percent.