Stocks fell sharply in Europe and Asia on Monday, and markets in New York appeared headed for a slump at the opening bell, as Greece’s financial difficulties spread worries about possible broader harm to the global financial system, and Chinese investors endured another topsy-turvy session. The Euro Stoxx 50 index of eurozone blue chips fell 4.6 percent shortly after the opening and by midmorning was still off 3.5 percent. The FTSE-100 index in London dropped 2.2 percent to start, moving to 1.56 percent lower by midmorning. In Greece, b anks and markets are closed until July 6, after Prime Minister Alexis Tsipras interrupted last-ditch debt negotiations early Saturday with the announcement that he was calling a referendum for July 5 on whether to accept the tough terms offered […]