The largest U.S. exchange traded fund slipped more than 1% Monday as acrimony in Europe weighed on financial markets. SPDR S&P 500 (SPY) had given up 1.32% by half-past noon Eastern time as investors grappled with the specter of a Greek exit from the eurozone. The ETF holds $146.47 billion in assets. Top holdings Apple (AAPL), Microsoft (MSFT)and Exxon Mobil (XOM) fell roughly a percentage point each.