British voters' surprise decision to leave the European Union certainly sent a shock through financial markets.In the two days after the June 23 referendum, global markets fell sharply, while in the United States, the S&P 500 index of blue-chip companies dipped 5%.There's no doubt that big events like the so-called Brexit (Britain exiting the E.U.) can rattle investors and set off intense periods of short-term trading. But it's important for those who are investing for long-term goals such as retirement to avoid impulsive behavior when worrisome news strikes.
