Six months after a sudden surge by the Swiss franc rocked financial markets around the globe, investors are largely steering clear of bets on a currency they once considered to be among the safest.

Fund managers, many of whom lost money after the Swiss National Bank surprised them by abandoning a limit on the franc's value early this year, say they are reluctant to risk exposing their portfolios lest the currency swings sharply again. Before January, a lack of movement in the franc reflected investors' faith in the SNB cap. Now it reflects uncertainty about what the central bank might do next, they say.