The Swiss franc has reached a record high against the dollar, with $1 being exchanged for just SFr1.0887 early on Monday.
The view that the US Federal Reserve will drop its main interest rate to ward off a potential recession has weakened the greenback on money markets.
The president of the Swiss National Bank, Jean-Pierre Roth, warned this weekend that there were serious concerns about the future of the US economy.
According to financial specialists, the Swiss franc typically does better at times of risk aversion, thanks in particular to its safe-haven status.
The dollar regained slightly in later trading, reaching SFr1.0927, according to the Dow Jones' Interbank foreign-exchange rates.
The euro also lost ground to the franc, dropping to SFr1.623 in early trading.
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