In the notoriously difficult art of forecasting foreign exchange movements, traders have been able to rely on one key relationship in recent years. The higher a country’s interest rates, the stronger its currency typically became as investors sought greater returns from yields.

Now traders may have to rethink. Foreign exchange markets could be on the verge of big shift, some strategists believe. The currencies of countries that cut interest rates could be rewarded with higher exchange rates. The pattern of currencies benefiting when central banks raised interest rates and weakening when monetary policy was eased held largely true last year, when cuts from the US Federal Reserve pushed the dollar down to record lows.