There are some signs that Swedish monetary policy may have reached its limits.

Over the past year, mortgage rates haven't budged and corporate loan rates have seen only marginal declines. That's despite the Riksbank driving its main lending rate well below zero and pushing through wave after wave of record bond purchases to drag down longer-term rates.

Policy is “already so extreme that we've already lost that interest rate sensitivity, and you will get very small effects on the economy from more rate cuts,” said Robert Bergqvist, chief economist at SEB, the Nordic region's biggest currency trader. Rates are unlikely to fall further because banks pass on negative rates to their corporate customers, he said.