Swiss National Bank chairman Philip Hildebrand has denied any "legal breaches" resulting from currency trades by his wife and said he would not resign.
Kashya Hildebrand bought $US504,000 in August, three weeks before the bank intervened to reduce the value of the Swiss franc. She later sold the dollars to buy a property.
The BBC reports it was the first time Mr Hildebrand has spoken about the matter.
On Wednesday, the SNB published details of an internal investigation by PricewaterhouseCoopers which, it said, cleared the bank head and his family of breaking any rules.
The SNB also published its own internal rules which had not previously been made public.
Mr Hildebrand said his behaviour had been both legally and morally appropriate.