The private aircraft, which bears a small U.S. flag, arrived at the Mehrabad Airport on Tuesday.
Brett King, one of the bank's executives in Salt Lake City, said the bank acted as a trustee for investors who have a financial stake in the plane.
“We have no idea why that plane was at that airport," he said.
Any U.S. aircraft would typically need prior approval from the Treasury Department's Office of Foreign Assets Control to set down in Iran.
Iranian officials aren't shedding any more light on the mystery.
“We don’t have any information in this regard. I refer you to the owner," said a spokesman for Iran's United Nations mission in New York.
[New York Times]