The share offer in Bank Mellat, the Islamic Republic's first partial privatisation of a bank, went ahead despite the Iranian stock market having fallen more than 30 percent since August, as oil prices tumbled.
"Of course the market situation is a problem but valuation is another problem here," a Tehran Stock Exchange official who declined to be named told Reuters, suggesting the requested price had been too high for many investors.
He said the shares traded at about 1,050 rials ($0.11).
Bank Mellat is among Iranian firms and other bodies that are subject to U.S. sanctions, imposed because of what the West says is a bid to build nuclear weapons.
Iran, the world's fourth-largest oil producer, says its atomic programme is peaceful. (Reporting by Fredrik Dahl and Parisa Hafezi; Editing by Andrew Macdonald)