The semi-official Mehr News Agency, citing an official of Iran's Privatisation Organisation, said it was the biggest trading of shares ever on the Islamic Republic's stock exchange.
It said two Iranian consortiums were competing for the stake in Telecommunication Company of Iran (TCI) and Etemad Mobin won, buying each share for 3,409 rials.
The official IRNA news agency said Etemad Mobin belongs to the cooperative foundation of the Guards, whose influence in Iran has grow since hardline President Mahmoud Ahmadinejad came to power in 2005.
Mehdi Aghdaie, deputy director of the Privatisation Organisation, said the stake sold in the telecommunications company amounted to around 10 percent of the stock market's total value.
Analysts say foreign investors are increasingly wary of Iran, the world's fifth-largest oil exporter, due to its dispute with the West over Tehran's disputed nuclear activities.
The gradual sale of TCI, which provides all of Iran's landlines, is part of a wider drive to speed up the sale of state-owned companies, though not in the upstream oil and gas industry which will remain in government hands.
Shares representing 5 percent of the company fetched $360 million when they were sold on the stock exchange last year, stock exchange officials have said.
The Islamic state tried to shake up its lumbering economy in 2004 by overturning an article in the constitution which decreed that core infrastructure should remain state-run.
But private business has shown little appetite for investing in privatisations in Iran, which is under U.N. and U.S. sanctions over its refusal to halt sensitive nuclear work.
(Reporting by Hashem Kalantari and Hossein Jaseb; Writing by Fredrik Dahl; Editing by David Holmes)
