The main gauge of Tehran Stock Exchange, TEDPIX, shed 15,354.48 points or 1.14% to retreat to at 1,332,948. The benchmark had gained more than 5% a week before.
A total of 462 tickers dropped for the day, accounting for 71% of the total with 29 others closing the session in positive territory.
Net capital outflow by retail investors amounted to 7.08 trillion rials ($27 million) amid panic selling. Retail trade dropped 8% to reach 41 trillion rials ($159m).
About 9.13 billion shares valued at 55.6 trillion rials ($213.8 m) changed hands at TSE for the day.
Trading at TSE and the junior exchange Iran Fara Bourse starts on Saturday and ends Wednesday.
Iran Tractor Forging Company was the biggest winner as its shares went up 4.99% to 4,757 rials per share. Bama Mining Company incurred the biggest loss among all TSE-listed companies and went down 4.99% to 6,090 rials per share.
National Iranian Copper Industries Company contributed the most to the benchmark's fall, followed by Bandar Abbas Oil Refining Company, Social Security Investment Company and Esfahan Oil Refining Company.
Pardis Petrochemical Company gave the biggest boost to the benchmark index followed by Chadormalu Mining And Industrial Company, Shiraz Petrochemical Company and Pars Petrochemical Company.
IFX Down 0.5%
Iran Fara Bourse main index, IFX, lost 87.63 points or 0.48% to close Saturday trade at 18,180. About 2.69 billion share and securities valued at 75.15 trillion rials ($289m) were traded at the junior exchange for the day.
Lavan Oil Refining Company, Saba Tamin Investment Company, Iran Fara Bourse and Arya Sasol Polymer Company had the most negative impact on IFX.
Hormozgan Steel Company gave the biggest boost to IFX, followed by Damavand Power Generation Company, Omid Taban Hour Energy Management Company and Goharan Omid Development Investment Company.