The main index of the Tehran Stock Exchange, TEDPIX, lost 37,986.61 points or 2.55% to end trading at 1,450,225.
The majority of stocks ended in the negative territory, including 415 tickers or 84% of the total.
Net capital outflow by retail investors amounted to 8.45 trillion rials ($31 million) on Saturday, up 103% compared with a session before.
Stocks moved sideways in the past two weeks after the benchmark hit the psychological 1.5 million-point level. To break past the resistance point, observers say stock market investors are awaiting half-yearly financial reports from major commodity companies.
About 8.8 billion shares valued at 80.6 trillion rials ($298.5 million) changed hands at TSE for the day.
Arian Chimia Tech Industrial Group Company was the biggest winner as its shares went up 4.98% to 30,790 rials per share.
Loghman Pharmaceutical and Hygienic Company incurred the biggest loss among all TSE-listed companies and went down 5% to 45,610 rials per share.
Mobarakeh Steel Company contributed the most to the benchmark's fall, followed by Golgohar Mining and Industrial Company, National Iranian Copper Industries Company and Chadormalu Mining And Industrial Company.
Middle East Mines and Mineral Industries Development Holding Company gave the biggest boost to the benchmark index followed by Social Security Investment Company, Novin Investment Bank and Sabzevar Pars Steel Complex.
IFX Down 2.4%
Iran Fara Bourse's main index, IFX, lost 528.85 points or 2.4% to close Saturday trade at 21,468.
About 3.42 billion shares and securities valued at 378.46 trillion rials ($1.4 billion) were traded at the junior exchange for the day.
Gohar Zamin Iron Ore Company, Pasargad Insurance Company, Arya Sasol Polymer Company and Zagros Petrochemical Company had the most negative impact on IFX.
Sirjan Jahan Steel Complex gave the biggest boost to IFX, followed by Minoo Industrial Group Company, Damavand Power Generation Company and MAPNA Asaluyeh Power Generation Company.