TEDPIX, the TEDPIX's main gauge, finished trade 0.6% lower, shedding 7,385 points, to close the session at 1,238,397 points.
As seen in the past three sessions, the market-cap weighted TEDPIX was dragged down mainly by a selloff in large caps.
Buoyed by promising quarterly reports, the refinery shares were among the few blue chips that gained for the day.
Amid rising demand for stocks in many small-sized listed companies, the equal-weighted index closed in positive territory and gained 0.2%.
Wednesday featured a significant increase in trade value, such that both TSE and junior exchange Iran Fara Bourse reached 351.5 trillion rials ($1.4 billion), up 182% compared with a session earlier.
Refinery shares were among the top traded stocks on Wednesday in terms of trade value.
TSE Trade
About 6.04 billion shares valued at 70.7 trillion rials ($282.8 million) changed hands at TSE on Wednesday.
Trading at TSE and the junior exchange IFB starts on Saturday and ends Wednesday.
Data Processing Iran Company was the biggest winner, as its shares went up 5.96% to 26,120 rials per share.
Social Security Investment Company incurred the biggest loss among all TSE-listed companies and went down 2% to 22,050 rials per share.
Persian Gulf Petrochemical Industries Company contributed the most to the benchmark's fall, followed by Mobarakeh Steel Company, Social Security Investment Company and National Iranian Copper Industries Company.
Parsian Bank gave the biggest boost to the benchmark index followed by Bandar Abbas Oil Refining Company, Tabriz Oil Refining Company and Barakat Pharmaceuticals Group Company.
IFB Down 0.25%
Iran Fara Bourse main index, IFX, lost 43.97 points, or 0.25%, to close Wednesday trade at 17,590.0.
About 4.53 billion securities valued at 281.5 trillion rials ($1.12 billion) were traded in the junior exchange for the day.
Zagros Kowsar Power Generation Company had the highest number of traded shares, as 800 million shares worth 8 trillion rials ($32 million) were traded.
Pasargad Insurance Company, Arya Sasol Polymer Company, Saba Tamin Investment Company and Middle East Mines and Mineral Industries Development Holding Company had the most negative impact on IFX.
Shiraz Oil Refining Company gave the biggest boost to IFX followed by Damavand Power Generation Company, Tabas Parvardeh Coal Company and Day Insurance Company.