Tehran Securities Exchange (TSE) will set the Base Volume for all trading ISIN in its Main and Secondary Markets to one share, and cancel the "trading knot" regulatory mechanism from Monday, December 22, 2025.
Dr. Mahmoud Goudarzi, TSE’s CEO hailed the move as historic, stating: "The landmark decision to eliminate the Base Volume requirement marks the beginning of fundamental reforms in Iran’s capital market microstructure."
He added: "We hope this step and those that follow will gradually bring our market closer to international standards."
This reform follows a proposal by TSE’s Board of Directors and has been formally approved by the Board of Securities and Exchange Organization (SEO). Starting December 22, 2025, the Base Volume for all listed securities on TSE’s Main and Secondary Markets will be uniformly set at one share, and the trading knot restriction will no longer apply.
The recent change is expected to enhance price discovery, improve market liquidity, and strengthen alignment with global market practices.
The Base Volume mechanism was first introduced on TSE in 2003, a period marked by severe volatility and irrational investor sentiment in a small market. This initiative was designed by the market authorities as a regulatory tool to prevent unreasonable price movements in illiquid or shallow trading sessions by capping daily price fluctuations, conditional upon reaching a predefined minimum trading volume. The main objective was to foster relative market stability and improve pricing efficiency in an environment lacking sufficient market depth. As the market has reached a certain level of maturity since the launching of the mechanism, it will be fully eliminated from 22 December 2025.
