New A-share trading regulations take effect today, investors need to note three major changes.

Securities Daily reporter Mao Yirong

On July 6, a new change came to A-share trading rules.

On April 24 this year, with the approval of the China Securities Regulatory Commission, the Shanghai Stock Exchange (hereinafter referred to as the "SSE") revised and released the "Shanghai Stock Exchange Trading Rules (2026 Revision)", the Shenzhen Stock Exchange (hereinafter referred to as the "SZSE") revised and released the "Shenzhen Stock Exchange Trading Rules (2026 Revision)", and the Beijing Stock Exchange (hereinafter referred to as the "BSE") revised and released the "Beijing Stock Exchange Trading Rules" (hereinafter collectively referred to as the "New Rules").

The New Rules aim to optimize the securities trading system, promote stable market operations, and better meet investor trading needs. After more than two months of market technical and business preparations, the New Rules were officially implemented on July 6.

From a series of optimization measures in the New Rules, the core content includes optimizing the SSE fund closing trading mechanism, expanding the applicable varieties of after-hours fixed-price trading, and adjusting the price fluctuation limit of mainboard risk-warning stocks (i.e., mainboard ST stocks and *ST stocks). Investors need to pay timely attention to rule changes and prepare in advance for trading strategies, risk management, and other aspects.

Three major exchanges advance simultaneously

The SSE and SZSE will relax the price fluctuation limit of mainboard risk-warning stocks from 5% to 10%. The price fluctuation limit for risk-warning stocks on the ChiNext and STAR Market has been previously unified at 20%, while for the BSE it remains at 30%, all unchanged. At the same time, after-hours fixed-price trading will be expanded from STAR Market stocks and ChiNext stocks to all A-shares and exchange-traded open-end funds (hereinafter referred to as "ETFs").

The SSE plans to unify the trading method for fund products during the closing phase to call auction. Previously, SSE fund products used continuous bidding during the last few minutes of trading. Starting July 6, SSE fund products, including ETFs, LOFs, and REITs, will implement a closing call auction from 14:57 to 15:00, consistent with stocks, and determine the closing price based on the matching result of the call auction. This adjustment helps further enhance the price stability and pricing efficiency of fund products during the closing phase, improving the consistency of market mechanisms. The SZSE has already implemented call auctions for its fund products and will not make changes this time.

The SZSE introduces a market maker system for ChiNext stocks and adjusts the time for confirming the successful conclusion of block trades for ChiNext stocks. The trading of ChiNext stocks can implement a market maker mechanism, and related adjustments help enhance the diversification level of investors and trading strategies for ChiNext stocks, further improve pricing efficiency, and promote market vitality and resilience. The time for confirming the successful conclusion of block trades for ChiNext stocks is adjusted from 15:00 to 15:30 to 9:30 to 11:30 and 13:00 to 15:30. This adjustment helps improve the efficiency of block trades, meet investor trading needs, and attract medium- to long-term capital into the market.

The BSE plans to introduce after-hours fixed-price trading while strengthening trading supervision of risk-warning stocks. Investors can cumulatively buy no more than 200k shares of a single risk-warning stock through bidding trading, block trading, and after-hours fixed-price trading on the same day. The specific implementation time of the relevant adjustments is subject to further notice from the BSE.

"The three major stock exchanges are simultaneously advancing trading rule optimizations, aiming to enhance market pricing efficiency, liquidity, and stability, and better meet diversified investor needs. These adjustments help attract medium- and long-term capital and enhance market vitality," said Zhu Jieyu, chief analyst of BSE at Dongwu Securities.

"This round of rule adjustments is an inevitable choice for the evolution of the market ecosystem," said Tian Lihui, a finance professor at Nankai University, in an interview with Securities Daily. First, after the comprehensive implementation of the registration-based IPO system, there is a need to improve supporting trading mechanisms to enhance price discovery efficiency. Second, the increasing proportion of medium- to long-term capital forces the adaptation of trading mechanisms, with the expansion of after-hours trading providing institutional investors with rebalancing channels and reducing intraday impact. Third, the number of risk-warning stocks is growing, and unifying the price fluctuation limit rules can compress the arbitrage space of "shell resources," guiding the market to focus more on fundamentals. The relevant rule adjustments are both a precise patch to previous system deficiencies and a solid trading foundation for the "orderly entry and exit" market ecosystem under the registration-based IPO system.

Beneficial for improving market liquidity

This revision of trading rules has limited impact on investors' trading operations, but investors still need to pay timely attention to changes in trading rules.

First, adjust the trading habit for SSE fund products in the last few minutes, where orders cannot be canceled in the final three minutes.

Under the original continuous bidding mechanism for fund products, from 14:57 to 15:00, investors could submit limit orders and market orders, and unexecuted orders could be canceled, with trading occurring continuously in real time. After the new rules take effect, consistent with stocks, investors can only submit limit orders in the final three minutes, and orders cannot be canceled, with all orders matched through a unified call auction. Investors need to pay attention to changes in the order submission and matching mechanism during the closing phase.

Lu Zhe, chief economist of Dongwu Securities, told Securities Daily that previously, large amounts of funds concentrated on large-volume buying and selling during the final three minutes from 14:57 to 15:00, which easily caused sudden surges or dumps at the end of the session, distorting the day's closing price. After the new rules, institutional large-scale rebalancing, ETF subscription and redemption hedging, and index rebalancing can be transferred to the after-hours period from 15:05 to 15:30, without disturbing intraday prices, and the closing price can more truly reflect the day's equilibrium level of long and short positions, reducing abnormal fluctuations at the end of the session.

"The new rules can enhance market-wide liquidity and facilitate the entry of medium- and long-term capital," Lu explained. The impact cost of large-scale position building or reduction by allocation-based funds such as pension funds, insurance funds, public funds, and foreign capital significantly decreases, eliminating the need to split trades over multiple days, thereby reducing index tracking errors. The efficiency of ETF subscription and redemption and index rebalancing improves, and the liquidity of broad-based and sector ETFs continues to improve, benefiting continued passive fund inflows into A-shares.

Second, become familiar with the newly added after-hours fixed-price trading method.

After-hours fixed-price trading has no investor suitability threshold, and the minimum order quantity is consistent with bidding trading, extending trading by half an hour compared to bidding trading. For investors with trading needs, after-hours fixed-price trading can be an optional trading method.

It is worth noting that after-hours fixed-price trading executes at the closing price, and investors cannot set their own prices. At the same time, the trading activity level differs significantly from continuous bidding. Investors need to trade rationally based on the closing price and liquidity conditions. Tian Lihui suggested that investors should assess the probability of execution based on liquidity and avoid blindly placing orders.

Finally, participate cautiously in mainboard risk-warning stock trading.

Although the price fluctuation limit for mainboard risk-warning stocks has been relaxed, the related companies still have operational or other major risks. At the same time, the price fluctuation limit rules for ST stocks on different boards are not unified, and investors need to pay attention to distinctions when trading. Investors should fully understand the risk-warning system and trading regulations for stocks, pay attention to the fundamental conditions of the stocks and related risk warning announcements, and cautiously participate in the trading of risk-warning stocks based on their own financial conditions and risk tolerance.