Shanghai Stock Exchange Composite Index Series New Rules Take Effect Today

As the core broad-based index of the A-share market, the Shanghai Composite Index is like a "thermometer" for gauging market conditions. Today, the compilation methodology for the Shanghai Stock Exchange series of composite indices has undergone minor adjustments and optimization. The main content of this revision includes two aspects: first, adding a weight cap rule that limits the weight of any single constituent to no more than 15%; second, adjusting the removal timing for risk-warning securities from "the next trading day after the second Friday of the month following the date of implementation of the risk warning" to "the next trading day after the second Friday of the month following the date of the risk warning announcement." The rest of the index compilation methodology remains unchanged. Tian Lihui, a council member of the China Capital Market Institute and a finance professor at Nankai University, summarized this adjustment as installing a "flow-limiting valve" and a "filter" on the index. Tian Lihui: The Shanghai Composite Index is a long-established bellwether for the A-share market. As the market develops, some ultra-large-cap companies may grow ever larger in market value, while some companies perform poorly and are tagged with the ST label. On the one hand, by setting a weight cap, the index prevents individual giant companies from dominating and "hijacking" the overall market trend. On the other hand, by removing risk-warning stocks earlier, it promptly "escorts" ailing companies out of the sample pool. This addition and subtraction together reflect the regulator's determination to purify the index ecosystem at the underlying algorithm level, ensuring that the index levels we see can objectively, fairly, and truthfully reflect the overall quality and industrial transformation of Chinese listed companies.