Important adjustment to A-share indices takes effect tomorrow

The Shanghai Stock Exchange (SSE) website recently published the "Announcement on Revising the Compilation Methodology of the SSE Series Composite Indices." According to the announcement, the Shanghai Stock Exchange and China Securities Index Co., Ltd. have decided to revise the compilation methodology of certain SSE series composite indices. The revisions include: adding a weight cap rule limiting the weight of any single constituent to no more than 15%; and adjusting the removal timing for securities under risk warning 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 remainder of the index compilation methodology remains unchanged. The indices proposed for revision include the SSE Composite Index, the SSE A Share Index, the SSE Free Float Index, and the STAR Composite Index. The revisions to the compilation methodology of the above indices and their derivative indices will be implemented on October 26, 2026.