IDX Changes Rules: HSC Shares to Be Excluded from the Composite Index from 2 November

Jakarta, CNBC Indonesia — The Indonesia Stock Exchange (IDX) has adjusted the criteria for evaluating the Jakarta Composite Index (JCI). Under the new rules, shares classified as having High Shareholding Concentration (HSC) will no longer be included in the JCI calculation.

According to an information disclosure, the new rules will take effect on 2 November 2026.

The adjustment refers to two provisions: IDX Announcement No. Peng-00148/BEI.POP/05-2021, dated 31 May 2021, on the application of free float in index calculations; and the joint decree of the boards of directors of IDX and the Indonesian Central Securities Depository (KSEI), No. Kep-00047/BEI/03-2026 and KEP-0024/DIR/KSEI/0426, on the designation of concentrated share ownership in listed companies.

IDX said the measure was taken to ensure the index better reflects market dynamics.

Previously, all listed-company shares were included in the JCI calculation, except shares on the Acceleration Board. Under the revised selection criteria, the exclusion is expanded: shares on the Acceleration Board and those classified as HSC will not be counted in the index.

The index calculation methodology will remain unchanged. It will continue to use Capped Free Float Adjusted Market Capitalisation Weighted, with a cap of 9%.

The review schedule is also changing. Reviews were previously conducted in March, June, September and December; going forward, they will take place in January, April, July and October.

The effective dates will also shift from the first trading day of January, April, July and October to the first trading day of February, May, August and November.

IDX has also introduced a new provision for unscheduled reviews, which was not specifically regulated before. Shares added to or removed from the HSC list outside the index review periods will be adjusted in the JCI immediately.