IDX Composite rises on Wednesday amid HSC methodology changes

Jakarta (ANTARA) – The Indonesia Stock Exchange (IDX) Composite Index rose by 13.36 points, or 0.26 per cent, to 5,139.09 at Wednesday’s opening.

The index gained amid changes by the IDX to its methodology for calculating shares with high shareholding concentration (HSC). The changes increased the number of shares on the HSC list to 383, from 83 previously.

“With more shares excluded from the IDX Composite calculation, there is potential for significant changes to the structure and representation of the index,” Phintraco Sekuritas Head of Research Ratnam Lim said in an analytical report in Jakarta on Wednesday.

The HSC Committee decided that the calculation would cover companies in which 92.5 per cent or more of shares are held by 10 or fewer parties.

Ratna said the change could also prompt adjustments to share weightings and potentially lead investors to rebalance their portfolios in the short term.

Meanwhile, market participants should also monitor Indonesia’s retail sales, which slowed in September 2026. Retail sales grew by 0.6 per cent year on year, down from 1.3 per cent in August 2026.

This was the weakest growth since June 2026. The slowdown was driven by inflationary pressure and high borrowing rates.

Nevertheless, retail sales continued to grow for a third consecutive month, indicating that consumer spending has not contracted.

The development warrants attention because it could affect the performance of listed consumer and retail companies, particularly if weaker purchasing power persists.

Market participants should therefore track both changes to the HSC methodology and domestic consumption trends when assessing the IDX Composite’s direction.

Phintraco projects that the index will extend its gains and test the 5,200–5,235 level.