Indonesia Exchange Tightens Oversight as Sinar Mas Stocks Dominate High-Concentration Watchlist

JAKARTA, Investortrust.id — The Indonesia Stock Exchange (IDX) has expanded its list of High Shareholding Concentration (HSC) stocks after introducing a tougher surveillance methodology, with companies linked to the Sinar Mas Group, one of Indonesia's largest conglomerates, emerging as the most heavily represented names on the watchlist.

The move comes as the exchange rolls out a new Price Impact Ratio (PIR) screening system for companies with market capitalizations exceeding Rp10 trillion ($629 million), marking another step in its broader effort to strengthen oversight of Indonesia's equity market.

Indonesia's equity market has faced growing scrutiny over stocks with limited free float and sharp price swings that can expose investors to heightened volatility.

By tightening surveillance of concentrated ownership structures, the exchange aims to improve market transparency, reduce manipulation risks and strengthen confidence among both domestic and foreign investors.

Among the Sinar Mas-affiliated companies included on the latest HSC list are PT Dian Swastatika Sentosa Tbk (DSSA), PT Sinar Mas Agro Resources and Technology Tbk (SMAR), PT Golden Energy Mines Tbk (GEMS) and PT Ekamas Mora Republik Tbk (MORA).

The updated watchlist also includes several of Indonesia's largest publicly traded companies, including PT DCI Indonesia Tbk (DCII), the country's leading data center operator, PT Barito Renewables Energy Tbk (BREN), PT Bayan Resources Tbk (BYAN), PT Bank Mega Tbk (MEGA) and PT Bank SMBC Indonesia Tbk (BTPN).

Companies from sectors including banking, healthcare, logistics, technology, plantations, real estate and consumer goods also appear on the expanded list.

New Screening Method Targets Market Impact

IDX President Director Jeffrey Hendrik said the exchange has added Price Impact Ratio (PIR) as a formal criterion for identifying potential HSC stocks.

The metric measures how significantly a stock's price moves relative to its trading activity.

"PIR is calculated based on price movements relative to trading velocity," Jeffrey said during a press briefing at the IDX headquarters in Jakarta on Tuesday.

He explained that trading velocity is derived from average trading volume compared with a company's public free-float shares.

"Stocks with low trading volume naturally produce low velocity. When low velocity is accompanied by large price movements, the result is a high PIR. Those are the stocks we will screen for potential high shareholding concentration," he said.

Quarterly Reviews for Large-Cap Stocks

The new PIR methodology will apply to all listed companies with market capitalizations above Rp10 trillion ($629 million).

IDX said the screening will be conducted every three months alongside the exchange's major index reviews, while additional surveillance triggers can still be activated at any time if unusual trading patterns emerge.

Jeffrey said Indonesia currently has 171 listed companies with market capitalizations above the threshold.

The revised methodology initially identified 37 additional stocks for HSC monitoring, expanding the exchange's surveillance universe to more than 50 companies under the enhanced framework.

"We will continue reviewing every reform initiative we have implemented," Jeffrey said.

"We are actively communicating with all stakeholders to gather input on further capital market reforms that we can undertake together."

He said the reforms are designed to ensure Indonesia's stock market remains orderly, fair and efficient.

Foreign Investors Remain Net Sellers

The announcement came as Indonesia's benchmark Jakarta Composite Index (JCI) edged up 0.03% on Tuesday to close at 6,039.

Despite the modest gain, foreign investors remained net sellers, recording net outflows of Rp830.6 billion ($52.2 million).

The largest foreign selling occurred in shares of PT Bank Rakyat Indonesia Tbk (BBRI), Indonesia's largest lender by assets, followed by PT Bank Mandiri Tbk (BMRI) and PT Bank Central Asia Tbk (BBCA), the country's largest private bank.

The continued foreign outflows underscore why regulators are placing greater emphasis on improving market quality and strengthening investor confidence as Indonesia seeks to deepen its capital markets.