Expanded screening removes market-cap threshold as exchange pushes for greater ownership transparency.
Indonesia’s stock exchange has sharply expanded scrutiny of concentrated share ownership, placing hundreds of listed companies under a new screening framework designed to make its benchmark index more representative and transparent.
HSC List Jumps From 83 to 383 Stocks
The Indonesia Stock Exchange (IDX) has expanded its High Shareholding Concentration (HSC) list to 383 stocks, up from 83 earlier in November. IDX President Director Jeffrey Hendrik said the screening now covers all listed stocks instead of only companies with a market capitalization above Rp5 trillion (approximately S$400 million). The revised methodology added 300 stocks to the HSC category.
New Rule Focuses Directly on Ownership Concentration
Under the revised methodology, a stock can be classified as HSC when 10 or fewer shareholders collectively control at least 92.5 percent of total shares. IDX has also removed the price impact ratio, which previously measured how strongly trading activity affected a stock’s price, from the screening criteria. The exchange said the change allows ownership concentration itself to become the central consideration.
Flagged Stocks Removed From IDX Composite Calculation
The 300 newly identified HSC stocks account for an additional 6.16 percent of the IDX Composite’s market capitalization and are excluded from the benchmark’s calculation effective November 13. The shares remain tradable, and HSC classification does not automatically indicate a violation of capital-market regulations. Companies can be removed from the HSC list by demonstrating improved public share distribution through transactions on the regular market.
Major Listed Companies Also Appear on List
The screening is not limited to smaller issuers. The source reports identify major companies including PT Bayan Resources and PT Barito Renewable Energy among HSC stocks. IDX plans regular reviews of the list and said the exchange and market infrastructure institutions will continue monitoring shareholding information, with sanctions possible if inaccurate information is reported to the public.
Reform Comes Amid MSCI Scrutiny
The tighter screening follows concerns raised by global index provider MSCI about opaque shareholding structures and suspected coordinated trading in Indonesia’s equity market. In October, MSCI launched a consultation on potentially reclassifying Indonesia from emerging-market to standalone-market status, with a final decision due by June 30, 2027. IDX’s decision to exclude HSC stocks from its benchmark is part of broader efforts to improve transparency and make the index more representative of market movements.
The expansion from 83 to 383 HSC stocks represents a significant change in how Indonesia measures ownership concentration and constructs its main stock-market benchmark. For Indonesian investors, the reform increases attention on free float, shareholder distribution, and transparency. For Singaporean and other international investors with exposure to Indonesian equities, the changes are also relevant to how the IDX Composite represents the market and how global index providers assess Indonesia.
Sources: Asia News Network (2026) , The Jakarta Post (2026)
Keywords: IDX HSC Stocks, Indonesia Stock Market, High Shareholding Concentration, IDX Composite, MSCI Indonesia, Stock Ownership
