Business & economics / Trending Explained
IHSG Explained: Reading Indonesia’s Composite Stock Index
IHSG stands for Indeks Harga Saham Gabungan, commonly called the IDX Composite. It is an Indonesian equity-market index. A change in the index summarizes a basket of shares; it does not describe every company or every investor’s return.
By Farvenzo Explained · Published 22 October 2026 · Sources checked 22 October 2026
Jakarta business-district skyline seen from Hutan Kota GBK, 2024. Archival economic context, not a live stock-market chart.
Photo: Baqotun0023 · Hutan Kota GBK (02-02-2024).jpg / source · CC BY-SA 4.0.
Resized and converted to WebP; full frame retained, with no crop, filters or content edits. WebP renditions are offered under the same licence.
Open the original visual guide ↓
What the exchange says
Indonesia Stock Exchange’s index page describes IHSG as measuring the share-price performance of companies on its Main and Development boards. Its published handbook identifies a market-capitalization-weighted methodology.
The linked handbook is dated 2021. We use it for the basic explanation, not as a current constituent list, a live market quote or evidence of the latest trading day’s return. Current exchange data should be used for those questions.
Why company weights matter
In a weighted index, a larger constituent can influence the headline more than a smaller one. That means a rising index can coexist with declines among many individual shares. Market breadth asks how widely a move is shared across companies.
Reading the headline level together with the date, percentage move and breadth gives a more informative picture than reading the index number alone.
An illustrative two-company index
Imagine a simplified index in which Company A has an 80% weight and Company B has a 20% weight. If A rises 2% and B falls 2%, the weighted move is approximately 1.2%: 0.8 times 2%, plus 0.2 times minus 2%.
This is a teaching example, not an IHSG constituent calculation. It demonstrates how an index can rise even while one of its components falls. Real index maintenance, corporate actions and methodology require the exchange’s rules.
Index performance is not a personal account statement
An investor may hold a different basket, incur fees and trade at different times. A foreign investor can also experience currency effects when translating a local-currency result into another currency.
For example, a local asset gain and a currency depreciation can pull in opposite directions. Evaluating an international return requires both components, not a single market headline.
What the trend does and does not establish
“IHSG” rose in Google’s worldwide Business & Industrial list over the past week. That tells us people were looking for the term. We have not inferred a market rally, crash or specific cause from search growth.
Read next
Our Jio IPO guide explains the difference between a company offering and the broader market. Neither article is a recommendation to trade.
Sources
Keep exploring
- Jio IPO October 2026: Read the Filing Before the Hype →
What Reliance’s October 2026 Jio IPO filing says, how the subscription window works, and why offer price and valuation are different questions.