Direct Answer
The IDX80 is a rule-based measurement of Indonesian large and mid-cap equity benchmark, maintained by Indonesia Stock Exchange. Like every index it owns nothing: it is a number produced by applying a published weighting formula to a selected list of companies, revised on a schedule the provider sets.
What this index covers
The IDX80 covers Indonesian large and mid-cap equity benchmark, within the Indonesia market. Indonesia Stock Exchange defines which securities are eligible, how they are selected from that pool, and how much each one contributes to the published number.
The name states a target of 80 companies. A target is not a guarantee of the exact count on any given day: corporate actions, dual share classes and pending additions all move the real number around it.
How constituents are weighted
Capped free float adjusted market capitalization weighted: market cap times free float ratio, with the weight of any constituent capped at 9% at each periodic review. The capping step is repeated until no stock exceeds the cap.
The weighting method is the single biggest driver of how an index behaves. Two indexes covering the same market can diverge for years purely because they weight differently, which is why comparing index levels without knowing the method tells you very little.
What qualifies for inclusion
Chosen from IDX Composite members. A top 150 rank on 12 month regular market transaction value is required, plus no suspension and daily trading for six months, free float ratio of at least 10% and the IDX minimum free float market cap. Selection weighs liquidity and fundamentals.
Eligibility rules are the part of an index most readers never look at and the part that decides what it can possibly measure. A screen that excludes a whole sector, or admits only one listing venue, shapes the result far more than any day of trading does.
How long a listing must exist first
Stocks must have been listed for at least six months to enter the selection universe.
A seasoning rule is why a large new listing does not appear in an index the week it starts trading. It is a deliberate lag, and it means an index can under-represent a fast-growing part of the market for months at a time.
When the membership is revised
Evaluated quarterly: data months are January, April, July and October, with changes effective on the first trading day of February, May, August and November and announced 5 exchange days before the effective date. Incidental evaluations can occur at any time for significant events.
Reconstitution is the one date an index changes shape by design rather than by price. Funds tracking it have to trade toward the new membership, which is why the schedule matters to anyone holding the tracker rather than only to the provider.
The rule that surprises people
The index sits at the top of a funnel: its 80 constituents become the only universe for LQ45, which in turn is the only universe for IDX30.
References
- Indonesia Stock Exchange: Indonesia Stock Exchange, IDX80, LQ45 and IDX30 Indexes Guide and Methodology (appendix to IDX Announcement Peng-00058/BEI.POP/03-2024), as published 2024. Every rule described on this page is taken from this document.
Current IDX80 constituents
Indonesia Stock Exchange publishes and licenses the IDX80 constituent list. Swoopr does not republish it here. The provider's own page is the authoritative source for current membership and weights.
Related reading
- All stock market indexes: how indexes are built, weighted and revised.
- Emerging Markets indexes: others covering the same region.
- Index concentration: measuring how much of an index sits in its largest holdings.
- Index rebalancing and inclusion effects: what happens to a stock when index membership changes.
Frequently Asked Questions
Who maintains the IDX80?
Indonesia Stock Exchange maintains the IDX80 and publishes the methodology document that defines its eligibility and weighting rules.
What does the IDX80 measure?
It measures Indonesian large and mid-cap equity benchmark. The index is a calculated number applying a weighting formula to a selected list of companies, and it holds nothing itself.
Where can I see the current IDX80 constituents?
Indonesia Stock Exchange publishes the current constituent list. Swoopr does not republish it, because index providers license constituent data and Swoopr holds no such licence.