--- title: "BIST 30: Methodology" description: "BIST 30 is maintained by Borsa Istanbul and covers Turkish blue-chip equity benchmark. How the index selects and weights its constituents, and what it measures." canonical: https://www.getswoopr.com/stocks/indexes/bist-30/ source: "Swoopr Investment: https://www.getswoopr.com" --- # BIST 30: What It Measures and How It Is Built ## Direct Answer > The BIST 30 is a rule-based measurement of Turkish blue-chip equity benchmark, maintained by Borsa Istanbul. 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 BIST 30 covers Turkish blue-chip equity benchmark, within the Turkey market. Borsa Istanbul 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 30 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 Weighted by weighted free float market value: market value times the Capital Markets Board free float ratio and a weighting factor. The standard BIST 30 is uncapped, while separate Capped 10 and Capped 25 versions use capping ratios of 10% and 25% with threshold checks at 15% and 30%. 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 Thirty stocks selected from companies on the Stars Market. Watchlist Market, Venture Capital Market and pre-market stocks and investment trusts are excluded. Candidates are ranked on average free float market value and on daily average traded value over the review period, and the two rankings are merged into one final ranking. 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 Shares need at least 60 days of trading on Borsa Istanbul to enter the selection pool. A large public offering can skip this rule and enter from its fifth trading day, replacing the member with the lowest free float value. 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 Reviewed quarterly with index periods of January to March, April to June, July to September and October to December, announced at least 10 days before each period. The review day for share counts and free float is the last day of November, February, May and August. Rank 25 or higher enters, a member below rank 35 leaves, and 3 substitutes are named. 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 final ranking is not a weighted score: it is built by looking for stocks that sit in the top n of both the free float value list and the traded value list, with the higher free float value winning ties. ## References - [Borsa Istanbul: Borsa Istanbul BIST Market Cap Weighted Stock Indices Methodology (September 2026)](https://borsaistanbul.com/files/bist-mcw-equity-indices-m-eng-202609-clean.pdf), as published 2026. Every rule described on this page is taken from this document. ## Current BIST 30 constituents Borsa Istanbul publishes and licenses the BIST 30 constituent list. Swoopr does not republish it here. The provider's own page is the authoritative source for current membership and weights. [Borsa Istanbul: official BIST 30 page](https://www.borsaistanbul.com/en/sayfa/2316/indices) ## Related reading - [All stock market indexes](https://www.getswoopr.com/stocks/indexes/): how indexes are built, weighted and revised. - [Emerging Markets indexes](https://www.getswoopr.com/stocks/indexes/emerging-markets/): others covering the same region. - [Index concentration](https://www.getswoopr.com/technical-analysis/market-concentration/index-concentration/): measuring how much of an index sits in its largest holdings. - [Index rebalancing and inclusion effects](https://www.getswoopr.com/stocks/corporate-actions-catalysts/index-rebalancing-and-inclusion-effects/): what happens to a stock when index membership changes. ## Frequently Asked Questions ### Who maintains the BIST 30? Borsa Istanbul maintains the BIST 30 and publishes the methodology document that defines its eligibility and weighting rules. ### What does the BIST 30 measure? It measures Turkish blue-chip 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 BIST 30 constituents? Borsa Istanbul publishes the current constituent list. Swoopr does not republish it, because index providers license constituent data and Swoopr holds no such licence. ## About the author The [Swoopr Editorial Team](https://www.getswoopr.com/authors/swoopr-editorial-team/) writes Swoopr Investment's educational library, covering market structure, analysis methods and the mechanics behind the numbers investors read every day. Our [editorial policy](https://www.getswoopr.com/legal/editorial-policy/) and [corrections policy](https://www.getswoopr.com/legal/corrections-policy/) set out how this content is produced, reviewed and fixed when it is wrong.