--- title: "ATHEX Composite: Methodology" description: "ATHEX Composite is maintained by Athens Exchange and covers broad Greek equity benchmark. How it selects and weights its constituents, and what it measures." canonical: https://www.getswoopr.com/stocks/indexes/athex-composite/ source: "Swoopr Investment: https://www.getswoopr.com" --- # ATHEX Composite: What It Measures and How It Is Built ## Direct Answer > The ATHEX Composite is a rule-based measurement of broad Greek equity benchmark, maintained by Athens 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 ATHEX Composite covers broad Greek equity benchmark, within the Greece market. Athens Exchange defines which securities are eligible, how they are selected from that pool, and how much each one contributes to the published number. The index name does not state a fixed company count, so the number of constituents follows the eligibility rules rather than a target. ## How constituents are weighted Weighted by free float capitalization. Capping is applied semiannually: any share above 10% is capped at 10% and any sector of economic activity above 40% is capped at 40%. A total return version also exists that reflects reinvestment of cash distributions. 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 The first 60 shares of the Main Market ranking list that are classified High Trading Activity or Medium Trading Activity at the end of the evaluation period. Only one voting ordinary share line per company counts, actual free float must be at least 15%, the share must trade under continuous automatic matching, and it must have traded on at least half the business days of the period. 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 A share needs a minimum trading history of 30 business days after the start of official unconditional trading. A new IPO whose total market capitalization is above 2% of the index, or whose free float value ranks above 10th, can be added before the second business day after announcement, and the count rises by one until the next review. 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 Semiannual reviews cover 1 November to 30 April and 1 May to 31 October, with changes implemented after the close on the third Friday of June and December. Capping uses prices from the second Friday of the same months, and a reserve list of five stocks is published. 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 ranking blends 40% average market capitalization with 60% total trading value, so trading counts more than size, and only shares in the HTA and MTA categories compete for the 60 slots. ## References - [Athens Exchange: Athens Stock Exchange, Ground Rules for the Management and Calculation of the ATHEX Index Series, version 2.22, July 2025](https://www.athexgroup.gr/sites/default/files/2025-07/ATHEX_Composite_Index_Ground_Rules_V2_22_Jul25_EN.pdf), as published 2025. Every rule described on this page is taken from this document. ## Current ATHEX Composite constituents Athens Exchange publishes and licenses the ATHEX Composite constituent list. Swoopr does not republish it here. The provider's own page is the authoritative source for current membership and weights. [Athens Exchange: official ATHEX Composite page](https://www.helex.gr/el/web/guest/indices) ## Related reading - [All stock market indexes](https://www.getswoopr.com/stocks/indexes/): how indexes are built, weighted and revised. - [Europe indexes](https://www.getswoopr.com/stocks/indexes/europe/): 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 ATHEX Composite? Athens Exchange maintains the ATHEX Composite and publishes the methodology document that defines its eligibility and weighting rules. ### What does the ATHEX Composite measure? It measures broad Greek 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 ATHEX Composite constituents? Athens Exchange 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.