--- title: "SEMDEX: Methodology" description: "SEMDEX is maintained by Stock Exchange of Mauritius and covers all companies listed on the official market of the Stock Exchange of Mauritius." canonical: https://www.getswoopr.com/stocks/indexes/semdex/ source: "Swoopr Investment: https://www.getswoopr.com" --- # SEMDEX: What It Measures and How It Is Built ## Direct Answer > The SEMDEX is a rule-based measurement of all companies listed on the official market of the Stock Exchange of Mauritius, maintained by Stock Exchange of Mauritius. 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 SEMDEX covers all companies listed on the official market of the Stock Exchange of Mauritius, within the Mauritius market. Stock Exchange of Mauritius 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 Each company's market value is its total ordinary shares issued times the closing price, divided by a base value through a divisor. The formula uses issued shares, not a float adjusted count, and cash dividends are not adjusted for although special dividends are. 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 Since 12 September 2016 only ordinary shares listed and traded in rupees on the Official Market count, for companies incorporated in Mauritius or an acceptable foreign jurisdiction. Free float tests apply: 200 shareholders, MUR 20 million market capitalisation and 25% in public hands, with 15% or 10% allowed if the company undertakes to reach 20% by year 3 and 25% by year 5, and 10% only if market capitalization exceeds MUR 2 billion. 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. ## The rule that surprises people A suspended constituent stays in the index at its suspension price until the suspension of dealing is removed. ## References - [Stock Exchange of Mauritius: Stock Exchange of Mauritius, SEMDEX index description and eligibility](https://www.stockexchangeofmauritius.com/products-market-data/indices/semdex), as published 2026. Every rule described on this page is taken from this document. ## Current SEMDEX constituents Stock Exchange of Mauritius publishes and licenses the SEMDEX constituent list. Swoopr does not republish it here. The provider's own page is the authoritative source for current membership and weights. [Stock Exchange of Mauritius: official SEMDEX page](https://www.jse.co.za/services/market-data/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 SEMDEX? Stock Exchange of Mauritius maintains the SEMDEX and publishes the methodology document that defines its eligibility and weighting rules. ### What does the SEMDEX measure? It measures all companies listed on the official market of the Stock Exchange of Mauritius. 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 SEMDEX constituents? Stock Exchange of Mauritius 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.