--- title: "SEM-10: Methodology" description: "SEM-10 is maintained by Stock Exchange of Mauritius and covers top 10 companies listed on the Stock Exchange of Mauritius by market capitalisation." canonical: https://www.getswoopr.com/stocks/indexes/sem-10/ source: "Swoopr Investment: https://www.getswoopr.com" --- # SEM-10: What It Measures and How It Is Built ## Direct Answer > The SEM-10 is a rule-based measurement of top 10 companies listed on the Stock Exchange of Mauritius by market capitalisation, 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 SEM-10 covers top 10 companies listed on the Stock Exchange of Mauritius by market capitalisation, 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 name states a target of 10 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 Market capitalisation weighted: last transaction price times shares issued and outstanding, with no free float step in the formula. Cash dividends are not adjusted for, except where a payout is large enough to change a company's net assets. 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 ten largest eligible ordinary shares of the Official Market by average market capitalisation. Each needs average value traded of Rs100,000 a session and trading on half of sessions over the prior three months, plus 25% of shares publicly available, which the committee may waive for a large company. Actively trading investment funds are excluded. 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 listed for less than three months are not eligible, either for the index or the reserve list. 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 An independent Index Management Committee meets quarterly on the first Tuesday of January, April, July and October to review constituents. It publishes a reserve list of the five highest ranked shares to replace any constituent removed in between. 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 If fewer than ten shares pass both liquidity tests, the committee fills the index by ranking first on trading frequency, then value traded, then average market capitalisation. ## References - [Stock Exchange of Mauritius: Stock Exchange of Mauritius, SEM-10 index rules and method of computation](https://www.stockexchangeofmauritius.com/products-market-data/indices/sem10), as published 2026. Every rule described on this page is taken from this document. ## Current SEM-10 constituents Stock Exchange of Mauritius publishes and licenses the SEM-10 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 SEM-10 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 SEM-10? Stock Exchange of Mauritius maintains the SEM-10 and publishes the methodology document that defines its eligibility and weighting rules. ### What does the SEM-10 measure? It measures top 10 companies listed on the Stock Exchange of Mauritius by market capitalisation. 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 SEM-10 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.