--- title: "STAR 50 Index: Methodology" description: "STAR 50 Index is maintained by Shanghai/Shenzhen Stock Exchange and covers Chinese high-tech and innovation equity benchmark. How it weights its constituents." canonical: https://www.getswoopr.com/stocks/indexes/star-50/ source: "Swoopr Investment: https://www.getswoopr.com" --- # STAR 50 Index: What It Measures and How It Is Built ## Direct Answer > The STAR 50 Index is a rule-based measurement of Chinese high-tech and innovation equity benchmark, maintained by Shanghai/Shenzhen 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 STAR 50 Index covers Chinese high-tech and innovation equity benchmark, within the China market. Shanghai/Shenzhen 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 50 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 Free float adjusted market capitalisation weighted with a weight factor between 0 and 1 set at each rebalancing, so that each constituent is capped at 10% and the top five combined are capped at 40%. The factor stays fixed until the next rebalancing. 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 universe is stocks and red-chip CDRs listed on the Science and Technology Innovation Board that are not *ST and show no serious violations, financial problems or market manipulation. The bottom 10% by average daily trading value over the past year are deleted, and the top 50 by average daily total market capitalisation are selected. 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 Securities need more than six months of listing, rising to more than twelve months once the number of securities listed for twelve months reaches 100 to 150. Securities ranking in the top 5 by market value since listing can qualify after three months, and a top 3 security after one month if the Index Advisory Committee agrees. 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 Adjusted and rebalanced quarterly, effective the next trading day after the second Friday of March, June, September and December. Normally no more than 10% of constituents change. A buffer zone gives priority to new candidates ranked in the top 40 and existing constituents ranked in the top 60. 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 listing history requirement moves with the market: it is six months now but rises to twelve months once 100 to 150 securities have twelve months of history. ## References - [Shanghai/Shenzhen Stock Exchange: China Securities Index Co., Methodology of SSE Science and Technology Innovation Board 50 Index](https://oss-ch.csindex.com.cn/static/html/csindex/public/uploads/indices/detail/files/en/000688_Index_Methodology_en.pdf), as published 2020. Every rule described on this page is taken from this document. ## Current STAR 50 Index constituents Shanghai/Shenzhen Stock Exchange publishes and licenses the STAR 50 Index constituent list. Swoopr does not republish it here. The provider's own page is the authoritative source for current membership and weights. [Shanghai/Shenzhen Stock Exchange: official STAR 50 Index page](https://english.sse.com.cn/markets/indices/overview/) ## 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 STAR 50 Index? Shanghai/Shenzhen Stock Exchange maintains the STAR 50 Index and publishes the methodology document that defines its eligibility and weighting rules. ### What does the STAR 50 Index measure? It measures Chinese high-tech and innovation 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 STAR 50 Index constituents? Shanghai/Shenzhen Stock 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.