--- title: "SSE 380: Methodology" description: "SSE 380 is maintained by Shanghai/Shenzhen Stock Exchange and covers Chinese mid-cap equity benchmark. How the index selects and weights its constituents." canonical: https://www.getswoopr.com/stocks/indexes/sse-380/ source: "Swoopr Investment: https://www.getswoopr.com" --- # SSE 380: What It Measures and How It Is Built ## Direct Answer > The SSE 380 is a rule-based measurement of Chinese mid-cap 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 SSE 380 covers Chinese mid-cap 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 380 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 the SSE 180 universe. Securities in the top 90% by average daily trading value over the past year are eligible and those with an ESG rating of C or below are removed. Candidates are not SSE 180 constituents and rank below 160th by average daily total market capitalisation, and the top 380 of them 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. ## When the membership is revised Adjusted and rebalanced semi-annually, effective the next trading day after the second Friday of June and December. The number of constituents changed at each review will not exceed 10%. 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 It is the band below SSE 180: a security is excluded if it is an SSE 180 member or ranks within the 160 largest in the universe. ## References - [Shanghai/Shenzhen Stock Exchange: China Securities Index Co., Methodology of SSE 380 Index](https://oss-ch.csindex.com.cn/static/html/csindex/public/uploads/indices/detail/files/en/000009_Index_Methodology_en.pdf), as published 2025. Every rule described on this page is taken from this document. ## Current SSE 380 constituents Shanghai/Shenzhen Stock Exchange publishes and licenses the SSE 380 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 SSE 380 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 SSE 380? Shanghai/Shenzhen Stock Exchange maintains the SSE 380 and publishes the methodology document that defines its eligibility and weighting rules. ### What does the SSE 380 measure? It measures Chinese mid-cap 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 SSE 380 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.