Direct Answer
The ATX Prime covers all securities admitted to the prime market segment of Wiener Borse, making it the broadest benchmark in the ATX family. Unlike the ATX, which selects only the most liquid subset, the ATX Prime aims to represent the full investable Austrian equity market. It is free-float-adjusted and market-capitalisation-weighted, administered by Wiener Borse AG.
What this index covers
The ATX Prime covers the Austria equity market through the Vienna Stock Exchange (Wiener Borse). Wiener Borse AG defines which securities are eligible, how they are selected from that pool and how much each contributes to the published number.
The eligible universe is: All securities admitted to the prime market segment of Wiener Borse and meeting minimum free-float requirements, per the Wiener Borse published methodology.
Understanding the eligible universe is the most important step in understanding what an index measures. An index that selects by listing venue will behave differently from one that selects by company domicile, and a sector index will have very different risk characteristics from a broad market measure even if they share some constituents.
How constituents are weighted
Free-float-adjusted market-capitalisation weighting, consistent with the broader ATX family methodology published by Wiener Borse AG.
Weighting is the mechanism that translates a list of companies into a single number. Free-float-adjusted market-capitalisation weighting is the most common method: larger companies contribute more to the index level than smaller ones, and the free-float adjustment excludes shares that are not available to public investors (such as government-held strategic stakes or closely-held founder shares). This makes the index level reflect the actual investable market rather than total market size.
Eligible universe and eligibility rules
Eligibility rules determine which companies can be included at a review and which must exit. The key dimensions to verify are: which exchange or market segment is in scope; whether domicile or listing venue determines eligibility; the minimum free-float threshold; the liquidity screen; and whether there are sector restrictions.
For the ATX Prime, the relevant market is the Vienna Stock Exchange (Wiener Borse) and the administrator is Wiener Borse AG. Per the published Wiener Borse AG methodology (verification date: August 31, 2026), the eligible universe is defined as: All securities admitted to the prime market segment of Wiener Borse and meeting minimum free-float requirements, per the Wiener Borse published methodology.
Reconstitution schedule
Reviewed quarterly alongside other members of the ATX index family. Entry and exit are governed by the prime-market admission rules of Wiener Borse.
Reconstitution is the date on which the index changes shape by design rather than by price. Passive funds tracking the index must trade toward the new membership list, which creates predictable order flow around the review date. Active managers often position around reconstitution events to capture or avoid that flow.
How investors use this index
Used as the broad Austrian equity benchmark where a wider investable universe is required than the ATX provides; basis for products seeking exposure to the full Austrian regulated market.
For any index, three uses are distinct: as a performance benchmark (measuring how well a portfolio did relative to the market), as a product underlying (an ETF or structured product replicating the index), and as a research reference (tracking market-cap, sector weights or concentration over time). The same index can serve all three purposes, but the choice of which to use depends on the investment mandate and the specific question being answered.
Comparisons with related indexes
The ATX Prime is most often compared with:
- ATX: more concentrated flagship; selects only the most liquid prime-market securities; ATX Prime includes all qualifying prime-market stocks.
- Wiener Borse Index (WBI): even broader; covers the full regulated market, not limited to the prime segment.
When switching from one benchmark to another, the practical question is what changes in coverage: does the alternative add smaller companies, exclude a sector, change the weighting method or extend to a different currency? Each of these changes alters what the index can tell you about market performance.
References
- Wiener Borse: ATX Index Overview, as published per the provider's methodology page. All methodology claims on this page are derived from this source.
Current ATX Prime constituents
Wiener Borse AG publishes and licenses the ATX Prime constituent list. Swoopr does not republish it here. The provider's own page is the authoritative source for current membership and weights.
Related reading
- All stock market indexes: how indexes are built, weighted and revised.
- European Stock Market Indexes: others covering the same region.
- Index concentration: measuring how much of an index sits in its largest holdings.
- Index rebalancing and inclusion effects: what happens to a stock when index membership changes.
Frequently Asked Questions
What is the difference between the ATX and ATX Prime?
The ATX selects the most liquid shares from the prime market, typically around 20. The ATX Prime includes all securities admitted to the prime segment, resulting in a larger, more broadly representative universe.
Who administers the ATX Prime?
Wiener Borse AG administers the ATX Prime under its published index governance framework.
Is the ATX Prime tradeable as an index product?
ETFs and structured products may track the ATX Prime. Availability depends on product providers. The index itself is a measurement tool, not a tradeable instrument.
How is the ATX Prime weighted?
Free-float-adjusted market-capitalisation weighting: each constituent's index weight reflects its free-float-adjusted market value relative to the aggregate.
Where can I find current ATX Prime data?
Wiener Borse AG publishes current index data, including constituent lists, on its official index overview page.