Direct Answer
The ATX (Austrian Traded Index) is Austria's primary equity benchmark, tracking the performance of the most liquid shares admitted to trading on the Vienna Stock Exchange (Wiener Borse). It is a free-float-adjusted, market-capitalisation-weighted index administered by Wiener Borse AG under a published methodology.
What this index covers
The ATX 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: Austrian and dual-listed shares on the regulated market of Wiener Borse that meet minimum free-float and liquidity criteria per the published Wiener Borse 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. Individual constituent weight is capped at 20 per cent at each quarterly review, per the Wiener Borse published methodology.
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, 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: Austrian and dual-listed shares on the regulated market of Wiener Borse that meet minimum free-float and liquidity criteria per the published Wiener Borse methodology.
Reconstitution schedule
Quarterly. Wiener Borse AG reviews the constituent list each March, June, September and December based on the prior twelve months of trading data.
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
Austrian equities benchmark; reference for fund mandates, exchange-traded products tracking Austria, and performance comparison for regional European equity portfolios.
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 is most often compared with:
- ATX Prime: broader universe including all prime-market securities; ATX selects only the most liquid subset.
- ATX Five: price-weighted index of the five heaviest ATX components; much narrower and intended as a trading reference.
- EURO STOXX 50: euro-area blue chips across multiple countries; the ATX measures Austria alone.
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 constituents
Wiener Borse AG publishes and licenses the ATX 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
Who maintains the ATX?
Wiener Borse AG administers the ATX and publishes the methodology document that defines eligibility, weighting and review rules.
What does the ATX measure?
The ATX measures the price performance of the most liquid shares on the Vienna Stock Exchange. It is free-float-adjusted and market-cap weighted, reflecting the larger and more tradeable Austrian companies.
How often is the ATX reconstituted?
Wiener Borse reviews ATX constituents quarterly, in March, June, September and December, based on liquidity and free-float data from the prior twelve months.
Is there a constituent count target for the ATX?
The ATX has historically comprised around 20 constituents, though the exact number varies with market developments and the application of eligibility criteria at each review.
Where can I find current ATX constituents?
Wiener Borse AG publishes the current constituent list on its index pages. Swoopr does not republish licensed constituent data.