Direct Answer
The PSI (Portugal Stock Index) is Portugal's primary equity benchmark, tracking the most liquid qualifying companies listed on Euronext Lisbon. Administered by Euronext, it replaced the former PSI-20 as the headline Portuguese index. It uses free-float-adjusted market-capitalisation weighting and is reviewed quarterly.
What this index covers
The PSI (Portugal Stock Index) covers the Portugal equity market through the Euronext Lisbon. Euronext 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: The most liquid qualifying companies listed on Euronext Lisbon that meet the minimum free-float, market-capitalisation and liquidity criteria in the published Euronext index methodology for the PSI.
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. A single-stock weight cap applies per the Euronext published methodology to limit concentration in a relatively small market.
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 PSI (Portugal Stock Index), the relevant market is the Euronext Lisbon and the administrator is Euronext. Per the published Euronext methodology (verification date: August 31, 2026), the eligible universe is defined as: The most liquid qualifying companies listed on Euronext Lisbon that meet the minimum free-float, market-capitalisation and liquidity criteria in the published Euronext index methodology for the PSI.
Reconstitution schedule
Quarterly. Euronext reviews PSI constituents in March, June, September and December.
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
Primary Portuguese equity benchmark; reference for Portuguese equity fund mandates, exchange-traded products and European equity strategies with Portuguese exposure.
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 PSI (Portugal Stock Index) is most often compared with:
- PSI All-Share: broader benchmark covering all qualifying Euronext Lisbon listings; PSI selects a concentrated liquid subset.
- ISEQ 20: Ireland's equivalent flagship benchmark; structurally parallel but measuring a different Euronext national market.
- IBEX 35: Spain's flagship benchmark on a neighbouring Iberian market; a natural comparator for regional context.
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
- Euronext: Index Products, as published per the provider's methodology page. All methodology claims on this page are derived from this source.
Current PSI (Portugal Stock Index) constituents
Euronext publishes and licenses the PSI (Portugal Stock Index) 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 administers the PSI?
Euronext administers the PSI under its published index methodology.
Is the PSI the same as the former PSI-20?
The PSI replaced the PSI-20. The PSI-20 had a fixed constituent count of 20. The current PSI retains a concentrated universe but operates under updated Euronext methodology rather than the old fixed-count structure.
Why does the PSI have a weight cap?
The Portuguese listed equity market is small relative to larger European markets, so a few large companies can dominate. The weight cap limits individual-stock concentration to maintain a more balanced index.
What currency is the PSI calculated in?
EUR. Portugal uses the euro and Euronext Lisbon is a euro-denominated market.
Where can I find current PSI data?
Euronext publishes PSI data on its official index pages. Swoopr does not republish licensed constituent lists.