Direct Answer
The SOFIX is a rule-based measurement of Bulgarian blue-chip equity benchmark, maintained by Bulgarian 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 SOFIX covers Bulgarian blue-chip equity benchmark, within the Bulgaria market. Bulgarian 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 index name does not state a fixed company count, so the number of constituents follows the eligibility rules rather than a target.
How constituents are weighted
Market capitalisation weighted and free float adjusted, with a weight factor limiting any issue to 15% of the index free float value. If companies of one economic group together exceed 20% at a review date, group companies are taken out until the combined weight falls below that level.
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
Fifteen shares from the Main Market, each with free float market capitalisation of at least EUR 5 million and at least 750 shareholders. A simulated EUR 5,000 order must also be executable in 68.27% of observations over the prior six months.
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
An issue must have traded on a BSE market for at least three months before entering the SOFIX portfolio.
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
Ranking uses data as at 1 March and 1 September, and the Board decides at its first meeting after 2 March and 2 September. Changes take effect from the first session after the third Friday of that month, and free float factors are set on 2 June and 2 December.
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
Ranking adds four positions with equal weight: weekly median turnover, number of transactions, the average bid ask spread on simulated orders of 10,000, 7,500 and 5,000 euro, and free float market capitalisation. Ties go to the larger free float.
References
- Bulgarian Stock Exchange: Bulgarian Stock Exchange Rules for calculating the indices of Bulgarian Stock Exchange, as published 2026. Every rule described on this page is taken from this document.
Current SOFIX constituents
Bulgarian Stock Exchange publishes and licenses the SOFIX 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.
- Europe 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 SOFIX?
Bulgarian Stock Exchange maintains the SOFIX and publishes the methodology document that defines its eligibility and weighting rules.
What does the SOFIX measure?
It measures Bulgarian blue-chip 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 SOFIX constituents?
Bulgarian Stock Exchange publishes the current constituent list. Swoopr does not republish it, because index providers license constituent data and Swoopr holds no such licence.