Following a public consultation on its index calculation methodology, the Zagreb Stock Exchange (ZSE) has officially adopted amendments to six of its key indices, effective 1 June. The revisions aim to harmonize local practices with broader European exchange standards and to comply with the Act on Open-Ended Investment Funds with Public Offering.

Effective from June 2025, ZSE introduces two extra regular reviews per year, in addition to the existing March and September cycles. However, these June and December reviews will not alter index composition, meaning no stocks are added or removed within these. Instead, they are solely focused on technical adjustments, including updated number of listed shares, free float factor revisions, and weighting factor recalibration. This enhancement ensures greater data accuracy and timeliness for index-tracking instruments and improves market transparency.

Furthermore, the timing for calculating the maximum weight cap for individual stocks within all the affected indices is now set to six business days before the regular review date. This provides increased predictability for index managers and stakeholders when planning portfolio rebalancing.

In addition to the general methodology updates, the CROBEX10 and CROBEX10tr indices will undergo a slight reduction in concentration risk – the maximum weight of any single constituent is being reduced from 20% to 19%.

All of these index methodology changes have been implemented to ensure alignment with common practices across European stock exchanges and to comply with the provisions of the Act on Open-Ended Investment Funds with Public Offering.

For detailed information, you can check the ZSE website for the official publication here.