Founded in 2000, Euronext is the result of the merger of the Amsterdam, Brussels and Paris stock exchanges. A major player in the European stock markets, Euronext is positioned as a cross-border market, facilitating financial exchanges within Europe. It offers a wide range of indices representing the performance of European financial markets. The Euronext 100 is one of Euronext's main indices. It comprises the 100 most valuable companies listed on Euronext exchanges. The Next 150, on the other hand, tracks the performance of a further 150 companies after the Euronext 100. These two indices provide an overview of large and medium-sized European companies. But Euronext also manages country-specific indices, such as the CAC 40 in France, the AEX in the Netherlands, and the BEL 20 in Belgium: crucial indices for assessing the performance of national stock markets. The Euronext indices are calculated on the basis of the market capitalisation of listed companies. This method ensures that higher-valued companies have a greater impact on the index. The composition of the Euronext indices is regularly revised to reflect changes in the stock markets and the economy. These adjustments ensure that the indices remain relevant and representative of current market conditions. Euronext indices are used by investors and financial analysts to monitor market performance, assess economic trends and make informed investment decisions.