Started in 1983, the index is composed of a maximum of 25 of the most frequently traded securities on the exchange.

The AEX started from a base level of 100 index points on 3 January 1983 (a corresponding value of 45.378 is used for historic comparisons due to the adoption of the Euro).

[citation needed] The following table shows the annual development of the AEX index since 1983.

At the main March review date, the 23 companies listed on Euronext Amsterdam's regulated market with the highest share turnover (in Euros) over the previous year are admitted to the index.

Companies which have fewer than 25% of shares considered free float on Euronext Amsterdam are, however, ineligible for inclusion.

[8] At the three interim reviews in June, September and December, no changes are made to the AEX unless either the index has seen one or more constituents removed, or a non-constituent possesses a share turnover ranked 15th or higher overall over the previous 12 months.

[9] If vacancies are to be filled, the highest-ranking non-AEX companies are selected to join the index.

The index weights are calculated with respect to the closing prices of the relevant companies on March 1.

At the interim reviews, weightings after adjustment are left as close as possible to those of the previous day and are not re-capped.