According to our models, the rail transport group was relatively well-positioned to make its comeback to the CAC 40 during the next index review. Prior to the slump, Alstom ranked 35th in Paris based on free-float market capitalization and trading volumes. The stock's plunge of over 30% has seen it abruptly demoted to 42nd place, effectively removing it from the list of contenders for the benchmark index.

This situation could benefit Renault, which is currently the most vulnerable constituent of the CAC 40. Even with Alstom sidelined, several companies carry more weight on the Paris market than the automaker. However, the manufacturer should be protected by the "buffer rule," which grants a preference to existing index members. Based on our analysis, Alstom was the only candidate capable of overriding this buffer principle.

Further down the rankings, Ipsen is likely to move from the CAC Mid 60 to the CAC Next 20. This forecast is driven by the stock's 36% rise since January 1st and a 78% gain over one year. Elis finds itself in a similar position, albeit with less breathing room: its case for promotion is bolstered by a 24% gain accumulated over the past year.

A word of caution, however: things can still change, as the Index Steering Committee will not meet until June 11 to finalize its quarterly review. The countdown has begun.