The CAC Next 20 is an index of security prices used with the Euronext Paris or Euronext Amsterdam. It gathers the 20 companies whose market capitalizations are ranked after those of the 40 companies who compose the CAC 40. These 20 are possible candidates to replace the members of the CAC 40 index. The CAC Next 20 was launched on 31 December 2002. Like the CAC 40, this new index is calculated uninterruptedly every 30 seconds. Wikipedia