Anthropic Could Join the Nasdaq-100 Only 15 Trading Days After Its IPO, Just Like SpaceX Did

Anthropic, the developer of the Claude artificial intelligence models, has reportedly selected the Nasdaq exchange for an initial public offering slated for November, with potential valuation estimates reaching near $2 trillion. Under a Nasdaq fast-entry rule introduced in May, mega-cap debuts that rank within the top 40 listings by total market capitalization can become eligible to join the Nasdaq-100 index after just 15 trading days. This fast-track mechanism was demonstrated earlier in the year when SpaceX listed on June 12 and was integrated into the Nasdaq-100 before the market opened on July 7. Index inclusion triggers mandatory buying from index-tracking funds and exchange-traded products managing over $800 billion in benchmarked assets. Despite the multitrillion-dollar headline valuation, index weighting rules cap new listings based on the value of freely floating shares rather than full market capitalization. As a result, newly public companies with locked-up insider equity typically debut with an index weighting around 1%, before expanding during subsequent quarterly rebalances as lockup periods expire.