The S&P Dow Jones Indices announced on Friday that three companies - KKR & Co, CrowdStrike, and GoDaddy - will be added to the benchmark S&P 500 index before markets open on June 24. This change will see them replace Robert Half, Comerica, and Illumina in the index.

Following this announcement, the shares of CrowdStrike rose by 6% in extended trading, while KKR and GoDaddy saw increases of 9% and 3.6% respectively.

Conversely, the stocks of the companies being removed from the S&P 500 experienced declines. Robert Half's shares fell by 2.2%, Comerica was down by 0.4%, and Illumina saw a decrease of 0.6%.