Shares of KKR & Co. Inc. (KKR) , CrowdStrike Holdings, Inc. (CRWD) and GoDaddy Inc. (GDDY) gained 7.7%, 5.4% and 3.7%, respectively, in the after-market trading on Friday after the S&P Dow Jones Indices said that the firms would join the S&P 500 index.In a press release, S&P Dow Jones Indices said that as part of the quarterly rebalancing, KKR, CRWD and GDDY will replace Robert Half Inc., Comerica and Illumina Inc. in the S&P 500 index prior to the start of trading on Jun 24.In the last few years, the priva ...