S&P Dow Jones Indices said late Monday that Interactive Brokers Group Inc. will be added to the S&P 500 before trading opens on 28 August, replacing Walgreens Boots Alliance Inc., which is being taken private by Sycamore Partners. The change comes as part of the index provider’s latest quarterly rebalancing. Interactive Brokers, an automated electronic brokerage founded by billionaire Thomas Peterffy, will leave the S&P MidCap 400, where its slot will be filled by independent power producer Talen Energy. Kinetik Holdings is set to join the S&P SmallCap 600 on 2 September in a related reshuffle. The announcement sent Interactive Brokers’ shares up as much as 8 percent in post-market trading. Peterffy owns roughly 75 percent of the company, a stake valued at about $75.2 billion. Walgreens shares were little changed following the news.