Overview

• The index change becomes effective before Thursday’s opening bell following the late‑Monday announcement by S&P Dow Jones Indices.
• Interactive Brokers shares rose about 4% to 5% in after‑hours trading on the news.
• Talen Energy will enter the S&P MidCap 400 to replace Interactive Brokers on the same effective date, and its stock gained more than 3% after hours.
• Kinetik Holdings will join the S&P SmallCap 600 on Sept. 2, replacing Pacific Premier Bancorp as it is being acquired by Columbia Banking System.
• Shares of previously watched candidates, including Robinhood Markets and AppLovin, slipped in late trading after the selection was announced.