AppLovin (APP.US) and Robinhood (HOOD.US) were both included in the S&P 500 index, and their stock prices surged by 7% in after-hours trading.

S&P Global, Inc. announced on Friday that advertising technology company AppLovin (APP.US) and stock trading app Robinhood (HOOD.US) will officially join the S&P 500 index. After this news was announced, the stock prices of both companies soared by about 7% in after-hours trading. According to the announcement, this adjustment will take effect before the opening of the US stock market on September 22. After the adjustment, AppLovin will replace MarketAxess Holdings (MKTX.US), and Robinhood will replace Caesars Entertainment (CZR.US). Being included in the S&P 500 index usually leads to an increase in stock prices, as index funds and passive investment portfolios must buy relevant stocks to match the component stock adjustments. This phenomenon has been seen frequently in past adjustments. Earlier this year, Datadog (DDOG.US) and DoorDash (DASH.US) also successfully joined the S&P 500, reflecting the increasing weight of large technology and digital economy companies in the US stock market. AppLovin is a software company that provides precise advertising placement for mobile apps and games and has performed well since its listing on Nasdaq in 2021. This year, AppLovin even proposed to acquire TikTok's US business, which attracted high attention from the public. It is worth noting that in December last year, when the S&P committee chose Workday instead of AppLovin to join the index, the company's stock price plummeted by 15% at one point. In March, the short-selling agency Fuzzy Panda Research publicly called on the S&P committee not to include AppLovin in the component stocks. Robinhood also went public on Nasdaq in 2021 and is a platform popular among retail investors, especially known for the trading of "MEME stocks." Robinhood had previously attempted to challenge the S&P 500 index component stocks multiple times, but failed in December 2024 and June 2025. Although this adjustment did not include the bitcoin treasury company Strategy in the index, disappointing some market observers, the stock fell nearly 3% in after-hours trading.