Reddit to join S&P 500, triggering stock surge

Reddit Inc. is set to join the S&P 500 index effective prior to the market opening on August 18, 2026. The social media company will replace AvalonBay Communities, which is being acquired by Equity Residential. Following the merger, the combined entity will be renamed Vivmark Residential and will remain in the S&P 500.

Following the announcement from S&P Dow Jones Indices, Reddit shares experienced a significant surge, rising between 11% and 15% in extended trading. This rally is largely attributed to the expected demand from passive investment funds and ETFs that track the S&P 500 and must purchase shares to match the index changes. Analysts at JPMorgan estimate that passive funds may need to acquire approximately 16.7 million shares.

Reddit becomes only the second pure-play social media company in the S&P 500, joining Meta. The inclusion follows a period of strong financial performance, with the company reporting its eighth consecutive quarter of revenue growth exceeding 60% in its recent second-quarter results.

In a separate index adjustment, Sun Communities will join the S&P MidCap 400, replacing Webster Financial Corp., which is being acquired by Banco Santander.