Reddit stock is surging Friday after S&P Dow Jones Indices announced that the social media company will be added to the S&P 500 index, effective before the market opens on Tuesday. Shares are trading around 178 dollars, up roughly 13 percent, marking one of the biggest single-day moves for Reddit since its March 2024 IPO. The company will replace AvalonBay Communities in the benchmark index. AvalonBay is exiting after shareholders overwhelmingly approved a merger of equals with fellow S&P 500 member Equity Residential, with more than 99 percent of votes cast at each company's special meeting in favor. The combined real estate company will rename itself Vivmark Residential and begin trading on the NYSE under the ticker VMRK starting August 18, retaining the vacated index membership rather than replacing Reddit's new slot. For Reddit, S&P 500 inclusion is a major milestone that typically triggers substantial forced buying from index funds and passive investment vehicles that are required...