Reddit Inc. will join the S&P 500 next week as part of an off‑cycle change, S&P Dow Jones Indices announced Thursday, sending the social‑media platform’s shares surging more than 10% after the bell. The news, reported by Bloomberg Markets, marks a notable elevation for the company, which has long been eyed for inclusion in the benchmark gauge. Investors reacted swiftly, pushing the stock higher as the announcement signaled a new era of index exposure.

The addition will take effect prior to the start of trading on Aug. 18, according to the index provider, replacing Avalon Bay Communities Inc., a real‑estate investment trust that is being acquired by fellow S&P 500 member Equity Residential. This off‑cycle swap reflects the dynamic nature of the index, which occasionally adjusts to keep its constituents representative of the U.S. economy. The replacement also highlights the ongoing consolidation in the REIT sector.

Analysts say the move could benefit ETFs tracking the S&P 500, as they will need to rebalance holdings to accommodate Reddit while shedding Avalon Bay. The surprise inclusion underscores the growing weight of technology‑centric firms in major benchmarks and may encourage other high‑growth platforms to consider similar index listings. Overall, the change signals continued market confidence in Reddit’s business model.