Reddit will be included in the S&P 500 index before the U.S. stock market opens on August 18, replacing AvalonBay Communities, which is exiting the index due to its merger with Equity Residential.

JPMorgan estimates that index funds tracking the S&P 500 will need to buy approximately 16.7 million shares of Reddit; based on a post-announcement price of about $175.69, this corresponds to nearly $2.9 billion in passive allocation.

After the announcement of Reddit's inclusion, its stock price rose by over 11%, having previously fallen more than 31% this year. The buying pressure from the index adjustment is part of passive allocation replicating benchmark weights and does not equate to active bullish sentiment from fund managers regarding the company's fundamentals.

Passive funds typically complete their rebalancing around the effective date, but not all funds tracking the S&P 500 buy at the same time, price, or full amount; some institutions may trade in advance, use derivatives, or complete stock lending and hedging with market makers, with actual price impacts depending on liquidity and execution.

Reddit's revenue for the second quarter was $805 million, a 61% year-over-year increase; advertising revenue was $762 million, up 64%, and other revenue was $43 million, up 24%. Advertising still accounts for about 95% of total revenue, with data licensing and other businesses not being its main revenue source.

Reddit's inclusion in the S&P 500 meets the index committee's standards for market capitalization, liquidity, financial viability, and being a U.S. company. The passive buying effect stems from index rules, not from "pension bailouts" or funding support provided by regulators.

In market mechanics, inclusion in the S&P 500 will force ETFs, mutual funds, and some pension portfolios that fully replicate the index to increase their allocation to Reddit while selling AvalonBay or adjusting the weights of other components accordingly. Short-term beneficiaries are holders before the announcement, arbitrage funds, and market makers providing liquidity for passive funds; high short positions may amplify stock price volatility. Long-term pricing will still depend on Reddit's advertising monetization, user growth, search traffic, data licensing, and profit margins, rather than a one-time index rebalancing.

Source: Public Information