Reddit Stock Pops 11% on S&P 500 Inclusion Despite Google AI Traffic Concerns

Reddit shares surged 11% in extended trading Thursday after S&P Dow Jones Indices confirmed the platform will join the S&P 500.

Reddit is only the second pureplay social media stock in the benchmark index after Meta.

Reddit’s Index Debut, By the Numbers

S&P Dow Jones Indices said Reddit (RDDT) will replace AvalonBay Communities in the S&P 500 before trading opens on Aug. 18, 2026, once Equity Residential completes its acquisition of AvalonBay.

Reddit shares climbed to $175.38 in postmarket trading following the news, up from Thursday’s $153.12 close, a gain of nearly 11%, according to TradingView data.

Index funds that track the S&P 500 must now buy Reddit shares to match the benchmark, a mechanical demand shock that helps explain jumps like this even absent fresh business news.

The same announcement added Sun Communities to the S&P MidCap 400 effective Aug. 20, replacing Webster Financial as Banco Santander’s acquisition of Webster nears completion.

Reddit’s addition leaves Meta as the only two pureplay social platforms in the S&P 500. Pinterest and Snap both went public earlier but remain too small by market cap for inclusion, and Twitter exited the index once Elon Musk acquired the company and rebranded it X under SpaceX.

A Rally That Follows a Rough Earnings Reaction

Thursday’s pop arrives less than three weeks after Reddit’s second quarter results split investors. The company posted its eighth straight quarter of revenue growth above 60%, yet shares initially sold off after CEO Steve Huffman flagged uncertainty around Reddit’s dependence on Google for new users.

“Search referrals were choppy in the quarter, and traffic was more volatile later in the quarter.”

Steve Huffman, in a letter to Reddit investors

Huffman tied the volatility to Google’s growing use of Gemini-powered AI Overviews, which answer search queries directly on the results page instead of routing users to sites like Reddit. The concern is not unique to Reddit. AI-generated search summaries are reshaping how publishers and crypto projects compete for visibility online.

S&P 500 membership does not resolve that structural question. It does guarantee Reddit a new base of buyers uninterested in the AI-traffic debate, since index funds must now simply hold the stock.

Reddit joins a short list of once-fringe internet companies using S&P inclusion to cement mainstream investor legitimacy. Coinbase joined the index in 2025, a milestone Strategy has not achieved despite its size.

Whether Reddit’s search-traffic risk resurfaces once the passive-buying wave settles is the open question heading into Aug. 18.