Blog: How a Google URL Parameter Wiped out $3B in Reddit’s Valuation, and What Marketers Should Learn From It
Key Takeaways
- Hidden technical changes can have a major impact: An obscure change in Google’s URL parameters led to a sharp drop in Reddit’s stock price, highlighting how technical shifts can affect AI systems, data, and brand visibility.
- The &num=100 parameter was deprecated, impacting data scraping and AI visibility: Google quietly stopped supporting the &num=100 parameter, which caused Reddit’s citation share in LLMs to drop significantly, raising concerns for marketers about referral traffic and mindshare.
- Marketers need to adapt to volatile AI visibility: Marketers must distinguish between measurement anomalies and real performance shifts, prepare tactical experiments to monitor brand visibility in LLM answers, and expect more friction as Google limits bulk scraping.
Table of Contents
On October 1st, Reddit’s stock price dropped sharply. The spark? An obscure change in Google’s search plumbing. RBC Capital flagged that Google’s deprecation of the &num=100 parameter coincided with a sudden collapse in ChatGPT’s citations of Reddit content, spooking investors and raising concerns about Reddit’s visibility in the AI era.
This isn’t just a Reddit story. It’s a warning sign for every marketing leader: hidden technical shifts in search and AI ecosystems can ripple into dashboards, traffic, visibility, and even stock prices.
What Changed in Google’s Search Indexing
- The &num=100 parameter: For years, SEO tools and data scrapers used this trick to fetch 100 search results at once from Google’s SERPs.
- September 10–14, 2025: Google quietly deprecated the parameter. Now, only 10 results load per page. Tools must paginate 10x more, dramatically increasing the cost to retrieve the same number of results. To these trackers, 90% of SERP results vanished.
- Impact: Rank trackers scrambled (You can read Semrush’s statement here and Accuranker’s statement here), impression metrics in Search Console “fell off a cliff,” and AI bots scraping Google for training or citations suddenly had access to fewer results.
As one SEO analyst put it: “It’s not that rankings collapsed overnight, it’s that the way we measure visibility cracked.”
Why Reddit Got Hit Harder
Reddit has been a darling of LLMs like ChatGPT. Its vast trove of human Q&A made it one of the most cited sources in AI responses. RBC reports Reddit’s citation share dropped from ~29% to ~5% since September 10th, right after the Google change.
Investors took notice. If AI assistants cite Reddit less often, that could mean:
- Lower referral traffic from chatbots.
- Reduced mindshare in AI-powered discovery journeys.
- A potential dent in Reddit’s long-term monetization story.
The market quickly priced in that risk, even if the actual causal chain remains debated.
What Marketers Should Learn
1. Don’t Panic Over “Dashboard Shock”
If you saw impression drops in September, it may not mean traffic vanished. Sometimes, Google changes the plumbing, not the flow. Marketers need to distinguish between measurement anomalies and genuine performance shifts.
2. Citation Risk Is Real
If your brand relies on being cited or surfaced in AI answers, recognize that mechanical shifts, not just “quality,” determine your presence.
- Forums, reviews, and how-to sites are most exposed.
- All marketers should ask: “If AI assistants get less access to information from Google, am I still in view?”
3. Prepare Tactical Experiments
- Run query panels: Test how often your brand/industry shows up in LLM answers across 20–50 queries. Track before/after patterns.
- Benchmark peers: Compare against other domains to spot category-wide vs brand-specific shifts.
- Diversify KPIs: Don’t just count citations; monitor downstream clicks, conversions, and brand mentions.
4. Expect More Friction
Google has every incentive to limit bulk scraping as AI companies build on its results. This won’t be the last roadblock. Plan for a world where visibility in AI is harder to measure and less tied to traditional SERPs.
Staying Ahead of Change
For marketing leaders, the Reddit episode is less about Reddit itself and more about a new rule of the game:
Your brand’s visibility in AI can change overnight, due to factors outside your control.
That means leaders must:
- Stay curious about “under-the-hood” shifts
- Ask their teams to separate signal from noise in reporting
- Experiment proactively to map where their brand stands in AI answers
Because when the plumbing changes, those who adapt fastest keep the water flowing.
Closing Thought
The story of Reddit’s citation drop is still unfolding. Was it purely a Google parameter tweak, an LLM model update, or a mix of both? Time will tell. But one thing is clear: in the AI era, visibility is volatile.
And volatility is opportunity for those who are paying attention.
FAQ
Q: What is the Google &num=100 parameter and why does it matter?
A: It allowed fetching 100 results from Google SERPs at once. Google deprecated it in September 2025, limiting crawlers to 10 results per page unless they paginate.
Q: Why did Reddit’s ChatGPT citations drop after the change?
A: Reddit often appeared in lower-ranked results. With only 10 results captured, most Reddit links fell out of view.
Q: Did the change cause Reddit’s stock to fall?
A: The timing matches: citations collapsed in mid-September, RBC flagged it on September 30, and Reddit’s stock sold off on October 1–2. While correlation does not imply causation, investors viewed it as a visibility and monetization risk.
Q: Do fewer citations mean fewer visitors?
A: Not automatically. Citations are visibility, not traffic. But prolonged drops can erode referral traffic and awareness.
Q: How can marketers benchmark against peers?
A: Compare citation share trends across peer sites. For example, Reddit can be compared to forums like Quora or Stack Overflow. If all decline, the cause is systemic; if only one drops, it’s platform-specific.
Q: What steps should brands take now?
A: Track AI Search visibility across multiple AI Search platforms, monitor AI-driven traffic, benchmark against competitors, and diversify measurement beyond citations.
