• Alphabet stock fell about 12.6% on 29 October 2026, its worst day since the 2004 IPO, after a quarter in which Search revenue grew 12% against analyst expectations of about 15%.
  • AI Overviews clearly reduce organic clicks to websites. Paid clicks tell a different story: they still grew 8% in the quarter, and Google itself pointed to AI Mode, currency moves and Asian advertisers as the causes of the slowdown.
  • Google still sends about 91% of search engine referrals to websites, and a visit from a ChatGPT ad earned 64% less than a visit from a Google search ad in the largest study so far. In 2027, keep Google Search as the base and run measured tests on AI channels.

I build Google Ads search campaigns and log every AI bot that visits my own site. In the last 30 days, AI bots visited content-managers.com 2,986 times, and 675 of those visits were page fetches made while a user was asking ChatGPT, Claude or another AI tool a question. The user asked, the AI read the page, and the open question is how many of those users ever reached the site. That is the tension investors tried to price the day after Alphabet’s third-quarter report. This article works through three questions with the data: what actually sank the stock, what is known about the link to AI Overviews, and whether advertisers should move budget to another platform in 2027.

What happened to Google stock in October 2026?

On 29 October 2026, Alphabet Class A shares fell about 12.6% to $283.82, wiping out between $475 billion and $511 billion of market value in a single day, depending on the source and the time of measurement. According to Fortune, it was the stock’s worst day since it began trading in 2004. The previous record was an 11.6% fall in March 2020.

The drop started in after-hours trading on 28 October, right after the results. Yahoo Finance called it the second-largest one-day loss of value for a US-listed company, behind Nvidia’s fall in January 2025. The slide continued: on 2 November the stock closed at $278.99, close to its 52-week low.

Why did Google stock drop?

The stock fell on a combination of five things in the report: slower Search growth, AI Mode earning less per query, currency headwinds, record AI infrastructure spending and lower earnings per share. None of them alone would have taken 12% off the stock. Together, they challenged the assumption that Google could move into AI search without paying for it.

Factor What the report showed Why investors reacted
Search growth “Search & other” revenue rose 12% to $63.35 billion, after 19% in Q1 and 17% in Q2. According to Fortune, analysts expected about 15% Search is Google’s profit engine, and this was its sharpest slowdown of the year
AI Mode Chief Business Officer Philipp Schindler said strong growth in AI Mode queries had an impact “because of the lower monetization we were seeing in AI Mode” It was the first time Google said AI was costing it Search revenue
Currency Schindler called foreign exchange “the single largest driver” of the Search slowdown versus Q2. CFO Anat Ashkenazi expected a slightly larger currency headwind in Q4 The effect carries into the next quarter
Asian advertisers Schindler said some APAC advertisers were hit by the EU eliminating its de minimis customs exemption for low-value parcels It is an external regulatory factor Google does not control
Spending and cash flow Capital expenditure of $51.4 billion in the quarter, up 114%, and free cash flow of minus $9.1 billion. No share buybacks Google is spending more on AI than it currently earns from it
Earnings per share Down 26% to $2.12, partly because of an $8.7 billion mark-to-market loss on the SpaceX stake The bottom line looked weak, even though part of the drop was an accounting item

The report had strong parts too. Total revenue rose 25% to $127.6 billion, Google Cloud grew 103%, and Sundar Pichai said year-over-year query growth was “the highest it’s been in the last 5 years”. People are searching on Google more than before, and Google is earning less on each search.

Analysts are split. Gil Luria of D.A. Davidson said investors may fear that “AI has finally come for Google”. Scott Devitt of Rosenblatt said “I don’t think it’s a sea change”. Wells Fargo forecasts Search growth of 9% in Q4 and 4% in Q1 2027, and Bank of America now calls Google “a 2H’27 story”.

Did AI Overviews reduce clicks to websites?

Yes. AI Overviews reduce organic clicks to websites, and in 2026 the first randomized field experiment measured the effect directly. Researchers Saharsh Agarwal of the Indian School of Business and Ananya Sen of Carnegie Mellon University randomly assigned 1,065 desktop Chrome users to groups. In the group where AI Overviews were hidden, organic clicks per search rose from 0.37 to 0.62. The study found that AI Overviews cut outbound organic clicks by 39.8% and raised zero-click searches by 34.5%. It is a working paper that has not completed peer review.

The result matches earlier studies. Ahrefs found AI Overviews correlated with a 58% lower average click-through rate for the top-ranking page. Pew Research Center found users clicked a link on 8% of visits when an AI summary appeared, against 15% without one. Wells Fargo estimates that AI Overviews appear on about 82% of queries worldwide.

Large sites feel it too. On Reddit’s earnings call on 29 October, CEO Steve Huffman said: “The reality is, AI Mode does not drive traffic.” He said Reddit’s search referrals in October fell by more than a million a week on average.

There is evidence in the other direction as well. Cyrus Shepard used Google’s opt-out controls to remove one site from AI Overviews and AI Mode, and found that its regular organic clicks dropped too. His explanation: appearing in several places on the results page strengthens the brand and earns clicks elsewhere. It is a single-site test, so treat it as an early signal that needs a wider sample. You can measure both sides on your own site with the Search Console generative AI report.

Did AI Overviews hurt Google’s ad revenue?

The available data shows ad clicks still growing alongside AI Overviews, and the revenue pressure coming from AI Mode, a separate product that earns Google less per query. That is the distinction most headlines missed.

Three data points support it. The first is the same randomized experiment: when AI Overviews were hidden, organic clicks rose and sponsored clicks stayed flat. The second is Alphabet’s 10-Q filing: paid clicks on Search grew 8% in the quarter and average cost per click rose 4%. Growth slowed from 11% over the first nine months, and it is still growth. The third is that on the Q3 2025 call Google said AI Overviews monetize at “approximately the same rate” as regular Search.

AI Mode is a different case. It is a conversational experience where queries run about three times longer, and Google is still learning how to place ads inside it. Schindler said “the majority of AI Mode queries are incremental”, meaning searches that would not have happened in classic Search, and many sit at the top of the buying funnel, where monetization is low anyway. Google’s response is more ads. On 28 October it announced ads in AI Mode for ten more markets, with Brazil, Mexico and the UK planned for Q4, plus multiturn ads in the US. I covered what that means for budgets in my piece on Google adding ads to AI Mode.

My conclusion: the popular assumption is half right. AI Overviews cost websites clicks, and that is a real problem for anyone who depends on organic traffic. On ads, the data points to AI Mode and to macro factors. Alphabet does not report AI Mode revenue separately, so no one outside Google can say exactly how much of the slowdown it caused.

What is verified and what is still speculation?

Verified Speculation or interpretation
A fall of about 12.6% on 29.10.2026, the worst since 2004 That the fall was mainly about AI. Google’s management ranked currency first
Search revenue grew 12%, below expectations of about 15% That Search growth slows to 4% in Q1 2027 (Wells Fargo forecast)
Google said explicitly that AI Mode earns less per query How much of the slowdown came from AI Mode. Google does not disclose it
AI Overviews reduce organic clicks (field experiment, Ahrefs, Pew) That they also reduce ad clicks. The field experiment found no change
Paid clicks on Search grew 8% and cost per click 4% That Google will raise prices for advertisers to compensate. There is no direct evidence

Should advertisers give up on Google in 2027?

No. Google still controls the traffic and the buying intent, and the alternatives currently earn far less per visit. The smart change is in how you split the budget and how you measure it.

According to StatCounter, in August 2026 Google sent 91.02% of the traffic that search engines refer to websites, and ChatGPT sent 0.24% of the combined Google and ChatGPT referrals. Even in its weak quarter, Google earned $63 billion from Search in three months. ChatGPT ads reached a run rate of about $1 billion a year at the end of August 2026, according to OpenAI.

For an advertiser, the number that matters is how much each visit earns. A study by Maximilian Kaiser of the Vienna University of Economics and Business and Christian Schulze of the Frankfurt School of Finance & Management covered nearly 10 billion sessions on online stores. In the US, a visit from a ChatGPT ad earned $0.89 on average, against $2.45 for a visit from a Google search ad. Conversion rates were 0.37% against 1.17%. The authors note the comparison is descriptive, since advertisers chose to buy the ads, and that one advertiser accounts for 66% of purchases in the sample. Even with those caveats, it is the most detailed data published so far.

ChatGPT ads now run in 89 countries, and US advertisers can buy them through Ads Manager. If you sell to B2B buyers, I set out when a paid slot is worth it in my guide to ChatGPT ads for B2B.

What should you change in your 2027 ad budget?

Keep Google Search as the base, assign a small share to AI channel tests, and invest in content that AI engines cite. The right split depends on your market and your model.

Your situation What to do in 2027
US advertiser with a working search account Keep Search as the core, check how your ads appear in AI Mode, and prepare creative for multiturn ads
UK advertiser AI Mode ads are planned for Q4. Review product feeds and landing pages before they arrive
Testing ChatGPT ads Allocate 5% to 10% of the search budget, track conversions yourself and set a revenue-per-visit target before launch
Business built on organic traffic Expect fewer clicks from the same impressions, and track AI impressions alongside clicks. Build pages AI engines cite, using the principles of generative engine optimization
Online store Make sure your Merchant Center feed is complete and accurate, because product ads appear inside AI Mode. Google says click-through rates are already similar for sponsored and organic product listings there

In every case my rule is the same: revenue per visit is the deciding metric. A new channel with cheap clicks that earns a third per visit ends up more expensive. If you want me to look at how your budget is split today and where to test, that is part of our search and AI visibility services.

Frequently asked questions about Google stock and AI search

Why did Google stock drop in October 2026?

Alphabet reported on 28 October 2026 that Search revenue grew 12%, below expectations of about 15%. Management attributed the slowdown to currency, Asian advertisers and lower monetization in AI Mode. Capital expenditure of $51.4 billion and negative free cash flow added to the concern. The next day the stock fell about 12.6%.

Do AI Overviews hurt Google Ads performance?

The available data shows ad clicks holding up. In a randomized experiment that hid AI Overviews from users, sponsored clicks did not change. In Q3 2026, paid clicks on Search grew 8%. The revenue pressure comes mainly from AI Mode, which earns Google less per query.

How many organic clicks do AI Overviews take?

A field experiment with 1,065 users found a 39.8% drop in outbound organic clicks. Ahrefs found a 58% lower click-through rate for the top-ranking page, and Pew found users click a link on 8% of visits with an AI summary against 15% without one.

Should I move budget from Google Ads to ChatGPT ads?

A limited test makes more sense for now. In a study covering nearly 10 billion sessions, a visit from a ChatGPT ad earned $0.89 against $2.45 for a visit from a Google search ad. Set a revenue-per-visit target and track conversions yourself before scaling.

Where do ads appear in AI Mode?

Ads in AI Mode run in the US and, since 28 October 2026, in ten more markets including Australia, Canada, India and Singapore. Google plans Brazil, Mexico and the UK for Q4 2026, and multiturn ads are launching in the US.

Is Google losing its grip on search?

The data says no. Google sends about 91% of search engine referrals to websites, and Sundar Pichai said query growth is at its highest in five years. What is changing is how Google earns from each search and how many clicks it sends to websites.

Summary

Google’s stock fell on a report that showed slower Search growth, AI Mode earning less per query, currency headwinds and record AI spending. AI Overviews mainly cost websites organic clicks, while paid clicks keep growing. For advertisers, Google stays the base in 2027, with measured AI channel tests judged on revenue per visit. For site owners, it means planning for fewer clicks per impression and building content AI engines choose to cite.

Sources

  • Alphabet, Form 10-Q for Q3 2026, 28 October 2026
  • Alphabet, Q3 2026 earnings call transcript (Investing.com)
  • Fortune, Yahoo Finance and The Next Web, coverage of the share fall, 29 October 2026
  • PPC Land, Is AI Mode doomed? What Alphabet’s $482bn sell-off really says
  • PPC Land, Google ad clicks gain 8% in Q3, slower than 11% over nine months
  • Agarwal and Sen, The impact of Google AI Overviews on publisher traffic and user experience: evidence from a field experiment, SSRN, 2026
  • Ahrefs, Update: AI Overviews Reduce Clicks by 58%
  • Pew Research Center, Google users are less likely to click on links when an AI summary appears in the results
  • Search Engine Roundtable, Google AI Overviews and AI Mode 0.9% click-through rate, opt out study, 30 October 2026
  • Let’s Data Science, Reddit CEO says Google’s AI Mode does not drive traffic, 29 October 2026
  • Kaiser and Schulze, Can Advertising Fund Free AI? Evidence from ChatGPT’s International Advertising Rollout, October 2026 (via PPC Land)
  • StatCounter, search engine market share, August 2026 (via Digital Applied)
  • OpenAI, ChatGPT Ads expansion to 89 countries, 21 October 2026
  • Google Ads & Commerce Blog, Ads in AI Mode expand to new markets, 28 October 2026
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