Alphabet loses $500B in a day after saying AI Mode is hurting Search ad revenue

Alphabet shares fell 12% on Thursday, the company's worst day on record according to TechCrunch, taking more than $500 billion off its market value. The drop followed third-quarter results in which Alphabet disclosed that its AI summaries, now the top answer to many search queries, were affecting its core search advertising revenue. The stock fell another 1.4% on Friday.

Google's Search advertising business, which makes up roughly half of revenue, saw growth slow to 12%, its weakest pace in five quarters. Chief Business Officer Philipp Schindler said, as quoted by Latent Space, that strong growth in AI Mode queries had an impact because of lower monetization in AI Mode. Google does not break out AI Mode figures in detail.

The selloff spread on Friday. The Nasdaq closed 2.8% lower, according to the BBC, and ended October with its worst monthly slide since March 2025. Intel fell 28%, losing more than $130 billion in value, after forecasting weak fourth-quarter revenue. Reddit dropped 29% after warning that Google's AI-driven search was hurting referral traffic, and Roblox fell 18%.

The episode puts a number on a tension that publishers have raised for years: a good AI summary reduces the need to click through. Here the affected party is Google itself, which is spending heavily on the technology that may undercut its most profitable business. Alphabet reported negative free cash flow of $9.1 billion in Q3, its second straight quarter in the red, with capex of $51.4 billion and up to $205 billion expected this year.

Alphabet is not alone. Amazon reported negative free cash flow of $42.4 billion over twelve months and plans $220 billion in capex. Meta reported negative free cash flow of $2.1 billion in the quarter. Microsoft was the exception, with $18.6 billion in positive free cash flow. S&P Global Market Intelligence data cited by TechCrunch shows five large tech companies raised $326 billion in debt in 2026, triple last year's figure.

The timing complicates the AI IPO pipeline. Anthropic filed to go public this week, and the Financial Times reported that Blackstone warned investors it might not qualify for an investment-grade rating afterward. Latent Space notes OpenAI reportedly raised at $1.25 trillion rather than $1.4 trillion.

Analysts quoted by the BBC point to the coming days as a test. XTB's Kathleen Brookes noted that November is typically a strong month for stocks, but said continued struggles could suggest the AI trade is past its peak.

Also open is whether Google can monetize AI Mode as well as classic search, and how Anthropic's IPO fares in a weaker market. Despite the drops, the Nasdaq is still up 7.8% over the past year.