For three years the market rewarded Big Tech for spending on AI. In the last week of October 2026 it sent a different message.

What happened

On October 29, the day after its third-quarter results, Alphabet’s shares fell nearly 13%, its worst day on record, beating the 11.63% fall of March 2020, according to CNBC. About $500 billion of market value disappeared.

The trigger was cash. Alphabet reported free cash flow of negative $9.07 billion for the quarter, against analyst expectations of positive $2.7 billion, as spending on data centres outran the cash its businesses generated. It held its 2026 capital spending guidance at $195 billion to $205 billion.

Microsoft had a different problem: it spent less than expected, $45.2 billion in the quarter against about $50 billion, which TechCrunch reports the company put down to delays in capacity from third parties. Investors worried about that too.

The scale of the build-out

The numbers TechCrunch collected show why investors are nervous:

  • More than $740 billion of combined 2026 capital spending planned by Alphabet, Amazon, Meta and Microsoft, including about $220 billion at Amazon and up to $145 billion at Meta.
  • $326 billion raised in debt in 2026 by Microsoft, Alphabet, Amazon, Meta and Oracle, roughly triple the previous year, according to S&P Global.
  • Circular deals. Much of the money flowing into AI labs comes from the companies selling them compute. OpenAI’s $122 billion round, for example, included up to $50 billion from Amazon and $30 billion from Nvidia, alongside expanded deals to buy their capacity.

Not everyone sees a turning point. Rosenblatt analyst Scott Devitt told CNBC he didn’t view the sell-off as a sea change.

Why it matters

  • The build-out now runs on debt. When AI infrastructure was paid for out of spare cash, interest rates and investor moods mattered less. Now they matter a lot.
  • Discipline may follow. Pressure on free cash flow tends to lead to tougher pricing and tighter rationing of expensive GPU and TPU capacity.
  • For developers: expect cloud AI pricing and quotas to keep changing. Providers that are spending heavily want that capacity used at a profit, which can mean fewer free tiers and more committed-spend deals.

Sources

  1. CNBC: Alphabet, Google and Microsoft shares after earnings (Oct 29, 2026)
  2. TechCrunch: Cracks are emerging in the AI spending boom (Oct 30, 2026)
  3. CNBC: OpenAI funding round (Mar 31, 2026)

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