Investors are growing uneasy about AI infrastructure spending at the very moment the largest technology companies are escalating their commitments. Over the past two weeks, Alphabet, Amazon, Meta, and Microsoft have collectively outlined plans to spend more than $740 billion on capital expenditures this year—spending that Wall Street interprets as AI infrastructure investment, encompassing data centers and chips.

In the earlier phase of the AI boom, investors generally cheered such large outlays, interpreting them as evidence of confidence in the technology's growth prospects. But as the fourth quarter begins, that enthusiasm appears to be shifting toward worries about negative free cash flow (spending more cash than a company takes in), rising debt loads, and whether these massive investments will ever produce sufficient returns.

The anxiety rippled across the market on Friday. The Nasdaq fell 2.9%, and chip stocks absorbed heavy losses as well: Nvidia dropped 4%, Broadcom more than 5%, and Qualcomm 11%. Alphabet, which plunged 12% on Thursday—its worst day on record, erasing $500 billion in market value—declined again.

A central part of the worry is that companies which once enjoyed overflowing free cash flow from their core businesses are now being squeezed as AI threatens the economics of those very businesses. Alphabet offered the clearest illustration this week. Google's parent company reported negative free cash flow of $9.1 billion in the third quarter—its second consecutive quarter in the red—even as quarterly capex climbed to $51.4 billion. Alphabet expects to spend up to $205 billion this year and anticipates that spending will continue rising in 2027.

Meanwhile, the runaway success of AI Mode—Google's AI-powered chatbot feature built directly into Search—is eroding the company's cash cow. Google's Search advertising business, which accounts for roughly half of its revenue, saw growth slow to 12%, its weakest pace in five quarters. That leaves Google navigating a tightrope: it is spending billions on AI technology that could undermine the search business funding it.

Amazon finds itself in a comparable position after reporting negative free cash flow of $42.4 billion over the past 12 months, compared with $14.8 billion in positive free cash flow the year before. The company says it expects to spend $220 billion in capex this year. Even though revenue at its cloud business, AWS, grew 39%, Amazon's stock tumbled 7% after it reported earnings Thursday.

Meta is also burning cash, reporting negative free cash flow of $2.1 billion in the third quarter as capex outpaced its operating cash. It's guiding to as much as $145 billion in capex this year. The company noted that Muse, its new free personal AI agent, is something of a money pit (it's "very compute-intensive to run," CEO Mark Zuckerberg has said). But ad revenue grew 26%. Still, no amount of good news spared Meta from a 10% hit to its stock last week.

Microsoft was the sole exception on free cash flow—it recorded $18.6 billion in positive free cash flow in its latest quarter, with capex spending at $45.2 billion, below the $50 billion it had projected. Microsoft said that wasn't an intentional pullback from AI spending, attributing it instead to capacity delays from third-party providers. As a result, shares of smaller companies that rent out AI computing power sank.

It's worth noting that the money financing all this AI infrastructure isn't coming solely from the Big Tech companies' profits. It's also showing up in stock and bond sales. According to S&P Global Market Intelligence, Microsoft, Alphabet, Amazon, Meta, and Oracle raised a combined $326 billion in debt in 2026, triple the amount raised last year.

Demand for AI compute remains strong. Google, Amazon, and Microsoft all saw gains in their cloud businesses. But investors are getting spooked by the costs of meeting that demand.

These muddied waters could complicate Anthropic's highly anticipated IPO. The AI company filed to go public earlier this week, and its future growth depends on securing enormous amounts of compute. The Financial Times reported Friday that Blackstone has warned investors the company might not qualify for an investment-grade rating after its IPO, meaning it might end up being more reliant on the hyperscalers and third parties to fund its infrastructure ambitions.