Microsoft prices $25 billion bond sale, its first since 2017, for AI

Microsoft priced a $25 billion sale of bonds on Wednesday, October 29, 2026, its first large borrowing in the US investment-grade bond market since 2017. The company announced the pricing of $25 billion of senior unsecured notes, split into as many as ten parts with maturities from two years to 40 years. The sale came a day after Microsoft reported quarterly results showing heavy spending on data centres and equipment for artificial intelligence (AI) and cloud computing.

A bond is a loan that investors make to a company in return for regular interest payments and the return of their money on a fixed date, called maturity. Senior unsecured notes are bonds that rank ahead of other debts if the company runs into trouble but are not backed by a specific asset. Microsoft holds one of the strongest credit ratings of any company in the world, so it can borrow at rates close to those paid by the US government. A tranche is one slice of a bond sale with its own maturity and interest rate; splitting a deal into many slices lets the company reach investors who want short, medium or very long loans.

For years Microsoft paid for its growth from its own cash. The decision to borrow on this scale shows how expensive the AI build-out has become. The data centres that train and run large AI models need specialised chips, cooling and vast amounts of electricity, and each new site costs billions of dollars. Microsoft, Alphabet, Amazon and Meta are all spending at record levels, and several of them have now turned to debt markets for part of the money. Alphabet sold $25 billion of bonds in August and Amazon raised $25 billion in July, according to market reports.

Borrowing is not a sign of weakness in itself. Interest on debt is often cheaper than issuing new shares, and a company with steady cash flow can repay long-dated bonds comfortably. But it changes the risk. If the AI investments do not bring the profits the companies expect, the interest still has to be paid. That is why bond investors, rating agencies and shareholders are watching the size and speed of this spending closely, especially after Alphabet's shares fell sharply on October 29 over similar concerns.

For Indian companies the story has an indirect link. Indian IT services firms earn a large part of their revenue helping businesses around the world move to the cloud and adopt AI tools, often on platforms such as Microsoft's. How much the biggest cloud providers spend, and whether they keep spending, shapes demand for that work.

Short-term: The sale adds a large block of high-quality corporate debt to the market in a single week, and investors will compare its pricing with the borrowing of other technology companies. Settlement of the notes is expected in early November.

Long-term: More borrowing by the biggest technology companies could become a regular feature of the AI build-out. That would make the bond market, and not just the stock market, a key judge of whether the spending makes sense.

Who is affected: Bond investors such as pension funds and insurers; Microsoft shareholders; suppliers of chips, power and data-centre buildings; and enterprise customers and IT services firms, including Indian ones, whose business depends on cloud and AI demand.

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