U.S. debt is competing with a record supply of corporate bonds, pushing up the cost of federal borrowing just as war spending piles up

The AI capital expenditure boom has created a gusher of corporate debt, forcing the Treasury Department to make its bonds more attractive to investors as the U.S. war on Iran adds to the deficit.

Last Tuesday saw the single busiest day on record for U.S. corporate bond sales as President Donald Trump’s hint that the war may end soon briefly calmed markets and sparked a mad dash for companies to issue fresh debt.

By the end of the day, total investment-grade issuance topped $65 billion, exceeding the prior one-day record of $52 billion in 2013. The flood of debt was led by e-commerce giant and AI hyperscaler Amazon, which raised $37 billion, sources told the Financial Times.

That beat the company’s guidance for $25 billion-$30 billion as investor demand far outpaced the available supply, attracting about $123 billion in orders.

The corporate debt surge was enough to move the needle in the Treasury market, where daily trading volume exceeds $1 trillion. Analysts at Deutsche Bank said in a note last week that the bond sales added some upward pressure on the 10-year yield, which climbed 6 basis points to 4.16% at session...