Data: FactSet; Note: Net debt is defined as total debt minus cash and cash equivalents. The AI giants here are Amazon.com, Alphabet, Nvidia, Oracle, Meta and Microsoft. Chart: Matt Phillips/AxiosThe AI-related call on American capital markets continues, with Nvidia's reported effort to borrow some $20 billion in the bond market. Why it matters: Nvidia's bond sales are part of an AI-related wave of change now sweeping through both bond and stock markets, as the world's largest and most cash-rich companies find that they too need investors to finance the AI buildout. Driving the news: Nvidia set out to sell $20 billion in corporate bonds Monday.It was Nvidia's first debt sale since 2021 and is four times the size of its last two offerings, Bloomberg reported. Context: Axios' Emily Peck reported last week that Wall Street has already showered twice as much capital this year on the AI hyperscalers — the giant companies building the AI data centers — as in all of 2025.Elsewhere, growth in issuance of new shares of stock — most recently SpaceX — after decades in which the stock market has essentially shrunk could change the balance of supply of, and demand for, shares of stock.That could be a big deal for prices.What they're saying: "Consensus estimates suggest the hyperscalers will spend $770 billion on capex in 2026, equivalent to 100% of cash flows from operations. In order to fund continued capex growth, the companies have increasingly turned to debt and equity issuance and pulled back on buybacks," Goldman Sachs analysts wrote in a note Friday.Yes, but: As a chipmaker, Nvidia isn't in the same capex league as others in its AI cohort — the large hyperscalers spending hundreds of billions of dollars on data centers.Nvidia is projected to spend just $7.95 billion this fiscal year.And with $62.6 billion in cash and cash equivalents as of the end of last year — more than Apple's cash pile — $20 billion in new debt is nothing to worry about. The bottom line: Still, Nvidia's expected capital expenditure is 150% higher than it was two years ago. Monday's bond sale shows that even those with some of the deepest pockets in corporate America are thinking about how best to finance their part in the economy's giant bet on AI.And they've decided to take the money now.