The cost of financing the artificial-intelligence build-out has emerged as one of the crucial tests for markets.

Some of that cost already can be felt in the selloff in the $31.5 trillion Treasury market, where benchmark yields this week touched fresh highs during President Trump's second term in the White House.

Logic says pressure will soon intensify, given the increased competition for dollars and rough estimates for $200 billion in new U.S. investment-grade corporate bond supply in the month of September alone.

Between Labor Day and Christmas, "it's going to be manic," said Thomas Kikis, head of markets for the U.S. and the Americas at Standard Chartered. He pointed not only to the deluge of expected corporate bond supply, but also more potential mega IPOs after a nerve-racking summer for the Treasury market.

Beyond this year, AI capital expenditures are expected to reach almost $1.1 trillion next year, with room to grow into 2030.

"We are really in a market that needs stability and trust," Kikis said.

U.S. Treasury Secretary Scott Bessent's recent attempts to calm the bond market have done little so far. A bigger source of comfort has been a building trust on Wall Street that Federal Reserve Chairman Kevin Warsh will act as a steady hand for markets since his Jackson Hole speech.

Building on that stability will be crucial as U.S. companies start rushing to tap the bond market for funding.

"Our forecasts suggest that net U.S. [investment-grade] supply will reach a new all-time high this year, narrowly surpassing the refinancing surge seen during the pandemic in 2020," said Jim Reid, global head of macro research at Deutsche Bank, in a Thursday client note.

Record corporate bond supply is being met by an influx of investor cash into the sector.

On an optimistic note, "strong inflows [into investment-grade bond funds] continue to absorb the increase in issuance," Reid wrote.

That should encourage historically low corporate bond credit spreads - a second cost component in the bond market - to stay mostly in check. Corporate bonds are priced at a spread, or premium, above the prevailing Treasury rate to help compensate investors for default risks.

Long-dated Treasury yields recently were around 4.75% to 5.25%, while the rate on new Alphabet 30-year corporate bonds issued in August was closer to 6.4%.

Bessent, in announcing his intervention in the Treasury market last month, said the so-called hyperscalers of the AI build-out "don't really care what they are paying."

Amazon (AMZN), Alphabet (GOOGL) (GOOG), Meta Platforms (META), Microsoft (MSFT) and Oracle (ORCL) belong to the hyperscaler group, while Anthropic and OpenAI are expected to go public in 2026 and 2027 following SpaceX's (SPCX) initial public offering this June.

Those financing needs are part of a "crowding out" effect that bond-market investors and observers have been talking about. The U.S. has big borrowing needs because of its large deficit, but the world's largest technology companies also need billions of dollars to finance the AI race.

Related: The national debt just hit $40 trillion. Here's how it can hurt Americans.

With long-dated Treasury yields rising this summer, Bessent's argument has been that the bond market has been missing something.

Bond investors aren't of one mind on whether the AI boom will transform the U.S. economy, trigger a crash or result in both. Wells Fargo Investment Institute analysts on Thursday estimated AI now accounts for more than 40% of economic growth, with the build-out already appearing to be bigger than investments in building the nation's railroads, its highways and the foundations of the internet.

The 10-year Treasury yield BX:TMUBMUSD10Y eased a bit on Thursday after Federal Reserve governor Christopher Waller said he's leaning against a September interest-rate hike. But at 4.75%, the benchmark yield is still near its highest levels since January 2025.

Rising debt levels and higher bond yields already have the U.S. spending $1 trillion yearly on interest expenses - more than on healthcare or national defense, according to Treasury data.

AI "alone may not solve America's fiscal challenges," the Wells Fargo team wrote. But they said they do foresee it boosting productivity growth, which "can help offset fiscal concerns."

The next big test, however, will be whether policymakers can provide more calm in the coming weeks as supply from the corporate bond market kicks into high gear.

"Let's see what [Treasury Secretary Bessent] does over the next few weeks as the market picks up after Labor Day," said Standard Chartered's Kikis. "Is there enough room for both [Treasurys and corproate bonds]? September and October will show us the way."