Treasury Partners puts the equity trigger at a 5.25% ten-year Treasury yield
Fortune's account of the global selloff traces a chain from oil above $100 a barrel to the debt behind AI data centers. The single testable number in it is a yield level named by one investment chief.
The Investor · Invest desk

What happened
- Global stock markets fell again and bond yields rose further, with investors worried that US government debt is becoming increasingly risky, according to Fortune's morning newsletter.
- Fortune traces the pressure to the war with Iran, which has driven oil above $100 a barrel and is feeding US inflation on top of a 2% target missed for five straight years.
- The AI capex cycle that higher borrowing costs would squeeze is estimated at $1 trillion of total spending this year, which is the sum Fortune says a correction would call into question.
Why it matters
- What it costs cost Taxpayers carry the $33.4 billion already spent. The weapons inventory shortfalls the report describes put a resupply bill on top of the fighting cost.
- What it limits constraint In this account the path from yields to share prices runs through the debt hyperscalers use to build data centers, so an equity call here is really a call on credit supply.
- Who has to decide decision With a stated trigger of 5.25% on the 10-year, a duration or equity book can be sized against a number, and the question becomes how far the yield sits from that level.
- What doesn't add up contradiction Trump's account of defense factories running around the clock and the Inspector General's finding of munitions resupply bottlenecks point in opposite directions on how fast inventories refill.
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The route from the oil price to share prices runs five links in Fortune's account: oil above $100 a barrel feeding US inflation [6], inflation expectations climbing on Piper Sandler's numbers [7], a bond market demanding a bigger risk premium on long-dated paper [19], a Fed pressed into higher rates [20], and then corporate credit, where the AI hyperscalers raised the money for their data centers [21]. The figure sits at the far end of that chain: an estimated $1 trillion of AI capex this year [11].
The war's own bill is small beside it. The Pentagon's Lead Inspector General put the cost to US taxpayers at $33.4 billion through June [2], about 3.3% of one year of AI spending at Fortune's estimate [16]. Fourteen US service members have been killed [12]. The borrowing described in that report is too small to push yields up. If the war is doing that, it is working through the barrel and through expectations.
One number in the piece can be tested. "Rising bond yields driven by unchecked inflation can potentially put pressure on the stock market. Stocks are likely to react unfavorably if the 10-year Treasury yield rises above 5.25%," said Richard Saperstein, chief investment officer at Treasury Partners, which manages $16 billion [4][5]. His sentence is a conditional, twice hedged. The distance to his trigger has to come from somewhere else: the newsletter does not report where the 10-year traded that morning [18].
"New era" is the newsletter's phrase [10]. Inflation has run above the Fed's 2% target for five straight years [8], which puts the start of the overshoot around 2021 [17]. Duration holders have been repricing against it since then.
Oil at $100 is a supply shock. Trump said Iran "wants to make a deal, quickly and badly" [14]. A deal removes the first link, and inflation expectations follow the barrel down. If instead the term premium widens while the Fed cuts anyway, equities pay through the discount rate and hyperscaler credit stays open. That is a different trade from the one the analysts quoted by Fortune describe [22]. And if the 10-year clears 5.25% while equities hold, Saperstein's threshold has failed.
The report describes "strategic inventory shortfalls" of weapons and "industrial base bottlenecks for munitions resupply" [1]. It also counts hundreds of buildings damaged or destroyed at US bases in Kuwait, Bahrain, Qatar, UAE, Saudi Arabia, Iraq, Oman and Jordan [3]. Trump, posting on Truth Social, said "Our Defense Company Factories are moving 24/7" [13].
What to watch
- The next Lead Inspector General report, which would show whether the $33.4 billion through June kept accruing at that rate.
- Whether Piper Sandler's inflation expectations series turns down if the barrel falls back under $100.
- Hyperscaler bond issuance and spreads, the only place the credit-supply link in this chain can be observed directly.
Information, not investment advice. This story is general information about companies and markets, drawn from cited reporting. It is not a recommendation to buy, sell or hold any security; check the cited sources before acting.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence62
- Adoption
- Not scored
- Hype gap+20
- Incentives45
- Confidence58
Perspective Coverage
3 publishers- Builder
- Builder 7%
- Operator
- Operator 53%
- Investor
- Investor 40%
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
The report said the conflict "resulted in strategic inventory shortfalls [of weapons] and revealed industrial base bottlenecks for munitions resupply".
- [2]
The war with Iran cost U.S. taxpayers $33.4 billion through June, according to a new report from the Pentagon's Lead Inspector General.
- [3]
The report states: "Iranian strikes damaged and destroyed hundreds of buildings and structures at U.S. bases in Kuwait, Bahrain, Qatar, UAE, Saudi Arabia, Iraq, Oman, and Jordan during the conflict."
- [4]
"Rising bond yields driven by unchecked inflation can potentially put pressure on the stock market. Stocks are likely to react unfavorably if the 10-year Treasury yield rises above 5.25%," according to Richard Saperstein, chief investment officer at Treasury Partners.
- [5]
Treasury Partners is an investment firm with $16 billion in assets under management.
- [6]
The war has driven the price of oil to more than $100 per barrel, and that is fueling inflation in the U.S.
- [7]
Inflation expectations are on the increase, as shown in a chart from Nancy R. Lazar and her team at Piper Sandler.
- [8]
Inflation has been above the Fed's 2% target for five straight years.
- [9]
Global stock markets continued their decline and bond yields continued to rise, as investors worried that U.S. government debt is becoming increasingly risky.
- [10]
Fortune's newsletter described the bond market as entering a "new era" of risk.
- [11]
The AI capex cycle is estimated at $1 trillion in total spending this year.
- [12]
Fourteen members of the U.S. armed forces have lost their lives in the conflict.
- [13]
Posting on Truth Social, President Donald Trump said: "I've just received a Report that the United States is producing more Exquisite and Elite Weapons than at any time in our History. They are being delivered on a daily basis to our Forces in the Middle East, and beyond. Our Defense Company Factories are moving 24/7."
- [14]
Trump blamed former President Joe Biden for the high price of oil and said Iran "wants to make a deal, quickly and badly."
- [15]
The Fortune newsletter carrying these items is dated September 15, 2026.
- [16]
The $33.4 billion war cost through June is about 3.3% of the $1 trillion estimated AI capex spending this year.
- [17]
Five straight years of above-target inflation, measured back from a September 2026 report, dates the start of the overshoot to about 2021.
- [18]
The Fortune newsletter does not state the current level of the 10-year Treasury yield anywhere in its account of the selloff.
- [19]
When inflation stays high, the bond market usually reacts by increasing the risk premium on long-dated bonds, because a holder needs a greater reward if returns are being eaten by inflation.
- [20]
High inflation pressures the Fed to reduce the money supply by increasing interest rates, making cheap credit harder to get, which is bad for stocks because future rounds of new money become scarcer and more expensive.
- [21]
Increased interest rates will eventually feed through into the corporate credit market, where AI hyperscalers have obtained the capex they need to build out their data centers, and will lower the supply of that debt because companies will be more reluctant to spend cash on higher interest payments.
- [22]
Some Wall Street analysts are wondering whether the war with Iran could tank the stock market, and Fortune sets out the logic ending in the AI capex cycle coming into question and a potential correction.
Sources
2 independent publishers whose own reporting we read for this story.
- cryptobriefing.comPentagon reports $184M damage from Iranian strikes on US facilities across the Middle East
1 article · September 15, 2026
- fortune.comThe Pentagon admits that Iranian strikes damaged and destroyed hundreds of buildings at U.S. bases across the Middle East
2 articles · September 15, 2026
- scmp.comPrice of Fury: report details Iran war’s toll on US bases, weapons and more
1 article · September 14, 2026
Topics and entities
Topics
- US-Iran war
- Foreign Military Sales Support
- Inflation
- Treasury Yields
- Hyperscaler AI Capital Expenditure
- Munitions Industrial Base
Entities
- Operation Epic Fury
- US State Department
- Treasury Partners
- Richard Saperstein
- Donald Trump
- Piper Sandler
- Pete Hegseth
- Federal Reserve
- Pentagon Inspector General