On the world’s largest bond market, investors are quietly — and not so quietly — revolting against President Donald Trump’s grand tax-cut plan. In what looks suspiciously like a vote of no confidence, yields on benchmark 30-year Treasuries surged to 5.1% last week, just shy of their highest level in two decades, as administration officials scrambled to persuade sceptical Republican lawmakers to back the latest iteration of a deficit-doubling bill.

What’s at stake? Only the prospect of adding several trillion dollars to an already bloated fiscal deficit, and doing so precisely when the global appetite for U.S. paper shows signs of fatigue.

This is investors’ message: make no mistake, the bond market is voting on the budget bill — and so far, it’s voting ‘no.’ Neither this president nor this Congress seems remotely capable of controlling the deficit. The mood worsened following a lukewarm 20-year Treasury auction, a demand-sapped embarrassment that fueled an ongoing bond rout. The result: Treasury prices down, yields up, stocks lower, dollar weaker. Yes, all in a day’s work in Trump-era fiscal strategy.

Even Republican deficit hawks took to social media to pile on. Chip Roy called it a “horrific auction.” Fellow Republican Warren Davidson cited soaring yields as a cautionary tale, linking rising deficits to default risk.

“The Fed has cut rates, and yet yields are exploding. Something’s broken,” read one viral post, shared gleefully by congressional sceptics. The market, it seems, is having none of it.

Yields on long-dated bonds have surged in the U.S., Japan, and the UK, a sign that this is not just a localised hiccup. Markets are sending a global warning shot on fiscal credibility.

This selloff has emboldened the return of the so-called bond vigilantes — market participants who enforce fiscal discipline not through policy memos but through the brute force of higher borrowing costs. They last made an appearance during the Clinton years. Now they’re back with a vengeance.

And here’s the kicker: while yields of 4–5% might look tame next to the 1980s, the debt stock is now nearly $30 trillion, compared to under $14 trillion in 2016. The U.S. is spending more on debt interest than on national defence. In 2024 alone, interest payments are projected to hit $880 billion.

This surge in borrowing costs is happening just as Moody’s downgraded the U.S. credit rating, joining the chorus questioning America’s fiscal trajectory. It’s the last of the three major agencies to blink — and markets noticed.

Meanwhile, demand for U.S. Treasuries is becoming increasingly selective. China trimmed its holdings (though, to be fair, not by much), and traders are now openly speculating when exactly global investors will “rebel.”

“It’s hard to know when investors will push back,” admitted Treasury Secretary Scott Bessent — a rare moment of candour from an administration better known for wishful thinking than actuarial prudence.