The bond market is usually quiet.

But it can send strong warning signals.

These signals can shake stock markets.

They can also get the attention of world leaders.

The alarms grew louder over the summer.

Then the Trump administration acted on Wednesday.

The U.S. Treasury Department said it will buy back more U.S. government bonds.

It will buy back more than double the amount.

This move helped push longer-term yields down.

That is true for now.

Yields around the world went up.

They reached highs not seen in many years.

Oil prices jumped because of the war with Iran.

Worries about big government debts also pushed yields up.

Other concerns did too.

In the U.S., the 10-year Treasury yield went above 4.70%.

Then it fell back to 4.65% on Wednesday.

That is up from 3.97% before the Iran war began in late February.

The 30-year yield went above 5%.

That level was last seen in 2007.

High yields slow down economies.

They also put pressure on stock markets.

They make borrowing cost more for people and companies.

That includes mortgage rates and loans for building factories.

Big investments in data centers for AI help U.S. growth a lot.

So higher costs are very risky now.

High yields also pull investors away from risky things.

Those things include stocks, gold, and bitcoin.

Some analysts do not think the Treasury move will last.

Krishna Guha works at Evercore ISI.

He said the operation changes little about the main issues.

Those issues include big government deficits.

They also include heavy borrowing by Big Tech for AI data centers.

He warned the move could backfire.

Its limited impact might fade.

The Federal Reserve could cut short-term rates.

But bond investors set longer-term yields.

Fed Chair Kevin Warsh will speak on Aug. 28.

He will speak at the Fed's annual meeting in Jackson Hole, Wyoming.

That may be the next big event for markets.