30-year Treasury yield just hit 5.31% — highest since 2006.

When long-term rates spike like this, it's not just a number. It's a warning sign. Borrowing costs for mortgages, corporate debt, and government spending all rise. Equity valuations get squeezed because the risk-free rate just got a lot less "free."

This kind of move doesn't happen in a vacuum. Either inflation expectations are running hot again, or bond market participants are losing confidence in the Fed's ability to control the situation without breaking something.

Watch credit spreads, regional banks, and highly leveraged sectors. History says when the long end moves this fast, something usually cracks.