The 30-year US Treasury yield surged to 5.00% for the first time since July before pulling back to 4.98%, a level investors view as a critical "line in the sand".

At 5%, bond yields become attractive enough to pull capital away from equities, while simultaneously raising borrowing costs for mortgages, corporate loans, and government debt.

This level has been breached twice before, in 2023 and 2025, but failed to hold for more than a few trading sessions each time.

On all 4 previous occasions over the last 3 years when the 30-year yield approached or exceeded 5%, the S&P 500 saw a pullback each time.

A sustained break above 5%, or an eclipse of the 2023 peak of 5.17%, would push yields into a trading range not seen in nearly 2 DECADES.

This comes as the Iran war has driven oil prices above $105 per barrel, fueling inflation expectations and reducing the likelihood of rate cuts that markets had fully priced in before the war began.

The world's largest bond market is now impossible to ignore.