Government borrowing rates have hit 5% and could shoot up much higher in a short burst, which would be bad news for anyone needing a mortgage.

• The 10-year yield just touched 5%, a level it has not seen in a while.
• The setup points to a possible sudden spike rather than a slow grind higher.
• The same thing happened in the early 1980s, when trouble with Iran sent oil prices and yields soaring together.
• Short bursts like this can also send stocks and crypto jumping before they fade.
• If it plays out, home loan rates could reach 10%.

Outlook: A fast run higher in yields would push mortgage rates into double digits, even if growth cannot hold up at those levels for long.