Last month 10-year US dollar swap yields fell below Treasury yields to produce, for the first time, a negative spread. A great deal of ink has been spilt since, suggesting this is a harbinger of doom in the financial world.

The descent of dollar swap spreads has been rapid. On Monday, March 22, 10-year levels were three or four basis points above Treasury yields, but by the close of the following day they had fallen below zero to close at an historic low of minus 2.25bp.