Markets are spooked by the 10-year yield nearing 5% because it is the outer limit of an entire generation’s experience with prevailing interest rates, says DataTrek Research.

Just days into the new year, a sharp selloff in the world’s largest bond market has already sent shockwaves among financial-market investors.

U.S. Treasury yields have soared over the past week, propelling the rate on the 10-year note

TMUBMUSD10Y

4.764%

to the brink of the 5% mark rarely seen since the global financial crisis. 

To be sure, it’s not the first time the 10-year yield has flirted with the 5% level over the past few years (see chart below). So why is it getting so much attention this time around?