This key benchmark is headed into no man's land

Wolfgang Kaehler | Getty Images

The 10-year Treasury yield could soon be making history, heading into a virtual no man's land.

One of the closest-watched indicators in U.S. financial markets, the 10-year is the yield that determines the rates for home mortgages and a host of other loans.

Some bond pros say it may be about to sink below its July 2012 record low of 1.38 percent, given the right circumstances. One of those events could be next week's June nonfarm payrolls.

The 10-year was at 1.48 percent Thursday, pulled lower as bunds and U.K. gilts flirted with new low yields. But the big question is what will happen if it cracks the old low and falls into uncharted territory.