The Treasury yield curve inversion has long been a reliable recession indicator - and it's been flashing for a month straight

• The yields on the 2 and 10 year Treasury notes have been inverted for the last month.
• A deeper yield curve inversion is an expression of investors' expectations for a recession in the near term.

The spread between the yields on the 10-year and 2-year Treasury notes has been inverted for more than a month, as the closely-watched recession indicator continues to deepen.

The 10-year Treasury yield on Thursday stood at 2.688%, compared to the 2-year Treasury yield of 3.047%, a spread of about 35 basis points.

An inverted yield curve has historically been a reliable indicator of a coming recession, coming most recently before downturns in 1990, 2001, and 2008, according to Datatrek. While brief inversions typically don't predict a downturn, ones that last beyond a momentary flashing can have stronger predictive power.

Even before summer, the closely watched 2- and 10-year yields had inverted several times as the Federal Reserve tightened monetary policy at a pace that sparked fears of a recession among market watchers.

Commentators have warned that the central bank will have trouble avoiding a recession and it combats high inflation, and that a so-called soft landing will be difficult.

Last week government data showed the US had two consecutive quarters of negative economic growth, the definition of a technical recession. However, some have pointed to a strong labor market as reason to shrug off fears of a downturn, and the NBER remains the only official body that can declare a recession, which it hasn't done yet.

Meanwhile, investors will be monitoring Friday's jobs data, as it could add fuel to recession fears if it shows a slowdown in labor market momentum.