A key US economic indicator is on an ugly streak that has never occured outside of a recession

There has been increasing focus on the US economy's probability of heading into a recession.

According to John Hussman of Hussman Capital, it's not just probable, it's nearly guaranteed.

"Since October, the economic evidence has shifted from supporting a growing risk of recession, to a guarded expectation of recession, to the present conclusion that a U.S. recession is not only a risk but an imminent likelihood, awaiting confirmation that typically only emerges after a recession is actually in progress," Hussman said in a post Monday.

His key piece of evidence stems from Friday's US industrial production report. The data was disappointing, missing expectations and indicating the sector is in contraction. Hussman also noted there is more to it than just the headline disappointment. Here's his analysis:

"Industrial production has now also declined on a year-over-year basis. The weakness we presently observe is strongly associated with recession. The chart below (h/t Jeff Wilson) plots the cumulative number of month-over-month declines in Industrial Production during the preceding 12-month period, in data since 1919. Recessions are shaded. The current total of 10 (of a possible 12) month-over-month declines in Industrial Production has never been observed except in the context of a U.S. recession. Historically, as Dick Van Patten would say, eight is enough."

Hussman gained notoriety for his skepticism in 2007 just before the start of the global financial crisis, though he admits he called a recession in 2011 that "did not emerge."

This time, however, he said that the data, even beyond the flashing red indicator of industrial production, is irrefutable. Additionally, he named 4 indicators that will confirm the downturn:

1. "A sudden drop in consumer confidence about 20 points below its 12-month average (which would currently equate to a drop to the 75 level on the Conference Board measure)..."
2. "A decline in aggregate hours worked below its level 3-months prior..."
3. "A year-over-year increase of about 20% in new claims for unemployment (which would currently equate to a level of about 340,000 weekly new claims)..."
4. "Slowing growth in real personal income."

Hussman's advice is for investors to protect themselves, as he expects the recession will also bring about a collapse in the stock market, noting "substantial crash risk."

You've been warned.