Wall Street titan Jeremy Grantham has been warning of a “superbubble” in the U.S. since last year, arguing the S&P 500 is set to be cut in half as an era marked by exceedingly risky investor behavior begins to fade.

Now, the cofounder and chief investment strategist of the Boston-based asset management firm Grantham, Mayo, and van Otterloo (GMO) is warning the U.S. may be headed toward a housing crisis as mortgage rates soar, and the effects on the economy could be devastating.

So far, his prediction about the S&P 500 has proved to be prescient, if a little dramatic, as the index is now down roughly 15% year to date. Stocks, particularly in the once high-flying tech sector, have been hammered as the Federal Reserve continues to raise interest rates in hopes of combating levels of inflation not seen in four decades.

Grantham argues the U.S. economy can weather dramatic drops in the stock market, as evidenced by the merely mild recession that surrounded tech stocks’ blowup during the dotcom bubble. But when it comes to a housing crisis, he says, the economy is unlikely to come through unscathed.

The dotcom bubble of “2000 showed you can just about skate through a stock market event, but Japan and 2008 showed you can’t skate through a housing crisis,” Grantham told Bloomberg in an interview published on Friday.

Grantham is convinced that we’re in the midst of a fifth great bubble of the modern era, following the Wall Street crash of 1929, the Japanese asset bubble of 1989, the dotcom blowup in 2000, and the Global Financial Crisis of 2008.

He argues that both stocks and the housing market have been lifted to unsustainable levels owing to speculation from investors and unsustainably loose monetary policies from the Federal Reserve.

Grantham—who is well known for accurately predicting the housing bubble and subsequent crash of 2008—warned late last year that a “day of reckoning” for the housing market would come.

Now, with interest rates for a 30-year fixed-rate mortgage rising to 5.27% this week, their highest levels since 2009, he sees that point coming ever closer.

Home prices surged 19.8% year over year in February, only adding to the 19.2% annual gains seen in January, according to S&P CoreLogic Case-Shiller U.S. National Home Price Index data released in April.

The rapid increase in the cost of housing has led some market experts to back up Grantham’s view that the red-hot market is now in bubble territory, including the Federal Reserve Bank of Dallas. In a paper published in late March titled “Real-time market monitoring finds signs of brewing U.S. housing bubble,” Fed researchers said home prices “appear increasingly out of step with fundamentals.”

Of course, not everyone is convinced that the housing market is set for a dramatic drop.

Mark Zandi, chief economist at Moody’s Analytics, said that while he sees the U.S. housing market cooling through the end of the year, a substantial national home price correction is unlikely.

“In terms of house prices, I expect [growth] to go flat,” Zandi told Fortune on Monday. “There will be markets where we will see a price decline of around 5% to 10%.”