(Bloomberg) -- Jeremy Grantham, well known for his bearish market calls, is sounding another one, saying the “current market seems lost in one-side optimism when prudence and patience seem much more appropriate.”

His comments come after his firm, GMO, said it was slashing its exposure to equities. GMO reduced the net equity exposure in its Benchmark-Free Allocation Strategy to 25% from around 55%%, said Ben Inker, head of asset allocation, in a quarterly report Thursday that included a note from Grantham.

“We have never lived in a period where the future was so uncertain,” Grantham, 81, wrote. “The key here is uncertainty, which in some ways seems the highest in my experience.”

The legendary money manager, who co-founded Boston-based GMO and is its long-term investment strategist, said that the price-to-earnings ratio for stocks is now in the top 10% historically, while the U.S. economy is in the worst 10%, or perhaps the worst 1%.

“This is apparently one of the most impressive mismatches in history,” he wrote.

The firm managed about $60 billion as of the end of February.

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