The last time fund managers hoarded this much cash, the Arizona Diamondbacks defeated the New York Yankees 4 to 3 to win the World Series.

Today the Diamondbacks and the Yankees are struggling in their respective divisions, and by the amount of cash investors are stocking away, one might think that they fear the global markets are melting down too.

Cash positions rose to 5.7% in June from 5.5% in May, the highest level since November 2001, as fund managers have become increasingly bearish, according to a Bank of America Merrill Lynch survey published Tuesday.

Worries about “‘summer of shocks” stemming from Brexit—the potential U.K. exit from the European Union—and low expectations for a new “radical” stimulus from central banks to revive the global economy are prompting managers to stock pile cash despite record high corporate and U.S. stock prices, according to Michael Hartnett, chief investment strategist at Bank of America Merrill Lynch.

What do you consider the biggest ‘tail risk’?

Bank of America Merrill Lynch

A recent poll by market research firm TNS showed that 47% of voters backed leaving the EU, compared with 40% who wish to remain. That contrasts with two thirds of fund managers surveyed by Bank of America who believe that a Brexit is “unlikely” or “not at all likely.” That disparity in so-called Brexit outcomes highlights the shocks that some investors are bracing against.

Brexit has emerged as the single biggest risk ahead of the June 23 referendum to decide whether the U.K. will remain a part of the EU. Global stock markets have swooned as investors shy away from risk averse amid the uncertainty.

Bank of America’s “Risk & Liquidity Index” fell to 32 in June versus 34 last month, the lowest in four years, underscoring the weak demand for risky assets such as stocks.

BofAML Risk and Liquidity Index

Bank of America Merrill Lynch

This level of risk is normally consistent with a recession, according to Hartnett. Even so, expectations for global growth jumped to a six-month high in June with 23% of respondents projecting a stronger economy in the next 12 months, he said.

Meanwhile, the most crowded trade at the moment is investors gobbling up high-quality assets, according to 27% of fund managers. The preference for comparatively less risky investments has led to a rally in government bonds, pushing the yield on the 10-year benchmark German bond TMBMKDE-10Y, -0.481% into negative territory for the first time ever. The yield on the U.S. benchmark 10-year Treasury note TMUBMUSD10Y, 0.701% also was under pressure, sliding 1.5 basis points to 1.601%, its lowest since November 2012.

What do you think is currently the most crowded trade?

Bank of America Merrill Lynch

Still, despite the gloomy tone of the report, there is a reason to be optimistic, Hartnett notes, citing the average cash level above 4.5%. That move tends to serve as a contrarian buy signal for stocks whereas when it drops below 3.5%, it is a contrarian sell sign, he said.

This story was first published on June 14, 2016.