• Norges Bank Investment Management (NBIM), one of the world's largest investors, says heightened uncertainty and concerns over the economic outlook mean that stock market risks are tilted to the downside.
• "I think it is a time of being a little bit cautious," Trond Grande, deputy CEO of NBIM, told CNBC's Silvia Amaro on Tuesday.
• Norway's sovereign wealth fund, the world's largest, was established in the 1990s to invest the surplus revenues of the country's oil and gas sector.

Norges Bank Investment Management (NBIM), one of the world's largest investors, said heightened uncertainty and concerns over the economic outlook mean that stock market risks are tilted to the downside.

NBIM, which manages Norway's $1.8 trillion sovereign wealth fund, said that it was important to be clear-sighted about concerns down the road, even as it stands by its position of not making large asset allocation shifts on a short-term basis.

"We [started] with 70% in equities and 30% in bonds, and that's typically where you will find us in any market situation. Now, that said, you have to be realistic," Trond Grande, deputy CEO of NBIM, told CNBC's Silvia Amaro on Tuesday.

"The fund that we run has doubled in size over the last five years. Our equity portfolio has returned more than 100%. So, I think it is a time of being a little bit cautious."

Norway's wealth fund, the world's largest, was established in the 1990s to invest the surplus revenues of the country's oil and gas sector. To date, the fund has put money in more than 8,760 companies in 71 countries around the world.

NBIM's Grande cited concerns including the political climate in the U.S. ahead of next month's presidential election, China's stimulus-fueled bid to restore confidence in the world's second-largest economy and the narrative of "stagnant growth" in Europe.

"So, it is a time to be a little bit cautious, and I think the risks are more on the downside in the equity markets than on the upside," Grande said.

NBIM's stock market warning comes shortly after Norway's sovereign wealth fund reported a third-quarter return of 4.4% and profit of 835 billion Norwegian kroner ($76.1 billion).

The results, which came in marginally below a benchmark index against which the fund measures itself, were boosted by stock market gains on falling interest rates.

Several major central banks have taken steps to ease monetary policy in recent months as inflation falls in many high-income countries.

On Tuesday, the International Monetary Fund said that while the global fight against inflation is "almost won," the downside risks are "increasing and now dominate the outlook."

'A tough, tough environment'

It's not just Norway's sovereign wealth fund that's worried about the outlook for equities over the coming months.

Eric Johnston, chief equity and macro strategist at Cantor Fitzgerald, said last month that downside risks for the assets were very high.

Johnston cited three major concerns for the U.S. economic outlook over the next three to six months: declining excess savings, consumer prices that are "simply too high," as well as somewhat restrictive Federal Reserve monetary policy.

"And then, oh by the way, you have China, which is 17% of global GDP, that is a drag," Johnston told CNBC's "Closing Bell" on Sept. 12. "So, I think it is a tough, tough environment."

Johnston's comments came before the Fed delivered a jumbo interest rate cut of half a percentage point last month.