Investing.com -- The head of Norway's $2.3 trillion sovereign wealth fund said Wednesday that investors should not expect the strong equity returns seen in the first half of this year to continue.

Nicolai Tangen, CEO of Norges Bank Investment Management, made the comments after the fund reported a record first-half profit of nearly $185 billion. The fund's equity portfolio fell 2.6% in the first quarter before rising 15.98% in the second quarter, resulting in a first-half return of 12.95%.

Tangen said he was surprised by market resilience following the U.S.-Iran war and renewed inflation pressure. "If you went back two years and told me this is going to happen with the Hormuz strait, trade barriers, geopolitical tensions, and so on, I would never have thought that the market would be as resilient as it is," he said.

"For sure, we should not be expecting the same kind of returns going forward as we've seen over the last six months," Tangen added.

The CEO advised investors to maintain their positions during periods of volatility. "I would say the way to make money is one, be very, very long term — don't change your strategy — and be well diversified," Tangen said.

The fund's first-half performance was driven largely by a rally in semiconductor stocks, with top holdings including Samsung, SK Hynix, TSMC, ASML, Intel and Nvidia.

The fund owns 1.5% of all listed companies globally and roughly 3% of European listed companies.

Tangen warned that a market downturn would affect the fund, which provides about 25% of Norway's fiscal budget. "I don't think we'll have a repeat of the last 30 years going forward; I think there'll be tougher times ahead," he said.