The world's biggest sovereign wealth fund has lost $40 billion in the past month

Norway's sovereign wealth fund took a big hit in the global market sell-off.

The fund lost 5% in the past month, according to a Bloomberg report which cited an interview chief executive officer Yngve Slyngstad recorded in a podcast.

That represents a $40 billion loss for the world's largest sovereign wealth fund, which manages $840 billion.

The losses follow a rocky patch for markets around the world, as concerns over China's growth put investors on edge.

The Norwegian fund had about $27 billion invested in China and Hong Kong at the end of 2014, according to the Bloomberg report.

"We get a lot of information on the micro-level (in China) but it's difficult to get a read on the full picture of what is happening," Slyngstad said on the podcast.

From 1998 to the second quarter of 2015, the fund generated annual returns of about 3.9 percent.

Read the full Bloomberg article here.