(Bloomberg) -- Norway’s $1 trillion wealth fund has stepped up its efforts to ensure the companies it owns aren’t exposed to the coal industry.

The world’s biggest sovereign investor is excluding Glencore Plc and Anglo American Plc from its portfolio, after tightening its criteria.

The fund’s list of excluded companies also names Sasol Ltd, RWE AG and AGL Energy Ltd after a limit was introduced in September that capped thermal coal production at 20 million metric tons a year, Norges Bank Investment Management said in a statement on its website. It also placed BHP Group, Vistra Energy Corp, Enel SpA and Uniper SE under observation.

The new rules, which set a cap on output and power capacity, are meant to close what activists and opposition politicians called a loophole in previous restrictions, which excluded companies that got more than 30% of their income from steaming coal.

Anglo American’s exclusion comes as it plans to exit its biggest thermal coal business within the next three years by spinning off its South African operations. The company has spent decades positioning itself as an environmental and social champion. But it’s risked getting left behind on thermal coal, after Rio Tinto Group sold its last coal mine in 2018 and as BHP looks at options to exit the business.

Norway’s wealth fund struggled to offload the shares of the excluded companies, saying that for several of them, the market situation, including the liquidity of individual shares, meant that it took a long time to sell the shares “in a reasonable manner.”

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