The federal Securities and Exchange Commission (SEC) is investigating how oil giant ExxonMobil calculates the value of its assets in a world looking to force stricter rules on fossil fuel emissions, according to multiple reports.

According to the Wall St. Journal, which broke the story, the SEC asked ExxonMobil and its auditors, PricewaterhouseCoopers, for documents last month.

The SEC probe is examining how the oil company’s financials allow for international efforts to cut greenhouse gas emissions and how the company “evaluates the economic viability of its projects” under climate change laws, the WSJ reported.

The investigation puts an ever-brightening spotlight on ExxonMobil’s current and historical dealings with climate change.

The company is facing probes from several attorneys general into whether the company lied about what it knew about the risks of burning its products.

Those investigations came after reports in the LA Times and Inside Climate News that found the company’s own scientists were warning about the risks of human-caused climate change in the early 1980s.

Exxon, and later the merged ExxonMobil company, went on to pour millions of dollars into groups which denied the link between fossil fuel burning and climate change.

Climate change campaigner Bill McKibben, of 350.org, said in a statement: “This is a remarkably important development — the federal government is joining the courageous state attorneys general, and they’re all following the trail of clues that began with powerful investigative journalism.

“Before they’re done we’ll understand considerably more about how the world overheated — but in the meantime, every institution that invests in Exxon should take real note of who you’re keeping company with.”

An ExxonMobil company spokesperson, Alan Jefferson, told CNBC: “The SEC is the appropriate entity to examine issues related to impairment, reserves, and other communications important to investors.

“We are fully complying with the SEC request for information and are confident our financial reporting meets all legal and accounting requirements.”

News of the investigation saw ExxonMobil’s shares drop by 1.5 percent at the close of trading on Tuesday, reported Reuters.

Main image: SEC headquarters in Washington, D.C. Credit: Flickr/SEC