The Securities and Exchange Commission (SEC) has closed an investigation into oil giant Exxon Mobil Corp. without taking any action.

The probe was opened in 2016 to examine how Exxon Mobil accounts for its oil and natural gas reserves and factors the costs of climate change into its operations, including whether it is truthful enough with shareholders about the financial risks of climate change and climate policies.

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Exxon Mobil provided a letter from the SEC Friday saying that the investigation had been closed with no action, but that such a notification was not an exoneration. The SEC doesn’t comment publicly on its investigations.

“The SEC initiated its investigation in January 2016, and ExxonMobil cooperated fully with the inquiry, ultimately producing more than 4.2 million pages of documents. After a thorough investigation, including a review of these documents, the SEC issued its closure letter,” Exxon Mobil spokesman Scott Silvestri said in a statement.

Activists have for years tried to hold Exxon Mobil financially accountable for its contribution to climate change. The campaign has included ongoing investigations by the New York and Massachusetts attorneys general into potential fraud, lawsuits and shareholder resolutions to increase transparency.

Exxon Mobil has fought most of the efforts, but it cooperated with the SEC one.

“As we have said all along, the SEC is the appropriate entity to examine issues related to impairment, reserves and other communications important to investors,” Silvestri said. “We are confident our financial reporting meets all legal and accounting requirements.”