(Bloomberg) -- Mineral Resources Ltd. has begun an investigation into undeclared payments made to companies owned by its tycoon founder, Chris Ellison, sending its shares down as much as 14%.

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Ellison, who is managing director of Mineral Resources and still a major shareholder, said the payments pre-dated the company’s 2006 listing, and came from overseas entities he and his business partners operated, and which sold mining equipment and parts. He did not declare the income from the supply contracts.

“Regrettably, revenue generated by the overseas entities that we were beneficiaries of was not disclosed to the Australian Taxation Office at that time,” Ellison said in a statement on Monday. “This was a poor decision and a serious lapse of judgment.”

According to a report in the Australian Financial Review over the weekend, Ellison struck a deal with the Australian Taxation Office to pay up the outstanding amount. In exchange, authorities did not disclose the figure owed and he will avoid a police or regulatory investigation.

The Australian Taxation Office declined to immediately comment.

Mineral Resources said it retained confidence in Ellison, and would update the market once it had completed internal inquiries.

“Ellison self-reported to the Australian Taxation Office, repaid amounts owed and disclosed these matters to the board,” it said in a statement. “While this does not diminish what happened, Mr Ellison profoundly regrets his errors of judgment.”

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At 2:32 p.m. in Sydney, the stock was trading down 12% to A$40.38, giving the company a market value of about A$8 billion ($5.4 billion).

”While we understand that these concerns raise questions over corporate governance, we think the share price move today is overdone,” Kaan Peker, an analyst at RBC Capital Markets, said in a note, adding the key detail was that no sales had taken place after the company’s listing.

“The added scrutiny and rigor, the current concerns placed on corporate governance, ultimately, should be positive for the organization.”

Earlier this year, Ellison — a larger-than-life figure even by the standards of Australian business — made headlines after stating he wanted to prevent employees at the company’s office from leaving the building to buy coffee.