Christen Sveaas' Viking Supply Ships (VSS) has said a former employee is being investigated over insider trading.
The Swedish Economic Crime Authority is looking into possible offences by "several persons" regarding its stock.
None of the suspects is a current employee, but one former staffer is on the list.
"VSS is in contact with the Swedish Economic Crime Authority and intends to cooperate fully with the investigation," it said.
The company said last month it will soon be debt-free following vessel sales, but expects a tough OSV market this year.
The owner, which despite its name now has no supply ships, said the net loss including discontinued operations for the fourth quarter was SEK 123m ($13.33m), down from SEK 132m in 2017.
