Shareholders of the company that owns Dreamworld have gone to court to seek compensation for losses following the Thunder River Rapids Ride tragedy which killed four people.
Ardent Leisure confirmed in a statement a shareholder class action has been served against it in connection with the 2016 deaths, and said it would "vigorously defend the proceedings".
Cindy Low, Kate Goodchild, her brother Luke Dorsett and his partner Roozi Araghi were killed when a water pump on the ride malfunctioned, causing water levels to fall dangerously low.
Three criminal charges were filed against Ardent Leisure this week, alleging a failure to comply with a health and safety duty that exposed an individual to a risk of death or serious injury.
The maximum penalty for each breach is $1.5 million, or $4.5 million in total.
Separately, proceedings have been filed by legal firm Piper Alderman in the Federal Court on behalf of people who acquired Ardent shares between June 17, 2014 and October 25, 2016.
"The claim alleges Ardent misled investors about the safety measures and corporate governance standards in place at Dreamworld in the years preceding the accident causing Ardent's shares to trade at an artificially inflated price," Piper Alderman states on its website.
The class action argues claims by the Ardent Leisure Group over guest safety contradicted the findings of an inquest into the four deaths.
The findings were handed down in February after months of evidence in 2018.
This latest claim by shareholders accuses Ardent of "misleading and deceptive conduct" for claiming it adhered to best practices and Australian Standards and had systems in place to maintain a safe environment for guests.
The claim argues Ardent "likely knew or ought to have known" from January 2001 that Thunder River Rapid Ride rafts could collide and capsize, posing a risk to patrons.
It also says evidence presented at the inquest shows "no proper safety system or document management system was in place at Dreamworld" while it was under Ardent Leisure Group's control.
The class action action is against Craig Davidson, the chief executive officer of Ardent's Theme Park division until July 2018 as well as Ardent Leisure Limited, Ardent Leisure Management Limited and Ardent Leisure Group Limited.
Ardent said it will fight the allegations.
"Ardent strongly denies any contraventions as alleged and believes the proceedings to be without merit," its statement said.