According to the commission, High Court judge Justice Patricia Courtney said although Online Realty was not a "ringleader" in the case, its conduct had brought a "significant and lasting" change to the market as most Hamilton real estate agents continued to pass on the cost.
To date the cases have seen more than $18.97m in court-imposed penalties on the real estate sector.
This includes $9.8m against the head offices of Ray White, Barfoot & Thompson, Harcourts and LJ Hooker collectively.
Bayleys was also previously ordered to pay $2.2m and Property Page Limited $100,000 towards the commission's costs.
Two other Hamilton real estate agencies, Lugton's Limited and Success Realty, were earlier ordered to pay $1m and $900,000, respectively. Cases against more Hamilton agencies and their directors are still before the court.
Three Manawatu real estate agencies have also been penalised: Manawatu 1994 was earlier ordered to pay $1.25m, Unique Realty $1.25m, Property Brokers $1.45m million and its director Tim Mordaunt $50,000.
The commission alleged the real estate agencies breached the Commerce Act by agreeing a planned industry response to Trade Me's pricing scheme.
It also claimed the parties agreed vendors would have to pay the listing fee to have their property advertised on Trade Me, and the agencies would not commit to any preferential or discounted listing fees with Trade Me.
Ray White has been approached for comment.
