The couple operated a Nelson financial consultancy for more than two decades and invested money on their clients' behalf.
Although the civil proceedings against the Mounts have been on the boil for four years, a suppression order over the case was lifted by the Court of Appeal only last month.
In the action, the former clients alleged funds were missing and that the values of some investments were overstated, which meant the Mounts had claimed fees they were not entitled to.
As well as this, they accused the Mounts of keeping the proceeds of some investments for their own personal benefit.
The investors filed for summary judgment against the Mounts and their company, which was heard in the High Court at Nelson last year.
In his decision on the matter, Associate Judge John Matthews found the Mounts had breached their duties, including to act honestly in their dealings with the clients and not defalcate their money. He was also satisfied that, as a consequence, the clients had suffered losses.
He entered judgment in the clients' favour for close to $3 million, with interest, which brought the total award to over $4 million.
The Mounts challenged that decision in the Court of Appeal, questioning whether the case was suitable for summary judgment.
But in a ruling this month, Justices Christine French, Geoffrey Venning and Robert Dobson confirmed the High Court decision, although they reduced the amount awarded by close to $55,000.
The lawyer for the former clients, Rick Farr, told the Herald they were in the process of enforcing the judgment, including through the sale of Mount's house.
"We haven't finished with Mr Mount yet," Farr said.
He said the action had been "a very difficult and challenging time" for the Mounts' former clients, who watched as their own money was used to defend the claim.