Four former directors of Lombard Finance have lost their Court of Appeal bid to have their convictions overturned.
The company collapsed in 2008 owing investors more than $111 million.
In 2012, the High Court convicted William Jeffries, Michael Reeves, Sir Douglas Graham and Lawrence Bryant of making false statements in a company prospectus.
The Court of Appeal on Thursday released a judgement supporting the conviction, saying the prospectus was untrue because it omitted important information.
That included details about Lombard Finance's deteriorating cash position, serious delays in the recovery of loan repayments and the extent of the directors' concerns about those matters.
All four were sentenced to community work and Sir Douglas and Mr Bryant were ordered to pay $100,000 each in reparation.
The court has also ruled in favour of an appeal from the Solicitor-General that the men's sentences were manifestly inadequate. It will issue a final judgement once it receives reports on possible home detention.
Prime Minister John Key says he will seek advice on what could happen with Sir Douglas's knighthood and it may be stripped. It was awarded for his service in facilitating Treaty of Waitangi settlements.
Boost for investor confidence - FMA
The Financial Markets Authority says the Court of Appeal's decision to uphold the convictions will help to restore investor confidence.
The original prosecution was brought by the authority's predecessor, the Securities Commission.
Head of enforcement Belinda Moffat says Thursday's ruling shows directors must ensure that statements in offer documents such as prospectuses are true - even if that is not in their company's best interests.