Carol Anne Braithwaite has been found guilty of misleading National Finance investors.
The 53-year-old was convicted this morning on one charge of making untrue statements in a National Finance 2000 prospectus.
The charge carries a maximum penalty of five years in jail or a fine of $300,000.
Braithwaite was the first director of a failed finance company to have a case tried by a jury.
The jury of 12 had been deliberating since Wednesday afternoon and reached a majority rather than a unanimous verdict this morning.
This means 11 of them all believed Braithwaite was guilty while one juror believed she was not guilty.
According to prosecutors there were 10 material untruths in the document, an allegation Braithwaite accepted.
She defended the charge on the basis that she believed the prospectus was correct when she signed it in 2005.
She needed to prove it was "more likely than not" that she believed the statements were true and that she had reasonable grounds to do so.
Her lawyer, Quentin Duff said Braithwaite had information kept from her by her defacto husband - National Finance boss Trevor Allan Ludlow - before she signed the prospectus.
In his closing submissions, Quentin Duff referred to a contestant in reality show American Idol who genuinely thought they could sing but was actually terrible.
"The question isn't,'can Carol sing?' The question is, 'at the time did she genuinely believe she could sing?' The answer to that is 10 times yes," Duff said.
On the other hand, Crown lawyer John Dixon queried whether Braithwaite had even read the prospectus properly and had understood it.
"She wasn't qualified in the first place, [she had] never been a director of a company, never seen a prospectus before," he said.
The Crown argued Braithwaite "abdicated her responsibilities" as a director.
National Finance went into receivership in 2006, owing investors $21 million. Some investors have recovered 49c in the dollar.
Ludlow is serving a sentence of six years and four months' after being convicted of Serious Fraud Office and the Financial Markets Authority charges.
He was found guilty last July of defrauding investors of an estimated $3.5m.
The Financial Markets Authority (FMA) has welcomed the guilty verdict.
FMA Head of Enforcement Belinda Moffat said the decision should act as a reminder for what is reasonably expected of directors in their governance role and disclosure document obligations.
"A high level of professionalism amongst directors is essential for restoring market confidence," Ms Moffat said.
"Directors need to be aware of their obligations and it is no excuse to say they did not understand them or relied upon others."By Hamish Fletcher @hamishfletcher Email Hamish