A scathing inquiry has criticised former Cabinet minister Michael Wood for "a worrying and ongoing lack of awareness" over the need to quickly correct errors when managing conflicts of interest.
Wood - who resigned as a minister last month - has now been referred to Parliament's Privileges Committee, where MPs will consider whether he is guilty of contempt.
Registrar of Pecuniary Interests Sir Maarten Wevers launched an investigation in June after it was revealed the then-transport minister had failed to sell his shares in Auckland Airport despite repeatedly being told by Cabinet officials to do so.
His report, published on Tuesday, concluded Wood "did not turn his mind to his interests as he should have".
"In so doing, he has damaged his own standing as a member and has also cast a shadow over the entire register, and the trust and confidence that the public are entitled to expect they can have in their elected representatives."
Sir Maarten said he was "surprised and concerned" Wood could not say whether had read the material given to all MPs every year which outlines their obligations.
"Wood also demonstrated a worrying and ongoing lack of awareness of the need to correct errors and omissions in his pecuniary interest returns and that the corrections should be notified in a timely manner," he said.
"Wood was very tardy in correcting his prior returns."
Sir Maarten interviewed Wood face-to-face on 28 June, and noted the MP brought along "a senior partner in a leading law firm" without any warning before their meeting.
"After some consideration, I decided to allow that gentleman to remain in the room, but only as an observer, and adviser - if requested - to Wood."
Wood returned to Parliament for the first time since his resignation on Tuesday. Speaking to reporters earlier, he said the public could trust him.
"Like a lot of people, I do sometimes make mistakes. I have in this case. I've apologised for those and I've spent the last few weeks putting things right."
Wood said he had received a "really good response" from the public over the past few weeks in his home electorate of Mount Roskill.
"A lot of people have sort of said, 'Look, you're a silly goose, you got this wrong, you need to sort these things out... and get focused on the issues.'
"That's what I'm doing."
Wood confirmed he intended to contest October's election and seek re-election in Mount Roskill.
"There are a lot of important issues there, and I want to get on with helping people with those as part of the next Labour government."
National MP Chris Bishop - who sits on the Privileges Committee - said the MPs would meet in due course to consider next steps.
"It would be inappropriate for me to make any comment as I'll be sitting on the committee considering the matter. Everyone knows the background to exactly what happened... we'll be meeting in due course, and that'll be it."