The General Secretary of the Financial Services Union has said there must now be a very thorough independent review of Davy stockbrokers.
John O'Connell said the €4.1m fine from the Central Bank and subsequent resignations do not go far enough.
Speaking on RTÉ's Morning Ireland, Mr O'Connell said there was a reputational issue for the whole sector, given the lack of transparency and the fact the Central Bank accused Davy of being vague and misleading at the outset of the investigation.
The Central Bank last week fined Davy €4.13m for breaching market rules in relation to a transaction in November 2014 involving 16 of the broker's own staff.
The fine was the biggest of its kind ever levied on a broker in Ireland.
The board of the company also accepted the resignations of Kyran McLaughlin from his role as a non-executive Director and of Barry Nangle from his executive role as Head of Bonds at Davy.
The company said all three offered to step down following the recent fine by the Central Bank.
John O'Connell said there is a reputational issue here for the whole sector that needs to be addressed and it needs to be investigated further, very quickly.
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"I think the length of the investigation needs explaining as well, why it took that long to get to this point. I think there needs to be a very thorough review independently of Davy to see what else is there," he said.
Mr O'Connell said there is now a feeling of "them and us" following the controversy.
He also questioned why nobody spoke up, adding that the initiatives for people to speak up in the finance sector are "not working".
He said that Senior Executive Accountability Regime (SEAR) legislation would allow more "effective" situations, where rather than a bank as a whole being held accountable the senior executives involved could be held accountable for such issues.
He said in the absence of such regulation, people are looking for the Government to "give a lead" and show that when wrongdoing is identified, as it has been here, that there are consequences.
Mr O'Connell said Davy should be publicly accountable, and should appear before the Oireachtas Finance Committee to explain themselves.
He said his concerns did not stop at Davy, adding that they were sector-wide.