The stock exchange has penalised Tim Po Securities for failing to enforce internal controls and to inform the securities regulator about a shareholding change.
The exchange's disciplinary committee resolved after hearings last month to have Tim Po publicly censured and imposed a fine of $120,000.
The committee said it had taken into account previous punishment imposed on Tim Po when it considered the penalties.
Regulators found Tim Po had failed for the nine months to February 31, 1996, to demonstrate control of client accounts or to mail statements to clients.
A stock exchange spokesman said: 'Basically, Tim Po was found to have mixed up two client accounts.' In the first two months of 1996, Tim Po had been found guilty of changing its shareholder base, increasing its authorised share capital from $5 million to $20 million and shifting allotment of shares without first seeking the stock exchange's approval.
Two shareholders, holding 51 per cent and 49 per cent of Tim Po, were found to have transferred their stakes in the company to a corporation without prior written approval of the stock exchange.