Goldman Sachs (Asia) president and managing director Philip Murphy has breached stock exchange council election rules by starting his lobbying effort too early.
Mr Murphy is seeking election as a category B member of the council and sent out a letter introducing himself to brokers two weeks ago.
Sending the letter at this early stage breached exchange rules which state candidates must not lobby market practitioners before the exchange has announced the candidates' names.
It is expected a formal announcement of the candidates will be made today.
The council is understood to have received complaints from other candidates about Mr Murphy's move and discussed the case at a council meeting yesterday.
The meeting concluded Mr Murphy was unaware of the rule and said it would take no action against him apart from writing him a letter asking not to break the rules again.