The Old Bailey heard that Gerald O’Mara, 52, handed out free verification checks while working at the Chartered Institute for Securities & Investment.
The events organiser repeatedly provided the service to a favoured firm at no charge between May 2005 and September last year.
He appeared at the Old Bailey to plead guilty to a single charge of fraud.
Judge Paul Worsley QC adjourned sentencing until August 2 to allow reports to be prepared.
He said: “The court must be in a position to consider all options. But, I must say, at the moment the most obvious one is an immediate custodial sentence.”
David Kitson, defending, said he would be asking for Mr O’Mara to be spared jail. “He has lost his job as a result of this,” said Mr Kitson. “It is a large amount of money but it was for no personal gain to him.
“There has been a financial settlement where the amount has now been settled with the CISI.”
Mr O’Mara, of Lewisham, southeast London, was bailed on condition he stays at his home address ahead of the sentencing hearing.
