The Serious Fraud Office expects to conclude its investigation into Allan Hubbard's investment fund, Aorangi Securities, in the next two to three months.

The SFO launched its investigation into Aorangi after the government placed Hubbard and his wife, along with seven charitable trusts, under statutory management in June last year.

SFO chief executive Adam Feeley told Radio NZ the investigation was one of their biggest to date and he expected the office to reach a decision soon on whether to lay charges.