State-Owned Enterprises Minister Tony Ryall said the government expects between 85 per cent and 90 per cent of the MOMco shares to remain New Zealand owned, including the government's stake.
Strong appetite is expected from managed funds, including KiwiSaver providers, as well as from retail investors.
"The government remains on track to proceed with the first share offer, for MightyRiverPower, in the third quarter of 2012, market conditions permitting," said Ryall in a statement.
The FMA has granted some exemptions from restrictions on what the government could say about the potential investments, which Ryall said was "quite common" and had occurred in the sale of stakes in both Contact Energy Auckland International Airport.
In February, the Treasury appointed Chris Major, a former senior communications adviser and one-time private secretary to Cabinet Minister Murray McCully, to the marketing and communications director role overseeing the partial privatisation plan.
The department also appointed Senate Communications to run its public relations and Clemenger - for many years state-owned Meridian Energy's advertising agency -the advertising contract.