"The mixed ownership model progress is the one single initiative the Government could do to have an impact on the size of the listed market."
Cameron said it was an opportunity for a broad range of investors to participate in the sharemarket.
Mighty River had been expected to float in October last year but was delayed by a challenge from the Maori Council. That challenge was overcome last week after the council's appeal to the Supreme Court failed.
Cameron said the delay had probably worked in the Government's favour as the sharemarket had recovered further and the extended timeframe had also allowed Mighty River Power to get market ready.
He said the country had gone through a period of household saving and money in the bank was now at record level. Now was the time for people to look at what to do with that money.
"I think we are going to be surprised by the interest."
People will be able to invest a minimum of $1000 in the float and the Government has said it will not scale down the amount of shares for those who buy under $2000 worth.
Brian Gaynor, a fund manager at Milford Asset Management, said if 250,000 people bought $2000 worth that would equate to only $500 million - just a small portion of the $1.92 billion float. But he thought those who bought more than $10,000 could face being scaled back.
About 228,000 investors bought into the Contact Energy float and Gaynor expected between 200,000 and 300,000 investors buy into Mighty River.
Latest Reserve Bank figures show there is $112 billion sitting in banks and Gaynor said if just $1 billion of that money was invested as well as local and institutional investors buying in, the offering would easily be filled.
Frank Aldridge, managing director at Craigs Investment Partners, which is one of the lead broking firms in charge of selling the shares, said the company had been building up its resources in the past 18 months in preparation for the float.
Craigs had set up a call centre, something it had never had before, and hired more specialist investment advisers.
Neil Paviour-Smith, managing director at Forsyth Barr, the other lead broker, said the confirmation of the float was exciting and had been a long time coming.
"We have been doing a lot of preparations and we are looking forward to getting out there."
Shane Solly, portfolio manager at Mint Asset Management, said he expected to see an appetite for Mighty River Power shares, despite a growing number of new investment opportunities acting to divert investor interest.
"I think there is an appetite for an organisation with appropriate governance in place with well-located assets."
