About 440,000 New Zealanders have pre-registered their interest in buying Mighty River shares in what is likely to be the biggest share float in New Zealand.
The Government intends to sell up to 49 per cent of Mighty River in what will be its first partial privatisation under the so-called mixed ownership model.
It also intends to partially privatise the other state-owned generators, Genesis and Meridian.
The financially troubled state-owned coal company, Solid Energy, has been taken off the block, but the Government still intends to sell down its majority stake in Air New Zealand.
The past 18 months have seen new issues from Summerset, Trade Me and the small brewing company Moa. Mighty River, estimated by brokers to be worth $3.2 billion to $4.8 billion, will dwarf last year's float of the $500 million Fonterra Shareholders Fund.
Mighty River is one of New Zealand's largest electricity companies. Its generating assets mostly comprise a series of hydro dams along the Waikato River. It also has extensive geothermal assets.