The next stage of the Mighty River Power float begins on Tuesday with the bookbuild which will help determine the share price.
The price will be announced late on Wednesday, and the energy company is expected to be listed on the stock exchange on Friday.
During the bookbuild process, institutional investors will bid for shares and the price they are prepared to pay will influence the stock market price.
It will be up to government ministers to set that price and decide how many shares will be allocated to retail investors.
Of the available shares, 85% - 90%will go to New Zealand shareholder groups, and the Government will retain a majority shareholding.