What the brokers think the company is worth is likely to have a big impact on pricing as they will be involved in a book build process used to help set the listing price.
Caution was also evident in what information has been included in the reports.
Macquarie Securities was the only firm to give a clear figure on the price per share which it puts between $2.44 and $3.06 based on 1.4 billion shares being issued.
Macquarie, First New Zealand Capital and Goldman Sachs are the lead investment bankers on the deal, which will see the Government sell up to 49 per cent of Mighty River Power.
Goldman Sachs did not include any clear forecasts on valuation, dividend yield or share pricing, leaving it up to its clients to work through the numbers and do the calculations.
A source said Goldman Sachs appeared to have stuck closely to the information in the investment document, providing the shortest report.
The research shows expectations for the value of Mighty River Power also vary widely.
The lowest view is held by Forsyth Barr with a range of $3.2 billion to $3.5 billion, well below the Government's own valuation of $3.91 billion.
The Goldman Sachs report states it would value the power company at a multiple of 13.5 to 13.9 times earnings before interest and tax, putting it around $4.78 billion based on its forecast of financial year ebit for 2014 of $349 million.
There also appears to be consensus that the net dividend yield will be between 4 per cent and 5 per cent with most firms expecting Mighty River to pay out between 90 per cent and 110 per cent of underlying net profits.
The biggest risk to Mighty River Power highlighted in the reports remains the closure of the Tiwai Pt Aluminium smelter.
Rio Tinto is the country's single biggest user of electricity and is in discussions over whether to keep its business in Bluff.
If the smelter closed it would hit all the power companies as usage would drop across the sector.
Other risks to the company's profits noted in the research were fuel and plant availability, variability in hydro output and the wholesale electricity market.
More than 385,000 Kiwis have already pre-registered their interest in buying shares in Mighty River. Pre-registration for the share offer closes on Friday.
Infographic: Claudia Ruiz