Flotation has long been on the sidelines of the Fonterra agenda. It may not be too long before it takes centre stage.

It might appear unlikely that any business which is undergoing such a shake-up as Fonterra, the New Zealand dairy giant making big reforms to share ownership, would have an appetite for a further change.

But think of the current reforms as work in progress. What the numbers accompanying the co-operative's transformation reveal is that the logical destination is a stockmarket listing.

Changing priorities? 

They show that, for the first time, Fonterra's farmer members will have a huge incentive to vote for the float.

Sure, they've dumped on the idea in the past, preferring the security of 100% control rather than uncertainties which can come with allowing external investors in.

But that was before it became so apparent that opening the door would let in huge windfall gains.

Devil in the discount 

The rub is in the discount that Fonterra is introducing to its shares to reflect the fact they are not freely traded.

Grant Samuel , the accountant called in by Fonterra to value its equity, hasn't pulled its punches in applying this principle to the co-operative, with the shares so far gaining a discount of NZ$0.58 apiece, equivalent to NZ$725m overall.

And that's only the start. If it weren't for a phased introduction of the new regime, the shares would be worth NZ$1.27 a share, or 25%, below fair value. That's a discount of nearly NZ$1.6bn, or roughly NZ$150,000 per farmer.

There seem few alternatives to Fonterra shares trading freely on the stock market if they want that money back.

Keeping it 'strong'?

Indeed, a potential flotation makes an attractive case for Fonterra farmers to take up an offer from December 7 of buying an extra 20% of shares beyond their milk production entitlement, and so raise their potential windfall gain.

Such a move would also expand their clout within the organisation.

Sir Henry van der Heyden, the group's chairman, has called this entitlement an opportunity for farmers who "have made it clear they want Fonterra to remain wholly farmer owned" to "back the co-operative and keep it strong".

It may in fact hasten an end to the co-operative structure.