The deal is likely to be worth at least $10 billion, commentators say.

Westpacs plans to sell its New Zealand business could mean it ends up in local investors hands, commentators say.
The bank announced to the New Zealand and Australian sharemarkets on Wednesday that it was considering a demerger of its operations.
It cited Reserve Bank plans to require New Zealand banks to hold more capital against their lending, and its requirement that banks separate their business operations from those in Australia, as potential reasons for the move.
The announcement was made the same day the Reserve Bank ordered Westpac to pay for two independent reports into its risk governance process.
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Robbie Urquhart, a senior portfolio manager specialising in Australian shares at Fisher Funds, said there was a lot of water to go under the bridge before Westpac made a final call on the future of the local business.
If it decided to list it on the New Zealand sharemarket with an initial public offering (IPO), it would be a big offer and consideration would have to be given to whether a range of investors, from strategic to retail, were included to make it digestible.
If they decided to sell to another party in its entirety that would bring a range of complexities.
He said the Reserve Bank had been pushing Australian banks to run their local operations as more robust, standalone entities in recent years, including increasing their capital requirements. That made it more likely that the parent companies would look at options such as a demerger, he said.
Banking expert Claire Matthews, of Massey University, said she did not think another Australian bank was likely to buy the Westpac business, and Kiwibank rumoured to be interested in acquiring other bank business in order to grow was not likely to have the capital.
A Westpac buyer will probably need at least $10 billion.
Kiwibank is owned by New Zealand Post, the New Zealand Superannuation Fund and ACC, but the Super Fund and ACC might not want to add more New Zealand banking to their investment portfolios.
NZ Super Fund and ACC have already blown quite a large chunk buying bits of Kiwibank, Tripe said. They dont have much left.
It is expected that Westpac New Zealand would be worth at least $10 billion.
Matthews said a Chinese or Indian-owned bank might see it as an opportunity to get a foothold in the New Zealand retail market. But Im not convinced thats what the Government wants.
Her colleague, David Tripe, said the most straightforward option for a sale would be to one of the Chinese big three Bank of China, CCB or ICBC.
Sam Stubbs, the founder of KiwiSaver provider Simplicity, said the banks were well known for fearmongering when put under pressure by the Reserve Bank.
New Zealand operations of the Australian banks were too profitable for them to want to withdraw completely, he said.
Aussie-owned banks make about 20 per cent more from a New Zealand customer than the equivalent Australian. New Zealand operations of the big banks are regularly referred to as the jewels in their crowns. Unless they were seriously in trouble at home, and there is no indication they are, they wouldnt want to sell the family silver.
And trans-Tasman trading and business links are too close for any Aussie bank to pull out of New Zealand. It would put their operations at a severe disadvantage to their competitors.
But Stubbs said the big banks would need to find about $8b between them to meet the new Reserve Bank capital requirements, and it was likely that they might choose to sell part of their businesses to do so.
The most logical [option] to me is a partial listing on the stock exchange in New Zealand. That would allow the banks to retain control and raise the capital required. It would also get local investor scrutiny over their operations, something that would please the Reserve Bank.
A partial listing would also take the sting out of the criticism about the banks milking New Zealand customers for the benefit of their Australian owners. Our stock exchange would love it too. It was delivered a windfall with the partial listing of the power companies, and this would be another. And it is very unlikely that Westpac will be the only bank announcing a review of its operations.
They will want to be at the front of the queue for capital raising, but the other Australian banks are likely to follow, especially if Westpacs capital raising is successful.
It is also possible that Westpac will engage in a trade sale and not raise money on the stock exchange. That is likely to get a higher price in the short term, but doesnt have the benefit of a retail listing.
Stubbs said it helped household name brands to have households owning a share. It had allowed Australian banks to defend their consistently high profits, he said.
So, strange at it may seem, I read Westpacs announcement of a possible demerger as a sign that they are actually interested in remaining in New Zealand and raising the money required to do so.
Tripe said it was also possible that the bank would not do anything, citing previous attempts by National Australia Bank to sell Bank of New Zealand. The example that comes to mind is the BNZ having been for sale numerous times but no sale eventuating, presumably because no-one is willing to pay what the NAB thinks its worth.
Urquhart did not think Westpac was simply posturing. I dont think its a coincidence that it was timed to be announced with the Reserve Bank reviews into Westpac. But they would have been looking at this as a broader response to the policy the Reserve Bank has been following over the past few years.