Alison Gerry has quit Spark's board with immediate effect, citing a "perceived conflict of interest" issues.
Gerry is also a director Infratil, which disclosed on Friday that it is in early-stage or at least "ongoing and incomplete" talks with Vodafone over the potential sale of its NZ operations.
An AFR report earlier the same day had talks at a "late stage."
Gerry's abrupt departure from Spark could be an indicator that the Australian paper is closer to the mark.
Gerry has been a Spark director since 2016 and chaired the telco's Audit and Risk Management Committee.
"While according to Infratil's statement the discussions with Vodafone are 'ongoing and incomplete and may not result in a transaction occurring', Ms Gerry has offered her resignation as she is concerned about a potential or perceived conflict of interest going forward. I regretfully accepted that resignation today," Spark chairwoman Justin Smyth said in a statement to the NZX.
Gerry's move comes as reports of two private equity players coming forward with higher bids for Vodafone NZ than the $2.65b said to be offered by Infratil.
Meanwhile, investment bank Macquarie has said Infratil will need to raise around $445m from investors to maintain its 40 per cent gearing target, assuming the purchase price is around $2.65m.
Good fit for Infratil
Buying into Vodafone would not be Infratil's first tech investment.
In 2016 it bought a half share in Canberra Data Centres (CDC) for A$392m and a year later invested a further A$50m to help fund its growth.
Last month Infratil said the value of its 48 per cent stake in CDC had risen from $487.8 million to $841-$942m.
And when Vocus put its NZ assets (Orcon, Slingshot) on the block, Infratil was one of the rumoured bidders. The Vocus board eventually ended the process without a buyer.
Fat Prophets' Greg Smith noted that Infratil chief executive Marko Bogoievski was one of Theresa Gattung's top lieutenants at Telecom before he left in 2007, so has experience in the telco market.
"Vodafone is a good cashflow generator, it fits well with Infratil and makes a bit of sense … even though there is competition, it does have a dominant position, is number one in mobile and two in broadband.
"And it's not like there's going to be a whole host of new disrupters coming into our market."
Vodafone NZ by the numbers
For 2017 (its most recently reported financial year), Vodafone NZ made a profit of $57.5 million, turning around a loss of $18.3m. Revenue increased 2.8 per cent to $2.05b.
In the mobile market, it has around 2.4m mobile customers, putting it neck-and-neck with Spark and well-ahead of third-placed 2degrees.
In fixed-line broadband, Vodafone NZ has around 430,000 customers, putting it second behind Spark (around 670,000) and well ahead of third-placed Vocus (around 200,000).
Vodafone NZ's new chief executive Jason Paris has set about making the telco a more attractive proposition, by taking an axe to costs, then seeking new digital opportunities.
In February Paris told the Herald that as a proud Kiwi, he would like to see his company listed on the NZX but said the decision could well be made higher up Vodafone's global foodchain.
Asked then if the company was being positioned as a growth or value stock he said:
"I'd like to think both, right? It's good to have your cake and eat it, too. But the reality is we're in a very competitive industry where low single-digit revenue and margin growth is the norm. So a yield and dividend stock is where we'll be positioned initially."