New Zealand Telecom's trans-Tasman subsidiary, AAPT, is thought to be on the auction block again after it failed to offload the underperforming unit two years ago.
Even if the Sydney-based AAPT fetches an estimated price of $400 million, NZ Telecom is still expected to be down about $2 billion of shareholder money.
NZ Telecom bought AAPT in 1999 at the height of the internet and telecommunication bubble.
AAPT spokeswoman Louise Di Francesco said the company would not comment on market speculation.
Craigs Investment Partners director Geoff Zame said the loss in shareholder value could run into the billions of dollars for NZ Telecom shareholders over the past decade.
Mr Zame said AAPT could be a hard sell for potential buyers. "It has not proved to be attractive to potential buyers in the past. That is not to say, in an NBN world, should that eventuate, it might not have some attractions for the future."
He said aggregate services providers such as TPG could be interested in AAPT assets. AAPT's most prized asset is more than 10,000 kilometres of fibre, which connects cities throughout the country.