That means the negotiations had kicked off in early 2009, when the fall-out from the financial crisis had pushed assets values to their lowest levels in at least five years. The NZX 50 Index slumped to its lowest level since early 2004 in March 2009.
In its 2010 annual report, Infratil said the counter-cyclical Shell transaction was one of the "positives from the turmoil" because it allowed the company to "invest in a market-leading business at a price which reflected a low level of competition amongst prospective buyers."
"It has been a fantastic investment," Mark Flesher, corporate development executive at Infratil manager Morrison & Co, told BusinessDesk.
Z Energy won't see any of the funds raised in the IPO, which is simply designed to allow Infratil and the Super Fund to realise some of their investment.
Super Fund spokesman Stewart Brooks said Z Energy "has responded well" to capital investment and re-branding over the past three years and as a result "now represents a significantly larger proportion of the Fund than it did when we purchased it in 2010." Selling down its holding would help to diversify the Fund's portfolio.
Infratil's Flesher said Z Energy "has a very strong balance sheet that still allows them to grow" and there are assets within its portfolio that could be recycled in future, such as the stake in NZ Refining.
Shares of Infratil rose 0.4 per cent to $2.485 on the NZX today and have gained 8.8 per cent this year. The stock is rated a 'buy' based on five analysts surveyed by Reuters.