Auckland International Airport carried out a major review of its capital structure in 2013.
That process culminated in $454 million being returned to shareholders last year and an associated re-leveraging of the firm's balance sheet.
To finance the share buyback, the company undertook over $1 billion in successful debt financings in both the domestic and international markets.
The judges said those transactions significantly lowered the cost of capital for the organisation and optimised tax efficiency.