"Australian airline Qantas has seen its plan to ally with Air New Zealand thrown out by regulators in both countries.
The deal, which would have given Qantas a 2.5% stake in exchange for NZ$550m (£175m; $276.5m) and created a regional powerhouse.
But the rulings from the watchdogs were uncompromising in their certainty that the arrangement would cut competition on routes across Asia - and damage New Zealand's economy by controlling the domestic New Zealand market.
"The fact is that there is a very large gap between the harm caused by the sharply reduced competition and the possible benefit," said Allan Fels, chairman of the Australian Competition and Consumer Commission.
"And that makes it very hard to envisage what further undertakings could be offered to meet our concerns."