Etihad has increased its stake in Virgin Australia to 6.1% after spending A$10.6 million ($11.1 million) on share purchases between 24 July and 17 August.
In a disclosure sent to the Australian Securities Exchange, Etihad says it paid between A$0.39 and A$0.45 per share for 24.4 million additional shares.
The Abu Dhabi flag carrier had initially acquired 3.96% of Australia's second largest airline in June - growing the stake to 4.99% within days.
It subsequently received approval from the Foreign Investment Review Board to increase the shareholding to as much as 10%.
The regulator's green light stirred unrest among some Australian politicians and trade unions, who voiced fears that Etihad might seek to damage flag carrier Qantas by pursuing predatory pricing at Virgin Australia's domestic unit.
Qantas has since entered into negotiations with Dubai-based Emirates and Qatar Airways over possible codeshare agreements.
Etihad and Virgin Australia formed a strategic partnership in August 2010, when they agreed to work together on codesharing, marketing and frequent flier programmes.
Etihad also has a 3% stake in Dublin-based Aer Lingus; a 30% controlling interest in Air Berlin; and a 40% shareholding in Air Seychelles.