The Australian Securities and Investments Commission (ASIC) filed a civil suit alleging that Citigroup Global Markets Australia engaged in "unconscionable conduct" while it was advising logistics firm Toll Holdings in a 4.6 billion dollar (3.3 billion US) takeover bid for ports operator Patrick.

ASIC said Citigroup engaged in "substantial proprietary trading" for its own benefit in Patrick Corp shares on August 19, 2005, the business day before Toll announced its hostile bid for the rival company.

Citigroup, one of the world's largest financial services conglomerates, strongly denied the charges and accused ASIC of trying to regulate the proprietary trading desks of major investment banks.