The corporate regulator has alleged insider trading by Citigroup Global Markets Australia Pty Ltd while it was advising Toll Holdings Ltd in its $4.6 billion takeover bid for Patrick Corp Ltd. The Australian Securities and Investments Commission (ASIC) has filed civil proceedings in the Federal Court against the global investment house. Citigroup has denied the allegations, saying it is an attempt by ASIC to regulate the proprietary trading desks of major investment banks.