March 23 (Bloomberg) -- Citigroup Inc. said it will fight claims the firm breached its duty to a client when Australia's first insider-trading case against a company starts next week.

The world's biggest bank by value failed to protect the interest of Toll Holdings Ltd. when it traded Patrick Corp. shares, according to the Australian Securities & Investments Commission. Citigroup, which advised Toll in its $4.2 billion bid for Patrick, acted ``appropriately,'' the New York-based bank said in a statement today.

The trial in Sydney's federal court is the first test of a two-year-old law governing how securities firms manage conflicts of interest between their advisory roles and proprietary trading on their own account. The case may have global implications, said Justin O'Brien, professor of corporate governance at the Australian National University in Canberra.

``If the regulator wins, it creates enormous problems for an integrated investment bank engaging in proprietary trading in stocks held by a company for whom it's also providing corporate advisory services,'' said O'Brien in an interview.

The trial, which starts March 26, is expected to last three weeks, Judge Peter Jacobson said today.

`Wider Issues'

``We've seen from the beginning that this case would raise wider issues for the investment-banking community,'' said Duncan Fairweather, executive director of the Sydney-based Australian Financial Markets Association, whose group represents global banks including Citigroup, Morgan Stanley and UBS AG.

``This is new law that took effect on Jan. 1, 2005, and the extent of the obligation has not yet been defined by the court,'' Fairweather said last week.

Citigroup had no fiduciary relationship with Toll and acted in the best interests of its client, said Stephen Roberts, Citigroup's head of investment banking in Australia, in a statement today. The bank's proprietary traders, who bought shares of Patrick on Citigroup's account, didn't know the bank was advising Toll on its bid for Sydney-based Patrick, he said.

``The conflicts were appropriately managed,'' said Roberts. ``If greater levels of disclosure are required this is best dealt with through industry consultation rather than the courts.''

`Never Been Tested'

The suit will test how global securities firms manage conflicts of interest. The trial will challenge the model under which investment banks trade shares on their own account while giving advice to clients, according to lawyers and academics following the case.

``Potentially, this case has enormous implications,'' said O'Brien. ``At what stage an investment bank owes a fiduciary duty to clients has never been tested. That's why this is a landmark case.''

The Australian Financial Markets Association sought unsuccessfully to intervene in the case. The country heads of Deutsche Bank AG, Morgan Stanley, UBS, Citigroup's Roberts, and Goldman Sachs JBWere Pty. Chief Executive Officer Craig Drummond all sit on its board. Citigroup didn't participate in the association's decision to apply to join the case.

The association's bid to join the trial ``seems to be a sign that people are concerned the court could lay down guidelines that have wider impact,'' said Andrew Jeffries, a partner of law firm Allen & Overy LLP in Hong Kong.

Charles Prince

The trial is a setback for Citigroup CEO Charles Prince, who overhauled internal controls in the past 3 1/2 years to limit chances of the firm becoming embroiled in financial scandals.

Citigroup was forced to pay $4.7 billion in the past three years after being accused of helping bankrupt Enron Corp. and aiding WorldCom Inc. defraud investors. The bank has also settled claims that its research was biased, that it misappropriated mutual fund fees, and shut its private bank in Japan in 2004 amid money laundering charges.

``The aggressive U.S. banking and financial model that has developed since 2000 may not be suitable for all other places that the U.S. banks try to do business,'' said Charles Geisst, professor of economics and finance at Manhattan College and author of ``100 Years of Wall Street,'' in an e-mail.

Citigroup has denied any wrongdoing and none of its employees are defendants in the Australian suit. The trial will test whether Citigroup had ``adequate arrangements for managing inside information and dealing with conflicts of interest,'' Judge Jacobson said March 15.

Trading Triggers Probe

The regulator's case stems from trades made by one of Citigroup's traders on Aug. 19, 2005, the last business day before Melbourne-based Toll made its bid for Patrick.

A breach in Citigroup's so-called Chinese wall is alleged to have occurred when Paul Darwell, head of equity derivatives, met with trader Andrew Manchee outside the firm's Sydney office for a cigarette break Aug. 19 and told him to stop buying Patrick shares for Citigroup's account, according to a claim filed by the regulator in March last year.

Manchee, who then sold 192,353 Patrick shares, had bought more than 1 million earlier that day. His trades triggered a probe into whether he knew Citigroup was advising Toll on its bid for Patrick, whose shares surged 13 percent on Aug. 19.

``There have not been many legal cases on Chinese walls and how they should operate,'' said Jeffries in an interview. ``That's why we and colleagues in New York and London are watching this case.''

The regulator is seeking a fine of as much as A$1 million and orders for Citigroup to keep price-sensitive information on deals away from traders who buy and sell shares for the firm.

The case is Australian Securities & Investments Commission v. Citigroup Global Markets Australia Pty. No. NSD 651 of 2006.

To contact the reporter on this story: Kevin Foley in Sydney on at k.foley@bloomberg.net

Last Updated: March 23, 2007 00:46 EDT