reading a couple of other articles on this, it seems that ASIC is not after citibank because a proprietary trader bought more shares than anyone else on the day. they're going after them because he sold some after allegedly hearing that citibanks commercial arm were unhappy about his trading. it seems this may be a test of new insider trading laws in australia, the regulator wants these laws to be interpreted as meaning that proprietary traders cannot trade in company stocks where the company is being advised by the same firms commercial department.
This was blatant: "The next day Citigroup's top-rated transport analyst, Jason Smith, failed to publish an expected research report on Patrick, and speculation in the stock became frenzied. According to a statement of claim filed by ASIC with the Federal Court, one of the most active buyers of Patrick stock was Andrew Manchee, a trader on Citigroup's proprietary trading desk. He bought over one million shares in Patrick. Patrick's price spiked up from $5.70 at the close of business on Thursday, August 18, to $6.45 when the market closed next day. ..... Patrick's stock closed at $8.06 last night. "" Corrupt as they come.