Citigroup was penalised by the Australian Securities and Investments Commission (Asic) for a breach of market integrity rules after placing a priority crossing order in shares of Fantastic Corporation in mid-May.

The Citigroup trader placed a sell order for 119,231 shares of the stock at a price of $O.024, instead of $2.40. Within seconds of the order being punched through the market price of FAN crashed to $0.024, a decline of 99%.

Citigroup cancelled the trades and contacted the ASX within eighty seconds of the fat-finger calamity.

Asic's investigation founds that the trader had recently moved to a new seat in the dealing room, using a new computer not set up with the appropriate pre-set limits and warnings that would have triggered an alert when the order was made.

In fining the bank $30,000, Asic accepted that the trader's conduct was careless, rather than deliberate or reckless, and that Citi had acted quickly to resolve the error, leading to a timely resumption of trading in the stock.

In a statement, Asic says: "Citigroup has co-operated with Aasic and attempted to address concerns arising from the investigation, by way of engagement with Aasic. Citigroup did not derive any actual or potential benefit from the contravention, nor did Citigroup cause any actual or potential damage to a third party."