The difference between the letters TAM and ABU has proven to be a $64,000 question for stockbroker Hartleys.
The corporate watchdog has fined the Perth-based company after a senior dealer typed the wrong company code in a sell order and fuelled a day trader feeding frenzy.
Hartleys is blaming "fat fingers" for a bungle on October 25, 2012, that saw the dealer put 500,000 shares in Tanami Gold up for sale at the then bargain-basement minimum price of 5.3ï¿½.
The broker was actually trying to complete an order to offload a total of 35 million shares in ABM Resources at 5.3ï¿½ after earlier selling 34.5 million ABM shares.
It created a windfall for clients of internet broking firms, including CommSec and CMC Markets, which had placed orders near and well below Tanami's previous trading price of 79.5Â¢.
By the time the dealer realised his mistake, the stock exchange's automated system had matched the Hartleys sell order to 25 bids for 350,000 Tanami shares starting at 78.5Â¢ to as low as 50Â¢.
This left Hartleys at least $29,000 out of pocket and facing an investigation by the Australian Securities and Investments Commission and a potential fine of up to $600,000.
ASIC's markets disciplinary panel fined Hartleys $35,000 after ruling the breach was inadvertent and the result of the dealer incorrectly keying in Tanami's stock exchange code of TAM instead of ABM's code, ABU.
Hartleys chief executive Charlie Ransom said the dealer, who he would not identify, had to cover the shortfall and the fine.
Mr Ransom said the broker was rushing at the end of the trading day and was "looking at one thing and working another".
He said brokers would have agreed to reverse mistaken trades in the days before online traders became prevalent.