Trades in hundreds of thousands of QBE Insurance Group Ltd shares were cancelled today after a butter fingers broker entered a sell order in the $22.80-plus stock at a mere two cents.
The blooper effectively pushed the giant insurer out of the bluechip S&P/ASX 200 index momentarily and sent the index itself plummeting almost 100 points.
The Australian stock exchange (ASX)at 1435 AEST notified the market that trades in QBE shares from 1420 AEST at or below a price of $22.20 were to be cancelled.
An ASX spokesman said the stock had been trading at $22.85 before the erroneous two-cent order was placed.
Some orders at 0.1 cents were also placed before the price improved above $19 although the ASX eventually decided to rule out all trades below $22.20.
The initial erroneous two-cent order had been for more than 500,000 shares.
The total volume of shares cancelled and their value was not released.
The alarming dip had an immediate effect on the bluechip index S&P/ASX 200 but it was soon rectified and had no ultimate impact on the end-of-day index results.
"We've already corrected for the error," a Standard & Poor's spokeswoman said.
"It was only when the trade went through that the index was impacted for a moment."
The index finished up 89.28 points at 4936.7.
Seasoned stockbroker Michael Heffernan, at Austock Securities, said the sudden dip in the benchmark index had caused some consternation when it first noticed among his colleagues.
"It looked like we fell off a cliff," Mr Heffernan said.
"You look at the graph and it's like The Gap in Sydney. It's a sheer cliff."
Mr Heffernan said he soon realised it was mistake after he scoured the market but could find no reason for the index to plummet.
QBE did not respond to request for comment.
QBE closed 51 cents, or 2.29 per cent, higher at $22.81.
Finance reporter Ross Greenwood has told 2GB's Philip Clark, it was the type of bizarre accident that haapens very rarely.
"They were sitting around $22.85 at the time. They were sold for, well not even a cent.
"They went for $0.001, which is a tenth of a cent. As a result of that it caused the whole market to basically tank."