An investigation has begun in the US following a remarkable drop in share prices on Wall Street last night that saw the Dow Jones fall nearly 1,000 points.
It had been speculated that a dealer there had mistaken billions for millions when keying in a transaction and as a result set off the record plunge.
The US Securities & Exchange Commission and the Commodity Futures Trading Commission have said they will review the unusual trading activity.
Last night's 9% plunge on Wall Street panicked traders as about $1 trillion was wiped off the value of US shares for a brief time.
While the Dow later recovered to close 3% lower, traders were left asking what had caused three months of solid gains to be wiped out in a matter of minutes.
It has been suggested that a major firm accidentally triggered a trading programme worth $16bn, instead of $16m.
However, some sources have also suggested the trade could have been an attempt to exploit the market turmoil to make illegal profits.
US President Barack Obama confirmed that authorities were probing 'unusual' stock market activity.
'The regulatory authorities are evaluating this closely with a concern for protecting investors and preventing this from happening again and they will make findings of their review public along with recommendations for appropriate action,' he said.
World markets continue to remain under pressure as concerns over the Greek debt crisis grow.
At yesterday's close, the Dow had recovered to 10,520.32, down 347.80 (3.20%), while the Nasdaq was down 82.65 points (3.44%) at 2,319.64.
The Standard & Poor 500 Index was down 37.72 points (3.24%), to 1,128.15.
