The New York Stock Exchange yesterday started an investigation into a possible computerised share sell-off that triggered yet another turbulent day on world markets.
The Dow Jones Industrial Average lost nearly 1000 points, 10% of its value, in less than 30 minutes in the biggest drop during a trading day.
The Dow recovered two-thirds of the loss before the closing bell but that was still the biggest point loss since February last year.
No-one was sure what happened, other than automated orders were activated by erroneous trades.
Forsyth Barr broker Peter Young said there was a possibility being investigated that a trader accidentally placed an order to sell $US16 billion ($NZ22.5 billion) instead of $16 million ($NZ22.5 million).
That was known as a "fat finger trade", where the B for billions was pressed on the keyboard instead of M for millions.
"There's no doubt they will be investigating that."
About $US1 trillion was wiped off US equity values before prices clawed their way back.
After three days in which stocks had suffered triple-digit intra-day losses because of concern about Greece's debt crisis, it was clear that the sell-off was real for some investors, he said.
The Australian sharemarket staged a mid-trading rally as bargain hunters returned to buy shares of major resource companies - BHP Billiton, Rio Tinto and Fortescue - which had reached recent lows this week following talk of a steep resources tax.
The NZX-50 closed down more than 59 points at 3158 as investors remained wary.
The dive on Wall Street sent Asian stocks sliding, with the Nikkei average index down more than 4% to a two-month low. Hong Kong opened 2% down.
The euro continued its gain against the US dollar yesterday, helped by the news that the Group of Seven (G7) finance ministers would discuss efforts to aid Greece later in the day.
Gold hit a five-month high at $US1208 ($NZ1697) to a backdrop of turmoil in Europe and tumbling global stocks, while oil hit a 15-month low, before rebounding.
The precious metal has resumed its mantle of safe-haven status as worldwide investors, spooked by Greece's sovereign debt issues, sold their stocks and look for somewhere safe to put their cash.
On the London Metals Exchange, gold topped $US1200 in trading during the day and closed at $US1184.85.
On the Comex division of the New York stock exchange, gold hit $US1208.65 before falling off to $US1199.03.
Oil, which often tracks alongside gold hikes, has sustained a more than 10% fall in crude prices during the past four days, falling 4% in the US yesterday, according to Reuters.
The decline was oil's worst three-day run in 15 months and went down to $US74.58 a barrel, partly due to rising US oil inventories, its strengthening dollar and the almost 10% dive in major US stockmarket indices.
Oil later retraced some losses to trade above $US80 in the US. In London, Brent crude rose to $US82.78 a barrel.
