An explosion in trading propelled by computers is raising fears that trading platforms could be knocked out by rogue trades triggered by systems running out of control.
Trading in equities and derivatives is being driven increasingly by mathematical algorithms used in computer programs. They allow trading to take place automatically in response to market data and news, deciding when and how much to trade similar to the autopilot function in aircraft.
Analysts estimate that up to 60 per cent of trading in equity markets is driven in this way.
Concerns have been highlighted by news that NYSE Euronext, the transatlantic exchange operator, has fined Credit Suisse proprietary trading arm for the first time for failing to control its trading algorithms. In the Credit Suisse case, its system bombarded the NYSE's systems with hundreds of thousands of "erroneous messages" in 2007, slowing down trading in 975 shares.
The case was far from isolated, say traders. CME Group, the Chicago-based futures exchange, is investigating a case this month where a trader in "mini" S&P Index futures contracts "inadvertently traded approximately 200,000 contracts as both buyer and seller".