As more details of last Thursday's collapse become clear, there is less evidence to suggest a "fat-finger" data-entry error caused the collapse. Instead, the picture is one of a highly rare confluence of events, some linked, some unrelated, that exposed weaknesses in the stock market large and small. Within five minutes, the Dow Jones Industrial Average had lost 700 points as trading seized up in individual stocks such as Procter & Gamble and even exchange-traded mutual funds.
"It did point out that there is a structural flaw," said Gus Sauter, chief investment officer at Vanguard Group. "We have to think through how you preserve the immediacy and yet preserve the liquidity."
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This diversity has made stock-trading cheaper, a plus for both institutional and individual investors. It has also made it more unruly and difficult to ensure an orderly market...
via online.wsj.com