Fragmentation That Fed May 6 Crash Is SEC Focus One Year Later

One year ago, regulators were unable to arrest a market collapse that erased $862 billion from stock values in less than 20 minutes. Yesterday, they agreed that their work to prevent a recurrence has yet to be completed.

Exchanges established circuit breakers to curb price swings across about 50 equity venues, adopted uniform rules on when to cancel transactions and eliminated quotes that let companies such as Accenture Plc fall as low as a penny from about $41 on May 6, 2010. David Shillman, associate director of the Securities and Exchange Commission’s division of trading and markets, said yesterday that while the initiatives have worked so far, more needs to be done.