"We have greater coordination and controls in place, both in futures and equity markets, but we still need more harmonisation between markets, both in the US and abroad," Commodity Futures Trading Commission member Bart Chilton said in a speech at the University of Chicago.

The CFTC and the Securities and Exchange Commission have been working on rules to govern when to halt trading in stocks if they suffer a quick and severe price movement since May 6, 2010, when the Dow Jones Industrial Average plunged nearly 1,000 points before quickly rebounding.

Chilton said that regulators were considering many new safeguards as a result of the crash, including circuit breakers, limit up/limit down rules, and requiring "kill switches" that would allow brokers and exchanges to shut down trading programmes that go awry.

Press release