Interesting analysis of the Flash Crash: http://www.nanex.net/20100506/FlashCrashAnalysis_CompleteText.html Recommendations: - Quote and trade data must be time stamped by the exchanges at the time it is generated. This will ensure delays can be detected by everyone. Reasoning: Changing the procedure to time stamp at the time a quote or trade is generated is a near trivial exercise. It probably comes as a surprise to many that time stamping isn't done that way now. - Quote-stuffing should be banned. Reasoning: It is a manipulative device designed to overload the quotation system. Quote and trade dissemination (data feed) is a finite resource, and should be treated as such. - Add a simple 50 millisecond quote expiration rule: a quote must remain active until it is executed or 50ms elapses. If the quote is part of the NBBO, it may be improved (higher bid or lower offer price) at any time without waiting for the expiration period. Reasoning: The exchanges must protect the integrity of the National Best Bid/Offer system. What is the point of having a National Best Bid/Offer, if not everyone in your nation (apologies to Alaska/Hawaii) can reasonably execute a trade against it? 50ms is approximately the time it takes light and electronic communication to travel from New York to California and back. It is impossible to transmit information any faster. This rule would not limit quote/trade rates. So long as trades are executing, quotes can update thousands of times a second. Only a small percentage of quotes today would be affected and the potential for catastrophically high rates would be eliminated.