I continue to be surprised that certain orders are being cancelled, even though there is no evidence yet that those orders were fraudulent or were improperly executed as the result of a mechanical failure of some sort.
This is a pretty frightening admission by SEC Chairman Mary Schapiro:
One of the challenges we face in recreating the events of last Thursday is the reality that the technologies used for market oversight and surveillance have not kept pace with the technology and trading patterns of the rapidly evolving and expanding securities markets.
Ms. Schapiro's testimony, as well as the testimony of Commodity Futures Trading Commission Gary Gensler, is available as links from this New York Times article.
The CFTC would like more data:
Independent from Thursday's events, the CFTC currently is considering the implications of co-location and high-frequency trading. We also are considering a rule related to account identification so that the CFTC can collect better and more-detailed information on each trader in the futures markets.
Sounds like our financial regulators need more data and better analysis tools. Hopefully they can figure out a better answer for "what happened on Thursday" than they've been able to provide so far.