I know the exchange can automatically put a halt to the trading of an asset, and that seems (to me) like a good tool in this case. e.g. if there is a certain pre-defined amount of volatility in a certain time. Do you think that would address this concern?
Definitely an avenue for exploration. I'd argue that the exchanges have been doing this over time, but that market manipulators will always move faster than the exchanges can tune circuit breakers and other mechanisms to prevent manipulation. Folks who stand to benefit from the type of volatility embodied in the flash crash will always be able to outrun these sorts of changes.
Oh, also don't forget that the exchanges are subject to regulatory capture from the firms who benefit from real investors losing money to market manipulators. It's not like Goldman Sachs is going to be pounding the table for the NYSE to make it harder for HFT desks to manipulate markets.
I know the exchange can automatically put a halt to the trading of an asset, and that seems (to me) like a good tool in this case. e.g. if there is a certain pre-defined amount of volatility in a certain time. Do you think that would address this concern?