Re: @ Vladimir Plouzhnikov
"If you add HFT to some of the ingredients in that list, you get a nasty broth."
So you would if you add HFT to, say, an exchange system crash or a a major bankruptcy or nuclear war. That in itself does not make HFT any worse or more dangerous than any other routinely used systems - payments processing, comms, transport, power grids etc. If any of them breaks, it's usually unpleasant and disruptive and people want it fixed ASAP.
"Whoever knows the quirks, errors and biases of a given HFT algorithm - .... - has a powerful tool to perform price fixing and/or related malfeasances."
No, not really. If you know the deficiency of an algorithm you can theoretically exploit them against the company that uses it, yes. You will need to find a serious backer though. If you are a disgruntled programmer you won't have the capital needed to set up your own HFT trading outfit to play the algorithm. So, you will need to go to the competition, not that such cases are unheard off, but it's not easy and it will be detected unless your backer is very, very patient and careful - which they won't be or they wouldn't try it in the first place.
But as for rigging the markets with HFT? That just not how it works. You can move the markets unintentionally, sure, but there it's - you move them, you pay for it.
Rigging is done by humans through collusion, disinformation, fraud, social engineering, exploiting or cornering the OTC markets.