There still hasn't been a good explanation for the flash crash
I think this is exactly what happened back in 2009, at least in part, and then again to lesser extent in 2011 (US default). Computers programed to mass-sell if prices drop below a certain level (stop/loss orders) -- and then all operators around the world panicked at the same time, seeing their portfolios thinning out at accellerating speed and unsure whether they should pull the plug (no time to reprogram) or wait and sell even more with increasing losses. Well, at least some parties did not pull the plug and later went shopping for real cheap...
I wouldn't mind paying a little more per trade to know there isn't some computer trying to game me.
(1) I think Europe tries to "solve" this (haha!) by giving out licenses: the bigger the trader, the more expensive the license. And several stock markets, or rather selected stocks, have repeatedly been suspended from trade for a day or two (at least in Spain) to prevent chain reactions.
(2) I too wouldn't mind paying a little more (like what: 0.1 to 10 cents per trade?), it's better than being beaten by a computer (by what: 0.1 to 10 cents?). Either way, I think I can afford. But I rather pay it to the state as tax [-- states sure are not our saviours(!), but if they positively assure me and then actually
do administer the money to the greater good of the people(!!), and if they don't I'll vote for the other neck-tied scarecrows next time --]] well, then I prefer taxation rather than giving it to some caffe-latte art aficionado free-market junkie brokers.
(3) The IEX idea sounds interesting; however, it's a free market and as such it knows many "legal" ways to elegantly get rid of unwanted competition.
But you are absolutely right: high-speed trading is a problem. Ever noticed that sometimes prices drop totally without reason by up to a couple of dollars/euros/pounds/whatever, just to go up again (and even to a few cents higher than before) only a few minutes later? Highly dubious activities that look much like "attacks". It's called a "bear trap": shamming people/computers into selling by tricking/activating programmed stop/loss orders, i.e. placing massive sell orders without execution and then go buy for cheaper. Absolutely great
Sometimes it's caused by "auctions at opening of market" on the other side of the globe, but not always. Anyway, most high-speed trading is about cents and fractions of cents (a game that private investors can't keep up with). But, whenever I see such a curve (sudden, massive dip of up to 10 minutes) I feel assured that the price of that particular stock will continue to rise, cos someone has an interest to massively buy into it.
Anyway, my personal decisions are entirely independent of all this. I look at fundamentals and than at charts and trends.
Either way, we are talking fractions of cents here and maybe a few dollars at a time, not hundreds of dollars disappearing as with Bitcoins.