For decades, high speed trading has been sucking the blood out of the world's capital markets, and the answer has been clear for some time: find some way to force transactions to move more slowly.
So today's approval of IEX as an exchange is a big deal. How much do you have to slow down trades to get a fair deal? IEX has found that 350 microseconds is enough! Less than 1/100 of the time of an eyeblink for a human, that's enough time for a photon to travel about 60 miles. For computers, that is apparently slow enough to make high-speed arbitrage completely untenable.