I don't know that much about quants, but my understanding is they focus almost exclusively on micro time frames and arbitrage opportunities. There are other automated systems that trade on larger time frames, but those are no different than hand traders, except the executions are done without human error, provided they were programmed correctly. I'm probably wrong, so please correct me. And because the market is a zero sum game, if the big banks are hiring theoretical physicists from mit to help them make money, then someone else has to lose. So my question is who are the losers? Is it always retail traders, more specifically day traders, or are the quants competing against each other, and hand traders are by and large isolated from them.