A lot of Wednesday's market unwind was driven by quantitative trading and the retail crowd, Mizuho's Daniel O'Regan says. ...

Given enough data points, every stock will have a natural drift — the range of price activity which the target security gravitates toward over a period of time. However, trading based on this drift can be a maddening exercise because of the myriad directions the market can take. Further, determining a specific outcome from the aggregate of all pricing behaviors is a fool’s errand. That’s where the quantitative approach comes to the rescue. Rather than trying to decipher the randomness of share prices, I i ...