Yesterday (July 19), CNBC reporter Bob Pisani noted interesting (in the suspicious sense) sawtooth patterns in a few stocks. One of them was Coke (NYSE:KO).
Looking at yesterday's intraday chart of the stock, you can definitely see buying pressure on the hour followed by a large runup until the half hour where selling pressure forces the stock in the reverse direction.
Coincidence? That's a tough possibility to swallow, although the action is not being repeated today. Perhaps a quant testing out a new algorithm..?