WAG outperformed CVS going into the summer then got hit after announcing an acquisition which didn't include a corporate inversion tax-reduction scheme. Now WAG is turning up from deeply oversold as CVS hits a new high as they dump cigarettes. This is a ratio-trade where you see that two stocks move together, then when they separate it sets up a trade to profit from the laggard returning back to the mean (or average).
Earnings aren't due for a month - not the early October earnings release date.