Assuming that there is no relevant news, a hedge fund would buy the stock that is down and short the stock that is up and rely
upon regression to the mean to fix this disparity in time.
a
Regressions of winter SLP and SAT trends
upon the normalized leading PC of winter SLP trends in the CESM1 Large Ensemble, multiplied by two
to correspond
to a two standard deviation anomaly of the PC; b CESM1 ensemble -
mean winter SLP and SAT trends; c b − a; d b + a. SAT in color shading (°C per 30 years) and SLP in contours (interval = 1 hPa per 30 years with negative values dashed).