Paper: https://www.math.nyu.edu/faculty/avellane/AvellanedaLeeStatArb071108.pdf
One thing I am a bit confused is that although many cointegration techniques rely on long term relationships among stocks, pca factors approach seem to look at the relationships based on a point in time returns?
For example, in this paper, although model estimation and building pca factors use historical data, to see if a next period residuals is above or below standard deviation threshold, doesn't it simply fit the factors based on loadings and one period returns? So even if one stock has been constantly outperforming the other ones, it would not consider that historical returns.