“…For instance, El Karoui (2008), Bickel and Levina (2008), Cai and Liu (2011), and Fan, Liao, and Mincheva (2013) propose estimating the largedimension covariance matrix via the thresholding method. Among many others, Ledoit and Wolf (2012), Bailey, Pesaran, and Smith (2016) and Hafner, Linton, and Tang (2016) suggest using different shrinkage methods and provide a detailed computation algorithm. Lam and Fan (2009) and Cai, Zhang, and Zhou (2010), on the other hand, theoretically derive the asymptotic properties of the large covariance matrix estimator through shrinkage estimation using penalty functions.…”