“…Previous literature has investigated the impact of water environmental protection regulations on pollution emission [ 13 , 16 , 17 , 18 ] and firm productivity [ 10 , 19 ], while a few researchers focus on the reallocation effect of firm production. Most of the existing literature focuses on the reallocation effect of pollution [ 20 , 21 ], capital [ 4 , 22 ], and labor demand [ 14 , 23 , 24 ] across regions, but little pay attention to the reallocation effect of production across firms within the same region [ 25 ]. Prior studies find that the reallocation effect of production from regulated to unregulated firms appears not only within the same regulated industries [ 25 , 26 ], but also within the same conglomerate [ 27 ].…”