...Grupo Mexico, S.A.B. de C.V.'s (BBB+/Stable) ratings are underpinned by the strong business position of Southern Copper Corporation (SCC), which is 86% owned by Americans Mining Corporation (AMC; BBB+/Stable), which in turn is 100% owned by Grupo Mexico. Fitch Ratings used its Parent and Subsidiary Rating Linkage criteria to rate these three companies. Grupo Mexico' s credit profile also benefits from its 75% ownership stake in GMexico Transportes, S.A.B. de C.V. (AAA[mex]/Stable), which is the largest railroad company in Mexico (BBB/Stable)....