The system was privatized in 1999, becoming part of Ferrocarriles Chiapas-Mayab (FCCM) until 2007  and since part of Ferrocarril del Istmo de Tehuantepec.
This passage describes the ownership history of a system, starting with privatization in 1999 and then transitioning through different entities: Ferrocarriles Chiapas-Mayab (FCCM) and finally Ferrocarril del Istmo de Tehuantepec.