Los40 Ciudad de México 101.7 FM (Stream alternativo)

LOS40 101.7 (XEX-FM) broadcasts from Mexico City with a contemporary hit radio format featuring hits in Spanish and English, and is the flagship station of the Mexican Los 40 network. It transmits from a tower atop the World Trade Center Mexico City and operates as a Class C1 station with an effective radiated power of 51,190 watts.

XEX-FM signed on October 1, 1975, becoming the third FM station in the Radiópolis/Televisa Radio system. It began with an adult contemporary sound as "Stereo 102", though most of its history has been marked by frequent format changes. In the early 1980s it was "Radio Romántica" and then "Estelar FM", both with romantic music. In 1988 it returned to pop music in English and Spanish as "Estéreo 102".

It later became "Yo 102", a contemporary hit radio format that brought the station some ratings success. In 1994 it experimented with the name "Kiss FM", which failed to catch on. In 1996, after a brief return of Stereo 102, XEX-FM became "Vox FM".

In 2002, Televisa Radio and Spain's PRISA began a partnership and launched the "Los 40 Principales" brand in Mexico, which was popular in Spain and other Latin American countries. Televisa Radio and Grupo Radiorama signed an agreement allowing the much larger Radiorama to syndicate the Los 40 Principales format to its stations for wider coverage across Mexico.