HILVERSUM/BUENOS AIRES, December 15: Endemol is picking up a minority share in Underground, the well-known Argentine production outfit behind Lalola and The Successful Mr. and Mrs. Pell$.

It was a nostalgic event for fans of the Mexican pop group, which first debuted in the 2004 telenovela “Rebelde.” (Alfonso Herrera was an original member of the group but declined to ...