Marco Daniel Borrero, known professionally as Mag, is an American record producer and songwriter from Brooklyn. He is recognized for his work with Bad Bunny, particularly on the album Un Verano Sin Ti, and has collaborated with artists such as Rauw Alejandro, Bebe Rexha, Imagine Dragons, Demi Lovato, and Selena Gomez. According to Warner Chappell Music, he is also a protégé of producer Max Martin.