Complex sentence: It was founded by in São Paulo, as a competitor for then-dominant Rede Tupi from Diários Associados, thus breaking the three-year old monopoly the station had in the city.
Split into simpler sentences: It was founded by in São Paulo, as a competitor for then-dominant Rede Tupi from Diários Associados. It broke the three-year old monopoly the station had in the city.