Brazilian media mogul Roberto Marinho, owner of Organizacoes Globo, died Wednesday in Rio de Janeiro. He was 98.

The media tycoon was admitted to a local hospital Wednesday morning with pulmonary edema. He underwent surgery that night, but did not survive the operation.

Brazilian President Luiz Inacio Lula da Silva decreed a national mourning period of three days. The lower house of Congress stopped its nightly session for a minute of silence on news of Marinho’s death.

Marinho had retired years ago, and the Globo group has since been run by his three sons and a professional management team.

From a single daily paper in Rio that he inherited in the 1920s, Marinho built a media empire, becoming, in the opinion of many, the most powerful man in Brazil.

Organizacoes Globo is the catch-all name for the holdings controlled by the Marinho family. They include leading broadcaster TV Globo, which commands a 75% share of local free-to-air TV ad spend; leading Brazilian cabler Net Servicos; top local pay TV programmer Globosat; No. 3 Internet portal Globo.com; theatrical production company Globo Filmes; stakes in satcasters Sky Brazil and Sky Multi-Country Partners; and a 50% share in reality show producer Endemol Globo.

Globo also owns newspaper and radio chains; the country’s largest printing facility; and music, homevideo and DVD distrib companies.

Marinho’s dominance of the local media sector began in the 1960s, when he founded TV Globo, which became the first national TV network.

Marinho’s critics charged that TV Globo was a virtual monopoly serving the military dictatorship that ruled Brazil from 1964 to the mid-’80s. Even today, TV Globo has an audience share of about 50%, largely on the strength of its popular telenovelas.

In the 1990s, Marinho gradually ceded the group’s command to his sons, Roberto Irineu, Joao Roberto and Jose Roberto. At the same time, TV Globo and the other media companies adopted an independent stance relative to the government.

Currently, the group financial holding company Globopar is renegotiating its debt payment schedule with creditors. The financial difficulties stem from heavy investments in the pay TV sector in the 1990s and the steep depreciation of the local currency in 2002, analysts said.

Even so, Organizacoes Globo remains a solid media group — and its dominant position is unchallenged.