House flag of the Sociedade Geral de Comercio Industria e Transportes, Lisbon. A rectangular triband in red, white and red with the black intials 'S. G.' on the central white stripe. The flag is made of a wool and synthetic fibre bunting. It has a cotton hoist and is machine sewn. A rope is attached.

The Sociedade Geral de Comércio, Indústria e Transportes (General Society of Industry, Commerce and Transport) was founded in Lisbon in 1919 by Portuguese entrepreneur Alfredo da Silva. The Sociedade handled shipping for the large Portuguese company Companhia União Fabril (Union Manufacturing Company) which was involved in many different businesses including oil, animal feed, chemicals and textiles. The first sailings began in 1922, with trips from Portugal to North Africa, Northern Europe and North America. The large fleet operated until 1972 when the company officially merged with Companhia União Fabril.