If it's Sunday night, then the senior partners of BTG Pactual are likely gathered at the local home of chief executive André Esteves, plotting how to turn the Brazilian investment bank into Latin America's Goldman Sachs.

The regular meetings are coffee-and-water affairs that reflect the firm's intense, if Spartan, partnership culture, as well as its obsession with growth. "It's a time to discuss the long-term opportunities, the culture, the project," says Mr. Esteves, who at 41 is Brazil's youngest self-made billionaire.