Shark Tank is the US adaptation of the business-pitching format that includes BBC's Dragon's Den.
The American programme places entrepreneurs before a panel of investors, who hear pitches and may offer money in exchange for equity or another ownership arrangement. It follows the same broad international format lineage as Dragon's Den, which originated from Japan’s Money Tigers.
The titles differ because each country markets the concept with its own animal metaphor and television identity. In the UK, the investors are dragons; in the United States, they are sharks. The programmes are therefore related adaptations, not two seasons of one transatlantic series.
A common error is to call Shark Tank the American version of the BBC programme in a literal remake sense. More precisely, both are local adaptations of the same underlying format. Shark Tank premiered in the United States in 2009, several years after the British Dragon's Den began broadcasting.