While some firms build cars or smartphones, Rocket Internet builds companies. The incubator and investment firm has pioneered an extreme approach to new venture creation that is often referred to as a "startup factory:" it rapidly assembles and scales new companies, replicating business models...

The stereotype of the "angel investor" is a retired wealthy entrepreneur who sees potential, asks tough questions, takes a large stake, and in a few years makes a massive return in an IPO. This outsider fills the gap between the venture capitalist and the professional investor, swooping in with...