As anyone who’s read my work knows, I’ve been influenced by the writings of Clayton Christensen, particularly his description of how the performance of technology products can advance beyond the needs of customers. In his book The Innovator’s Dilemma, Christensen describes how this “overshooting” phenomenon opens the door to “disruptive innovations” – cheap and initially inferior products that take hold at the bottom of a market and then rise to displace the dominant technology.

It’s a brilliant insight into the workings of technology markets, but I’ve become convinced that Christensen’s view of disruptive innovations is too narrow. In addition to the bottom-up variety of disruptions that he portrays, there are also many examples of what I call “top-down disruptions” – products that initially appeal to an elite segment of a market but then shift downward into the mainstream, ultimately changing all customers’ buying behavior. I describe my idea in more detail in an article in the Summer 2005 issue of Strategy + Business, which has just been released. Among the examples of top-down disruptions that I examine are overnight package delivery, satellite radio, and Apple’s iPod.

So if you’re seeking to instigate a disruption, or simply to protect yourself from one, you should always look up as well as down.