I recently wrote an essay, for Strategy + Business, about disruptive innovations. In addition to the well-known bottom-up model of disruption (documented by Clayton Christensen), I argued that there’s a top-down model as well. Bottom-up disruptions initially underperform the existing products in a market (on the purchasing criteria traditionally used by customers), but as their performance improves they move up into the mainstream, displacing the incumbents. Top-down disruptions, in contrast, outperform existing products initially, and then move down into the mainstream as their cost falls.

One of the examples of a potential top-down disruption I pointed to was satellite radio. It strikes me that you could argue that podcasting now represents a potential bottom-up disruption in the same market. Although I’m sure there are other examples in the past, I can’t immediately think of another instance when we’ve so clearly seen an existing market under threat from bottom-up and top-down disruptions simultaneously. I have no idea how the market will ultimately shake out, but the process should be fascinating, and instructive, to watch.