The splinternet — the fragmented world of incompatible web, social, video, and mobile touchpoints — is where your customers live now. They want to reach you in more touchpoints, but you can't afford to be everywhere. To help companies invest with insight, we developed the splinternet engagement index, a single measure that tracks the depth of connection across these four touchpoints. It reveals, for example, that the highest online spenders in Europe demand investment across all touchpoints, but many of the high-net-worth investors that Fidelity might target don't. Market insights professionals should use the index to help corporate strategists know which touchpoints to invest in and to prepare for agile commerce that connects across those touchpoints.