XAd today raised $4 million from Emergence Capital in order to build out its LocalAdXchange network and its technology platform.

The company continues to cross milestones including profitability and 20 percent growth. It’s also built a strong backbone of mobile publishers including MetroPCS, WhitePages and Poynt. Ad partners include Millennial Media.

This adds up to 200 mobile ad placements per month, 80 percent of which it claims are geographically and contextually relevant. This is an accomplishment if you consider how local segmentation can spread relevant ad inventory thin.

This targeting is fulfilled through a proprietary mobile ad optimization engine, and a blitz on publisher partners whose content and mobile experiences are inherently local (i.e., YP apps). The former boosts relevance while the latter ensures local user intent.

XAd meanwhile grows among a crop of mobile ad networks that focus on different versions of this local ad targeting. These include Chitika, WHERE and CityGrid, all of which consistently report greater ad performance when compared with non-local targeting.

We’ll have a panel discussion on this very topic at our upcoming Interactive Local Media conference in Santa Clara, California, in December. Hope to see you there.