This is only the fourth time the phrase “cross-device retargeting” has appeared in a MediaPost story. Think that’s low? A week and a half ago, it had only appeared in one. That means we have seen a 400% increase in “cross-device retargeting” news in our publications in a little more than a week. In bad press release terms, we could develop a metric to measure phrases signifying trends like these: MediaPost’s RTM Daily, the world’s leading real-time media and marketing daily email newsletter, has announced the launch of its own proprietary, first-party data metric, optimized for marketers who like to read, called phrase-to-article, or PTA, which has revealed groundbreaking insights in its first day of operation, including a 400% increase in “cross-device retargeting” PTA. All joking aside, this mini-trend was hard to miss from where I sit. Two weeks ago AdRoll said it now supports cross-device retargeting, and last week Struq launched its own cross-device retargeting platform. (I’m not ready to call it a full-blown trend yet; two new platforms do not make a trend, even if they were released within a week of each other.)When taking a look at Google Trends, we see "retargeting" has been steadily rising since 2007, while "cross-device" has parred the course since 2009. "Cross-device retargeting," however, doesn't have enough search volume to spit out results. But what does it take to actually do cross-device retargeting? There is a connecting thread between AdRoll’s and Struq’s offerings: they both rely on privileged partnerships. In AdRoll’s case, the company says it is the only retargeting firm integrated with both Facebook’s Custom Audience and Twitter’s Tailored Audience offerings. For Struq, the company has built partnerships with a number of Web sites and online services that utilize user logins. Both AdRoll and Struq touted their ability to offer retargeting based on account IDs rather than probabilistic models. Consumers have stretched themselves out with all of their devices, and it appears that marketers are starting to catch up. If my theory is right, marketers are catching up not because of breakthroughs in technology but because of strong human relationships, which ultimately lead to strong business partnerships. That's an RTBlog for another day.