Roughly six months after he became CEO of Omnicom’s in-house interactive shop OMG Digital, Sean Finnegan is leaving for the job of chief media officer of in-text advertising start-up Vibrant Media, AdAge reports. At Vibrant, he will lead marketing, business development and product innovation. That’s a sharp contrast to heading the digital group for all of Omnicom. Finnegan was at Omnicom for seven years.

It’s the second high-level personnel move for Vibrant in a week: AOL’s (NYSE: TWX) John Sedlack joined the company last week as SVP-sales and strategic alliance.

David adds:  No announcement of a successor expected for a month or so but Omnicom CEO Daryl Simm told staffer via an internal memo: “As you know, we have been making aggressive investments in Digital to stay ahead of our client’s needs.  In the past year we have rounded out of our leadership team in key digital functions, which now include OMG level executives in Digital Investment, Search, Gaming, Mobile and Ad Operations.  In addition, we have appointed OMG Digital executives as regional leads in Asia, EMEA and Latam as well as Shelley Paxton as Global Strategy Director, OMG Digital focusing on our global accounts.  These developments are helping grow our digital business (as most recently evidenced with the win of Visa digital).  There will be no interruption to this strategy.”

He also pointed out that many people at Omnicom will still be working with Finnegan in his new role “on the other side of our business.”