(Reuters) – Omnicom Group Incs media services division signed a deal worth $230 million with Twitter Inc that will integrate Omnicoms automated ad buying unit Accuen with Twitters mobile ad exchange MoPub. The two-year deal will lock in ad rates and inventory access for Omnicom agencies and will also give Omnicom a first look at new ad units and opportunities being developed by the microblogging site. Wall Street Journal reported the deal first. This is the first holding company agreement weve done on the mobile ad exchange side, Adam Bain, Twitters president of global revenue, told the newspaper.