More on Millennial Media: The company expects Q1 revenue of $48M-$50M and 2013 revenue of $270M-$280M, below a consensus of $56.4M and $286.4M. No explanation is given for the shortfalls. Is the culprit weak mobile display ad demand, competition from the likes of Google (AdMob) and Apple (iAd), or some combination? Ad network reached 400M+ monthly unique users and covered 39K+ apps in Q4, up from 380M+ and 38K+ in Q3. Opex +60% Y/Y, a little below revenue growth. MM -26.4% AH. CC at 5PM ET (webcast). (PR)