UM Australia CEO Mat Baxter said the appointments, which are effective immediately, reflect the agency's rapid growth in investment and digital capabilities.
Griffiths' role as national investment director is across four offices (Sydney, Melbourne, Canberra and Brisbane), where she will oversee and lead the quality of negotiations, strategy and buying decisions being made across all clients in all media, according to the agency.
The investment leads for all UM offices will report to her. Griffiths will work closely with the previous UM national investment director, Victor Corones, who is managing director of MagnaGlobal, the investment and intelligence unit that operates across all Mediabrands companies. Griffiths has been investment director at UM Sydney since November 2011.
The role of Grivas, who reports to Griffiths, reflects UM's focus on applying rigorous criteria to digital media assessment, selection and implementation, according to an agency spokesperson. She has been digital investment director at UM Sydney since October 2011.
Filmer was previously chief digital officer. Prior to joining UM in November last year, he was senior strategy planner with the respected UK agency AKQA. His remit now broadens to encompass innovation across all media including traditional. Filmer will report to UM's chief strategy officer, Stefan Burford.