People on the move featuring: Yahoo, Aviva, AppNexus and more

This week has seen another wave of appointments and departures at brands, media owners and agencies. The Drum has rounded up the key moves from the EMEA, APAC and North America regions below.
EUROPE 
Channel 4 
Channel 4 has confirmed that chief executive David Abraham will step down from the role by the end of 2017 after seven years at the helm.
The broadcaster, seemingly prematurely, announced Abraham's departure in a tweet containing quotes relating to the decision fr