Amazon just made a big hire from ad agency Dentsu to help it take share of the $70 billion TV-advertising business

· *Amazon has hired Maggie Zhang, formerly an advertising exec at advertising holding group Dentsu Aegis Network, to lead OTT measurement and research.*
· *The hire reflects Amazon's growing ambition to build out its video advertising business by cutting into TV ad budgets.*
· *Zhang previously helped advertisers solve...