
The day-to-day running of the business will now be handled by .Fox Networks sales director Francis Turner.
Aperio leaves the company after the departure of chief executive Phil Cooper last month. It is not known if she has another job to go to.
Aperio had been responsible for overseeing sales, publisher services and ad operations for all products.
She was promoted to UK managing director in September 2008 from director of publisher services for Europe. Prior to joining .Fox, she served as publisher services director for Advertising.com.
Cooper founded online video network Utarget in 2003 and FIC acquired a majority stake in Utarget in 2008 for an undisclosed sum.
The merging of commercial operations meant Utarget's 18-strong team, based in Windsor and headed by Cooper, moved to the Shepherd's Bush offices of .Fox Networks.