Stephen Haines, the head of agency strategy, resigned this week and will now follow the commercial director, Blake Chandlee, and the head of agency sales, Miles Lewis out of the door.
Chandlee quit last month to join Facebook as its UK sales director, and sources suggest that Haines will join the social networking site as head of UK sales. Lewis left Yahoo! two weeks ago and has been linked with a move to the online music service last.fm.
Yahoo! reacted to Chandlee's departure by placing Glen Drury, the vice-president for Northern Europe, and Javier Zapatero, the vice-president of sales for Europe, in temporary charge of the UK commercial operation.
Haines joined Yahoo! in 2004 to head a team which focused on building Yahoo!'s ad revenues by targeting traditional agencies to convince them of the role online can play as part of wider brand building campaigns.