WPP downgraded by Moody's to 'negative' after Sorrell's exit

Blow to world’s biggest advertising group comes as it begins search for new chiefSir Martin’s Sorrell’s departure from WPP has prompted the leading ratings agency Moody’s to downgrade its outlook for the group, citing concerns including a breakup, the loss of clients and its poor performance compared with rivals.The downgrade, from “stable” to “negative”, comes as WPP’s 11-strong board was set to meet on Tuesday with the task of finding Sorre