Aegis, which also has a media buying arm, said on Wednesday it would return £200m to shareholders via a special divided and added that the balance of the sale proceeds would provide it with the means to invest in acquisitions in fast-growing geographies and with digital expertise.
The £525m value of the sale, which Aegis had flagged in June when it was in exclusive talks with Ipsos, was slightly higher than the £500m value analysts had attributed to it.
"Aegis Media's strategy is based on capturing organic growth from the rapidly changing media market. The outcome of this transaction will enable us to accelerate the delivery of that strategy and focus our resources on value-enhancing acquisitions," said Chief Executive Jerry Buhlmann in a statement.
Analysts have in the past said the sale of the unit is expected to focus attention on the rest of Aegis, which has long been seen as a merger target for French group Havas, with financier Vincent Bollore the major shareholder in both companies.