UK marketing content firm Tag strikes £533m deal with Japan’s Dentsu

Exclusive: One of UK's biggest ad deals for 15 years is expected to be signed this week but may yet fall through

The Japanese marketing giant Dentsu is understood to have struck a 533m (600m) deal to buy Tag, the British-headquartered global content production group, in one of the largest UK ad deals of the last 15 years.

The move by Dentsu - which became a global force in advertising with its 3.2bn takeover of the UK media group Aegis in 2012, the largest-ever deal for a British-based ad group - marks its latest push to challenge rivals including WPP, IPG and Omnicom in the US and France's Publicis Groupe.