Although All3media declined to indicate how long the review would take, it said GA's role was to brief analysts, investors and media, and advise staff on how a float or sale would affect them.
GA CEO Richard Constant and UK chief executive Fergus Wylie lead the account, which was secured after a competitive pitch. They report to All3media founder Steve Morrison.
Morrison – a former Granada Media chief executive – created All3media in 2003 alongside Jules Burns and David Liddiment through the acquisition of the then Chrysalis TV Group.
Some media reports have suggested that a listing would value All3media at around £300m, making it larger than rival RDF Media – the firm behind Wife Swap – which floated on the AIM last May.
All3media last June acquired Phil Redmond's Mersey TV, the production company behind Hollyoaks and Grange Hill. This year it has already bought Artists Rights Group, the talent agency that represents household names such as Chris Evans, James Nesbitt and Sacha Baron Cohen, the creator of Ali G.
* Gavin Anderson this week confirmed the arrival of former Cubitt Consulting co-head of investor relations Bernard Compagnon as MD. Compagnon had been tipped to join in a European IR post after his exit from Cubitt last year (PRWeek, 6 January).