What is the parent company of TBWA?

Could you please elaborate on the parent company of TBWA? I understand that TBWA is a well-known advertising agency, but I'm curious to know who owns and operates it at a higher level. Is there a specific holding company or conglomerate that oversees TBWA's operations globally? It would be great if you could provide a brief overview of the parent company's background and any notable achievements or accomplishments it has made in the industry.