Founded in 2010 by Juan and Lanya Zambrano, Firewood’s digital capabilities include creative, strategy and planning, performance media and technology services. Headquartered in San Francisco, it employs more than 300 people in seven offices across the Americas and Europe.

Firewood uses the ‘embedded’ model of client partnership, a collaborative way of working with clients to deliver on speed, quality and value.

It deploys teams of creative and strategic marketing professionals who work as extensions of their clients’ internal marketing team.

Sir Martin Sorrell, senior monk and executive chairman of S4 Capital said: “This merger is a further step in creating a new era communications services leader. Firewood has an enviable client list comprising many of Silicon Valley’s finest; and we are delighted to welcome Juan, Lanya and their colleagues to the S4 Capital family. We will now have over 1,800 professionals in 23 countries, with over 500 in each of two nodes, one in Silicon Valley and one in Amsterdam.”

Lanya Zambrano added: "This merger is recognition of all our people. The richness of our differences creates our collective value. We embrace finding diverse talent; as a certified Women/Minority-owned Business Enterprise, 38% of our employees are from diverse ethnic backgrounds, 67% are women, and our leadership team is comprised of nearly 64% women. We look forward to developing further a new, disruptive model in the communications industry with MediaMonks and S4 Capital."