Embryo Acquires Serotonin, Its Third Deal in Under a Year

Embryo has acquired Serotonin, a Manchester-based creative and digital agency founded in 2019 by Dom Carter and Clair Heaviside, completing its third acquisition in under a year and positioning the combined business as one of Manchester's largest independent agencies.

The deal follows Embryo's purchases of Making You Content in April 2025 and Novaro in November 2025. Founded by Ross Green and James Welch in 2014, Embryo built its reputation on performance marketing and organic search before accelerating into M&A. Carter and Heaviside will both join the Embryo board as part of the transaction; no financial terms were disclosed.

Serotonin brought a client roster that includes ASSOS of Switzerland, New & Lingwood, and national property developers Legal & General and Grainger plc. The agency had itself been on an acquisitive path before this deal, having bought Unparalleled, a digital agency with strengths in Google and Meta media buying whose clients included The Private Clinic and Ebrands. At the time of that earlier deal, Carter said it "forecasts our EBITDA for 2025 at over £1mln."

Ross Green framed the strategic logic in terms of closing a capability gap. "We believe exceptional marketing results come when strategy, creativity, and execution work seamlessly together," he said. "By bringing Serotonin into Embryo, we're strengthening our ability to deliver even greater impact for our clients, combining Embryo's strategy-led approach with Serotonin's creative excellence, media capabilities and strong client base across EMEA."

Embryo described the combined offer as spanning "brand, strategy, performance marketing and creative," with an end-to-end capability "from positioning and storytelling through to digital performance, technology and growth."

Dom Carter said the fit was strategic rather than opportunistic. "We've always believed that great marketing sits at the intersection of strong strategy and standout creativity. Embryo has built an impressive reputation for performance and growth, and the opportunity to bring Serotonin's brand and creative capability into that environment felt like a natural next step. Together we can offer clients something more complete, combining strategic clarity, creative thinking and digital performance under one roof."

Clair Heaviside, reflecting on six and a half years building Serotonin with Carter, said the conversation with Green resolved any uncertainty quickly. "From the moment we started talking with Ross Green about the acquisition, it felt right. The same ambitions. The same values. The same belief that great work should actually move things forward."

Three acquisitions in roughly eleven months is an unusually aggressive clip for an independent UK digital agency, and with Carter and Heaviside now on the board, Embryo has signalled that the people behind each deal are as much a part of the strategy as the client books they bring with them.