Alex Barr and Neil Gibson, who co-founded the firm in 2000 along with Graham Isdale, will transfer ownership of Big to six fellow board members over the next five years.
Big, which employs 115 people, has five offices across the UK and generated turnover of £8.3m for the year to May 2015.
The buyout involves Zoe Ogilvie, head of the agency’s Aberdeen office, along with head of digital Allan Barr, long-standing employees Bryan Garvie and Sharon Mars, who both joined the board in 2014, Edinburgh office head Andrew Baird and finance director Graham Leitch.
Gibson said: “Big’s growth has been built on our ability to produce great content, backed up by trusted advice to clients. By taking a planned, strategic approach to the company’s future, we are doing the right thing for the business, for our team and for our clients.”
Shareholder and director Ogilvie, who joined the firm in 2002, said talks about the buyout began in 2013 “and it quickly became clear that there was a pretty straightforward and consensual route which would see the senior management group undertake a phased MBO over the next few years”.
She added: “We actually concluded the deal in the summer of 2014 and we’ve ensured a smooth transition for our people and our clients. We’re very happy with how seamlessly it’s gone so far and the new structure is working well.”
Barr said Big’s board had been “significantly strengthened” in 2014 with the addition of Baird, Garvie and Mars.
“While Neil and I still have plenty of ambition to grow the business and expand its reach both sectorally and geographically, it was the right time to plan for the company’s long-term future,” he said.
“Over the next three to five years, Neil and I will undertake a managed change in our input to the business, which is still currently full-on, and will retain a small shareholding in the business.”