Volution portfolio company Flagstone has appointed Arman Tahmassebi as Chief Executive Officer, with co-founder Simon Merchant stepping down from the role for health reasons. Merchant will remain closely involved as Chairman of the Board and strategic adviser. 

Tahmassebi joined Flagstone as Chief Operating Officer in early 2024 and brings more than 25 years of senior leadership experience across UK fintech and financial services. He has played a key role in strengthening operational execution, scaling the platform and shaping the company’s long-term strategy. 

His prior experience includes five years as COO at AIM-listed LendInvest, senior leadership roles at ETX Capital including CEO and almost 15 years at IG, where he served as Global Head of Operations. 

Flagstone enters its second decade from a position of strength, reporting £55m in revenue in its last full financial year and ending 2025 with almost £19bn of assets under administration, a 21% year-on-year increase. Growth in the business savings division was particularly strong, with UK SME deposits increasing by 82% during the year, from £1.7bn to £3.1bn. 

The company was recognised in Deloitte’s Technology Fast 50 for the second consecutive year, named in Sifted’s Top 250 fastest-growing companies in Europe and listed #26 in the Sunday Times 100 Tech 2026: Software league table.

Volution looks forward to supporting Arman Tahmassebi and the Flagstone team as the business continues to scale. Read more about the new appointment here.