Flagstone Names Arman Tahmassebi CEO to Lead £19bn Savings Platform into Next Growth Phase

The UK’s largest savings platform appointed fintech veteran Arman Tahmassebi as CEO, replacing co-founder Simon Merchant, to drive continued growth.

Arman Tahmassebi has been appointed as the new Chief Executive Officer (CEO) of Flagstone, the largest savings platform in the UK with nearly £19 billion in assets under administration. This is a strategic leadership change as the business moves into its next stage of expansion.

Tahmassebi, a seasoned financial operations specialist with over 25 years of industry experience, takes charge as CEO of Flagstone after co-founder Simon Merchant resigned due to health concerns. As Chairman of the Board and strategic adviser, Merchant will continue to be actively involved.

Tahmassebi, who became Chief Operating Officer (COO) of Flagstone in early 2024, was essential in establishing the company's long-term strategy, scaling the platform and advancing operational excellence. Prior to joining Flagstone, he had top leadership roles at well-known fintech and financial services firms, including ETX Capital, where he served as both COO and CEO, and LendInvest, where he served as COO. He previously spent over 15 years working for IG, where he eventually became the Global Head of Operations.

According to Simon Merchant, who cited his strong internal leadership and extensive operational experience. As the company continues to gain momentum, Merchant reaffirmed his support for new CEO.

Arman Tahmassebi stated his excitement about building on Flagstone's solid basis upon his hiring, pointing out the company's goal of helping savers in viewing cash not just as a safety net but as an asset class capable of delivering competitive, risk adjusted returns.

Flagstone ended 2025 with almost 19 billion pounds in savings under administration, up by 21 percent year over year. The leadership shift follows yet another year of record revenues and consistent profitability. With cash deposits from UK SMEs rising by 82 percent over the course of the year, the platform's business savings section enjoyed especially strong development.