Many great businesses are born from frustration. As a young Estonian working in London, Käärmann was unimpressed with the exchange rate and charges he incurred when he transferred a £10,000 bonus back home. He felt his bank had left him about €500 (£422) out of pocket. This spurred Käärmann to create his own international money transfer service, quickly growing his customer base by undercutting banks and other existing providers. TransferWise, as it was initially known, attracted backing from high-profile investors, including Richard Branson, PayPal’s Peter Thiel and Skype founder Niklas Zennström. A spell of higher interest rates boosted Wise’s value as it was able to make money on customers’ balances. Between March 2023 and March 2024, its users grew by 29 per cent to 12.8 million – new business largely won by word of mouth.