Belgian authorities are investigating money-transfer fintech Wise for its controls around suspicious transactions worth over €500 million ($577 million) across 30 European countries. The current investigation only concerns the fintech’s EU operations, but the company has a history of fines for weak financial controls in several regions, including the U.S. and the Middle East.

Ruth Prickett graduated from Cambridge University with a BA hons in History and has specialized in business and finance journalism for the past 20 years. She was editor of Financial Management, the magazine...