Turkey has arrested Tera Yatırım founder Emre Tezmen over an alleged $18bn Ponzi scheme that has affected the savings of more than 455,000 investors. Tera Yatırım board members Kerem Alkin and Emre Alkin were arrested with him, while two other executives were jailed pending trial in the aggravated fraud and criminal organisation investigation.

The Capital Markets Board, or SPK, said investors held stakes in 131 funds with about $18bn in assets, which are now being liquidated. Justice minister Akın Gürlek said necessary steps would be taken to address grievances, while President Recep Tayyip Erdoğan was closely following the investigation.

Prosecutors have frozen executives’ assets, restricted transactions by spouses and close relatives, and sought data on money and crypto transfers sent abroad since 2024. Kerem Alkin was Turkey’s ambassador to the OECD from 2021 to 2024 and previously sat on the boards of Halkbank and Turkey’s sovereign wealth fund. His brother Emre Alkin is an economist, television commentator and rector of Topkapı University.

The scandal has put pressure on finance minister Mehmet Şimşek, though there are few signs of a broader financial crisis. The Bist 100 fell 8 per cent before steadying, lira deposits rose by $12bn in the week to September 15 according to Goldman Sachs, and attention is turning to why regulators did not intervene earlier.