Crimestoppers is targeting those believed to be involved with so-called boiler-room fraud, where people are duped into buying junk or non-existent shares here and in Serbia and Spain.
The crime-fighting charity is working with police in the UK, the National Crime Agency and Spanish police. It said the fraudsters steal the life savings of elderly people and using the money to live lavish lifestyles.
The four men profiled as part of Crimestoppers' campaign are wanted for their suspected role in high-value fraud and money laundering offences and are all believed to be involved in large-scale global networks of investment fraudsters.
Graham Hawrysh, 37, is suspected of boiler room-fraud based in Spain and involvment in a large-scale global network of investment fraudsters targeting UK consumers.
American Jeffrey Gordon, 54, is accused of boiler -rioom fraud, and has links to Romania and possibly Colombia and Ireland. He is also known as Jeffrey Darren Goodman and Michael Goodman.
He 5ft 11in and stocky with blue eyes, and he wears glasses.
Robert Douglas Lynch, 53, is believed to be involved in running boiler rooms under fake names and setting up accounts in Spain and the UK for laundering cash from the UK from investment fraud.
Turkish Cypriot Tunch Kashif, 48, is believed to have been involved in investment frauds for years, including deceptions involving upmarket wines.