Investment scams cost the UK an estimated £1.2 billion a year, according to national fraud and internet crime reporting centre Action Fraud.
It surveyed 500 men aged 36 and above, finding that almost half admitted to giving out personal details before checking the credentials of the person who contacted them. Only 57% said they were confident they could spot frauds from genuine offers.
It said that investment scams often went unreported, pointing to Financial Services Authority estimates that only 10% are reported.
Peter Wilson, director of the National Fraud Authority, said: 'Some of the biggest personal fraud losses reported to police are from investors, a group that we think of as savvy and entrepreneurial. Our intelligence shows that amounts ranging between £10,000 to over £1 million are being handed over to fraudsters by victims.'