There was a 74% increase in the volume of investment fraud attempts in the first half of the year, according to a new survey.
The Red C survey, conducted on behalf of Bank of Ireland, also found that 94% of the population had been targetted by fraudsters in the past year.
Text message was the most common way for scammers to try to contact people, followed by emails.
The survey also found that WhatsApp was an increasingly common route used by scammers.
Bank of Ireland said the majority of successful investment fraud started on social media, with scammers following on with customers via phone or message.
It said follow-up calls after clicking on a link or ad is one of the red flags of a suspicious investment offer.
Other red flags include promises of large returns in a short timeframe, pressure to act quickly, and a requirement that the investment is done in secret.
Bank of Ireland also said there has been an increase in fraud victims being re-targetted, where scammers pose as someone else and claim to be assisting them in recovering their money.
"The growth in investment fraud attempts is the most concerning trend we are seeing at the moment," Nicola Sadlier, head of fraud at Bank of Ireland. "The level of highly personalised targeting of consumers continues to grow year on year, and everyone needs to be on their guard.
"When it comes to this serious criminal activity, there is no room for complacency. Being alert to the 'red flags' - including too good to be true returns and pressure to act quickly – is vital."
However the survey did suggest a high degree of complacency amongst consumers.
It found that 43% of people rate themselves as having little or no risk of fraud in the next six months.
That rose to 52% among people aged 18 to 30.
