The poll by Visa Canada found that 45 per cent of this demographic group also shared their payment card information via email, loaned their cards and didn't keep their PIN confidential.
This behaviour mirrors similar habits of sharing personal information on social media sites, said Gord Jamieson, head of payment system risk at the credit card company.
"Yet they're really not totally aware of who has access to this information and who else can be seeing this information and what would be done with it," he said from Toronto.
The survey, released Tuesday, marks the start of fraud prevention month in March.
Individuals in the 18-34 group also reported the highest level of online sharing activities, including keeping an open profile on a social network site and posting to it daily, publicly sharing photos and posting their employment history.
"Just be careful what you put out there," Jamieson said, noting that public WiFi networks for mobile devices aren't necessarily secure.
For the older generations, they tend not to overshare quite as much.
Among those aged 35 and older, the survey found that 32 per cent reported taking risks with their payment card information. This group also reported less sharing of personal information online.
The survey also found that 43 per cent who had engaged in behaviour such as sharing payment card information or loaning their card had experienced some kind of fraud.
"So, is that a coincidence?" Jamieson asked. "They are creating that opportunity by engaging in that risky behaviour. Those people are twice as more likely to be victims of fraud today."
The survey also found that 56 per cent of respondents said they were more concerned now about identity theft than they were five years ago. While 50 per cent of respondents said they were more concerned about payment card fraud today compared to five years ago.
"They acknowledge it, but sometimes they don't practice what they should be doing," Jamieson said.
The survey found that less than half — 41 per cent — reported checking their payment card statements more than once a month.
Jamieson recommends setting up an alert system so a cardholder would be notified via email or text every time a transaction is made.
The Canadian Bankers Association says credit card fraud was $436.6 million in 2011, its most recent statistic, up about 19 per cent from 2010.
The online survey was conducted by market research firm Fabrizio Ward with 1,000 major credit and debit cardholders from Dec. 26 to Jan. 2.
Visa also produced a video about the perils of oversharing credit card information. It can be viewed on YouTube at www.TheConcertByVisa.ca.
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