84% of consumers say they are at least somewhat concerned about providing their personal information when shopping online. And less than 33% of shoppers believe most web sites are safe for shopping, an 11% dip from 2009, according to a new Harris Interactive survey commissioned by McAfee.

But only 6% of consumers say they don’t worry about security on the Internet.

Consumers’ increased concern is likely due to a range of factors, says Sam Rastogi, McAfee’s senior product marketing manager, web security group. “While we didn’t ask consumers specifically about why confidence is down, our opinion is that it has to do with the economy in general, and people’s fears about spending money,” he says. “ It could also be that they’ve heard horror stories about people falling for scams and aren’t sure who to trust.”

And those anecdotal incidents dovetail with high-profile situations, such as a breach at Sony Corp.’s San Diego data center that resulted in the theft of personal information about more than 100 million customers, he says.

“While consumers are faced with more options than ever for shopping online it’s clear that one of their biggest concerns—security—remains,” says Steve Petracca, senior vice president of global consumer marketing at McAfee. “It is important for online retailers to recognize, understand and assuage these concerns in order to increase sales and earn trust from their customers.”

The survey found that retailers can assuage consumers’ concerns with a trust mark on their site that assures shoppers that the site is trustworthy. In fact, 33% of shoppers say they would buy from a small independent retailer that featured a trust mark over a more well-known site without the seal. And, nearly 40% of consumers say they might spend more money online if they see a security guarantee.

Aside from a security trust mark, a discounted price can also help displace consumers’ security concerns. Roughly 40% of consumers say a 30% discount might lead them to purchase at a merchant’s site, even if they were unsure that the site would protect their personal information.