There's been a ton of buzz about a study about the power of Twitter to predict the stock market. That's not the only Twitter-business connection.

Loic Venance | AFP | Getty Images A new report finds that social media has a huge impact on buying habits. Consumers are checking in with friends on Twitter and Facebook before they buy.

A new report finds that social media has a huge impact on buying habits. A full 45 percent of consumers check with friends on the likes of Facebook before they buy.

That means individuals can impact many more of their friends' purchases than ever before — "word of mouth" is now a much more powerful, fast-moving Tweet or status update.

Shoppers do a huge amount of research — 67 percent go to retailers' and manufacturers' websites, according to WSJ Strategic Retail's report "How America Shops From Buzz to Buy." Only 13 percent actually visit websites like Facebook.com, Twitter.com — but that's misleading in this day and age where people can get tweets and status updates straight to their phones in stores.

Millennials spend the most hours social networking online, but they don't do the most shopping, GenXers (age 33-44) do. Still all demographics often consult with friends before pulling the trigger on a purchase.

What does that mean for retailers?

Products matter more than marketing does — consumers will do the marketing for you. But at the same time, retailers would benefit from giving products a presence on those social media sites, with product fan pages or Twitter profiles. And based on these stats, retailers would be wise to support that free social media presence with advertising, so they can be part of the discussion among friends.