More than three-quarters of consumers who used an established login on retailer sites served by Gigya Inc. entered their Facebook credentials to do so, according to a new report from Gigya. Its technology lets consumers sign into e-retailer sites using their established logins with such sites as Twitter, Facebook and Google Inc.’s social network Google Plus.

In the fourth quarter, 76% of consumers using a social login on Gigya’s retail clients’ sites did so through Facebook, up from 74% in the third quarter, it says. Another 16% used their Google Plus credentials (down from 17% in the third quarter), 3% Yahoo (unchanged from the third quarter), 2% Twitter (down from 3%), 1% PayPal (down from 2%), and 2% logins from other social media sites.

63% of consumers using a social login on Gigya’s clients’ sites while on a mobile device used their Facebook credentials in the fourth quarter, down from 66% in the third quarter. Another 25% used their Google Plus login (up from 20%), 6% Twitter (down from 9%), 5% Yahoo (unchanged from the third quarter) and 1% logins from other social media sites.

The vendor, which counts Dell Inc., Barnes & Noble Inc. and Kate Spade among its more than 200 retail clients, says that Facebook’s market share dominance is larger on retail sites than it is on other industries’ sites, such as those in travel and hospitality. For example, 59% of consumers using a social login to sign into Gigya’s travel and hospitality clients’ sites did so via Facebook, while 26% used Google Plus, 9% Yahoo, 2% Twitter, 2% LinkedIn and 2% other credentials.

Across all Gigya sites, 51% of consumers using a social login used their Facebook credentials in the fourth quarter. Another 28% used their Google Plus login, 15% Yahoo, 4% Twitter, 1% LinkedIn and 1% logins from other social media sites. Gigya says roughly 40% of consumers use a social login when presented the option.

Facebook’s market share dominance on retail sites makes sense because the social network offers merchants the richest tools to personalize their sites to the consumers’ preferences, says John Elkaim, Gigya’s vice president, marketing. For example, once a consumer signs into a retail site using his Facebook login, the retailer can present him with items his friends Like and it can also use the personal information the consumer has shared in his Facebook profile, such as his Likes and interests, to tailor the products it shows him.

“Facebook gives retailers a way to differentiate their on-site experience by customizing their content,” he says.