Nearly three-quarters of consumers using an established login on retailer sites served by Gigya Inc. used their Facebook  credentials in the third quarter, according to a new report from the social media optimization firm. The vendor 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 third quarter of this year, 74% of consumers using a social login on Gigya’s retail clients’ sites did so through Facebook, down from 79% in the second quarter, it says. Another 17% used their Google Plus credentials (up from 12% in the second quarter), 3% Twitter (down from 4%), 3% Yahoo (unchanged from the second quarter), 2% PayPal (a new option offered by Gigya), and 1% logins from other social media sites.

66% of consumers using a social login on Gigya’s clients’ sites while on a mobile device used their Facebook credentials in the third quarter. Another 20% used their Google Plus login, 9% Twitter, 4% Yahoo and 1% logins from other social media sites. This is the first quarter Gigya reported social logins from consumers using mobile devices. 

The vendor, which counts Barnes & Noble Inc. and Kate Spade among its more than 200 retail clients, says that Facebook’s dominance as a way to log onto web sites is more pronounced on retail sites than on those of other industries, such as travel and hospitality. For example, 50% of consumers using a social login to sign into Gigya’s travel and hospitality clients’ sites did so via Facebook, while 29% used Google Plus, 13% Yahoo, 4% Twitter, 2% LinkedIn and 2% other credentials.

While Facebook continues to account for most social logins on retail sites, its share will likely continue to fall, says Patrick Salyer, Gigya CEO. “We’re starting to see more variance as other players like Google, Amazon, PayPal and others have become accepted identity providers,” he says. “Google in particular continues to make strides as an e-commerce identity provider because of its attachment to payments.” Google Wallet stores consumers’ payment and billing information so shoppers can check out in two steps from any web-enabled device. When a shopper signs into a site using his Google Plus account, he can click a button to access his Google Wallet account.