• by Erik Sass , Staff Writer @eriksass1, September 18, 2015

The world’s largest social network is barreling into e-commerce through an expanded relationship with e-commerce platform Shopify. It will allow Facebook users to buy products directly from Shopify merchants on their Facebook pages, the companies announced this week.

Stores with Shopify accounts can create a new Shop section on their Facebook pages, which can handle the transaction within Facebook or refer them to the store’s Web page outside Facebook, with the logistics handled by Shopify.

The mobile-compatible service is available to roughly 175,000 small businesses that have signed up with Shopify and presumably, the Facebook partnership will help recruit even more.

Facebook first revealed it was experimenting with Shops in Facebook pages, enabling brands to transact e-commerce directly from the Facebook platform, back in July.

The new Shop section builds on Facebook’s previous introduction of a “buy” button by giving products their own section on the vendor’s main page, adding product discovery for a more complete shopping experience.

Facebook is also testing a new mobile ad format that allows users to interact with several layers of advertiser content without leaving Facebook’s app; demo versions of the new ad showed users engaging with in-depth product profiles.

Of course, Facebook has plenty of competition in the e-commerce arena.

In July, Google began testing “buy” buttons in its mobile search results. After a limited test period beginning last September, Twitter is also rolling out its new “Buy” buttons more widely through a partnership with Shopify, as well as other e-commerce platforms. Finally, Pinterest has partnered with Shopify to create shoppable Pins.

While social-media companies have big ambitions in e-commerce, so far their share of the total business remains small, according to a study by Business Insider’s BI Intelligence. Citing data from Moovweb, BI Intelligence found that Facebook accounted for 1.32% of all referrals to mobile e-commerce sites, representing half of all traffic from social media sites and 64% of total revenue from social referrals.

By contrast, Pinterest generated just 0.16% of all referrals to mobile commerce sites, and Twitter contributed a paltry 0.04%. Pinterest accounted for an outsized share of revenue from social referrals, at 16%.