Some users may have gathered that, on Black Friday, Wal-Mart Stores, Inc. (NYSE:WMT) was widely present in Facebook Inc (NASDAQ:FB)’s mobile news feed. That’s because the retailer was conducting an experiment; it featured 50 million ads on the social network in an endeavor to attract users to its Web site for holiday deals.

 Facebook mobile

This trial was Facebook’s largest mobile advertising operation ever, and there are possibilities that there will be more to come, according to the Wall Street Journal.

Wal-Mart Stores, Inc. (NYSE:WMT)’s alliance with Facebook Inc (NASDAQ:FB) was different from an archetypal mobile ad campaign on the social network. Instead of paying by ad clicks, Wal-Mart pre-bought millions of ads that then weighed down any other retailers advertising on the cyber shopping weekend.

In total, the retailer bought 2 billion ads on Facebook Inc (NASDAQ:FB) to post during the holiday season, which includes the 50 million ads that it bought during the Black Friday try out. Wal-Mart refused to reveal the cost of ads.

According to the Wall Street Journal, it’s unclear how much the ad campaign drove Wal-Mart sales, but the retailer’s marketing chief, Stephen Quinn did tell the newspaper that he “never saw this level of engagement” before with a digital-ad campaign.

Many people clicked on Wal-Mart Stores, Inc. (NYSE:WMT) ads and products for sale, and also, the Wal-Mart page received 164,000 new Facebook fans’ “like”. But there were some others who complained of the propagation of ads in their feeds, as reported by Wall Street Journal.

Whether Facebook will be able to draw some revenue via mobile, has been a sizzling subject of conversation since the social network giant went public for $38 a share in May. There are many analysts who observed that in order to keep share prices from declining, the social network had to figure out how to serve its growing number of mobile users. Facebook’s shares have more than 50 percent from their September all-time low. But whether the company will be able to attract back investors will rest on deals like its Black Friday experiment with Wal-Mart Stores.

Facebook now seems to be recovering. According to the Wall Street Journal, Facebook’s mobile-ad revenue was enhanced in the previous quarter, rising to $153 million and its shares are currently up more than 50 percent since September.

On Thanksgiving, Facebook Inc (NASDAQ:FB) Chief Operating Officer Sheryl Sandberg sent Wal-Mart’s marketing chief Stephen Quinn a text, which simply said, “Good luck!”