Yet Another Facebook Metric Mishap

Shares of Facebook Inc FB disclosed yet another metric mishap. The company said Friday it undercounted traffic from certain publishers who uploaded content to the social media's Instant Articles platform.

Facebook's Instant Articles platform allows content publishers to publish their material directly on Facebook rather than through their own websites.

Facebook and COMSCORE, Inc. SCOR announced a partnership earlier this year in which comScore would provide viewability metrics for video and display campaigns running on the social media's platform.

According to The Wall Street Journal, comScore said mobile traffic from Facebook's iPhone users were undercounted from September 20 through November 30 but traffic from Android devices and iPads weren't impacted.

Facebook also acknowledged the error in a blog post and said it has now fixed the issue and working with comScore to produce updated estimates for the time periods for what it says was a "small group of partners" that were affected.

Facebook's investors have reason to be concerned following Friday's report, which is not the first time this occurred since September.

The latest metric mishap may have resulted in a notable impact for some publishers. Wall Street Journal cited "a person familiar with the matter" who suggested that some publishers' traffic was undercounted by as much as 20 percent and at least one site's unique user numbers was off by around 30 percent in November.