Facebook Inc. (FB) has foregone a stock increase of as much as 18 percent in extended trading after Chief Financial Officer David Ebersman said on a conference yesterday that promotions appearing in users news feeds won’t increase significantly. His comments follow third-quarter sales that exceeded analysts’ estimates as marketers focus more on targeting users on smartphones and tablets.

Chief Executive Officer Mark Zuckerberg of the popular social networking website has been adding features to facebook that allow advertisers to reach consumers more directly. He’s trying, however, to walk a fine line in maintaining the balance between advertising profits and user annoyance. Constant marketing pitches as users try to check posts, pictures, and updates would make their experience on the website unpleasant, but the company still aims to generate higher ad revenue and boost its users to over 1 billion.

Facebook reported that in the last quarter revenue surged 60 percent to $2.02 billion, surpassing average projection for $1.91 billion. A hefty 49 percent of total ad revenue in the third quarter came from mobile promotions, exceeding 41 percent in the previous period and analysts’ estimates for 45.6 percent.