Facebook showed Wall Street that even with over 1 billion users, it can still post blockbuster growth. But one of the main drivers of its expansion will taper off next year, an executive said.

Increasing ad load — the number of ads on the website — has been one of three main factors of Facebook's growth, along with user growth and increasing time spent on the platform, Facebook's chief financial officer David Wehner said on Wednesday. But ad load could "come down meaningfully" after mid-2017, Wehner said, reiterating last quarter's comments, and revenue growth could decline in the fourth quarter.