The forecast: Following an excellent Q1 and Q2 in 2021 with 46% and 56% growth respectively, Facebook's US ad revenue is projected to hit $50 billion by year-end 2021, accounting for a 23.8% share of the US's total digital ad spending in 2021.

Dive deeper:

• Facebook's strongest verticals in H1 2021 have been ecommerce, retail, and CPG—the same ones that performed well during 2020's pandemic year.
• The social network boasts a uniquely diverse advertiser base with over 10 million different advertisers ranging from brands, direct response, and small and medium-sized businesses to large organizations.
• Facebook's revenues are still primarily mobile: 97% of US ad revenues come from mobile devices.
• Our latest forecast shows lower ad revenues for future years than previously projected, dropping from 17.7% to 15.5% growth in 2022 and from 14.6% and 12.2% in 2023. This is partially due to the recent iOS changes that have made it more difficult for Facebook to provide accurate ad performance readings, leading to lower growth in iPhone spending.
• Our decreased growth projections are also a result of more scrutiny from governments over recent antitrust, privacy protection, and child mental health concerns.

Looking ahead: In 2023, Facebook's US ad revenues will top $65 billion, though that figure may change as the company faces new challenges.