What is the largest ad agency in the US?
By revenue, the largest US-based advertising agencies in 2026 belong to the four major holding companies: WPP, Omnicom, Publicis, and Interpublic. Individual agency ranking shifts year-to-year, but Ogilvy, BBDO, McCann, Publicis Worldwide, and DDB consistently sit in the top 10 by US billings. Independent agencies rarely crack the top 20 by revenue but often lead in creative recognition.
How the sizes distribute
The Wall indexes US independent firms rather than the global holding companies, so it cannot name the largest. It can show how thin the top of the distribution is. 52 listings across the whole index publish a team size of 1,000 or more.
Inside the advertising group specifically, 14 of 374 firms run 250 or more people. The median founding year is 2011, so the large firms here are mostly old firms.
Minimums move with headcount. 88 of the 353 advertising firms that publish a minimum project size require $25,000 or more, while 179 open at $5,000 or less. The floor is a better proxy for what kind of shop you are calling than the staff count is.
How to use this
Largest is rarely the buying criterion it looks like. Ask instead how many people would be on your account by name, because that number is often the same at a 60-person shop and a 600-person one.
How this was computed. Every figure on this page is counted from The Wall's own directory of approved, US-headquartered, machine-verified-live listings: 3,460 of them in the snapshot captured 2026-09-14. Rates, minimum project sizes, team sizes, founding years and ratings are provider-declared figures published on public profiles. 1,738 of those listings publish a service list, and that field holds at most 4 services per firm, so service counts are counts of what firms name first rather than everything they sell. Percentages of disclosed values exclude listings that publish no figure. Nothing here is modeled or estimated. Sourcing standards: editorial policy.
Why this matters
Google puts this question in People Also Ask for the "marketing agency" query, which means buyers are asking it while they shop. The Wall answers it from the directory position: we index 3,460 verified US growth-services vendors across 10 pillars, so the figures above come from those records rather than from a survey.
If you are evaluating vendors in this category, the Marketing pillar page carries the full US firm list with rate, team size and headquarters filters.