ads.txt in the Fortune 500: Ecopetrol Leads With 1,074 Entries
Published 2026-04-20 · PROGEOLAB Research
ads.txt is an IAB standard, published 2017, that declares which advertising technology companies are authorized to sell a website's ad inventory. It has no direct AI connection — but it is part of the /.well-known/ and root-file ecosystem that AI crawlers now inspect, and its adoption pattern is worth documenting alongside llms.txt, security.txt, and the emerging standards.
Of 500 Fortune 500 companies probed in April 2026, 33 have a body-validated ads.txt file (6.6%). The leader is not Disney, Comcast, or News Corp. It is Ecopetrol, the Colombian state oil company, with 1,074 ads.txt entries — more than any other Fortune 500 company.
The Ecopetrol surprise
Ecopetrol's 1,074-entry ads.txt is at first unexpected — an oil company doesn't obviously sell much programmatic advertising. But Ecopetrol operates ecopetrol.com.co as a corporate news and investor-relations domain with substantial Spanish-language traffic across Latin America, and the site runs programmatic ads against that traffic. The 1,074 entries authorize every SSP, DSP, exchange, and ad-tech vendor that the site's monetization team has approved.
The finding is a reminder that programmatic advertising is not exclusive to obviously media-centric companies. A corporate site with enough traffic can monetize it, and monetization at scale requires a comprehensive ads.txt. Ecopetrol's file is the largest example of this pattern in the Fortune 500.
The distribution
| Company | Sector | ads.txt entries |
|---|---|---|
| Ecopetrol | Energy (Colombia) | 1,074 |
| Comcast (NBCUniversal) | Media | 621 |
| Disney | Media | 198 |
| Walmart | Retail | 149 |
| Target | Retail | 96 |
Five outliers drive most of the volume. The median ads.txt has 12 entries; the average is 47. The long tail is dominated by single-entry or empty-header files that declare minimal advertising relationships.
Why this doesn't correlate with AI-readiness
Unlike security.txt (4.8× correlation with AI-readiness), ads.txt presence doesn't correlate with AI-readiness. Ecopetrol has a strong ads.txt and scores well on AI visibility — but that's coincidental. Most of the 33 ads.txt adopters do not score above the Fortune 500 median on AI-readiness.
The reason: ads.txt is a signal about programmatic advertising infrastructure, which is owned by monetization teams that rarely overlap with the content, security, or infrastructure teams that determine AI accessibility. security.txt is different because its publication requires coordination across security, legal, and web operations — the same coordination AI visibility requires. Organizational overlap produces signal correlation; isolated infrastructure produces noise.
What this means for measurement
When auditing a company's root-file ecosystem (robots.txt, llms.txt, ai.txt, agents.json, security.txt, ads.txt, humans.txt), treat ads.txt as an independent data point. Its absence doesn't predict AI-visibility deficits. Its presence doesn't predict AI-visibility strength. Unlike security.txt, it's not a useful maturity proxy. It is, however, a precise signal about a different question: how seriously a company treats its programmatic advertising supply chain.