The 2026 AI Commercial Citation Authority Index: Which Domains Have the Broadest and Deepest Citation Authority Across 283 Markets and Six AI Platforms

Answer Capsule

AI citation authority is not one number.

The July through September 2026 LLM Authority Index benchmark contains 283 qualifying commercial markets, 876,605 retained AI responses, and 8,718,629 citation occurrences resolved to registrable domains. Within the strict platform portfolios, 36,273 domains entered at least one eligible Top 100, but only 2,743, or 7.56%, ever reached a Top 10.

The authority distribution is extremely concentrated at the top and extremely fragmented underneath it.

Only 14 domains reached a Top 10 in at least 50 markets. Only four reached 100 markets. Only two reached 200:

• reddit.com: Top 10 in 280 markets
• youtube.com: 269
• forbes.com: 184
• google.com: 132

But even that ranking does not describe the full authority structure.

A source can be broad across markets but shallow inside them. It can be deep in a narrow category. It can appear on all six AI platforms somewhere in the study without appearing deeply on all six in the same market. It can lead on one platform while being secondary on another.

That last distinction produces one of the strongest findings in this index. 142 domains reached a Top 10 on all six platforms somewhere in the cohort. Only 118 ever reached a Top 10 on all six platforms in the same market. Only 10 domains did that in at least five markets, and only three did it in at least 10.

Forbes reached the Top 10 on all six platforms in 33 markets, Bankrate in 17, and Healthline in 10. Reddit did so in only two markets despite reaching a Top 10 somewhere in 280 markets. YouTube reached a Top 10 in 269 markets but never reached the Top 10 on all six platforms simultaneously in one market.

That is why this Commercial Citation Authority Index does not collapse authority into an arbitrary weighted score. It reports inspectable dimensions:

1. market breadth: how many commercial markets contain the domain in an eligible Top 100 or Top 10;
2. platform breadth: how many of the six AI platforms contain the domain at that depth somewhere in the cohort;
3. market-platform depth: how many eligible market-platform cells contain the domain;
4. same-market platform repetition: how often a source is deep on several platforms in the same category;
5. depth conversion: how often broad Top-100 presence becomes Top-10 presence;
6. category concentration: whether that authority is broadly diversified or concentrated in a coherent commercial sector.

The result is an authority map, not a claim about publisher quality, recommendation influence, traffic, revenue, or future ranking performance.

This pillar develops the measurement framework introduced in Citation Breadth vs Citation Depth: Which AI Authority Metric Should CMOs Care About? and the market-fragmentation findings in AI Search Has a Tiny Universal Core and a Massive Specialist Long Tail.

Key Findings

What the Commercial Citation Authority Index Measures

Questions This Section Answers

1. What does AI citation authority mean when one source can be broad, deep, platform-specific, or category-specific?
2. Why does the Commercial Citation Authority Index avoid a single weighted authority score?
3. Which domain-level metrics should a CMO or publisher inspect before calling a source an AI citation authority?

The word authority is easy to overuse in AI search.

A domain with millions of raw citation occurrences may simply operate in heavily sampled categories. A domain appearing across many markets may be shallow in most of them. A niche publisher can dominate a small group of categories without appearing broadly elsewhere. A source can rank highly on ChatGPT and barely appear on Microsoft Copilot. A domain can be cited as factual support without its associated company ever being recommended.

Those are different phenomena.

This index therefore keeps six dimensions separate.

Market breadth

Top-100 market breadth is the number of qualifying markets in which a domain appeared in at least one eligible platform Top-100 portfolio.

Top-10 market breadth uses the same logic at Top-10 depth.

Market breadth answers: How widely does this source appear across commercial categories?

Platform breadth

Platform breadth counts the number of AI surfaces on which the domain appears at the relevant depth somewhere in the cohort.

A six-platform domain has been observed on ChatGPT, Gemini, Perplexity, Microsoft Copilot, Google AI Overviews, and Google AI Mode at that depth somewhere in the study.

It does not mean the source appears on all six in every market.

Market-platform cell breadth

There were 1,655 eligible market-platform Top-100 portfolios in the strict cohort. Each market-platform combination is one cell.

A domain's cell count therefore captures repeated authority across both category and platform dimensions.

Reddit, for example, entered 1,083 Top-10 market-platform cells, versus 749 for YouTube and 622 for Forbes.

Same-market platform repetition

This is stricter.

For each market, the analysis counts how many platforms place a domain in the Top 10. A domain that reaches the Top 10 on six different platforms in six unrelated markets has broad platform coverage, but it has not demonstrated six-platform depth inside one category.

The same-market test asks: How often do several AI systems independently place this source near the top of the same commercial source ecosystem?

Depth conversion

Depth conversion is:

Top-10 market breadth divided by Top-100 market breadth

It is descriptive, not a quality score.

Reddit converted 280 of 283 Top-100 markets into Top-10 markets, 98.94%. YouTube converted 269 of 283, 95.05%. NerdWallet converted 97 of 132, 73.48%. Forbes converted 184 of 273, 67.40%.

Other broad domains convert very differently.

Category concentration

Finally, market breadth can hide category concentration.

A domain can have meaningful commercial breadth while remaining concentrated in Finance, Technology, Legal, Health, or another coherent category family. For advertiser and publisher decisions, that concentration can be more useful than raw global breadth.

The index therefore should be read as a profile, not a score.

The Authority Universe Is a Long Tail Even at Top-10 Depth

Questions This Section Answers

1. How rare is broad Top-10 AI citation authority across 283 commercial markets?
2. Does narrowing the analysis from Top 100 to Top 10 eliminate the specialist long tail?

It does not.

Among the 36,273 domains that entered at least one eligible Top 100:

• 24,381, 67.22%, appeared in exactly one market;
• 2,936, 8.09%, reached at least five markets;
• 1,081, 2.98%, reached at least 10;
• 329, 0.91%, reached at least 25;
• 116, 0.32%, reached at least 50;
• 36, 0.10%, reached at least 100;
• 13 reached at least 200;
• and only three reached all 283 markets: Reddit, Google, and YouTube.

The Top-10 universe is smaller but almost equally long-tailed.

Among the 2,743 domains that reached a Top 10 at least once:

• 1,873, 68.28%, did so in exactly one market;
• 870 reached at least two markets;
• 248 reached at least five;
• only 102, 3.72%, reached 10 or more;
• only 38, 1.39%, reached 25 or more;
• only 14, 0.51%, reached 50 or more;
• four reached 100 or more;
• and only Reddit and YouTube exceeded 200.

So moving from Top 100 to Top 10 does not produce a small list of universal media brands. It produces a small universal core plus thousands of category-specific authorities.

That finding is consistent with the specialist analysis in Why Niche Publishers Matter More in AI Search Than Global Citation Rankings Suggest, but this index adds the platform and same-market depth dimensions.

The 14 Domains With Top-10 Authority Across at Least 50 Markets

Only 14 domains reached a Top 10 in at least 50 of the 283 commercial markets.

The table makes clear why no single column is enough.

Yahoo was far broader at Top-100 depth than Money.com, 256 markets versus 114, but Money.com reached almost the same number of Top-10 markets, 61 versus 58, and reached the Top 10 on all six platforms in six same-market cases.

CNBC reached only 111 Top-100 markets but accumulated 191 Top-10 market-platform cells. It reached Top 10 on three or more platforms in 42 markets.

Google reached the Top 100 in all 283 markets and the Top 10 in 132, but only eight markets placed Google in the Top 10 on at least three platforms.

Forbes reached fewer Top-10 markets than Reddit or YouTube, but its deep authority was more simultaneously cross-platform within the same category.

None of those facts makes one source universally more valuable than another. They describe different authority shapes.

Six-Platform Breadth Is Not the Same as Six-Platform Authority in the Same Market

Questions This Section Answers

1. If a domain reaches the Top 10 on all six AI platforms somewhere, does it usually do so on all six inside the same market?
2. Which domains show the strongest same-market six-platform Top-10 citation authority?
3. Why can Reddit and YouTube have enormous market breadth but limited all-six Top-10 consensus inside individual markets?

This is the most important new dimension in the 2026 index.

Across the strict cohort:

• 1,621 domains entered an eligible Top 100 on all six platforms somewhere;
• 1,362 of those appeared in the Top 100 on all six platforms in at least one same market;
• 259 achieved six-platform Top-100 breadth only across different markets, never all six at once in one market.

The Top-10 test is much narrower:

• 142 domains reached a Top 10 on all six platforms somewhere;
• 118 reached a Top 10 on all six in at least one same market;
• 24 had six-platform Top-10 breadth across the corpus but never all six inside one market.

Only 10 domains reached the Top 10 on all six platforms in at least five markets.

Only Forbes, Bankrate, and Healthline reached the all-six Top-10 threshold in at least 10 markets.

This produces several counterintuitive profiles.

Reddit: nearly universal depth, limited all-six simultaneity

Reddit reached a Top 10 in 280 markets and accumulated 1,083 Top-10 market-platform cells, the largest footprint in the study.

It reached the Top 10 on at least three platforms in 244 markets and on at least five in 102.

But it reached the Top 10 on all six in only two markets.

That reflects the platform-specific source structures documented elsewhere in the corpus, particularly Microsoft Copilot's unusual citation mix. It does not reduce Reddit's broad authority. It shows that authority is not equally portable to every platform inside every category.

YouTube: 269 Top-10 markets, zero all-six Top-10 markets

YouTube reached a Top 10 in 269 markets and on all six platforms somewhere in the cohort.

Yet no single market placed YouTube in the Top 10 on all six surfaces simultaneously.

It reached at least three platforms in 179 markets, but five or more in only three.

A global six-platform badge would completely miss that shape.

Forbes: less universal breadth, much stronger same-market cross-platform repetition

Forbes reached a Top 10 in 184 markets, well below Reddit and YouTube.

But it reached a Top 10 on at least three platforms in 114 markets, at least five in 60, and all six in 33.

Forbes therefore represents a different kind of authority: less universal by market count, but unusually repeatable across multiple AI systems inside many of the markets where it is strong.

Again, the index does not declare one profile superior. The useful question is which profile matches the advertiser, publisher, or measurement problem.

Every AI Platform Produces a Different Authority Leaderboard

Questions This Section Answers

1. Which domains reach the Top 10 in the most markets on ChatGPT, Gemini, Perplexity, Microsoft Copilot, Google AI Overviews, and Google AI Mode?
2. Can a global AI citation authority ranking substitute for platform-specific source intelligence?

No.

The leading domain order changes materially by surface.

Several patterns stand out.

Copilot is the clearest break from the global order. Reddit and YouTube do not appear among its five widest Top-10 domains. Forbes leads, followed by Amazon, U.S. News, NerdWallet, and Walmart.

That matches the independent Copilot work in Microsoft Copilot Lives on a Different Web and Which Source Types Overperform in Microsoft Copilot Compared With Other AI Engines?.

Perplexity favors YouTube over Reddit by Top-10 market breadth, 196 to 181.

Google AI Overviews favors Reddit, while Google AI Mode favors YouTube.

Gemini has a much narrower leading-source footprint than ChatGPT or the Google search surfaces. Reddit leads Gemini in 137 markets versus 259 on ChatGPT and 270 in AI Overviews.

This is why a publisher cannot credibly say, "We are a top AI source," without specifying the market and platform population.

The Global Leaders Change Again by Commercial Sector

A commercial authority index becomes more useful when it can answer a second question:

Where is this domain authoritative?

Top-10 market breadth inside the seven named macro sectors produces different leader groups.

This table should not be read as an advertiser recommendation list. It demonstrates why local category context matters.

NerdWallet is one of the most powerful domains in the full index, but its deep authority is strongly concentrated in Finance & Insurance. G2 is a technology authority. Healthline is a health authority. Justia is a legal authority.

A global breadth ranking can obscure that specialization.

For many campaigns, a domain with lower total market breadth but concentrated authority in the relevant sector is more informative than a universally present platform or social source.

Broad Citation Presence Can Still Be Shallow

Questions This Section Answers

1. Which widely cited domains rarely become leading Top-10 sources?
2. Why should a CMO avoid treating Top-100 market breadth as a stand-alone authority score?

Breadth without depth is common.

Among domains appearing in the Top 100 in at least 50 markets, the median Top-10 conversion rate was only 14.55%. The first quartile was 5.76%, and the third quartile 28.34%.

Several broad domains never reached a Top 10 anywhere in the strict portfolio set.

BusinessWire is the cleanest platform-breadth example. It appeared in eligible Top-100 portfolios on all six AI platforms and across 91 markets, yet never entered a Top 10 in the strict cohort.

That is real citation breadth. It is not deep source authority.

The same distinction matters when evaluating PR distribution. A distribution service can be broadly present in AI source portfolios without regularly becoming one of the most prominent sources for commercial decisions.

The P6 supporting article How CMOs Should Evaluate Publishers Before Buying Sponsored Content, PR, or Distribution applies this distinction directly to media diligence.

Narrow Domains Can Have Exceptional Citation Authority

The inverse profile is equally important.

A domain does not need global breadth to be deeply authoritative inside a category cluster.

These are not equivalent business models, and the table is not a publisher-quality ranking. It illustrates a structural point.

CCRM Fertility reached a Top 10 in both markets where it entered a Top 100 and did so on all six platforms in both.

ForThePeople.com reached a Top 10 in 10 of 13 Top-100 markets and reached the Top 10 on all six platforms in eight.

Chewy reached all-six Top-10 depth in nine markets despite having Top-100 breadth of only 20 markets.

That is category authority.

It is why the Commercial Citation Authority Index must preserve specialist profiles rather than treating the broadest domains as the only meaningful authorities.

The category-expansion implications are developed in How Publishers Can Build Category Authority Without Becoming a Generalist Media Site and How Publishers Can Choose Adjacent Verticals Based on Citation Stability and Platform Portability.

A Useful Authority Profile Has at Least Four Independent Axes

The corpus now supports a practical classification without inventing one magic score.

Broad and deep

These domains cover many markets and regularly reach leading positions.

Examples include Reddit, YouTube, Forbes, NerdWallet, TechRadar, CNBC, Money.com, G2, and Bankrate, although their sector and platform profiles differ sharply.

A broad-and-deep domain can matter for enterprise publisher mapping, but the advertiser should still check the actual category and platform.

Broad and shallow

These domains appear across many commercial source portfolios but rarely become Top-10 sources.

Examples include CB Insights, BusinessWire, The Guardian, eBay, AP News, Time, Medium, and PR Newswire under the observed strict portfolios.

Broad presence can still be useful evidence of discoverability or background-source use. It should not be described as deep authority.

Narrow and deep

These domains operate across relatively few markets but repeatedly reach Top-10 positions, often on multiple platforms.

Examples include CCRM Fertility, Mattress Nerd, Chewy, OutdoorGearLab, Security.org, and ForThePeople.com.

This is often the most important class for a company making a specific category decision.

Platform-concentrated

Some domains accumulate meaningful Top-10 market breadth on only one or two AI platforms.

WorldMetrics reached a Top 10 in 48 markets but on only two platforms. ZipDo reached a Top 10 in 42 markets but only one platform. LegalClarity reached a Top 10 in 40 markets but only two.

Those are real footprints. They are also platform-concentrated footprints.

The publisher-side implications are developed in How Publishers Should Think About Platform-Specific AI Citation Demand.

Do Not Turn the Index Into an Undisclosed Composite Score

Questions This Section Answers

1. Should breadth, depth, platform coverage, and persistence be combined into one AI authority score?
2. What would be lost if the Commercial Citation Authority Index assigned one weighted rank to every domain?

A composite score is possible as a management tool. It is not an objective fact contained in the evidence.

Any weighted score must answer questions such as:

• Should one additional market count more than one additional platform?
• Is a Top-10 appearance twice as valuable as Top 25, five times, or 20 times?
• Should five-platform depth in one market outweigh broad Top-100 coverage in 100 markets?
• Should category concentration be rewarded or penalized?
• Should a source's temporal persistence receive the same weight as its cross-platform depth?
• Should a Finance advertiser weight Finance authority more heavily than global authority?

Those are business choices.

The research can supply the raw dimensions. It cannot claim that one universal set of weights is naturally correct.

This is especially important because the axes do not move together perfectly.

Among domains that ever reached a Top 10, the descriptive Spearman relationship between Top-100 market breadth and Top-10 market breadth was 0.608. Top-100 cell breadth and Top-10 market breadth correlated at 0.642. Top-10 platform breadth and Top-10 market breadth correlated at 0.461.

Those relationships are meaningful but far from identity.

An index that collapses the axes would hide the differences the data is revealing.

The better approach is to show the dimensions and let the business specify its own decision rule.

How a CMO Should Use the Index

For a CMO, the index is a source-diligence map.

Start with the actual market. Identify domains with Top-10 and Top-25 depth in that category. Then inspect whether those sources repeat across platforms and whether they persist over time.

Use global breadth to answer a separate question: Does this source have authority that extends beyond one category?

Do not infer that a broad source is the best sponsorship target for every market. Do not infer that a niche source is weak because its global market count is small.

A useful publisher or source profile can include:

That is a stronger diligence process than buying media based on one domain-level global rank.

The next P6 article, What Makes a Domain an AI Citation Authority? A Practical Measurement Framework, formalizes those measurement dimensions.

How Publishers Should Use the Index

A publisher can use the same data in reverse.

Do not market a domain as "an AI authority" without showing the scope.

A stronger media-kit statement would specify:

• markets where the domain enters a Top 100, Top 25, or Top 10;
• AI platforms where that depth is observed;
• categories where multiple platforms cite the domain deeply in the same market;
• month-to-month recurrence where sufficient observations exist;
• cited URLs and page types;
• and the measurement population and date window.

That lets an advertiser distinguish broad cross-market authority from focused category authority.

It also protects the publisher from making claims the evidence cannot support.

A Top-10 source position is not a guarantee of future citation. Citation is not recommendation. A domain-level result does not prove every page on the site inherits the same authority.

The P6 publisher proof article, How Publishers Can Prove AI Citation Authority to Advertisers Without Promising Rankings, develops that reporting model.

Methodology and Limits

The index uses the frozen July through September 2026 LLM Authority Index benchmark of 283 qualifying tracked markets, 876,605 retained AI responses, 8,718,755 citation-array slots, and 8,718,629 citation occurrences resolved to registrable domains. The six measured surfaces are ChatGPT, Gemini, Perplexity, Microsoft Copilot, Google AI Overviews, and Google AI Mode.

The strict platform portfolio analysis contains 1,655 eligible market-platform Top-100 portfolios. A platform cell is eligible only when it contains at least 100 retained responses and at least 100 resolved domains. Thin or missing cells are excluded rather than assigned zero.

Within each eligible market-platform cell, domains are ranked by response presence, not raw citation occurrence count. A domain counts once per retained response even if it appears multiple times in that answer. Ties are resolved alphabetically under the frozen methodology.

For this article:

• Top-100 market breadth counts markets where the domain appears in at least one eligible platform Top 100.
• Top-10 market breadth counts markets where the domain appears in at least one eligible platform Top 10.
• Top-100 or Top-10 platform breadth counts distinct AI surfaces where the domain reaches that cutoff somewhere in the cohort.
• Market-platform cell breadth counts eligible market-platform portfolios containing the domain at the specified depth.
• Same-market multi-platform depth counts, for each domain, markets where the domain appears in the Top 10 on at least three, four, five, or all six eligible platform portfolios.
• Depth conversion equals Top-10 market breadth divided by Top-100 market breadth.
• Conditional median rank is calculated only in eligible Top-100 cells where the domain is present. Missing cells are not assigned a synthetic rank.

The full cohort contains 36,273 distinct domains that entered at least one eligible Top 100. 2,743 entered a Top 10.

Several limitations matter.

First, this is an observational study of changing response samples, not a certified identical-prompt panel. Of the retained responses, 104,071 used ingestion-date proxies. The broader persistence-portability work documents the date and population limitations in detail.

Second, platform breadth does not imply same-market platform breadth. This article explicitly separates the two.

Third, domain-level presence does not establish ownership, editorial quality, traffic, audience, paid inventory, or the relevance of every URL on the domain.

Fourth, a Top-10 position is a portfolio rank based on response-domain presence under the frozen method. It is not a search-engine ranking and does not establish future citation probability.

Fifth, citation authority is not recommendation authority. A domain can be cited in an answer that recommends another company, criticizes the cited company, or uses the page only for background evidence.

Sixth, the term Commercial Citation Authority Index describes a structured domain reference across commercial markets. It does not introduce a hidden composite authority score. All rankings in this article disclose the ordering metric being used.

Finally, this analysis does not establish causation. It cannot prove that sponsored content, PR placement, publishing frequency, technical changes, or any other intervention will produce future citations, recommendations, traffic, leads, conversions, or revenue.

Related Research

• AI Search Has a Tiny Universal Core and a Massive Specialist Long Tail: How Citation Authority Fragments Across 283 Commercial Markets
• Why Niche Publishers Matter More in AI Search Than Global Citation Rankings Suggest
• Citation Breadth vs Citation Depth: Which AI Authority Metric Should CMOs Care About?
• How to Find the Market-Specific Publishers AI Systems Actually Cite
• How Publishers Can Build Category Authority Without Becoming a Generalist Media Site
• How Publishers Can Choose Adjacent Verticals Based on Citation Stability and Platform Portability
• Six AI Engines, Six Different Webs: Comparing Citation Source Overlap Across ChatGPT, Gemini, Perplexity, Copilot, Google AI Overviews, and Google AI Mode
• Microsoft Copilot Lives on a Different Web
• What Makes a Domain an AI Citation Authority? A Practical Measurement Framework
• How CMOs Should Evaluate Publishers Before Buying Sponsored Content, PR, or Distribution
• How Publishers Can Prove AI Citation Authority to Advertisers Without Promising Rankings
• Which AI Citation Metrics Belong on a CMO Dashboard?
• AI Citation Authority vs AI Recommendation Authority: Why Being a Source Is Not the Same as Being Recommended

The earlier Persistence-Portability framework provides conceptual context. The 2026 AI Citation Authority Study covers an earlier high-stakes sample and is a separate population.