Glossary · Beginner
What Is Competitor Share? Definition and Example
Competitor share is the proportion of brand mentions, or recommendations, in a set of AI answers that goes to each competitor you track. It shows who AI assistants favour in your category and by how much. Together with your own share of voice, it reveals whether you're gaining ground or losing it.
On this page
- How is it calculated?
- Why does it matter?
- What should you watch for?
- How do you act on it?
- Which breakdowns are most useful?
- From MentionX data: how share shifts by intent
- Worked example: Ledgerline against Competitors A to D
- Mentions or recommendations?
- Common mistakes
- Common questions
- Related
Checked on 31 October 2026. "Our view" marks MentionX opinion. Ledgerline is a fictional company used for illustration.
How is it calculated?
For each competitor:
Competitor share = that competitor's mentions ÷ total mentions of all tracked brands
You can calculate the same with recommendations instead of mentions.
| Brand (illustrative) | Mentions | Share |
|---|---|---|
| You | 30 | 20% |
| Competitor A | 60 | 40% |
| Competitor B | 45 | 30% |
| Competitor C | 15 | 10% |
| Total | 150 | 100% |
Illustrative data.
Why does it matter?
A rising mention rate may still mean losing ground if competitors rise faster. Competitor share also shows where competitors win: by engine, by prompt type and by topic. That points to specific gaps you can investigate, for example the sources that cite competitors but not you.
What should you watch for?
- Changing the set: adding or removing competitors changes every share. Keep the set stable, or recalculate history.
- Unexpected brands: AI answers may name brands you didn't consider competitors. Track them if they appear often.
- Small samples: shares from a few dozen answers are noisy.
How do you act on it?
- Find prompts where a competitor leads.
- Look at the sources cited in those answers.
- Identify what those sources say about the competitor that they don't say about you.
- Close the gap with content, PR or review work.
Which breakdowns are most useful?
Report competitor share by engine, by prompt stage (problem, category, comparison, brand) and by topic. A competitor that dominates comparison prompts but is weak on problem prompts is winning late in the buying journey, and your response differs from a competitor that leads everywhere.
From MentionX data: how share shifts by intent
Method. Read-only aggregate queries over MentionX scans from 22 August to 29 October 2026 (UTC): 2,217 engine runs (2,154 completed) across 18 anonymised projects and six engines.
Share of voice for the tracked brand, which is the mirror of competitor share, moved a lot with intent:
| Intent | Brand mentioned | Share of voice |
|---|---|---|
| Brand-specific | 100% | 64.3 |
| Comparison | 91.9% | 44.6 |
| Recommendation | 29.2% | 26.8 |
| Best-of | 26.6% | 22.7 |
| Problem | 5.7% | 7.7 |
On alternative prompts, the tracked brand held 15.5 share of voice; competitors held the rest. Unbranded answers with citations named 1.11 tracked brands on average, against 1.44 for answers without citations.
Our view: competitor share is most useful on unbranded prompts. Brand-specific prompts hand the tracked brand most of the share by design.
Limits. A convenience sample of mostly B2B software projects, run through engine APIs, which can behave differently from the consumer apps. Perplexity, Copilot and DeepSeek figures come from a single day (26 October 2026), so treat them as a snapshot, not a trend.
Worked example: Ledgerline against Competitors A to D
Ledgerline is a fictional accounts-payable tool. Figures are illustrative.
Ledgerline tracks four rivals across 20 unbranded prompts on four engines. Competitor A holds 41% of mentions, Ledgerline 22%, Competitor B 19%, Competitors C and D the rest.
Split by engine, Competitor A's lead comes mostly from one engine whose answers cite two review sites. Ledgerline has a thin profile on one and none on the other. On the engine that cites Ledgerline's own guides, the gap is small. The plan targets the two review sites first.
Mentions or recommendations?
| Basis | Answers | Use it for |
|---|---|---|
| Mentions | Is the brand named at all? | Awareness, early-stage prompts |
| Recommendations | Is the brand suggested as a choice? | Buyer prompts |
| Position-weighted | How high on the list? | Best-of lists |
Pick one basis per report and say which. A competitor named often but rarely recommended is a different threat from one that's always first.
Common mistakes
- Comparing shares across reports with different competitor sets.
- Mixing branded and unbranded prompts in one share figure.
- Reading a one-point change as a trend; repeat the runs first.
Common questions
Is competitor share the same as share of voice? They're two views of the same split: yours is share of voice, theirs is competitor share.
How many competitors should I track? Four or five direct rivals, plus an other bucket.
Can share fall while mention rate rises? Yes, if competitors are named more often too.
Related
Questions
How is competitor share different from share of voice?
They're closely related. Share of voice usually means your share; competitor share looks at how the remaining share is split among rivals.
Which competitors should I track?
The ones buyers actually compare you with, plus any brands AI answers mention often in your category.
Can competitor share change quickly?
Yes. AI answers vary between runs and change as models and sources update, so track trends over repeated scans.