Market size without a competitor set is a floating number. Bottom-up sizing starts with who actually sells in the category. If the set is wrong, the TAM is wrong — and so is every share you quote in a pitch.
You do not need a 40-player matrix for every engagement. You need a disciplined ten: the names that explain revenue, price, and who can take share from you.
The ten roles that show up in almost every category
1–3. Global incumbents. The three firms whose annual reports already disclose the category, or a close proxy. They set list price and the published market narrative.
4–5. Specialists. Pure-plays or divisions that live only in your niche. They often grow faster than the conglomerate average and are the real SAM check.
6–7. Regional champions. The local leader in China, India, or DACH that global reports underweight. Country tabs exist because these firms dominate local share.
8. Channel or OEM gorilla. The distributor, hospital GPO, auto OEM, or cloud marketplace that controls access even if it does not “compete” on a product slide.
9. Adjacent invader. The company one category over with the customer relationship and a roadmap into yours.
10. The private/fast follower set. One representative private or PE-backed name so you do not pretend the market is only listed companies.
Where the numbers come from
Estimately’s bottom-up path identifies major and mid-tier players from competitive intelligence databases, then pulls segment revenue from filings, investor calls, and press releases. Private firms are estimated from employment, funding, and share intelligence, then checked against trade data.
You are not asked to maintain this by hand for 70,000 categories. You are asked to know, for your market, which ten names the analyst triangulation has to survive.
What to do with the list
Put them in the model: revenue where disclosed, implied share against the country TAM, and a growth flag. If your TAM cannot accommodate those revenues without absurd share, the TAM is the error.
Then use Estimately’s Excel the way it is built — Global for the ceiling, country tabs for where those competitors actually sell, segments for which product line is taking the dollars.
If your competitor list is only the three logos on the target’s website, you are sizing their pitch, not the market.