Business Buyer School Research · Methods · Version 2026.1

Methodology: The Acquisition Supply Study

How small firm supply was measured and scored across 152 industries, and what the study cannot show.

Business Buyer School calculation. Scores, ranks and rates are calculated by Business Buyer School from official Census Bureau data. These counts measure how many small firms exist, not how many are for sale. The top 100 is the 100 highest scores on the Acquisition Supply Index, which combines density, share and count of small firms; it is not a ranking by pool size.

Version 2026.1 published

October 6, 2026

Analysis prepared

October 6, 2026

Data year

Census Bureau Statistics of U.S. Businesses 2022: firms by enterprise employment size, four digit NAICS 2017

Owner age overlay

Business Buyer School Report 3, shown separately and not part of the index

Short version · Full study · Methodology · Data · How to cite

Version 2026.1. Run date 2026-10-06. Calculation version supply-score-v1. Every number in the study is reproduced from the public Census files by the study's scripts.

1. Question

Which industries score highest as a hunting ground for an individual buyer, measured by the density, share and count of small employer firms? This is supply density, not listings or willingness to sell.

2. Sources

Census Bureau SUSB 2022, national, by 4-digit NAICS and enterprise employment size (file us_state_naics_detailedsizes_2022.txt, STATE 00). SUSB 2022 is published on NAICS 2017 codes at this detail, matching the Report 1 universe, so no crosswalk is used. Overlays from Reports 1, 2 and 3 (same package version).

3. Universe and confidence

Report 1 universe: 167 industries, High 118, Medium 34 (ranked together, 152 in all), Low 15 (unranked). Rules U1 to U6 and tiers are in the Report 1 methodology.

4. Metrics

• Firms under 20 employees: SUSB enterprise size class <20. Firms under 5: class <5. Firms 20 to 99: sum of classes 20 to 99. Firms 5 to 99 = under 20 minus under 5 plus 20 to 99.
• Buyable Business Density = firms under 20 / industry employment x 10,000.
• Small-firm share = firms under 20 / all firms. Staffed small-firm share = firms 5 to 99 / all firms.
• Employees per firm = employment / firms (context).
• Owner age overlay (not in Model A): Report 3's share of incorporated self-employed workers aged 65 or older in the ACS group containing the industry, applied only where the 2017 NAICS code maps one-to-one to 2022 and the ACS groups cover the code completely (123 of 152 industries: 68 exact group, 55 pooled group, shared with other industries). It is a people-based, group-level figure.
• Omitted: mature-firm share (no public firm-age data below sector).

5. Score

Mid-rank percentiles (0 to 100) across the 152 ranked industries. Model A (pre-specified): density 40, small-firm share 20, small-firm count 40. Alternatives: B density-heavy 60/20/20; C count-heavy 20/10/70; D equal across density, share, count and staffed-firm count; E share-heavy 30/50/20; F winsorised z-scores (count logged); G adds owner age (30/15/30/25) on the owner-age subset; 3,000 Dirichlet weight draws. Minimum pairwise Spearman 0.884. Stability: 28 stable top quartile, 28 stable bottom quartile, 16 method-sensitive, 80 moderate.

6. Red-team review

1. Does the index just measure tiny firms? Largely yes: Spearman -0.90 with employees per firm. Mitigation: staffed-small-firm (5 to 99) counts are shown as a separate lens, and the buyer section says so.
2. Does size of industry dominate? The count component (40%) favors large industries (Spearman 0.43 with log employment); leave-one-out: dropping count gives top-25 overlap 19 of 25, dropping density 22, dropping share 24.
3. Franchises and subsidiaries. SUSB enterprises are whole firms; independent franchisees count as small firms. 26 ranked industries have 40 or more employees per firm and may include chain-dominated structures.
4. Double counting. A firm in several 4-digit industries is counted in each; industry counts cannot be summed to national totals.
5. Does supply mean for sale? No. Nothing in the study measures listings, owner intent or price.
6. Owner age. Where available it does not change the ranking much (Spearman 0.94 on 123 industries) and correlates -0.11 with supply.
7. Low-confidence industries are unranked; 0 of the top 25 are Medium confidence.
8. Time. One year (2022); no trend is claimed.

7. Limitations

Employer firms only (no non-employers); 4-digit groups mix trades; one year; size classes are enterprise-wide, not local; no firm age; supply is not demand or price; SUSB suppresses nothing in the cells used here (empty size cells are treated as zero firms).

8. Versioning

YYYY.N; a new SUSB release or change in universe, weights or definitions requires a calculation_version increment.

How to cite

Cite as: Business Buyer School, 100 Industries Ranked by Acquisition Supply (methodology), https://businessbuyerschool.com/research/acquisition-supply-index/methodology/. Version 2026.1. Published October 6, 2026.

A data license has not been published; short quotations with attribution and a link are welcome.

Take this into your own search

Industry research is context, not a verdict on any one business. These free parts of the school show how to use it.

• Write your Buy Box: set the type of business, size and hard exclusions before you search.
• Cleaning, landscaping and HVAC compared: how the same principles show up in three trades.
• See the curriculum or start free with Business Buyer School.