Automotive Parts and Accessories Retailers (U.S.)

NAICS 2022 code 44133 — an investor's primer (rollup level)

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1. Overview

NAICS (the North American Industry Classification System, the U.S. government's standard for grouping businesses) code 44133 covers the stores that sell new, used, and rebuilt car parts and accessories — brakes, batteries, filters, belts, motor oil, wipers, lighting, and the rest — to both do-it-yourself drivers and professional repair shops [1]. In practice these are the AutoZone, O'Reilly, Advance Auto Parts, and NAPA storefronts on nearly every commercial strip in America.

This is a five-digit NAICS "industry" that sits one rung above the individual store category. It is a need-based, unusually defensive corner of retail: demand comes from the roughly 289 million light vehicles already on U.S. roads, not from new-car sales, so it holds up — and can even improve — when the economy softens and people repair rather than replace [14].

Because this level contains only one child industry, everything of substance lives in that child. This page is a short summary: it explains why the level equals its child, gives the federal figures we hold for this exact level, and points you to the full 441330 primer for the investable universe, economics, demand drivers, regulation, and risks.

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2. What's inside — and why the level equals its one child

NAICS is a nested hierarchy: each five-digit industry breaks into one or more six-digit national industries. Code 44133 breaks into exactly one:

When a five-digit industry has a single six-digit child, the two are definitionally the same set of businesses; the U.S. drops to the six-digit level only to stay consistent with the rest of the classification, not because anything is subdivided. Every establishment, dollar of receipts, and employee counted under 44133 is also counted under 441330. So the scope statement is the child's: stores primarily retailing automotive parts and accessories, with or without light installation, serving DIY (do-it-yourself) consumers, DIFM (do-it-for-me) professional shops, or both [1].

What that scope excludes — and where those dollars land instead — is the same as the child's: tire dealers (NAICS 441340), repair-and-installation labor (NAICS 811), wholesale parts distribution (NAICS 423120), and the large volume of parts sold online or through general merchants like Walmart and Amazon (much of it NAICS 454110) [1]. The federal figure below is "parts sold over the counter at parts stores," not "all money spent keeping American cars running."

For everything past this point — the companies, how the money works, demand, regulation, consolidation, risks, and how to invest — read the 441330 primer. It is the full document for this level.

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3. How big it is (this level's federal figures)

Our ground-truth federal statistics for NAICS 44133 come from the U.S. Census Bureau's 2022 Economic Census (the concentration and receipts tables). Because 44133 and 441330 are the same businesses, these match the child level:

Average sales per firm work out to about $5.5 million, but that average is badly skewed by a few giants; the typical independent is far smaller [3].

Establishment, employment, and payroll counts for this level (roughly 38,567 store locations and 380,068 paid employees from the 2023 County Business Patterns) are carried in full in the 441330 primer, which draws on a separate Census survey vintage [2].

Concentration. The Herfindahl-Hirschman Index (HHI, a standard concentration gauge that sums the squared market shares of all firms) sits at just 645 — below the 1,000 mark and far below the 1,800 "highly concentrated" line in the 2023 federal Merger Guidelines — so the national market rates as statistically unconcentrated [3][24]. Yet the four largest firms already control 46.9% of sales. That is the industry's defining "barbell": a few national chains taking nearly half the market while thousands of small operators split the rest. Antitrust markets are often local or channel-specific, where concentration can be much higher [24].

Undercount caveat — two layers. First, the Census surveys cover businesses with paid employees, so they undercount nonemployer businesses, sole proprietors, and the very smallest independents — and small, individual ownership is common in this fragmented long tail, so the true operator count is higher than 17,199 [2][3]. Second and larger: the $95.35 billion captures only the specialty-store retail channel. Industry groups put the whole light-vehicle "automotive aftermarket" at roughly $400 billion-plus — the gap is scope, not error, because the bigger number folds in tires, repair labor, wholesale, and online/mass-merchant sales that sit outside this code [25].

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4. Investable universe (where value concentrates)

Because the level equals its one child, the investable universe is identical to 441330's — and it is unusually concentrated in a few public names for a retail industry. Full detail, tickers, and company figures are in the child primer; in brief, storefront value concentrates in:

• AutoZone (NYSE: AZO) and O'Reilly Automotive (NASDAQ: ORLY) — the two purest, most profitable operators, both essentially perpetual share-buyback compounders [5][6].
• Genuine Parts Company (NYSE: GPC) — the NAPA distributor, a dividend payer with a large industrial arm, planning to separate its automotive and industrial businesses into two public companies (targeted first quarter 2027) [7][10].
• Advance Auto Parts (NYSE: AAP) — a higher-risk turnaround [8].
• CarParts.com (NASDAQ: PRTS) — online-only, economically relevant but generally outside this store-based code [11].

On the private side, value is far more dispersed: thousands of independent NAPA, Carquest, Auto Value/Bumper to Bumper, and Federated member stores, private-equity-backed distributors, and single-tenant net-lease real estate under the chains [7][12][13]. See 441330 for the full list.

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5. How the money works

Same economics as the child. Retailers earn the spread between selling price and product cost, net of store labor, rent, distribution, delivery, and returns. The levers: comparable-store sales ("comps," sales at stores open at least a year — O'Reilly has posted 33 straight positive years [6]); a two-channel mix (higher-margin DIY versus lower-margin but stickier professional/commercial); and a moat built on parts availability, not shelf price, via expensive multi-echelon, hub-and-spoke distribution [5][6]. Gross margins run rich for retail (low-40s to low-50s percent), suppliers finance much of the inventory, and the best operators return excess cash through buybacks (AZO, ORLY) or a rising dividend (GPC) [5][6][7]. Full treatment in 441330, Section 5.

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6. Demand drivers

Demand tracks the fleet, not new-car sales — the whole investment case. About 289 million light vehicles are on U.S. roads, and the average one hit a record 12.8 years old in 2025; older, out-of-warranty vehicles need more parts and their owners buy from parts stores [14]. More miles driven (3.29 trillion vehicle-miles in 2024) means more wear [16]. Stretched new- and used-car affordability keeps cars on the road longer, and the segment is counter-cyclical — DIY repair rises in downturns. The long-term swing factor is electric vehicles (EVs), which need less maintenance and shift (rather than erase) the product mix [15]. Full detail in 441330, Section 6.

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7. Regulation

Lightly regulated as retail goes; the same policy areas apply at this level as at the child. The defining fight is Right to Repair — independent shops' access to vehicle diagnostic data and software, advanced by state laws and the federal REPAIR Act [23]. Other touchpoints: warranty-choice protection under the Magnuson-Moss Warranty Act [25]; vehicle-safety standards from the National Highway Traffic Safety Administration [22]; Environmental Protection Agency rules on used oil, batteries, and refrigerants [19][20][21]; California Air Resources Board exemptions for emissions parts [24]; and tariffs on imported parts, a live margin wildcard. No federal license is needed to open a parts store — part of why the independent long tail persists. Full detail in 441330, Section 7.

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8. Consolidation

The competitive race is decided on distribution density and delivery speed, especially in the professional channel, and consolidation is active: GPC reported 50-plus acquisitions adding 250-plus locations in 2025 (mostly independent NAPA stores), O'Reilly opened 207 net new stores, and Advance is pruning weak stores in a restructuring [6][7][8][9]. The strongest roll-up thesis is regional density; roll-ups destroy value when they overpay or keep weak stores. Private equity trades distributors and secondary chains regularly (Worldpac to Carlyle, 2024) [8]. Full detail in 441330, Section 8.

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9. Risks

Identical to the child's: the long-term EV mix shift (fewer wear parts per vehicle) [14][15]; e-commerce price competition from Amazon, Walmart, and RockAuto; tariff and supply-chain cost shocks; inventory/obsolescence risk; execution (Advance is the cautionary tale) [8]; leverage and interest-rate sensitivity in the buyback and roll-up models; and valuation — a great business can still be a poor investment at an excessive multiple. Full detail in 441330, Section 9.

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10. How to invest and outlook

Public-market routes mirror the child: AZO and ORLY for buyback-driven compounding, GPC for dividend income plus a possible 2027 automotive spin-off, AAP as a turnaround, PRTS for pure online exposure; there is no large pure-play auto-parts-retail exchange-traded fund (ETF), so the names appear inside broad consumer-discretionary and retail ETFs [5][6][7][8][10][11]. Private-market routes: own a franchised or independent NAPA/Carquest store, back regional roll-ups and distributors, hold single-tenant net-lease real estate, or lend against inventory and receivables.

Outlook (forward-looking judgment, not a guarantee). The base case is durable replacement-parts demand with a changing product mix: a record-old, still-growing fleet and stretched car affordability keep vehicles in the repair sweet spot, favoring scaled operators with the best availability, delivery, and data systems. The two things to watch are tariffs (near-term margin swing) and the slow EV transition (long-term ceiling on per-vehicle demand).

Because NAICS 44133 is identical to its single child, the complete analysis lives in the 441330 primer. Read it for the full picture.

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Sources

Drawn from the child primer (NAICS 441330); this rollup's own ground-truth figures are the Economic Census 2022 receipts and concentration tables [3].

1. U.S. Census Bureau, "2022 NAICS — 441330 Automotive Parts and Accessories Retailers: definition and exclusions (incl. 441340, 811111/811114, 423120, 423140, 454110, 4411)," 2022. https://www.census.gov/naics/?input=441330&year=2022
2. U.S. Census Bureau, "County Business Patterns (CBP), 2023 — establishments, employment, annual and Q1 payroll (NAICS 441330)," 2023. https://www.census.gov/programs-surveys/cbp.html
3. U.S. Census Bureau, "Economic Census 2022 — receipts, firms, and concentration (NAICS 44133/441330): CR4/CR8/CR20/CR50, HHI," 2022/2025. https://data.census.gov/table/ECNSIZE2022.EC2200SIZECONCEN
4. U.S. Small Business Administration, "Table of Small Business Size Standards (NAICS 441330: $28.5M average annual receipts)," 2023. https://www.sba.gov/document/support-table-size-standards
5. AutoZone, Inc., "Form 10-K, fiscal 2025 (ending Aug 30, 2025)," 2025. https://www.sec.gov/Archives/edgar/data/866787/000110465925102611/azo-20250830x10k.htm
6. O'Reilly Automotive, Inc., "Form 10-K, fiscal 2025," 2026. https://www.sec.gov/Archives/edgar/data/898173/000089817326000009/orly-20251231x10k.htm
7. Genuine Parts Company, "Form 10-K, fiscal 2025," 2026. https://www.sec.gov/Archives/edgar/data/40987/000004098726000003/gpc-20251231.htm
8. Advance Auto Parts, Inc., "Form 10-K, fiscal 2025; Worldpac sold to Carlyle (~$1.5B, 2024)," 2026. https://www.sec.gov/Archives/edgar/data/1158449/000119312526051305/aap-20260103.htm
9. Genuine Parts Company, "Announces Acquisition of Largest NAPA Independent Store Owner in the U.S. (MPEC, 181 stores)," 2024. https://www.genpt.com/2024-05-01-Genuine-Parts-Company-Announces-Acquisition-of-Largest-NAPA-Independent-Store-Owner-in-the-U-S
10. Genuine Parts Company, "Announces Plan to Separate Automotive and Industrial Businesses Into Two Public Companies (targeted Q1 2027)," 2026. https://www.genpt.com/2026-02-17-Genuine-Parts-Company-Announces-Plan-to-Separate-Automotive-and-Industrial-Businesses-Into-Two-Industry-Leading-Public-Companies
11. CarParts.com, Inc., "Form 10-K, fiscal 2025 (online-only aftermarket retailer)," 2026. https://www.sec.gov/Archives/edgar/data/1378950/000137895026000035/prts-20260103x10k.htm
12. Aftermarket Auto Parts Alliance, "About the Alliance (Auto Value, Bumper to Bumper; 50+ shareholders)," current. https://www.alliance1.com/
13. Federated Auto Parts, "Company Overview (4,000+ independently operated stores)," current. https://www.federatedautoparts.com/
14. S&P Global Mobility, "U.S. Vehicle Age Rises Again to 12.8 Years in 2025 — 289M light vehicles in operation, ~4.5% scrappage," May 21, 2025. https://press.spglobal.com/2025-05-21-U-S-Vehicle-Age-Rises-Again-to-12-8-Years-in-2025-According-to-S-P-Global-Mobility
15. U.S. Department of Energy, "Maintenance and Safety of Electric Vehicles," current. https://afdc.energy.gov/vehicles/electric-maintenance
16. Federal Highway Administration, "Highway Statistics 2024 — Annual Vehicle Distance Traveled (3.29T total, 2.22T light-duty)," 2026. https://www.fhwa.dot.gov/policyinformation/statistics/2024/vm1.cfm
17. National Highway Traffic Safety Administration, "Federal Motor Vehicle Safety Standards — aftermarket replacement equipment," current. https://www.nhtsa.gov/laws-regulations/fmvss
18. Auto Care Association, "Right to Repair and the REPAIR Act — fact sheet," 2025; and Congressional Research Service, "Access to Motor Vehicle Software and Data (R48131)," 2024. https://www.autocare.org/government-relations/current-issues/right-to-repair
19. U.S. Department of Justice & Federal Trade Commission, "2023 Merger Guidelines — Guideline 1 (HHI thresholds; relevant-market definition)," 2023. https://www.justice.gov/atr/merger-guidelines
20. Federal Trade Commission, "Auto Warranties and Service Contracts (Magnuson-Moss Warranty Act)," current. https://consumer.ftc.gov/articles/auto-warranties-and-auto-service-contracts
21. U.S. Environmental Protection Agency, "Managing Used Oil: Answers to Frequent Questions for Businesses," current. https://www.epa.gov/hw/managing-used-oil-answers-frequent-questions-businesses
22. U.S. Environmental Protection Agency, "Frequent Questions About Universal Waste (batteries)," current. https://www.epa.gov/hw/frequent-questions-about-universal-waste
23. U.S. Environmental Protection Agency, "Regulatory Requirements for Motor-Vehicle Air-Conditioning System Servicing (Section 609)," current. https://www.epa.gov/mvac/regulatory-requirements-mvac-system-servicing
24. California Air Resources Board, "Aftermarket, Performance, and Add-on Parts (Executive Order exemptions)," current. https://ww2.arb.ca.gov/our-work/programs/aftermarket-performance-and-add-parts
25. MEMA / Auto Care Association, "U.S. automotive aftermarket size (~$400B+ light-vehicle aftermarket)," 2024–2025. https://www.mema.org/