How AutoZone grows without spending a dime of its own cash

Today, I'm digging into AutoZone, Inc. (AZO). As I promised on Tuesday, I was going to profile another company with net negative working capital, and AutoZone is a prime example of that.

They sell replacement auto parts, batteries, brakes, wipers, and fluids to do-it-yourself customers and professional repair shops through more than 7,000 stores across the US, Mexico, and Brazil.

One of the headwinds that physical retail businesses face is the financing cost associated with holding their inventory. As you know, you need a certain quantity of inventory to attract customers. Traditional retail has to either sell or finance this inventory.

But not a business with net negative working capital. This is especially powerful after interest rates have risen by five percentage points or so over the last few years.

At fiscal year-end 2025, AutoZone owed vendors $8.0B in accounts payable against $7.0B of inventory on the shelves. That's 114% of inventory funded by suppliers. Working capital is negative $1.2B. On average, they sell a part roughly 18 days before they have to pay for it. Most retailers tie up cash to grow. AutoZone actually generates cash by growing.

Here are a few additional things that stood out to me:

• They have bought back a ton of stock over the last couple of decades. My research tells me that it's approximately $38 billion worth. Dividends get a lot of attention, but they are tax inefficient given that there are federal taxes payable on dividends. Buying back stock essentially saves shareholders from that dividend tax while increasing their pro rata share of the company's free cash flow.

• They have surprisingly high gross margins for a retailer of what I would consider commodity products. Their gross margins stand at 52%.

• Demand for auto parts has historically been quite durable, as cars break regardless of whether the economy is strong or weak.

But it's not all clean and perfect:

• The stock is down 19.9% over the past year, a rougher ride than O'Reilly (down 7.1%) or Genuine Parts (down 3.9%).

• There's a lot of uncertainty about how the growing adoption of fully self-driving cars is going to impact traditional auto businesses like this. To me, it's inevitable that it's a growing headwind.

• Operating margin has slipped from 20.5% in FY2024 to 18.0% on a TTM basis. About half of that is attributed to tariff-related COGS increases, and the other half is due to overhead associated with their expansion efforts.

AutoZone has built an impressive business with relatively high gross margins and inventory that's financed by their suppliers. If you end up in a situation where you have a business with net negative working capital, it's almost foolish not to grow.

Revenue and profitability get a lot of attention, but free cash flow is what really matters. When you're evaluating opportunities for your business or career, be diligent when it comes to cash flow modeling, not just income statement modeling.

With that, I'll see you on Saturday!

Nick

TL;DR

• AutoZone is the largest US auto parts retailer by market cap, selling replacement parts to DIY customers and repair shops through 7,000+ stores.

• Nearly all revenue comes from the stores themselves, with a small slice from ALLDATA repair software and e-commerce; the US is about 88% of sales.

• The balance sheet is the star: negative $1.1B of working capital, vendors financing 114% of inventory, and a cash conversion cycle of negative 18 days.

• Revenue reached $18.9B in FY2025 with 52.6% gross margins, though operating margin compressed to 19.1% as the company invests heavily in distribution and its commercial business.

• The stock has lagged lately (down 19.9% over the past year versus O'Reilly's 7.1% decline), but the 10-year return of +280% shows what relentless per-share compounding looks like.

• Operator lesson: structure your business so customers pay you before you pay suppliers, and growth becomes a source of cash instead of a use of it.

The 30,000-Foot View

AutoZone sells automotive replacement parts and accessories through a dense network of neighborhood stores. The core customer has always been the do-it-yourselfer with an out-of-warranty car, and the model is built around being close by, in stock, and staffed with people who will walk into the parking lot to test your battery or read your check engine light for free. Those free services aren't charity. They're the top of the funnel for parts sales.

The second engine is the commercial program, selling to professional repair shops with delivery and credit. This is where the growth push is: pros buy more often and in bigger baskets, but they demand speed, which is why AutoZone has been pouring capital into "mega-hub" stores that hold 80,000 to 110,000 SKUs and can feed surrounding stores same-day. That's what the elevated CapEx line is buying.

The economics work because parts demand is stunningly predictable at scale. AutoZone knows which parts fail on which vehicles in which zip codes, and it stocks accordingly. That predictability is also what lets them negotiate the supplier terms that produce the negative working capital position discussed below. Vendors effectively rent shelf space in the best parts distribution network in the country and get paid after the part sells.

Revenue mix (FY2025):

• Auto parts stores: ~98%

• ALLDATA software and other: ~2%

• Geography: US ~88%, Mexico and Brazil ~12%

Key Stats

• Market cap: $49.3B

• TTM revenue: ~$20.0B

• TTM gross margin: 51.8%

• 1Y total return: -19.9%

• Employees: ~130,000

• Industry: Specialty retail (automotive aftermarket)

Company History

• 1979: J.R. "Pitt" Hyde III opens the first store as Auto Shack in Forrest City, Arkansas, spun out of his family's Malone & Hyde grocery wholesale business.

• 1987: Renamed AutoZone.

• 1991: IPO on the New York Stock Exchange.

• 1996: Acquires ALLDATA, the repair diagnostic software business it still owns today.

• 1998: Acquires Chief Auto Parts, enters Mexico, and kicks off the share repurchase program that has run continuously ever since.

• 2012: Enters Brazil, its third country.

• 2010s: Builds out the hub and mega-hub distribution strategy to speed up parts availability and win commercial business.

• 2024: Phil Daniele becomes CEO, succeeding longtime chief Bill Rhodes.

• 2025: FY2025 revenue hits $18.9B; CapEx tops $1.3B as the mega-hub and distribution center buildout accelerates.

Show Me the Money

Standout financial features:

• The working capital engine runs backwards, on purpose. Working capital was negative $1.73B in FY2023, negative $1.41B in FY2024, and negative $1.18B in FY2025. Accounts payable of $8.0B exceeds the $7.0B of inventory it finances. Days payable outstanding is 318 days against 286 days of inventory, so the cash conversion cycle is negative 18 days. Read that again: AutoZone collects cash from customers about two and a half weeks before its suppliers get paid. At this scale, that's billions of dollars of permanent, interest-free financing from vendors.

• The buyback flywheel: FY2023 through FY2025 saw $8.4B of stock repurchased with zero dividends paid, shrinking diluted shares from 19.1M to 17.2M.

• Margins dipped as investment ramped: operating margin went from 20.5% in FY2024 to 19.1% in FY2025 (18.0% TTM) as CapEx climbed from $0.8B to $1.3B in two years and interest expense rose from $316M to $487M. They're spending to win the commercial market and paying more to carry the debt stack.

Financial Data

Working capital, for the theme of the day: ($1.73B) in FY2023, ($1.41B) in FY2024, ($1.18B) in FY2025, ($1.10B) TTM.

Stock Performance

1-year head-to-head:

The whole aftermarket group has pulled back over the past year, but AutoZone has taken the hardest hit of the three, giving back some of a long stretch of outperformance. The longer arc still tells the real story: a nearly 4x total return over ten years in a business selling brake pads, driven almost entirely by per-share compounding rather than multiple expansion.

The N.O.O.B. Nine — Competitive Powers

The Nerd Out on Business Nine is made up of Hamliton Helmer's famous "7 Powers" of competitive advantage (Scale Economies, Network Economies, Counter-Positioning, Switching Costs, Branding, Cornered Resource, and Process Power) combined with two of my own (Data Flywheel and Distribution Advantage).

Average Score: 3.0/5 - a scale and distribution moat, reinforced by brand, in a category where being closest with the part in stock wins the sale.

Memorable Marketing

AutoZone's marketing is service-led and store-led rather than campaign-led. The most effective marketing they do doesn't look like marketing at all: it looks like an employee in a red shirt testing your battery for free in the parking lot.

Notable campaigns and tactics:

• "Get in the Zone" jingle (1990s to present): Decades of consistency turned five notes into automatic brand recall. They've resisted every temptation to refresh it into oblivion.

• Free services as traffic drivers (ongoing): Free battery testing and charging, Fix Finder check engine light reads, and the Loan-A-Tool program pull anxious customers into the store at their moment of highest need, then convert the diagnosis into a parts sale.

• Duralast brand building (2000s to present): Private label treated like a national brand, with sports sponsorships and its own reputation for quality, capturing margin without feeling like a generic.

• AutoZone Liberty Bowl (2004 to present): Long-running college football sponsorship keeps the brand in front of its core demographic in its home region.

Tactical takeaways:

1. Give away the diagnosis, sell the cure. A free service at the customer's moment of stress is the cheapest customer acquisition you'll ever find.

2. Pick a brand asset and never change it. Recognition compounds like interest, and most companies interrupt the compounding.

3. Build your private label as a brand with its own story, not a cheaper knockoff on the bottom shelf.

4. Locate your marketing where the need happens. A store ten minutes from a broken-down car is a better ad than any billboard.

AI Uses & Opportunities

Current exposure:

• Demand forecasting and inventory placement are the quiet AI story here: deciding which of 100,000+ SKUs belong in which store, hub, or mega-hub is a machine learning problem AutoZone has been working for years.

• ALLDATA sits on a deep repository of repair procedures and diagnostic data used by professional shops, a natural foundation for AI-assisted diagnostics.

Future opportunities:

• Computer-vision part identification: snap a photo of the worn part, get the exact replacement in stock at the nearest store.

• Symptom-based lookup for DIYers, translating "it squeals when I brake" into a parts list and how-to content.

• AI-assisted commercial ordering that predicts what a shop will need based on the vehicles in its bays that morning.

• Routing and load optimization for commercial delivery, where minutes decide who wins the pro's order.

• An ALLDATA diagnostic copilot for technicians, turning the repair database into an interactive assistant.

Bumps in the Road

• The EV transition slowly shrinks the addressable parts market: fewer moving parts, less DIY maintenance. It's a decade-scale headwind, but a real one.

• $12.3B of total debt against negative equity leaves little cushion if operating profit slips; interest expense is already up 54% in two years.

• O'Reilly is a ferocious competitor in the commercial segment, where AutoZone is still the challenger and where the next leg of growth has to come from.

• Tariffs and import sourcing pressure gross margins in a business that leans heavily on overseas suppliers.

• Wage inflation hits a 130,000-employee retail workforce directly, and the free-services model depends on staffing stores with capable people.

Your Swipe File

• Get paid before you pay. AutoZone collects from customers roughly 18 days before paying suppliers. If your customers pay at delivery and your vendors extend terms, growth funds itself. Ask what it would take, in volume, predictability, and sell-through data, for your suppliers to extend your terms from 30 days to 60 or beyond.

• I can't emphasize the importance enough that supplier flexibility needs to be earned. If you see an opening for flexible payment terms, do everything in your power to earn them.

• Stock buybacks are superior to dividends, even if dividends win the popularity contest.

• Think of what free services you can offer your customers. The interactions that come from them are a powerful source of distribution and customer affinity.