Munger Mode rating: 4 out of 5 — Buy. Our own rating from the research report below, on business quality first: moat durability and management, with price separating the top three.
We have spent our lives looking for businesses that sell something people must buy, from a position competitors cannot assault, run by people who think like owners. Martin Marietta sells crushed rock. You cannot make a road, a runway, a data center pad, or a house foundation without it, you cannot ship it more than about fifty miles without doubling its cost, and you cannot get a permit to open a new quarry near an American city in under a decade — if you can get one at all. That is a genuine moat, dug into the earth, and it has produced something almost no industrial commodity business ever achieves: price increases every single year for roughly three decades, including through the housing collapse of 2008–2010 when volumes were cut nearly in half.
Recent filings analysed: 8-K (2026-09-16), 8-K (2026-08-24), 8-K (2026-08-18), 8-K (2026-08-14).
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