I tracked how Buffett's concept of "moat" evolved across 60 years of shareholder letters. He didn't even use the word until 1986
I built a knowledge graph from every Buffett shareholder letter (1965-2024) and every annual meeting transcript, tracking how his key concepts emerged and evolved over time. Here's what I found about "moat", one of his most famous idea:
The concept existed for 20+ years before Buffett named it.
From 1965-1985, Buffett was already buying "economic castles" i.e. businesses with durable competitive advantages, but he never used the word "moat." He described the “effect” without naming the “framework”.
His first recorded use: "In business, I look for economic castles protected by unbreachable moats." - 1986 Letter
Then it went through 4 distinct phases:
1970-1985 - Practiced, Unnamed: Buffett buys businesses with competitive advantages (See's Candies, Nebraska Furniture Mart) but describes them in terms of "franchise value" and "earnings power," not "moats"
1986-1999 - Structural Classification: The moat framework gets formalized. He identifies specific moat types: brand franchise (Coca-Cola), low-cost production (GEICO), local monopoly (dominant newspapers). Key insight from 1996: "The key to investing is determining the competitive advantage of any given company and, above all, the durability of that advantage."
2000-2015 - The Marauders: After watching digital disruption destroy newspaper moats, Buffett starts talking about moats as dynamic - "every day, the moat is either getting wider or narrower. There is no standing still." He shifts from measuring profits to measuring moat trajectory.
2016-Present - Platform Moats: The Apple investment (2016) marks a philosophical evolution. "The moat that surrounds Apple is the ecosystem. People become very attached to the products and the way they work together." (2021 Meeting). He recognizes that network effects and technological lock-in can create moats even more powerful than traditional consumer brands.
The interesting pattern: Buffett's most famous concepts weren't invented as theories. They emerged from practice - decades of doing something before articulating *why* it worked. The "Circle of Competence" followed the same pattern: practiced from 1957, not named until 1996.
I mapped 393 concepts like this across the full knowledge graph. You can explore the interactive version here: https://buffett.datax.app/explore
Hope this helpful. Happy to answer questions about other concepts or patterns I found.