What Are Base Rates?

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In this episode of our new show, 100 Year Thinkers, Robert Hagstrom and Chris Mayer explore how investors should think about base rates, extreme outcomes, and the realities of long-term wealth creation in markets. Applying the work of Michael Mauboussin, the conversation challenges conventional ideas like mean reversion and highlights why a small number of companies drive most stock market returns—and what that means for portfolio construction.

This episode brings together Robert Hagstrom and Chris Mayer to explore how investors should think about base rates, extreme outcomes, and the realities of long-term wealth creation in markets. The conversation challenges conventional ideas like mean reversion and highlights why a small number of companies drive most stock market returns—and what that means for portfolio construction.

Topics covered
• Why markets are driven by extreme outcomes and power laws, not averages
• The Best & Bessembinder research showing a handful of stocks create most wealth
• Base rates vs outliers and when to trust historical probabilities
• Why the 100 bagger framework focuses on studying winners, not predicting them
• Portfolio construction as a way to capture asymmetric upside
• Buffett’s approach to consistency, durability, and long-term operating history
• Inside view vs outside view and how narratives distort investing decisions
• Why AI may be breaking traditional base rate assumptions in software and tech
• The limits of mean reversion and why it can lead investors astray
• Return on invested capital and how competition erodes excess returns over time
• Identifying durable moats and why most advantages eventually get attacked
• Winner-take-all dynamics and how they shape long-term investing outcomes
• The twin engines of returns: earnings growth and multiple expansion
• Return on incremental capital as a key driver of long-term compounding
• Intangible assets and why accounting understates true business value
• Amazon as a case study in misunderstood profitability and reinvestment
• AI CapEx cycle and why current spending may not be sustainable long term
• Why great businesses matter more than great management in long-term investing

Timestamps
00:00 Why extreme outcomes drive stock market returns
01:00 Base rates vs studying 100 baggers
03:00 Power laws and why markets are a game of outliers
05:00 Just 46 companies created half of all market wealth
07:00 Buffett on consistency and long-term operating history
10:00 How to think about base rates in AI, energy, and macro cycles
12:00 Does AI invalidate historical base rates?
15:00 Inside view vs outside view in investment decision making
19:00 Buffett’s “certainty at a discount” framework
23:00 How often investors should evaluate businesses vs prices
29:00 Mean reversion myths and where it breaks down
33:00 Return on invested capital and competitive pressure
36:00 Moats, winner-take-all markets, and long-term dominance
41:00 Twin engines of compounding: growth plus multiple expansion
43:00 Return on incremental capital and forecasting future returns
47:00 Intangibles and why accounting distorts real business value
50:00 Amazon, CapEx cycles, and hidden profitability
53:00 AI infrastructure buildout and the future of returns