The Four Pillars of Investing

William Bernstein's The Four Pillars of Investing is a masterclass in investment theory disguised as a readable narrative. Bernstein, a neurologist turned financial theorist, argues that successful investing requires understanding four pillars: the theory of investing (risk and return), the history of investing (bubbles and crashes repeat), the psychology of investing (your brain is your worst enemy), and the business of investing (the financial industry profits at your expense).

The book is more intellectually demanding than most on this list, but the payoff is a deeper understanding of why markets behave the way they do and how to build a portfolio that can withstand any environment. Bernstein's asset allocation recommendations are specific, evidence-based, and designed for the long-term investor who wants to understand the 'why' behind passive investing, not just the 'what.'