15 Essential Finance Concepts

This paper brings together the fifteen ideas that do most to separate disciplined long-term investors from everyone else, from compounding and diversification to fat tails, sequence of returns risk and position sizing.

Each concept is explained in plain English, with the key numbers, the research behind it and what it means in practice for anyone building wealth over decades.

Key findings

• Compounding is the most underestimated force in investing, and the Rule of 72 (years to double your money) is confirmed by Federal Reserve research (St. Louis Fed, 2018).
• Markets crash far more often, and far harder, than standard models assume: empirical return distributions have fat tails (Mandelbrot, 1963; Fama, 1965).
• Survivorship bias distorts what investors believe: Dimensional Fund Advisors (2020) found it overstates median fund alpha by around 50%.
• When returns happen matters as much as what those returns are, which is why sequence of returns risk is central to retirement planning.
• Tax drag, trading costs and liquidity risk are among the most consistently overlooked costs, quietly eroding returns over decades.

What the paper covers

1. Compounding
2. Diversification and correlation
3. Fat tails and black swans
4. Behavioural biases
5. Sequence of returns risk
6. Survivorship bias
7. Inflation and real returns
8. Mean reversion
9. Kelly criterion and position sizing
10. Leverage and margin risk
11. Tax drag and tax efficiency
12. Liquidity risk
13. Trading costs and execution
14. Risk-adjusted returns
15. Base rate neglect and reference class forecasting