Systematic investing means a pre-defined rule makes the decisions, not a mood: entry, exit and weighting criteria are written down and applied mechanically, the same way every month. The opposite is discretionary investing — "I'll buy because it feels like it'll go up".
Why rules beat intuition
- Emotions cost more than commissions. Long-running investor-behaviour studies (e.g. the DALBAR series) show the average investor underperforms the very funds they hold — buying euphoria, selling panic.
- A rule can be examined. A mechanical strategy can be tested over decades of data, bad periods included. Intuition can't.
- A rule doesn't get tired — it doesn't doom-scroll at 3am or change its mind after one weak week.
Classic beginner mistakes
Overfitting: tuning parameters against the past until the backtest looks beautiful — and fails forward. Ignoring costs and dividends: "costless" results are fiction. Survivorship bias: testing on today's index members pretends the bankruptcies never existed. How we account for all three is in the methodology; the core risk concepts are covered in max drawdown and Sharpe ratio.
Where to start learning
By watching live, public track records of simple rules — trend following (Trend MA200), volatility-inverse weighting (Inverse-Vol), or the deliberately boring baseline (Safe Yield). All computed the same way, costs included, on total-return data — side by side on /compare.
Educational material — not investment advice or a recommendation.