You can't reliably predict which single stock will win — so the smartest defence is to not depend on any one of them. Spreading risk is the rare move that lowers danger without demanding higher returns in exchange.
Diversification: don't bet the farm on one name
If one company is 100% of your portfolio, its bad news is your bad news. Hold 25 companies across different industries and a single failure barely dents you. The magic is correlation: when holdings don't move in lockstep, their ups and downs partly cancel out, so the portfolio is steadier than its parts.
Why it's called the only free lunch: combining assets that don't move together reduces your overall risk without reducing your expected return. Almost nothing else in investing gives you something for nothing.
Asset allocation: the bigger lever
Your split between broad asset classes drives most of your risk — more than which individual stocks you pick.
| Asset class | Role | Typical behaviour |
|---|---|---|
| Stocks | Growth engine | Higher long-run return, bigger swings |
| Bonds | Stabiliser | Lower return, steadier; often holds up when stocks fall |
| Cash | Safety / dry powder | No growth, no drawdown |
A classic 60/40 (60% stocks, 40% bonds) has historically been markedly less bumpy than 100% stocks, giving up some upside for a smoother ride.
How to think about your mix
- Time horizon: the longer until you need the money, the more stocks you can stomach.
- Risk tolerance: the right mix is the one you'll actually stick with in a crash.
- Rebalancing: periodically trimming what's grown and topping up what's lagged keeps your risk where you intended — and quietly enforces 'sell high, buy low'.
Takeaway: diversify within stocks so no single company can wreck you, and set an asset allocation you can live through. Together they control risk far more than any individual pick.
