Compounding Math: Why Small Steady Returns Beat Heroic Ones

[Fairman]

Compounding Math: Why Small Steady Returns Beat Heroic Ones

Compounding means earning returns on previous returns. The effect is powerful, but its arithmetic is often misunderstood in trading.

Take 1 percent per month. After twelve months, an account grows to about 112.7 percent of its start, a 12.7 percent gain. At 2 percent a month, it reaches 126.8 percent. At 5 percent per month, about 179.6 percent. At 10 percent per month, 313.8 percent, which is the kind of figure that gets advertised and almost never sustained.

Drawdowns break the pattern. A 50 percent loss needs a 100 percent gain to recover, as discussed earlier. High-return strategies tend to have deep drawdowns, and a single deep drawdown can erase years of compounding.

Time is the key ingredient. A modest return sustained over many years outperforms a spectacular one that ends in ruin. Ten years at 15 percent per year multiplies capital about four times.

Consistency also matters more than average return. Two strategies with the same average return can end with very different results if one has big swings, because volatility drags down compounded growth.

For small accounts, the temptation is to speed things up with oversized risk. The math shows that this raises the risk of ruin far more than it raises expected growth.

Add capital from your income, as it often matters more than returns when the account is small.

Practical step: compute the account value after five years at three realistic monthly return rates, and compare with your income-based savings.

[Fairman]

The volatility drag point is the one most people never hear. Up 50 percent then down 50 percent isn't break-even, it's down 25. Big swings quietly cost you.

[Fairman]

Adding from income really is the main driver early on, and it's worth running the numbers once to see it. Take a 500 dollar account. A very good 3 percent month is 15 dollars. If you can put in an extra 50 dollars a month from your salary, that deposit alone is more than three times what the trading added. Over a year the deposits will usually beat the returns by a wide margin on a small account. That's not a reason to stop trading, it's a reason to stop forcing size. Let the savings build the account while the trading builds the skill and the track record. The returns only start to matter once the base is big enough for a percentage to mean something.