Reading the Market

Reading the Market

Observations on price, structure, and behavior

About this tag

Position sizing is the one input a trader fully controls. Entries miss, news breaks, other participants do what they do - but the amount risked on each trade is set in advance, from entry to stop. The standard form is percentage-based: risk a fixed slice of the account per trade, usually between half a percent and two, so a long losing streak stays survivable. The formula leaves no room for discretion. Account value times risk percentage, divided by the distance from entry to stop, returns the size. Conviction does not enter the equation.

Where the formula breaks down is not in the arithmetic but in its inputs. Stop placement that reflects chart structure produces a different size than a stop placed to keep the number feeling comfortable. Volatility that doubles between when the stop was set and when the trade is live changes the real distance traveled to fill that stop. Illiquid assets gap through stops entirely. The formula is sound; the inputs it receives from real markets are not always the ones it assumed.

This tag collects observations on how sizing calculations meet actual conditions. Fixed-fractional risk and its assumptions about stop reliability. Volatility-scaled sizing and what it does to position count during high-variance periods. The math of ruin and why drawdown depth makes recovery non-linear. Kelly fractions and the practical argument for betting well below the theoretical optimum. Small positions that hide binary risk inside a conservative-looking allocation.

The framing is mechanical, not motivational. Size does not predict whether a trade works - it determines what a wrong trade costs and whether the account survives to compound. Notes here treat sizing as the variable that decides how long you stay in the game.