Position Sizing When Your Stop Distance Changes Every Trade
Fixed lot size is the silent account killer in intraday trading. A ten-tick stop and a forty-tick stop on the same contract size mean you are risking four times as much on one trade as the other — often without realising it until a string of wide-stop losses arrives.
Start with a session risk cap, not a per-trade percentage
Drill participants set a monetary cap for the entire morning — for example, 500,000 VND across all trades — before the open. Individual trade risk is a fraction of that cap, typically one-third, so one bad streak does not exhaust the session on trade one.
This differs from the common "1% of account per trade" rule because intraday traders often take multiple correlated trades on the same index. Session caps force you to think about cumulative exposure.
The sizing formula we use on paper
Position size equals session trade risk divided by stop distance in currency terms. If your trade risk is 150,000 VND and your stop is 3 index points valued at 50,000 VND per point, size equals one contract. If the next setup requires a 6-point stop, size drops to half a contract or you skip if fractional sizing is unavailable.
Students write this calculation in the journal before entry. No calculation written means no trade — the same rule as unstated stops.
When tight stops tempt oversizing
Tight stops produce large calculated sizes. We cap calculated size at a pre-set maximum regardless of math — usually the size you would use on an average stop day. This prevents the "perfect tight stop" illusion where you stack size because the chart looks clean, then get stopped by normal noise.
Review sizing errors in chart review
Private chart review clients often discover that their best-looking setups had the worst sizing because tight stops inflated quantity. Aligning size with stop distance usually matters more than finding one additional valid entry per week.
Practice sizing under time pressure in the Intraday Drill Program, or bring your journal to a Private Chart Review for a full audit.