Position Sizing and the Divide-by-20 Rule
Position sizing is the only control in trading that works regardless of whether you are right. Everything else depends on the market cooperating in some way — sizing does not.
Every StaxInvesting article covering position sizing options · 3 posts.
3 articles
Position sizing is the only control in trading that works regardless of whether you are right. Everything else depends on the market cooperating in some way — sizing does not.
Let's be honest up front: position sizing does not make a strategy profitable, and most retail options traders lose money. Sizing is damage control, not an edge. Within that reality, there's a real argument for fixed-dollar sizing over percent-of-account — percentage sizing scales your losses up alongside your wins, so a single bad drawdown at a high account value can erase a long run of gains. Here's the honest math, a worked example of the divide-by-20 rule, and where each approach actually fits.
Roughly 85% of day traders fail, not because they lack intelligence, but because they lack a system and a support network. Trading is 10% strategy and 90% psychology — when you trade alone, your emotions are amplified. The markets are a battlefield. You wouldn't go into combat without a squad, a plan, and the best tech available.