Position Sizing: How Much to Risk
The strategy you pick matters far less than how much you bet on it. Get sizing right and a string of losers is a scratch. Get it wrong and one bad trade ends the game. This is the most important math in the course.
- The 1 to 2 percent rule and why it keeps you alive
- Why you size by max loss, never by the premium you collect
- What buying power reduction is and why to keep a reserve
- How spreading across positions protects the whole account
Two traders use the exact same strategy for a year. One ends up richer. One blows up. The difference is almost never the strategy. It is how much each one bet on every trade.
This is the lesson that decides whether you last. You can pick great trades all day, but if you bet too much on any single one, it only takes one bad break to undo everything. Position sizing is the quiet math that keeps a string of losses survivable and keeps you in the game long enough for your edge to show up.
The 1 to 2 Percent Rule
Here is the whole idea in one line: never risk more than 1 to 2 percent of your account on a single trade.
On a $50,000 account, 2 percent is $1,000. That is the most you let any one trade lose. Risk that little, and a brutal run of five losers in a row costs you 10 percent, painful but completely recoverable. Risk 20 percent per trade instead, and that same run wipes you out. Same trades, opposite endings, decided entirely by size.
The whole point is to make any one trade boring. When a single loss cannot hurt you, you stop trading scared, you stop revenge-trading, and you let probability do its slow, reliable work.
Size by Max Loss, Not Premium
Now the trap that catches almost everyone selling premium: sizing by the credit instead of the risk.
Say you want to put $1,000 to work. The wrong way is to keep selling until you have collected $1,000 in premium. That sounds reasonable and is quietly a disaster, because a small credit can sit on top of a large loss. Collect $1,000 of strangle premium and your real risk might be many times that.
The right way is to size by max loss, the actual worst case of the trade. An iron condor with $5 wings and a $1.60 credit risks $340. To stay near your $1,000 budget, you trade two of them, for $680 of true risk. Now your downside is known and capped, no matter what the stock does.
For undefined-risk trades like a naked strangle, where there is no fixed max loss, you size by a stress estimate instead: how much would this lose in a sharp move? Then keep each one small, a few percent of buying power, and run several rather than one big one.
Keep a Reserve: Buying Power Reduction
Every trade ties up some of your funds while it is open. That amount is your buying power reduction. A common mistake is to deploy all of it, leaving nothing in reserve.
Keeping a healthy cushion, often around half your buying power unused, is not timidity. It is what lets you manage. If a trade goes against you, you have room to adjust it, add a hedge, or roll it, instead of being forced to close at the worst possible moment because the account is maxed out. A full account has no options. A reserve gives you choices.
When I was advising clients, the ones who survived rough markets were never the ones swinging the hardest. They were the ones who always kept dry powder, sized every trade small, and were genuinely bored by any single position. Boring is what survival looks like.
Spread the Risk Around
Even a perfectly sized trade can surprise you, so the last layer is to not put all your risk in one place. Run several smaller positions across different, unrelated stocks rather than one large bet.
The reason is simple: one stock can gap on news overnight, and if that single trade is your whole account, the news is a catastrophe. Spread across a handful of uncorrelated positions, the same surprise is just one bad trade among several. You want your account to be a fleet of small boats, not one big ship with one big hole waiting to happen.
- Risk 1 to 2 percent of the account per trade
- Size by the max loss, not the premium
- Keep a buying power reserve for managing trades
- Spread risk across several uncorrelated positions
- Betting big on one trade to get rich fast
- Sizing by the credit you collected
- Deploying every dollar of buying power
- Putting your whole account in one stock
- Risk no more than 1 to 2 percent of your account on a single trade.
- On a $50,000 account, that is $500 to $1,000 of max loss per position.
- Size by max loss, never by premium, which hides the real risk.
- Keep a buying power reserve so you can always manage a losing trade.
- Spread risk across several uncorrelated positions so no one event can hurt you.
Pop Quiz
Three quick questions to lock it in. Pick an answer and the explanation shows up right away.
On a $50,000 account using a 2 percent rule, what is the most you risk on one trade?
2 percent of $50,000 is $1,000. Keep each trade's max loss at or below that, and even a long losing streak stays recoverable.
Why should you size a trade by its max loss instead of the premium collected?
The premium is what you hope to make; the max loss is what you can actually lose. Sizing by the credit quietly builds huge positions, because the real risk is hidden underneath a small credit.
Why keep a chunk of your buying power in reserve?
A maxed-out account has no choices. A reserve lets you roll, hedge, or adjust a trade that goes against you, instead of being forced to close at the worst moment.
Bottom Line
Position sizing is the closest thing to a survival guarantee in trading. Risk a small, fixed slice of your account on each trade, measure that risk by the real max loss, keep a reserve so you can always manage, and spread your bets so no single event can hurt you. Do this and no losing streak can take you out. Ignore it and the best strategy in the world cannot save you. Size first, then trade.
Next up: Portfolio Greeks. Once you have several positions sized right, you stop watching them one by one and start reading them as a single book. Net delta, theta, and vega tell you what your whole account is really betting on.