So I've been thinking about position sizing lately, and honestly the 3-5-7 framework is probably the most underrated tool most traders never actually follow. Here's the thing: it's stupidly simple, which is exactly why it works.

The core idea is this. You risk no more than 3 percent of your account on any single trade. If you've got correlated positions - like a few tech stocks or commodities tied to the same price driver - you cap that entire group at 5 percent. And across everything you have open at once, you never exceed 7 percent total exposure. That's it. Three numbers that keep you from blowing up.

Let me walk through the math because it's genuinely straightforward. Say you've got fifty grand. Three percent is fifteen hundred dollars. You find a setup - doesn't matter if it's an inverse head and shoulders pattern on the daily or a fundamental play - your entry is twenty bucks, your stop is eighteen. That's two dollars of risk per share. Divide fifteen hundred by two and you get seven hundred fifty shares max. That's your position size.

Now here's where most people mess up. They think position sizing is the whole game. It's not. You need to actually place your stop where the trade thesis breaks, not where the math looks pretty. If an inverse head and shoulders pattern invalidates below a certain level, that's where your stop goes. Then you size to the cap, not the other way around.

The correlation part is where things get interesting. Two biotech stocks reacting to the same FDA headline? Same risk. Three small caps exposed to the same commodity? One risk event. You've got to think about what could actually hurt all of them at once. If a single headline could tank your whole group, they're correlated. Use that five percent bucket to keep any single theme from destroying you.

For the total account exposure at seven percent, you're just adding up all your potential losses if every single position hits its stop. That's your hard floor. You can calculate this in a spreadsheet in about two minutes.

I've watched traders get absolutely wrecked because they ignored this. One guy I know concentrated everything in three tech names, caught a bad headline, and watched twenty percent evaporate in one day. After that, he actually implemented something like 3-5-7 - much tighter per-trade caps, explicit limits on sector clustering - and the difference was night and day. Not in his win rate, but in his ability to survive and keep playing.

Options complicate things a bit. For a long call or put, treat the premium you paid as your dollar risk and keep that under three percent. For spreads, use max loss. Short options are different - you probably need much smaller caps or collateral, and you absolutely need to stress-test scenarios.

Here's a practical move: build a simple spreadsheet. Each row is a trade. Columns for entry, stop, dollar risk, percentage of account. Set it up to flag anything hitting your three percent single-trade cap. That takes thirty minutes and saves your account.

The numbers themselves aren't sacred. In crazy volatile markets, maybe you drop to one or two percent per trade. If you've got a documented statistical edge and consistent results, you might go higher. But most people starting out should treat these as a baseline, not a ceiling.

Testing matters. Paper trade fifty to a hundred positions using these caps. See how your actual win rate and payoff interact with the drawdowns. Compare running the same trades at one percent per trade versus your chosen cap. Look at recovery times. That's your real data.

One thing people don't talk about enough: the psychological side. When you know your maximum loss on any given day is locked in, you sleep better. You're not panicking about headlines. You're thinking clearly. That matters more than people realize.

The biggest mistake? Thinking this is boring or too conservative. Markets aren't kind in predictable ways. A plan that keeps you solvent through bad stretches is what lets you actually compound gains when opportunities show up. Slow steady growth through multiple market cycles beats blowing up once, every single time.

If you're going to use this, write it down. Your per-trade cap. How you define correlated groups. Your total exposure limit. How you handle options. Test it. Adjust it based on actual results, not emotions. Then stick with it.