How many trades should you have open at once?

Fewer than you think, and the number matters less than what the positions have in common. Risking one percent on each of five trades does not mean you are risking five percent, it means you are risking somewhere between one and five percent depending on how similar those five trades are. If they all rise and fall together, you do not have five positions. You have one position in five costumes.

The gap between per-trade risk and total risk

Most people set a per-trade risk rule and stop there. One percent per trade, done. The rule is sound and it is incomplete, because it says nothing about how many of those trades can be open at the same time.

Open six positions at one percent each and you have six percent of the account exposed. If they are unrelated, a bad day takes out one or two of them and you lose one or two percent. If they are all essentially the same bet, a bad day takes out all six at once and you lose six percent in an afternoon.

Six percent is not catastrophic. But it is six times what you told yourself you were risking, and the surprise is the dangerous part. People size for the outcome they imagined, not the one the correlations allow.

Correlation, without the statistics

You do not need a correlation matrix. You need to ask one question about every new position: what would have to happen for this trade and my existing trades to lose together?

If the answer is “one specific company disappoints”, the trades are independent. If the answer is “the market has a bad week”, “oil falls”, “the dollar strengthens”, or “rates move”, they are not.

The usual hidden clusters:

• Same sector. Four bank stocks are one bet on banks.
• Same theme. A basket of unprofitable growth names all move on rate expectations, whatever their sectors say.
• Same currency exposure. Long several pairs against the dollar is one bet on the dollar, not several bets on separate economies.
• Same direction in one index. Six long positions in large caps during a broad selloff is one long position in the index.
• Same catalyst. Two positions reporting earnings in the same week are exposed to the same event risk.

The most expensive version is the one that feels most diversified: a dozen names across several sectors, all long, in a market that turns. Everything correlates to one in a crisis. That is the piece worth remembering, because it means your worst day is always more concentrated than your spreadsheet suggests.

Cap total risk, not just per-trade risk

The practical fix is a second rule sitting above the first. Mine has three layers:

1. Per trade: one percent of the account, as described in position sizing for small accounts.
2. Per cluster: no more than two percent across positions that would lose together. Two correlated trades at one percent, or four at half a percent, but not five at one percent.
3. Total open risk: a hard ceiling on everything at once, so that a genuinely bad day is survivable rather than memorable.

The numbers themselves are less important than having the second and third layers exist at all. Almost nobody does, and it is the reason otherwise careful traders occasionally take a loss that does not match anything in their plan.

How many positions can you actually manage?

There is a second constraint, and for a part-time trader it usually binds before the risk one does.

Every open position is something you have to monitor, evaluate, and eventually exit. If you have ninety minutes a week for trading, as I do in my weekly routine, you cannot meaningfully manage twelve positions. You will manage three of them and let the other nine drift, which means nine trades running without supervision, decided by whichever alert happens to fire.

Being honest about capacity is not a limitation to work around. It is a real input. Three well-chosen positions you actually understand beat ten you are vaguely aware of, and the difference shows up entirely in the exits.

Why do more positions rarely help a small account?

There is a persistent belief that spreading across many positions reduces risk. Within limits it does, but the limits arrive faster than people expect, and on a small account the costs arrive first.

Each position carries its own spread and commission. Splitting one percent of risk across five tiny positions multiplies the fixed costs while the potential gain per position shrinks. You end up paying five sets of costs to achieve roughly the diversification of two, and eating the difference. That interaction between costs and small positions is the same one I described in the risk to reward ratio.

There is also a subtler cost. Holding many positions makes it very hard to learn anything. When ten trades are running and the account moves, you cannot attribute the change to any decision. Fewer trades produce cleaner feedback, and feedback is the thing you are actually accumulating in the first years.

The number I use

Three to five open positions, with a hard cap on how many can be pointing the same way, and a preference for the low end when the market is moving fast or when my own recent decisions have been sloppy.

I would rather hold three positions I could each explain in a sentence than eight I would have to look up. When I catch myself unable to remember why a position is open, that is not a memory problem, it is a sign I took a trade that never had a thesis.

The check that takes thirty seconds

Before adding a position, look at what is already open and ask: if the market has a bad week, how many of these lose at the same time, and what does that add up to?

If the answer is uncomfortable, the fix is not to skip the new trade automatically. It is to size it smaller, or to close something you liked less. The new setup may well be better than one you already hold, and swapping is a perfectly legitimate move that people rarely make because closing a live trade feels like admitting something.

Log your total open risk next to each entry in your journal. Over a few months it will show you whether your bad days come from bad trades or from too many trades at once. Those are different problems with different fixes, and you cannot tell them apart from the equity curve alone. The logging habit is in why your trading journal beats your next strategy.

The full framework, including how exposure limits fit into a weekly routine, is in The 9-to-5 Trader.

Educational only, not financial advice. Trading carries a real risk of loss.