Five open positions at 1% risk each put 5% of the account at risk if every stop is reached. If all five sit in one sector and that sector falls, the stops can be reached on the same day. You hold five rows and carry the risk of one position five times the size.
What diversification means for a trader
Holding more than one position spreads a fixed amount of risk across several outcomes instead of one. That is the whole mechanism, and it is arithmetic rather than a market view.
Take five positions that together risk 5% of the account, and assume for a moment their outcomes are unrelated to each other. The combined result then varies less than one position risking the whole 5% would. For equally sized, unrelated positions, the spread of the combined result is 1 divided by the square root of the count, times the spread of that single large position. Five positions give about 0.45 times it, ten about 0.32 times.
That reduction depends entirely on the assumption. Unrelated is a strong condition, and the rest of this article is about how often it fails.
What concentration does instead
One position holding most of the account exposes the whole balance to one overnight gap, one earnings release and one piece of company news. The stop does not protect against a gap, because a gap opens past it and fills below it.
Types of diversification a trader can use
Position count
Spread capital across several trades rather than one. This article uses a cap of 20% of the account in any single position and a working range of five to ten open positions. Both are this article's parameters, not established figures. Choose your own and write them down.
A hypothetical $50,000 account under those parameters:
| Position | Value | Share of account |
|---|---|---|
| 1 | $8,000 | 16% |
| 2 | $7,500 | 15% |
| 3 | $7,000 | 14% |
| 4 | $6,500 | 13% |
| 5 | $6,000 | 12% |
| Cash | $15,000 | 30% |
Position value is not the same as risk. A $6,000 position with a stop 10% below the entry risks $600. An $8,000 position with a stop 3% below the entry risks $240. The larger position carries the smaller risk, which is why the risk column matters more than the value column.
Sector
Holding positions across different sectors reduces how much of the portfolio responds to one sector-wide move. An example spread, again with figures you replace:
| Sector | Share |
|---|---|
| Technology | 25% |
| Healthcare | 20% |
| Financials | 20% |
| Consumer | 15% |
| Energy | 10% |
| Cash | 10% |
Strategy
Trend following, mean reversion, breakout entries and pullback entries respond to different conditions by construction. A trend method needs price to keep going; a mean reversion method needs it to come back. Running both means one of them has conditions to work in more of the time, and it also means one of them is usually the one losing.
Holding period
Mixing hold lengths spreads exposure across different windows. An example mix: 60% of positions held for the standard swing window, 30% for two or three days, 10% for several weeks. A shorter hold carries fewer overnight gaps, which is true by construction, and gives up whatever the position would have done in the days you were not in it.
Correlation, and why the count on screen misleads
What correlation measures
Correlation is a number between -1 and +1 describing how two series move relative to each other.
- +1: they move together, in the same direction, every time.
- 0: knowing one tells you nothing about the other.
- -1: they move together, in opposite directions, every time.
Those are definitions, not claims about any particular pair of stocks. The correlation between two holdings is something you measure on their price history, not something you assume from their sector labels.
Why it matters to the risk arithmetic
The variance reduction at the top of this article assumed unrelated positions. As correlation rises towards +1, that reduction shrinks. At +1 the positions are one bet: the combined spread equals the single-position spread multiplied by the count, and holding three of them is holding three times the size of one.
Swingfolio's own heat calculator states the same caveat on the page: "These guidelines assume uncorrelated positions. If your positions are in the same sector or react similarly to market moves, treat your actual heat as higher."
That caveat is the product's own wording, on the tool's page.
Reading it on your own holdings
Three highly correlated holdings in one sector carry the risk of one position of three times the size. Three holdings in unrelated sectors are closer to three independent positions. Neither statement can be settled by counting rows. It is settled by checking whether the holdings have moved together in the price history you already have, and by asking what single event would move all of them at once.
Setting your own diversification limits
Maximum position size. Decide the largest share of the account any one position may hold, and the largest risk it may carry. This article uses 20% of value and 1% of risk. Both are examples.
Sector limit. Decide the largest share of the account any one sector may hold. This article uses 30%.
A limit on the correlated group. Treat holdings that move together as one line. This article caps a correlated group at five positions and at 5% of the account in combined risk, which is five positions at 1% each. If you hold three positions in one sector at 1% risk each, that group already carries 3%.
A cash level. Cash held back is capital that is not exposed and is available for the next setup. This article uses 20% to 30% during ordinary conditions. There is no figure here for how much cash a particular market calls for, because that would be a forecast rather than a rule.
Every number in that list is a parameter you set once, before the market gives you a reason to change it.
Where diversification stops helping
Too many positions
Each additional position adds a set of prices to follow, a stop to maintain and a round of brokerage. Past the number you can review, positions stop being managed and start being held. The limit is the number you can check in the time you have, and that number is yours to measure.
Positions taken to fill a slot
A target position count is not a reason to enter a trade. A setup that fails your criteria fails them whether or not you have room, and cash is a position you can hold indefinitely at no cost beyond opportunity.
Equal dollar sizing mistaken for equal risk
Five positions of $6,000 each are equal in value and unequal in risk, because the stop distances differ. Equal risk means the stop distance times the units is the same figure in every position, which produces different dollar values. Size from the risk, and let the value fall where the stop puts it.
Managing a diversified portfolio
Each session
- Check every open position against its stop and its target.
- Note which positions have moved together today.
- Add the risk on all open positions and compare it with your limit.
Each week
- Recalculate the share of the account in each sector.
- Check whether any position has grown past your value cap.
- Check the cash level against the range you set.
When a limit is breached
Rebalancing is triggered by the limits you wrote down, not by how a position feels. A sector above your cap, a position above your value cap, or a cash level below your floor each name a specific action. Writing them down in advance means the action is decided before the condition arrives.
Four diversification mistakes
Counting rows instead of risk. Twenty positions with correlated stops carry the risk of far fewer independent ones. Add the risk, then check what moves it together.
Ignoring the sector label on the way in. The question before an entry is not only whether the setup is good but whether the account already holds that exposure.
Holding no cash. A fully invested account has no capacity for the next setup and no buffer for a run of stops.
Treating equal dollars as equal risk. Covered above. It is the version of the error a spreadsheet that tracks position value but not stop distance cannot show you.
Seeing your concentration in Swingfolio
Allocation Breakdown, on a portfolio's detail page, is the view for exposure. It draws a donut with a legend beside it and three tabs: "By Sector", "By Ticker" and "By Exchange". Cash appears as its own slice, so the chart shows what is invested and what is not in the same picture. It reads the positions currently open in that portfolio.
Portfolio Heat is the risk figure, shown as a tile on the dashboard. It is the sum of entry minus stop, times the units still open, across every position and converted to your portfolio currency, divided by portfolio value. That is the percentage of the account lost if every stop is reached at once. The tile prints the percentage with a label under it: "Risk Under Control" below 6%, "Elevated Risk" from 6%, and "Excessive Risk!" from 10%.
One distinction worth holding onto. The Sector Performance card in the analytics page's "Trading Patterns" section, whose own header reads "Sector P&L", reports what your closed trades in each sector returned. It is a history of results, not a picture of what you hold now. Allocation Breakdown answers the exposure question; Sector P&L answers a different one.
Before you have positions to look at, the portfolio heat calculator takes an account size and a list of positions with symbol, shares, entry price and stop loss. It returns the position count, the total position value, the total risk amount and the resulting heat percentage, with the same three zones marked at 6% and 10%.
Add up the risk on every position you hold right now, then check what a single sector-wide move would do to that total. Start the 30-day trial.