Is owning five stocks too few?

With five equal positions, each is a fifth of the portfolio, so one company going to zero takes 20% of your money. Whether that is too few depends on whether you could accept that loss. A handful of stocks held alongside index funds is a different case, because the funds keep the single-company risk to a smaller share of the whole.

Does an S&P 500 index fund count as diversified?

It holds around 500 large US companies, so no single failure can do much damage. It is weighted by market value, though, so the largest companies take a big share of the fund, and it holds no small companies, no bonds and no foreign stocks. Diversified within large US stocks is the fair description.

How Many Stocks Should You Own? Concentration Against Diversification

Q: How Many Stocks Should You Own? Concentration Against Diversification

No single number fits everyone. Own enough stocks, spread across enough industries, that the failure of any one company would cost you an amount you can live with. With ten equal positions a 50% drop in one costs the portfolio 5%; with twenty-five it costs 2%.

The order ticket reads: buy 200 shares at $50. That is $10,000. In a $100,000 account it is one-tenth of everything you own. Before you send it, work out what happens to the account if this company halves, and then what happens if it disappears altogether, because the chart you are looking at on the day you buy shows neither possibility.

The answer sets your count.

What does one failure cost?

Take equal-weight portfolios of different sizes and knock one holding down by half.

A total loss doubles the damage: 10% with ten positions, 4% with twenty-five. That is the trade. Fewer positions let one good pick lift the whole portfolio. They also let one bad pick sink it.

Decide the worst single-company loss you would accept. Work back from it to the position size, then to the count. If losing 5% of the portfolio to one company is your limit even in the worst case, no position should be above 5%, which means at least twenty holdings. The position size calculator does the same arithmetic for trades with a stop.

What about unequal weights?

Most portfolios are not equal-weighted, and the count can hide a concentration. Twenty stocks with one of them at 20% of the account behave, for single-company risk, like a five-stock portfolio.

That one holding can do twice the damage of any position in the ten-stock example above. Size by the loss, then count.

Can you own too many?

Yes. Past a certain point you cannot follow each company closely, and the individual picks stop reflecting any research, while a long enough list of large companies also starts to look like the index, which you could have bought in one fund for less work and fewer trading costs.

Does the number of stocks matter more than which ones?

Often it matters less.

Twenty stocks in one industry are closer to one bet than twenty, because the same interest rate move, commodity price, regulation or slowdown in demand hits all of them at once, and on a bad day for the sector they tend to fall together regardless of how carefully you picked each company. Spreading across industries protects you from that. Count sectors as well as tickers.

Company size and geography add more layers. Large US companies can still fall as a block. A few holdings in different corners, or a fund that covers them, reduce that.

Where do funds fit in?

A broad index fund gives you hundreds or thousands of companies in one purchase, with no research on each and no need to rebalance individual positions. For many investors that is the whole portfolio.

A common structure puts most of the money in a core of index funds and holds a few individual stocks alongside, sized so that none can do serious damage. The core carries the diversification, and the individual picks carry your own views. Income investors face a similar choice, weighed in dividend ETFs vs dividend stocks.

Index funds have concentration of their own. A fund weighted by market value puts the most money in the largest companies, and when a handful of giants dominate the market, they dominate the fund too. The Mag 7 investing case study follows how a few companies can come to account for a large slice of a broad index, and what that means for someone who thought one fund made them fully diversified.

So how many is right for you?

There is no study-backed number to copy. The count depends on these things about you:

The largest loss from one company you could accept without abandoning your plan.
How many companies you can actually follow, reading each one’s results every quarter.
How much of your money sits in funds already, and what those funds hold.
Whether your picks cluster in the one industry you know best.

Someone with most of their savings in index funds and a few positions on top can hold five or six stocks comfortably, because each is a small share of the whole. An all-stock portfolio needs more names, across more sectors, for the same protection.

For more on building an investment portfolio, see the investing topic page, and the page on free data for traders collects the official sources for company filings and fund documents. Recount after big moves, since a rally in one name changes the answer.