When Should You Sell a Stock? Five Rules That Beat 'Hold Forever'

1. Something changed in the business

This is the obvious one - and probably the most important.

You bought the company for a reason. Maybe margins were expanding. Maybe it was taking market share. Maybe the balance sheet was exceptionally strong. Maybe you believed a competitive advantage could persist for another decade.

Now ask: is that still true?

A stock falling 20% doesn't necessarily mean the thesis has broken. A company losing the thing that made you buy it might.

That's why writing down the original investment thesis is so useful. Six months later, you aren't asking yourself whether you still like the company. You're comparing reality with what you originally expected.

2. Your own framework has turned against it

This one is uncomfortable. We love analytical systems until they disagree with a stock we own.

Suppose you bought a company when it had strong quality, financial strength and valuation characteristics. A year later, those same measures have deteriorated badly.

You don't need an algorithm to automatically sell it. But you shouldn't ignore the change either.

A rating deterioration should trigger a question: if I didn't own this stock today, would I still choose to buy it?

That's often much more revealing than asking whether you should continue holding it.

3. The market keeps telling you you're wrong

Fundamental investors sometimes treat price as an annoyance. It isn't.

A sustained downtrend doesn't prove that your analysis is wrong. Markets can be wrong for a long time.

But when a stock falls below its major long-term trend measures and remains there, it's information.

You can disagree with the market. You just shouldn't pretend the disagreement doesn't exist.

Sometimes the correct conclusion will still be ‘hold.’ That's fine. The important part is that it becomes a conscious decision rather than inertia.

4. The stock became too successful

This is a much nicer problem.

You buy a position at 5%. It performs spectacularly. A few years later it's 15%, 18%, perhaps 20% of your portfolio.

Nothing has gone wrong with the company. The problem is the portfolio.

At some point, the question changes from do I still believe in this business, to how much of my financial future should depend on this one business.

Those are not the same question.

Trimming a great company because the position became too large isn't a negative judgement on the company. It's portfolio management.

5. Your money has a better place to go

This is the rule people underestimate.

Holding a stock has an opportunity cost. Every CHF 10,000 sitting in Company A is CHF 10,000 that cannot be invested in Company B.

So 'this stock isn't terrible' isn't necessarily enough. The harder question is whether it is still one of the best uses of this capital.

That doesn't mean jumping from one exciting idea to another every week. That's chasing.

But if another company offers stronger fundamentals, a more attractive valuation and a better risk/reward profile, switching can be perfectly rational.

Selling doesn't need to be dramatic

The biggest improvement is probably to stop thinking of every sell rule as an automatic sell command.

Most of these are review triggers. Something changed. Look again. Re-run the thesis. Compare alternatives. Check the portfolio weight. Then make a decision.

'Hold forever' sounds disciplined, but sometimes it is simply a more elegant name for never reconsidering a decision.

Good investing requires conviction. It also requires being willing to change your mind.