Why does it feel easier to make a decision when other people are doing the same thing?

Most investors have felt this, even if only subtly. A trade idea that seemed uncertain on its own begins to feel more convincing once it appears elsewhere. It shows up in headlines, in commentary, in conversations. The logic may not have changed, but the level of comfort does. Acting no longer feels like stepping into the unknown. It feels like joining something already in motion.

This is where herd behaviour begins to take hold. It is not simply about copying others. It is about how the presence of others changes the way information is interpreted. When uncertainty is high, the actions of other people start to feel like a source of guidance. If enough participants are moving in the same direction, it can begin to look less like opinion and more like confirmation.

One of the clearest demonstrations of this comes from the work of Solomon Asch in the 1950s. In a series of simple experiments, participants were asked to match the length of lines on a card – a task with an obvious correct answer. When asked individually, most people answered correctly. But when placed in a group where others deliberately gave the wrong answer, many participants chose to agree with the group, even when the error was clear. The pressure was not explicit. It came from the discomfort of standing apart.

In markets, this can be seen in the way trends develop and accelerate. Early participants act on their own reasoning. As prices begin to move, others take notice. The movement itself becomes part of the signal. Confidence builds, participation increases, and what began as a small shift can develop into a widely shared position. At that point, the distinction between independent decision-making and collective behaviour becomes less clear.

What makes this difficult to recognise is how reasonable it feels in the moment. Looking for confirmation is not inherently irrational. In many areas of life, it is a sensible way to reduce uncertainty. The challenge is that in markets, the same behaviour can lead to crowded positions, where many participants are effectively relying on the same signal at the same time.

You may notice this in yourself when a decision feels more comfortable after seeing others take a similar view, or when acting against the prevailing direction feels unnecessarily risky. There can also be a subtle shift from asking “Is this a good decision?” to “What is everyone else doing?” The question changes, and with it, the decision.

Herd behaviour does not eliminate risk. It usually just postpones the moment until it becomes visible.

For Further Reading

Asch, S. E. (1955). Opinions and Social Pressure. Scientific American, 193(5), 31–35.