FUD (fear, uncertainty, and doubt) refers to negative news, rumours, or sentiment that pushes people toward panic-selling. It can be entirely legitimate (real bad news genuinely warrants concern) or deliberately manufactured to manipulate a market — the term itself doesn't tell you which.
The practical skill isn't dismissing all FUD as noise, or believing all of it outright — it's the same habit that helps against FOMO: slow down, verify the underlying claim independently, and avoid reacting purely to the emotional pressure of the moment.