There’s a famous maxim in the investing world that goes like this: “Buying is easy, selling is hard.” We can spend weeks and months analysing a company. But when the company’s shares crash for temporary reasons, we might panic-sell in an instant due to fear, erasing all our efforts spent on doing our due diligence on a stock. That emotionally-driven action would be detrimental to our long-term investment returns. Here are three guidelines to help us determine rationally when to sell a particular stock. (Hint: Selling due to a stock market crash is not one of them.)  Source: Giphy 1. When a Mistake Has Been Made  The first reason is an obvious one. This happens when we make a mistake in the original purchase of the stock, and the company is not as favourable as originally thought to be. To handle this situation, we must have self-control and the ability to be honest with ourselves....