Yesterday, shares in a company called Yangzijiang Shipbuilding (YZJ) plunged 20% in a single day. It is one of my major stock holdings. I don’t follow my portfolio in real time, so by the time I knew what was happening trading of the share was halted.

Naturally, people want to know what happened. There are rumors circulating that the CEO is involved in a corruption scandal. There are also suspicions of trading bots running haywire and causing the collapse in stock price. However, as investors, our job is not to speculate. Speculation about what happened is useless. What is more important is to learn from any potential mistakes and avoid similar mistakes in the future.

In this post, I cover something called black swan events. It has been less than a year since I started this blog, but sad to say my own experience is now a case study. With that,