Many years ago, I read a book called Fooled by Randomness by Nassim Taleb, the author who also wrote the book The Black Swan. https://www.amazon.com/Fooled-Randomness-Hidden-Markets-Incerto/dp/0812975219 The main theme of the book is that our brains evolved to be great at pattern recognition, a skill critical to survival in the ancient savanna. This skill lives on to modern times but it fools us to see patterns where there is none. We see patterns in random objects, such as in the clouds as well as in stock charts. It's difficult to "un-see" those patterns even if we rationally understand they are purely random. That's why it's so easy for us to be fooled by randomness. Motivated by this book, I created a spreadsheet to generate a time series to mimic daily stock prices, purely by random number. I was floored when I saw the chart patterns were essentially indistinguishable from a real stock chart. Trendlines and support/resistance are clearly visible and one can perform technical analysis on the time series to find some that works. But these are randomly generated values ! This is an example - Yesterday, I had a discussion with a friend on that subject. He asked me to re-create the excel, which I already lost. After finding a copy online, I modified it to fit more closely to a stock index time series. I'm sharing it here for those interested. Play with it to see the kind of chart patterns you can generate and then take a look at the formula to confirm that it is indeed generated by random numbers.