The Stock Market ties closely with Chaos Theory in that perfectly predicting when stocks will rise or fall is nearly impossible. Numerous factors play into the stock market including politics, interest rates, exchange rates, natural calamities, and more.1
However, stocks have an overarching trend as supply and demand increase and decrease over time. This allows stock brockers to know the best companies to invest in. However, as everything is not predicatble, stocks will rise and fall according to other factors, many out of our control.
One obvious, unpredicted event that had a large effect on the stock market was the COVID-19 pandemic in March 2020. This pandemic caused major rise and fall to various stocks. This example is being evaluated by economists and mathematicians as time continues to see the continual effects of one, unexpected event.