Preface: neural networks, nonlinear dynamics, and risk management in banking and finance.

When we launched the call for papers for this special issue in November 2018, we could hardly imagine what state the World would be in, just two years later, when writing this editorial for the completed work in November 2020. Their methodologies and findings may also encourage further research in a variety of challenging issues for the global financial markets associated with not only a post-Covid but also a post-Brexit environment. A clear focus of the special issue can be found in the application of machine learning techniques that are recurrent topics in the special issue's articles. [Extracted from the article]