This book is a greatly updated and expanded version of the first edition. The content continues to reflect my own interests and prejudices, based on my skills, such as they are. In the period between the first and second editions, the financial markets have expanded, the tools available to the modeler have expanded, and my girth has expanded. On a personal basis I have spent as much time being a practitioner in a hedge fund as being an independent researcher. Much of the new material therefore represents both my desire as a scientist to build the best, most accurate models, and my need as a practitioner to have models that are fast and robust and simple to understand. As I said, this book is a very personal account of my areas of expertise. Since the subject of quant finance has been galloping apace of late, I advise that you supplement this book with the specialized books that I recommend throughout, and in particular those in the quant library at the end.