Updated edition with a new foreword by Perry Mehrling. Throughout his career, Fischer Black described a view of business fluctuations based on the idea that a well-developed economy will be continually in equilibrium. In the essays that constitute this book, which is one of only two books Black ever wrote, he explores this idea thoroughly and reaches some surprising conclusions. With the newfound popularity of quantitative finance and risk management, the work of Fischer Black has garnered much attention. Business Cycles and Equilibrium-with its theory that economic and financial markets are in a continual equilibrium-is one of his books that still rings true today, given the current economic crisis. This Updated Edition clearly presents Black's classic theory on business cycles and the concept of equilibrium, and contains a new introduction by the person who knows Black best: Perry Mehrling, author of Fischer Black and the Revolutionary Idea of Finance (Wiley). Mehrling goes inside Black's life to uncover what was occurring during the time Black wrote Business Cycles and Equilibrium, while also shedding light on what Black would make of today's financial and economic meltdown and how he would best advise to move forward.