Quantitative equity management has origins in the multi-factor models of arbitrage pricing theory. Techniques have grown more elaborate as processing power has expanded. In my experience they sometimes work nicely for years and then crash. If you want to know what's under the hood, this is the book to read. Written by practitioners, it delves into the mathematics with plenty of citations of relevant literature. The book will appeal to the same audience as Grinold and Kahn (1999)—but it is more measured and more mathematical ...