The infrastructure of financial flows is changing in unprecedented ways as a consequence of technological advances in computational speed and telecommunication linkages. These innovations are facilitating globalization and encouraging regulatory arbitrage. At the same time, regulators – perhaps well intentioned – are trying to retrofit the emerging world of electronic trading to old rules that were designed to govern floor exchanges. Additionally, the entrenched interest groups associated with floor exchanges are striving to protect their dwindling franchises, at least until they can position themselves to compete in the new world of electronic trading. As evidence of the threat posed to floor exchanges by new technology, the International Securities Exchange, a purely electronic options exchange founded in 2000, in less than three years has grown to become the largest options exchange in the United States. This seismic shift in market structure has enormous implications for investors, asset managers, brokers and dealers, exchanges and policy makers. How do investors, such as pension funds, endowment funds, eleemosynary institutions and individuals, secure funding for their financial obligations? How do asset managers implement increasingly specialized strategies that require investment across a variety of markets? How do brokers and dealers prevent disintermediation? How do exchanges attract a critical mass of deal flow in the face of growing fragmentation? How do policy makers preserve the quality of markets, recognizing the new reality of electronic trading? The books reviewed in this article bring together the latest thinking of the industry’s leading practitioners and scholars. These books do not offer dispositive solutions to all of these questions, but they shine a bright light on the critical issues of market structure and trading practices, from the perspective of both economic theory and market reality.