Nothing has so altered the investment landscape in the past five years as the Internet and the CNBC network. The availability of real-time financial news, data and analysis, and instant order entry and execution have empowered investors and democratized financial markets. Barbara Rockefeller’s CNBC 24/7 Trading is a primer for what’s fast approaching–a trading day that never ends, where at least 500 international stocks can be bought or sold electronically anytime, anywhere.

The book’s main theme is the importance of including foreign stocks in a portfolio to lower risk and increase returns. Current portfolio-management theory, or “modern portfolio theory,” holds that foreign stocks have historically outperformed American stocks and tend to move up and down at different times, as well. Thus, a portfolio that includes both is not only less risky but also likely to perform better over time. The point of optimum diversification, the “efficient frontier,” is where the greatest returns are achieved with the least risk. They make the case that to not diversify is to actually take a bigger risk. In fact, today more money is invested and managed according to the tenets of modern portfolio theory than by any other method. Yet, missing in this book is any discussion about the impact of an increasingly wired world on stock volatility everywhere, and especially on the “noncorrelation” between U.S. and foreign stocks, on which modern portfolio theory is predicated. Recall how quickly the Asian financial crisis spread to Brazil and then to Russia just a couple of years ago. In the near future, events may well impact all stocks globally in the same way at the same time.

The book explains well the many risks in buying foreign securities. There’s currency risk; country-specific economic and political risks; foreign-market, liquidity, broker, and back-office risk; foreign-company operational risk; and accounting standards that are anything but standard. What’s more, it’s harder, at least for now, to get timely and accurate news and financial data from overseas. The book does cover several theoretically safer methods of investing abroad, including American Depositary Receipts, iShares (foreign index shares), and open- and closed-end funds. And there are sections on the basics of foreign exchange and even charting for beginners.

Investors interested in taking a financial worldview will find here all the reasons they should–and plenty of things to worry about if they do. — Scott Harrison

The first responsible book about a new area of economic activity …provides balanced information about alternative sources of around-the-clock financial information.” — The Journal of Investment Consulting