“What we need now is a new paradigm that dynamically adjusts to market risk and keeps us safe from the vagaries of today’s highly volatile markets. We need a way to earn long-term market returns while limiting our downside exposure. This book shows how momentum investing can make that desirable outcome a reality.’’

Although academic research has shown that momentum -- persistence in performance -- has been a valid investment strategy for more than 200 years, Antonacci says, he adds that its real-world application has been minimal.

He explains momentum principles, outlines its history, and applying modern financial theory, he shows us why dual momentum works.

On the other hand, Antonacci explains why he is less enthusiastic about hedge funds, private equity, active mutual funds and managed futures and other alternative strategies.

Which brings Antonacci to his chapter, “Asset Selection: The Good, the Bad, the Ugly,’’ which has some surprises, and next, to his alternative investment approaches.

“Using only a U.S. stock market index, an all-world non-U.S. stock market index, and an aggregate bond index, I show how investors using Global Equities Momentum (GEM) could have achieved long-run returns nearly twice as high as the world stock market over the past 40 years while avoiding severe bear market losses.’’

Antonacci believes in mining all the available data, which in the case of absolute momentum goes back to 1903, and for relative momentum, to 1801.

Dual Momentum Investing’ cites dozens of academic research studies and papers (more information on these works is available at Antonacci’s website, http://optimalmomentum.com). He provides more than 80 tables and figures (everything from GEM, leveraged and deleveraged, to parity portfolios), and he gives us both folksy and pointed quotes from experts and insiders, including George Soros, Warren Buffett,  Paul Krugman, Richard Thaler, Paul Tudor Jones, Jim Simons and others.

Antonacci admits that a comprehensive exploration of dual momentum can become weighty, as in sentences such as, “The beta coefficient of the CAPM regression equation tells you the sensitivity of an asset’s excess return to variations in the market’s excess return.’’ That is in Chapter 3, “Modern Portfolio Theory Principles and Practices,’’ which carries Antonacci’s note: “This and the next chapter are a bit wonkish. Some readers may wish to skip them and move on to Chapter 5.’’

Taking the advice of Simons, billionaire founder of Renaissance Technologies’ Medallion Fund, Antonacci says: “I have learned through my experiences with dual momentum the importance of firmly adhering to a proven, disciplined approach that has clearly shown it can successfully adapt to different market conditions.

“I have also come to recognize that I am no match for dual momentum and to value it as my best investment friend.’’