Optimal Momentum™ Optimal Momentum™

Frequently Asked Questions

It seems that a lot can happen between the beginning of the month when your momentum indices adjust their positions and the beginning of the next month when new signals are given.

Research has shown that stock prices are reactive rather than trending for shorter periods of time, such as days and weeks. Stocks are more likely to rebound from short-term fluctuations than continue in the same direction. It is usually better to ignore short term movements and retain a longer term perspective.   

If momentum investing is so great, why aren’t more people doing it?

It usually takes awhile for academic research to work its way into the investment marketplace. We saw that with indexing and value investing. Public awareness should grow as information about momentum gets better assimilated over time.

There are also other reasons why momentum investing has not caught on. First, it is not as psychologically appealing to buy things that have already gone up in price as it is to buy things that appear to be cheap. Second, momentum may seem too simple to some people who are think more complex approaches have more merit. Finally, some investors have strong prejudices toward other styles of investing.

Interestingly, the same behavioral factors that explain why momentum works can also explain why momentum has not caught on yet: anchoring, conservatism, and the slow diffusion of information.

     What are the main risks associated with dual momentum investing?

         One risk is that past history is driven by randomness, and the future may not be like the past.          However, there are now several hundred years of out-of-sample performance supporting          momentum. There are also strong behavioral biases contributing to why momentum has a good          chance to continue to work.

         There is some risk that momentum will attract substantial capital and not work as well in the          future because of too many participants. But stock indices are much more scalable than individual          stocks.


         Another risk are occasional timing miscues that cause dual momentum portfolio to lag behind its          benchmarks. Over the past 40 years, our Global Equities Momentum (GEM) model under performed          its benchmark in 1979-80 and 2009-11. No strategy outperforms all the time.

         There is also risk associated with the trend-following component of dual momentum being slow          moving to minimize whipsaws.This means that much of the short term volatility of the stock          market still exists with dual momentum.

         There are also re-entry lags when a new bull market begins after dual momentum has taken you          out of a prior bear market. Please see the Disclaimer page of this website for additional risk          factors.

      Should one invest using your papers’ momentum portfolios?

         My papers were meant to illustrate the principles of momentum investing and not as models for          actual investing. Historically, the highest risk premium has come from equities. Research shows          that momentum works best with geographically diversified stock indices.

         My book’s  GEM model is designed as a do-it-yourself approach using dual momentum focused on          stock indices. The section called “How to Use It” in Chapter 8 of my book shows how you can          easily implement the GEM model.

      How many sectors does your Dual Momentum Sector Rotation (DMSR) model invest in at any       one time?  

         The number of sectors can vary if you use a buffer zone for exits. The number of sectors also          depends on one’s attitude toward reward and risk. Fewer sectors mean higher expected returns          and higher volatility. You can use the principles in my book to develop a sector rotation model          that suits your own risk preferences. However, on a blog post I show that the performance of          DMSR using additional data since my book was published is no longer as attractive as the          performance of broader-based dual momentum models like GEM. I no longer use sector rotation,          nor do I encourage others to use it. Academic research shows that momentum gives the best          results with geographically diversified stock indices over the past 200 years. Momentum results          with sectors have been worse than with stocks or geographically diversified stock indices.

      Why do you update the performance of only your Environmental, Social, and Governance and       Global Equities Momentum models on your website?

        My ESGM and GEM models are publicly disclosed. Anyone who reads my book can easily implement         them. My other dual momentum models continue to do well, but are proprietary. I license them to         several investment professionals who use them to manage their accounts.  

      I like your Global Balanced Momentum (GBM) model because it holds both stocks and bonds.       What can I do along those lines?

        My GBM model is now different from what was published in my book. I license it and my other         proprietary models to investment professionals. To achieve a similar effect, you can use the         suggestion at the end of chapter 8 of my book and allocate a permanent percentage of your         portfolio to aggregate bonds and the remainder to GEM.

      My 401k plan does not include an all country world stock fund. What can I use instead?

         Most 401k plans include a fund for non-U.S. developed market stocks. You could use that instead.          To get better expected returns, if your 401k has an emerging market fund, you could create a          synthetic ex-U.S. all country world fund by allocating 25% to an emerging markets fund and 75%          to a non-U.S. developed markets fund. Your signals could then be derived from an ex-U.S. All          country world stock fund.

      Have you tried adding value, quality, low volatility, momentum, or small cap stock indices to       your GEM  model?

         They do not improve the results. Even if they did, I would be suspicious of them for two reasons.          First, most funds using these are subject to data mining and selection bias in their construction.          Second, real time results from factor-based investing has been disappointing due to price impact          and other real world influences. This is expected to get worse in the days ahead as the amount of          capital in factor funds increases. See “Factor Zoo or Unicorn Ranch?

       Are there any outside validations of your GEM model?

         There are a number of them. Two are by TrendXplorer and Sharpe Returns. You can also do your         own back testing with ETFs and mutual funds at Portfolio Visualizer. Use an S&P 500 fund to         determine “single absolute momentum.”

       Have you looked at whether there is a best time of the month to reevaluate and rebalance        your portfolios?

        There are minor performance differences based on what day you use. These may just be data noise.        Rebalancing around the beginning of each month has given good past results. It is important to        stay with whatever day you decide to use and not be swayed by emotion to change your signals        dates.

       During the past year, GEM has had some close signals for switching in and out of stocks. Is        there some rule of what to do when this happens?

         All our published results are based on month-end closing prices. I have tested using a 50/50         allocation to stocks and bonds when the signal is close. To reduce feelings of regret no matter         what happens, you may want to use this approach.

       It looks like the GEM model has under performed the S&P 500 since 2009. Has momentum        lost its effectiveness?

         Dual momentum has a trend following component that lags behind when a new bull market          begins.That is the cost of avoiding the carnage of the preceding bear market. It is unfair to look          only at the new bull market without also considering the preceding bear market.You need to look          at a full market cycle at least to make a accurate evaluation of performance. GEM has          outperformed an appropriate benchmark portfolio since 2008 and earlier.

         You also need to understand why GEM has outperformed over the long run. First, are its profits          from switching between U.S. and non-U.S. stocks according to relative momentum. Since 2009,          U.S. stocks have continuously outperformed non-U.S. stocks, so there have been no opportunities          for relative strength profits. Secondly, the current bull market has been one of the longest in          history, so there have been no opportunities for absolute momentum profits. It is difficult for any          trend following approach to keep up with the stock market when it is abnormally strong.

         You could make a case that GEM has lost its effectiveness if you believe U.S. stocks will always          outperform non-U.S. stocks and that there will never be another bear market. Finally, even if GEM          underperforms over shorter periods of time, many investors are willing to accept that because of          the drawdown protection it has given during bear markets.


       Has the FED policy keeping interest rates low for so long had any effect on dual momentum        profitability?

         Quantitative easing and low interest rates have helped boost stock returns. This is now the second         longest bull market ever in stocks.When there are abnormally positive returns in stocks, it is         difficult for any trend following approach that exits the market occasionally to keep up with it.

        Since there is no ETF for dual momentum investing, how tax efficient is it?

         75% of the gains from GEM have been long-term, and 100% of the losses have been short-term.          What many investors don’t realize is that over 40% of the long-run return of the S&P 500 has          come from dividends. These are taxed at ordinary income rates whether or not they are earned in          an ETF. What investors should pay attention to is the expected return they end up with after          taxes, as well as the drawdowns they will have to experience along the way.

        Stock valuations look high now, and bond yields are low. Will this adversely affect dual         momentum returns?

         High stock valuation levels can mean lower expected stock returns, and low bond yields point to          lower future bond returns. But stocks and bonds still fluctuate and can create opportunities. In          2000, there were also high stock valuations and low yields. But our GEM model had a compound          annual return of 11.6% over the next 10 years, while a 60/40 stock/bond portfolio returned 2.3%


                  Chart courtesy of SharpeReturns.ca


         Will dual momentum will lose its effectiveness when more people start using it?

         An anomaly can certainly lose profitability if it starts being widely followed. However, the          behavioral basis behind momentum has been strong and persistent. Human nature does not          readily change, and so I expect the momentum effect to continue to persist.

         It is unlikely that most people will become dual momentum believers. Many have been brought up          as value or buy-and-hold investors. Their biases may keep them from ever adopting dual          momentum.This is especially true of institutional investors who often have a strong aversion to          any kind of tactical allocation. Even if this were not the case, Shleifer and Vishny (1997) show          that asset managers are afraid of strategies that deviate from their benchmarks because investors          may leave them following periods of under performance.


         In aggregate the performance of actively managed funds is inferior to passively managed funds.          People have known about that for many years. Yet over 70% of all domestic equity funds are still          actively managed. Momentum investing may very well show the same disconnect.


       How do you determine the best look back periods for your models? Won’t shorter look back        periods get you into and out of the markets sooner?

         Academic research shows that over the long run, momentum for stocks works well with a look          back period of 3 to 12 months. Longer look back periods minimize transaction costs and increase          the likelihood of long-term capital gains.   

         While shorter look backs may get you out of and back into markets sooner, they can produce more          whipsaw losses and can actually lead to lower returns and larger drawdowns. A 12-month look          back period was found to work well by Cowles & Jones in their 1937 momentum study. It has held          up remarkably well ever since and is commonly used in other academic research. Staying with this          look back reduces concerns about data mining.    

       Some investors skip the last month when applying momentum. Why don’t you do that?

          It makes sense to skip the last month when you are applying momentum to stocks because           individual stocks can overreact to news and mean revert. If you want to use momentum with           stocks (not recommended), see our review of the book Quantitative Momentum. If you use stock           indices or other asset classes, you do not need to skip the last month. Academic research shows           momentum works best with geographically diversified stock indices rather than with individual           stocks or with other assets. See Geczy and Samonov (2015).

       Why does the performance of the GEM model begin in 1974 in your book and 1971 on your        website? Is this enough data to be robust?

          When my book was written, the earliest bond index data I could get was from 1973. Now I have           additional bond index data, so the GEM performance record on my website goes back to January           1971 where it is now constrained by the lack of data for aggregate non-U.S. stock indices. I can           go back to 1927 when looking at U.S. equities with absolute momentum where international           stock index data is not needed. See my blog posts, Absolute Momentum Revisited and And the           Winner Is… In addition, both relative strength and absolute momentum have been individually           tested back to 1801. See Geczy and Samonov (2015).

        When I back tested GEM, there were a few months in which I see GEM is in foreign stocks,         but you show GEM in aggregate bonds. Why is that?

           On page 101 and 112 of my book I give a simplified logic for GEM so anyone can easily            implement it using a free charting website. There is a minor difference if you calculate the            signals as discussed on page 98 of my book. I mention there that I determine absolute            momentum using only the S&P 500 index, since the U.S. leads world equity markets. I cite a            supporting reference. This means we may occasionally be in aggregate bonds if the trend in U.S.            stocks is down even when non- U.S. stocks are the strongest asset.  

        Isn’t value investing the opposite of momentum investing? How can both be valid?


           They operate on different time frames. Value is based on long-term mean reversion, while            momentum relies on intermediate-term (usually 3 to 12 months) serial correlation. Despite all            the attention it has received, there is strong evidence that value investing has not held up well            well in the real world. See my factor investing blog post.

        Why do you use absolute momentum for trend following instead of moving averages?

          With moving averages you compare an asset’s current price to an average of its prices over the           look back period. With absolute momentum you compare the current price to the price at the           beginning of the look back period. This means moving averages signals are more sensitive and           give more than 25% more trades than absolute momentum. Absolute momentum thus has fewer           false signals and whipsaw losses, as well as lower transaction costs.

          Zakamulin shows that absolute momentum outperforms 3 different types of moving averages on           155 years of stock market index data. Momentum is one of only two methods that outperform the           market with statistical significance.

       What about using stop-losses with dual momentum?

          Stop-losses were once thought to reduce returns when they reduce risk exposure. Recent research           shows that stops can actually enhance returns if they are used with care. I have a blog post           called “Momentum and Stop Losses” that discusses this. Dual momentum is more effective than           stop losses in reducing risk exposure and enhancing returns. Stops are therefore redundant and           unnecessary when using dual momentum.

       Since momentum works best geographically, why not use it with country index ETFs?

         Dual momentum works best when volatility is not too high. Individual countries can have very high          volatility. This can make it difficult to get in and out of them using trend following momentum          without giving up much of their profit. This is the same reason we do not use small cap indices or          stock sectors. Additionally, country indices often have lower liquidity and higher trading costs.

        How do leveraged ETFs perform with dual momentum?

          There are drawbacks to using leveraged ETFs. First, most leveraged ETFs use daily resets which           are best suited for day trading. There can be large tracking errors when holding leveraged ETFs           on a longer term basis. Daily resets are also not tax efficient since leveraged ETFs will result in           mostly short term capital gains or loses. Finally, leveraged ETFs have a leverage factor of 2X or           greater. This may be too much leverage. There is still considerable short term volatility with dual           momentum that may cause discomfort with 2X or greater leverage.

        Have you looked at using inverse equity instead of bond ETFs when absolute momentum

        tells you to exit stocks?

          Equities are the core of our models because they have shown the highest long-run risk           premium. Shorting stocks is therefore climbing an uphill battle. We want every advantage we can           get by having risk premium on our side to serve as a tailwind for future performance.

          There are also higher costs associated with inverse ETFs. You can own an S&P 500 ETF for an           annual expense of 4 basis points, while the expense ratio of an S&P 500 inverse ETF can be 89           basis points. Also, because stocks have an upside bias and our models are slow moving, there           is often not much profit from short positions by the time you enter and exit. The average bull           market duration since 1942 has been 32 months, while the average bear market has lasted only           12 months. Switching to bonds during stock market weakness as identified by dual momentum           has historically done better than being short stock indices.


        There are international stock ETFs that hedge their currency exposure. What do you think         about using these with GEM?

          There is a tendency for International stocks to outperform U.S. stocks when the U.S. dollar is           weak and non-U.S.currencies are strong. This lets us profit from the strength in non-U.S.           currencies. When non-U.S. currencies are weak, GEM is often out of international stocks. So there           is little reason to use hedged ETFs. GEM automatically deals with exchange rate risk.





        What is the best way for non-U.S. Based investors to use dual momentum?

            We have a blog post called “Dual Momentum for Non-U.S. Investors” that discusses this in detail.            The only idea I would add to it now is that non-U.S. Investors may want to include their home            country in their portfolio.

        Do you make your buy and sell decisions using month-end prices?

            Consistent with most academic work, my models’ entries and exits are based on monthly             closing prices that reflect total returns. If you want to trade the same day as your signals             instead of waiting until the next day’s open, you can set up a portfolio on SharpCharts that             updates real time during trading hours.

        What are momentum crashes, and do I need to worry about them?

           These are caused by the short side of long/short momentum suffering large losses when stocks            rebound sharply off severe bear market bottoms. This happened in 1932 and 2009. Since we do            not hold short positions, momentum crashes are irrelevant to us.

        How do you invest your own funds?

          I developed dual momentum specifically for my personal investing. Nearly all my liquid net worth           is invested with the same proprietary dual momentum models I license to investment advisors for           managing their customer accounts.

        How are your proprietary models different from the GEM model disclosed in your book?

          Like GEM, our proprietary models are simple and robust. But they are more adaptive to market          conditions, and they include a few more ETF choices. There are also conservative proprietary          models that incorporate dual momentum applied to the fixed income markets.

        With bonds being in a bull market over the past 35 years, does the use of aggregate bonds         with Global Equities Momentum (GEM) overstate future expected performance?

           Aggregate bonds have an average duration of only around 5 years. This means they are not as            sensitive to interest rate changes as longer duration bonds. As the following chart shows, their            returns have been relatively stable and steady. According to Nuveen, there have been three            rising interest rate periods since 1994. Aggregate bond returns have been positive during all            three periods. Furthermore, GEM and ESGM have been out of equities only about 30% of the            time, and aggregate bonds have been responsible for only 20% of our models’ profits.


           Absolute momentum is used to exit equities and enter bonds when it first identifies bear            markets in stocks. These usually precede recessions, which often lead to falling, rather than            rising, interest rates as aggregate demand lessens and the Federal Reserve tries to stimulate            the economy. When stocks are weak, there is also a tendency for investors to move from stocks            to bonds, thereby increasing demand for bonds. So it seems prudent to accept a little duration            risk then. If you disagree with this, you can substitute shorter term bonds or Treasury bills for            aggregate bonds with only a small fall off in performance.

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