One of my books, Investment Fables, is directed at answering one of the most puzzling questions in investments: How is that there seem to be so many ways to beat the market on paper but that so few money managers seem to do it in practice? A key reason, in my view, is that transactions costs have a much greater impact on returns than we realize.
Let's start with the good news. Both academics and practitioners have found dozens of ways to beat the market. To see the academic list of market inefficiencies, try this link:
And here is a link to sure fire money makers from practitioners:
Wow! Hundred ways to beat the market! Each new finding in academia seems to offer fresh opportunities for the "smart, informed" investor. The latest wave of schemes build off the behavioral finance literature. In fact, two prominent behavioral finance economists have set up their own money management firm (showing you that academics are not immune from greed):
Most of these beat-the-market approaches, and especially the well researched ones, are backed up by evidence from back testing, where the approach is tried on historical data and found to deliver "excess returns". Ergo, a money making strategy is born.. books are written.. mutual funds are created.
Now let's look at the bad news. The average active portfolio manager, who I assume is the primary user of these can't-miss strategies does not beat the market and delivers about 1-1.5% less than the index. That number has remained surprisingly stable over the last four decades and has persisted through bull and bear markets. Worse, this under performance cannot be attributed to "bad" portfolio mangers who drag the average down, since there is very little consistency in performance. Winners this year are just as likely to be losers next year...
So, why do portfolios that perform so well in back testing not deliver results in real time? The biggest culprit, in my view, is transactions costs, defined to include not only the commission and brokerage costs but two more significant costs - the spread between the bid price and the ask price and the price impact you have when you trade. The strategies that seem to do best on paper also expose you the most to these costs. Consider one simple example: Stocks that have lost the most of the previous year seem to generate much better returns over the following five years than stocks have done the best. This "loser" stock strategy was first listed in the academic literature in the mid-1980s and greeted as vindication by contrarians. Later analysis showed, though, that almost all of the excess returns from this strategy come from stocks that have dropped to below a dollar (the biggest losing stocks are often susceptible to this problem). The bid-ask spread on these stocks, as a percentage of the stock price, is huge (20-25%) and the illiquidity can also cause large price changes on trading - you push the price up as you buy and the price down as you sell. Removing these stocks from your portfolio eliminated almost all of the excess returns.
In perhaps the most telling example of slips between the cup and lip, Value Line, the data and investment services firm, got great press when Fischer Black, noted academic and believer in efficient markets, did a study where he indicated that buying stocks ranked 1 in the Value Line timeliness indicator would beat the market. Value Line, believing its own hype, decided to start mutual funds that would invest in its best ranking stocks. During the years that the funds have been in existence, the actual funds have underperformed the Value Line hypothetical fund (which is what it uses for its graphs) significantly.
In closing, I am not trying to dissuade you from being an active investor; I am one. My point is that you should be careful about taking the claims by anyone - academic on practitioner - about market-beating strategies. The market is certainly not efficient, if you define efficiency as an all-knowing, rational market, but it certainly seems efficient, if you define efficiency as investors being unable to take advantage of market mistakes. Talking about making money is easy.. actually making money is far more difficult.