The stock market will exhibit strength through June 7, and then weaken until the end of June.
This remarkably precise prediction comes from the stock-market timing system that has the best record of any tracked by the Hulbert Financial Digest over the past three decades.
Better yet, the system couldnât be simpler: It trades on nothing but the calendar, exploiting seasonal strength around the turns of each month as well as prior to stock-exchange holidays.
There is a catch, however, and itâs potentially a big one: Despite having an outstanding long-term record, this system has lagged the market over the last decade. Following its lead going forward depends on whether you think the past few years are the exception or the new rule.
This calendar-based market timing system was created by Norman Fosback in the early 1970s. Fosback at the time was President of the Institute for Econometric Research; he called this system one of the best short-term indicators he had ever encountered.
The system calls for being 100% in stocks at the turns of each calendar month and prior to exchange holidays. It is in cash at all other times.
I calculate that, over the 30 years through the end of April, this incredibly simple approach lagged a buy-and-hold by just 0.3 percentage points per year on an annualized basis â despite behind in the market only a third of the time. Thatâs a winning combination, according to the academicsâ Capital Asset Pricing Model, since you otherwise would have to give up a lot more than a half of a percentage point per year in order to reduce risk by that much.
This is why Fosbackâs seasonality system is in first place on a risk-adjusted basis over these three decades among any of the market timing systems tracked by the Hulbert Financial Digest.
There are several theories for why the system has worked. One is that short-term traders do not want to be short before a three-day weekend, and so tend to cover any of their outstanding shorts over the couple of sessions before. That means, for example, that the stock market is likely to rise on May 27, the last trading day before the Memorial Day weekend.
Another theory for why the seasonality approach works is that retirement plan contributions typically wind their way into the market around the beginning of each month.
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There is another theory â the Efficient Market Hypothesis â according to which erstwhile market-beating strategies will stop working once enough investors know about it and start acting upon it. This could very well be whatâs going on with Fosbackâs seasonality timing system, since it was spectacularly successful during the decades of the 1970s, 1980s and 1990.
Yet itâs hard to prove that this is whatâs going on. According to my PCâs statistical software, for example, you cannot conclude at the 95% confidence level that the marked deterioration in the Fosback systemâs performance over the last decade is due to anything but random bad luck.
Itâs of course frustrating that a decade of market-lagging performance is not enough to convince a statistician that a market-timing system is no longer worthwhile. But that is the price we must pay in order to follow strategies that have beaten the market over a long-enough period to prove with a high degree of confidence that theyâre better than flipping a coin.
For example, you wouldnât be on firm statistical ground to stop following Warren Buffett just because the net asset value of his Berkshire Hathaway
Â hasnât kept pace with the S&P 500
Â over the past five years. And the same appears to be the case with Fosbackâs seasonality timing system.
The bottom line? Assuming youâre willing to give Fosbackâs approach the benefit of the doubt, you might want to wait until the end of the first week of June before unloading any sell candidates. And, likewise, you might want until later in June before increasing your equity exposure.
For more information, including descriptions of the Hulbert Sentiment Indices, go to www.hulbertratings.comor email [email protected]
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