[November is the start of the strong six-month period of the year. The Almanac has covered some ways to exploit this effect. The following is an extract from the 2013 edition of the Almanac.]
We have already looked at the six-month effect in this book (the tendency for the November-April market to out-perform the May-October market), and how a portfolio based on this effect can dramatically out-perform an index fund. But it is not necessarily the case that the strong half of the year begins every year on exactly 1 November, nor that it ends exactly on 30 April. By tweaking the beginning and end dates it may be possible to enhance the (already impressive) returns of the six-month strategy. An obvious rationale for this is that if investors are queuing up to buy at the end of October and sell at the end of April, it can be advantageous to get a jump on them and buy/sell a little earlier.
This idea of finessing the entry/exit dates was first proposed by Sy Harding in his 1999 book, Riding the Bear – How to Prosper in the Coming Bear Market. Harding’s system takes the six-month seasonal trading strategy and adds a timing element using the MACD indicator. First, by back-testing, Harding found that the optimal average days to enter and exit the market were in fact 16 October and 20 April. Then, using these dates, his system’s rules are:
- If the MACD already indicates the market is in a bull phase on 16 October the system enters the market, otherwise the system waits until the MACD gives a buy signal.
- If the MACD already indicates the market is in a bear phase on 20 April the system exits the market, otherwise the system waits until the MACD gives a sell signal.
Following such rules, the entry or exit dates of the strategy can be one or two months later than the standard 1 November and 30 April. Harding calls his system the Seasonal Timing Strategy (or STS).
Commenting on the STS, Mark Hulbert of Marketwatch.com said in April 2012,
Harding’s modification of the Halloween Indicator [six-month strategy] produced a 9.0% return (annualized) over the same period [2002-2012], or 2.0 percentage points per year more than a purely mechanical application of this seasonal pattern, and 3.6 percentage points ahead of a buy-and-hold.
Can such a strategy work in the UK market?
We found it difficult to replicate similar results for the UK market using Harding’s STS system. One problem was that 1 November is such a good date for entering the market – it was difficult to consistently improve on it with any technical indicator. However, we did come up with one simple system that improved on the standard six-month strategy. Briefly, its rules are:
- The system enters the market at close on 31 October.
- The system exits the market on the first MACD sell signal after 1 April.
- The parameters of the MACD indicator were increased from the usual default values to 24, 52, 18.
In effect, the standard entry date is unchanged, but the exit date is determined by the MACD. In some years, this can delay exit to June or later.
To illustrate the performance of this system the following chart shows the returns on three portfolios since 30 October 1999:
- Portfolio 1: a portfolio tracking the FTSE All Share Index
- Portfolio 2: employing the standard six-month strategy
- Portfolio 3: employing the six-month strategy enhanced using MACD
It’s quite possible that further tweaking of the parameters and system rules could additionally enhance the strategy’s performance.*
* The 2014 Almanac details another variation on this strategy.
Further articles on the Sell in May Effect.