FuturesTechs Blog

‘Sell in May and go away, come again on St. Leger’s Day’, or so the ancient wisdom goes. According to convention, investors do well by exiting the stock markets during the quiet summer months, only returning in mid-September.

Not satisfied with old wives’ tales here at FuturesTechs Towers, we decided to do a little bit of empirical research and find out for ourselves if this had worked in years gone by.

In order to spice it up a little bit, and to add some “timing” to the whole affair, we also decided to consider the amendment offered by another technician (the excellent and well-respected Axel Rudolph at Dow Jones): “Sell in May and go away, come again on St. Leger’s Day so long as there is a Stochastic crossover sell signal.” Ooh-err!

The results?

It turns out that this rule hasn’t been too bad at all, looking back for the last 20 years.

We put the start of the summer period as the day of the first Stochastic crossover sell signal in May or, if there was none, as May 31^st. The end of the summer was defined as the day of the St. Leger Stakes, the horse racing meet in Doncaster that’s been running since the 18^th century, and which is always held in mid-September. We use the Slow Stochastic indicator with the typical parameters.

So here’s a simple comparison: the returns for each of the last twenty years (blue) versus the annualised returns for each summer (red):

Fig 1.

The chart shows that the red series was quite a bit lower than the blue series on a couple of occasions (1992, 1998, 2001, 2002, for example), meaning that summer returns were much worse than the annual returns in each of those years. And we also see that the years in which the summer significantly outperformed the year as a whole weren’t very common.

So now let’s compare the same annual returns versus the returns achieved by sitting out during the summer period (selling in May and coming back in September). The annual returns are in blue again, with the returns from the “Sell in May” strategy in purple:

Fig 2.

This shows that the returns from sitting out for the summer months were better than for the year as a whole in 1990, 1992, 1998, 2001, 2002, 2006, 2007 and 2008.

What’s also going on here, though, is that the returns from summer were greater than zero for 11 of the 20 years in question, so that for each of these years you were better off staying invested rather than sitting out. Even if the summer returns weren’t that great, they were better than the zero gained by doing nothing for that time.

In general, though, the records show that there has been some good success in leaving the fray for summer, as illustrated by this summary:

1989-2008                          Average Returns

Annual                                      6.03%

Summer (annualised)          -1.03%

Sell in May Strategy                7.39%

The average return for each of the past 20 years has been 6.03% but, by employing the Sell in May strategy, the average return rises to 7.38%. The average of the annualised returns for the summers has actually been negative.

Now let’s look at the suggested amendment to the rule, and use the Stochastic sell signal. We find that when you only sell out in the years when there was a sell signal, the strategy does improve a little. This is illustrated by Figure 3, where we simply stayed invested for the years when there was no signal:

Fig 3.

Waiting for a Stochastic sell signal meant that you would still have been protected from summer losses in 1990, 1992, 2001, 2002, 2006, 2007 and 2008 (you would have suffered pretty big losses last year anyway, of course). This strategy performed worse than simply staying invested for the year in 1989, 1991, 1993, 1995, 1997 and 2005. The average return from this strategy, however, is still an improvement on simply selling out (which was already an improvement on staying invested):

1989-2008                                  Average Return

Annual                                             6.03%

Sell in May                                      7.39%

Sell Signal Strategy                      7.49%

Looking exclusively at the years when there was a sell signal, the worst return (except for 2008) was -3%! Some people might consider this to be good value risk management, even if it means missing out on some growth during good years

Our summary box looking only at the years with a sell signal helps to prove how the rule made a big difference:

Sell Signal Years                     Average Return

Annual                                              5.75%

Summer (annualised)                  -3.64%

Sell in May Strategy                         8.01%

This isn’t a very formal analysis, of course, but could be worth thinking about. In terms of this year, we had a Stochastic sell signal for the FTSE on the 13^th of this month (the vertical line on the chart below).

Fig 4: Stochastic sell signal for the FTSE-100 index, 13^th May 2009

The market has gained a little more since the signal, but anybody who thinks that the rally is probably over now might take encouragement from the historical record of weak summer trading. That would make this an opportunity to get out, only coming back for race day in Doncaster next autumn.

Graham Neary (graham@futurestechs.co.uk)

We included the RSI and Parabolic SAR indicators in the new levels sheet available in our Members Area, so thought that it would be worthwhile to briefly introduce them to anyone who might not be familiar with how they worked or how to use them.

Fig 1: The New Levels Sheet. (Click to enlarge)

RSI (Relative Strength Index)

One of the most popular oscillators, the Relative Strength Index was first introduced by J. Welles Wilder in his popular, now-classic book, “New Concepts in Technical Trading Systems” (Trend Research, 1978).

The calculation might not look intuitive, but it really isn’t too complicated:

where RS is the “Relative Strength” of up days versus down days over the period being used (typically fourteen).

As originally calculated by Welles Wilder, the strength of up days is calculated as follows: for each day, “Up” is recorded as: the difference between the close and the prior close if there was on increase, or as zero if there wasn’t. “Down” is recorded similarly: the size of the difference between the close and prior close (always a positive number) if it decreased, or zero if it didn’t. The exponential moving averages of “Up” and “Down” are calculated, with the EMA of “Up” then divided by EMA of “Down” to give us the Relative Strength.

RSI is bounded in the range 0-100, and the use of the exponential moving averages makes it reasonably smooth, solving two issues which often arise with oscillators (for example: the simple Momentum indicator - the difference between latest close price and the price n periods ago - is neither smooth nor bounded, making for volatile swings which can’t be compared across markets).

The key takeaways from RSI are:

The ideas that hold true for oscillators in general hold true with the RSI. The oscillator will frequently turn around before the price does – for example, a price still rising that is accompanied by a falling RSI produces a bearish divergence between price and oscillator, a major warning that the up trend is running out of steam (see Fig 2 below).

Fig 2: NASDAQ Futures, September 1999 – May 2000. Divergence between price and RSI at the height of the bubble. (Click to enlarge)

It’s worth reinforcing that extreme RSI readings do not by themselves constitute buy or sell signals. For example, the most that a high RSI, even one above 70, can indicate is that if the market is ranging, it is now due for a correction. The sell signal won’t actually be produced until RSI starts declining back toward neutral levels, and if the market is trending instead of ranging, then it could stay at elevated levels for extended periods of time. As with any indicator, trader discretion is advised.

When looking at our levels sheets, simply checking whether the RSI is above or below 50 tells you something about the internal strength of that market. Additionally, we highlight the figure in yellow if it is in one of the extreme overbought/ oversold zones. A cluster of extreme overbought/oversold markets in the same sector of our equities, commodities or Forex sheets provides interesting information about general market trends, while also helping us to identify specific opportunities.

Parabolic SAR

Another invention by Welles Wilder, the Parabolic Stop-and-Reverse is designed as a trailing stop system with a difference. Originally called the Parabolic Time/Price System, the stop is calculated as function of price and time.

The SAR alternates between providing stops for shorts and longs, switching as soon as a stop is activated. In the chart above, the blue marks are the stops for shorts, with the red marks the stops for longs. As you can see, this system is “always in”, meaning that it always indicates an uptrend or a downtrend (depending on which type of stop was the last one to be activated), so that somebody who focused exclusively on it would always have a position in the market. This makes it unsuitable for ranging markets, where a trader using it would be constantly whipsawed (see Fig 3 below).

Figure 3: NASDAQ Futures, January - May 2009. Whipsawed until mid-February, and then helpfully following the trends. (Click to enlarge)

The stop is calculated by:

Today’s SAR = (Yesterday’s SAR) + (Acceleration Factor)*(Yesterday’s Extreme Price – Yesterday’s SAR),

where yesterday’s extreme price is the high in a downtrend, or the low in an uptrend, and the Acceleration Factor is a fraction which increases incrementally each day up to a maximum value, providing the distinctive parabolic shape (this is the part of the formula incorporating time).

The recommended use of the Parabolic SAR is as a stop in a trending market where other, primary tools of analysis have originally motivated the trade. The stops which it provides won’t rush to the price action too quickly at the start of a serious move, thus giving it some initial time in which to develop. However, the increasing “Acceleration Factor” means that it will pick up speed when it isn’t activated, until it races quickly towards the price. This means that when the trend does eventually lose momentum, it will quickly catch up with the price and close out the trade.

Our levels sheets provide the SAR stop in green if it’s the stop in an uptrend, or in red if it’s the stop in a downtrend. Again, simply browsing which sectors are predominantly in uptrends or downtrends according to the SAR provides useful information, even if you aren’t using the stops in trading a specific market.

A Note on Parameters

Note that as with all indicators, the parameters of the RSI and the Parabolic SAR can be tailored to suit the individual markets under consideration. Our levels sheets use the most commonly used parameters for each indicator (14 periods for the RSI, an acceleration factor of .02*(t) up to a maximum of .2 for the Para SAR), for the same reason that we look at 10, 20 and 50-day moving averages: besides being reasonable parameters to use most of the time in their own right, they are the parameters that a majority of people automatically use anyway, and therefore gain technical significance purely on that basis.

Other Indicators, Other Markets?

The levels sheets are there to assist our members and if there are particular indicators and/or markets which you would like to receive automated levels for, please let us know and we’ll do our best to include them. While automated indicators and levels are never going to be a trader’s panacea, when incorporated into an overall strategy they are a key ingredient of successful trading.

Graham Neary (graham@futurestechs.co.uk)

Neither, I suspect, is the answer to the above question, at least not as far as where we are at this very moment is concerned:

We have been bullish since early March, and have seen the market “climbing the wall of worry” as we predicted, with no-one quite believing the rally. We are not doing the “Harry Hindsight/told you so” bit here. Just ask one of our clients, or feel free to check our “Media” page on our website and listen to what we’ve said on CNBC in recent months.

But just now everyone (else) we seem to see and hear on CNBC and Bloomberg TV is getting bullish. So we’re starting to think we’re near a top for now on that basis (when too many people are getting bullish it’s time to find the exit!), and the last few days have seen some pretty uncertain price action to back this up.

When I say “starting to think we’re near a top” I don’t mean the top of a bear market rally, though. We think there will be a pullback some time soon, which may well last the whole summer (“Sell in May and go Away” is a pretty watertight strategy if you don’t take it completely literally, and if you exercise some finesse or process re timing your “sell”!). During this time you will see many commentators saying “told you so” with respect to the bear market rally story (probably the same guys who this week have been saying we’re going up; Hmmm…).

But we will not make a new low. In fact we don’t think the S&P will drop below 766, or the Dow below 7240 , and we will look for the FTSE 100 to hold above 4000 or at worse 3850 on any retracement move. The sell off will only go on long enough to get the weak longs panicking out, and only long enough to have the “bear market rally” camp saying “told you so”. THEN we will start to rally again, and we will end 2009 in fine fettle.

Our customers will benefit from knowing if and when our views change, because we WILL happily change our skew if we are proved wrong, such is the flexibility of a short term approach utilising Technical Analysis.

For now I am preparing to “Sell in May…” and it will be interesting to see what happens this week, prior to my appearance on CNBC on Thursday evening (May 14th). For now key supports are holding and we’re still short term Bullish, but this could change very quickly, and evidence is mounting in favour of a pullback.