Posts Tagged ‘normal distribution’

Is trend following trading risky?

Tuesday, January 30th, 2007

In a nutshell, Trend Following is a trading strategy that buys (or technically speaking, go ?long?) when prices are in an uptrend and short sell (or technically speaking, go ?short?) when prices are in a downtrend. Unlike other trading and investing strategies, trend following only look at one thing for its buy or sell decisions: price. Also, trend following does not try to anticipate price movements or foresee long-term fundamental outlook?it merely reacts to price behaviour.

Does trend following works? Michael Covel, in his book, Trend Following?How Great Traders Make Millions in Up or Down Markets made a thorough case for this trading strategy. We suggest you read his book if you are interested in the idea of trend following.

However, there are some in the finance industry who claim that trend following is very ?risky.? The underlying reason for such a claim is based in the fact that trend following exhibits very volatile returns. Is there any flaw behind such a claim?

First, how is volatility measured? Standard deviation is most often used for measuring volatility. The calculation of standard deviation requires the statistical mean as one of its input. Here lies the weakness for the claim that trend following is ?risky??the underlying assumption behind standard deviation is that prices follow a normal distribution As we said before in How the folks in the finance industry got the idea of ?risk? wrong!, this assumption is generally not true in practice. Price often moves in trends, and the incidence of extreme movements (e.g. 1987 stock market crash) shows that normal distribution is an invalid assumption. Therefore, according to the assumption of normal distribution, meltdowns like 1929 and 1987 are so rare that they occur once every billions of years (we are not sure of whether it is billions or millions, but you get the idea). Thus, if you believe in trend following, you cannot believe in the idea that volatility that is defined by standard deviation is ?risk.?

One more thing: since most of the financial industry uses the faulty normal distribution example as the basis for measuring ?risk,? we cannot help but feel that perhaps much of the financial risks in the world are being wrongly appraised. If that is the case, the next fat-tail event will indeed draw many nasty surprises.

What if the Israelis strike Iran?

Monday, January 22nd, 2007

Today, we will look at a Middle-Eastern geopolitical scenario that we believe can possibly happen?an Israeli strike on Iran. However, the likelihood of it is impossible to quantify. Nevertheless, it is our firm conviction that investors will do better to be prepared for it (even though it may be an arguably improbable event) than completely ignore it because its effects will have a massive impact on their portfolio.

It is interesting to note that ING, one of the world?s largest investment banks, had came up with an internal report to analyse the possibility and effects of this scenario. It is certainly even more interesting to note that they had come up with a possible timeframe (February to March 2007) for such an extraordinary event. For the sake of today?s discussion, we will assume that the report is genuine. We encourage you to read this report with an open mind. Please note that ING is not predicting that this scenario will happen?rather, they are saying that this scenario is possible and that should it happen, what the impact on the financial markets will be.

As we said in How the folks in the finance industry got the idea of ?risk? wrong!, this is an example of a ?fat-tail? scenario in which by definition of the normal distribution curve assumption (which we sees it to be an academic assumption that does not fully reflect reality), is so highly improbable that it borders towards the realm of impossibility. Hence, we believe that this scenario is a risk that is not fully appreciated and ?priced in? by the financial markets. Thus, there are some in the financial industry who have the mind-set that since it is impossible to quantify the probability of such a scenario, it should be ignored.

As contrarian investors, we believe that it is unwise to adopt such a mind-set. Firstly, though the probability of an Israeli strike is impossible to quantify, its impact on our investments will be extremely severe. Since the financial markets will be taken by surprise by such an event, we can be assured that it will trigger a massive shift of capital from one asset class to another. (No prize for guessing which asset class we prefer!) Thus, a high impact but low probability event is something which should not be completely ignored. Secondly, though we cannot do everything to hedge every aspect of our lives if such a scenario eventuates, we certainly can do something now to hedge ourselves in terms of our investments. Doing something now is certainly better than doing absolutely nothing.

Assuming that a military strike is being seriously considered, what is the most logical course of actions to take?

Definitely, military training is the first step. Indeed, there are rumours of it in this news report. Secondly, preparation for Iranian retaliation will have to undertaken. Already, there are unusually significant US navel and marines deployment in the region. The recent deployment of 20,000 more US troops in Iraq may perhaps be not what it seems. Thirdly, oil will have to be stockpiled because there is no doubt that oil supplies will be disrupted. The recent fall in oil prices in response to reports of rising oil inventories may be the result of such accumulation. Lastly, it is certainly interesting to note the Saudis? nonchalance about the recent falls in oil prices?they declined to agree on another OPEC oil production cut to prop up the price of oil. We do know that the Iranian economy is not in good shape and they have heavy reliance on oil revenues. The Saudis (who are Sunni Muslims) have the motivation to undermine the Iranians (who are Shias Muslims), who looks to be taking steps towards dominating the Middle East.

Are we implying that there will be military action? Again, we stress that we don?t know the answer. We believe it is possible. But we would not want to place our heads on the chopping board by making geopolitical predictions.

Is an Israeli strike on Iran so improbable and ?mad? that only those who belong to the conspiracy theorists fringe groups will even bother to consider it?

To answer this question, we have to consider this: As investors, since we may often see things through an economic prism, we can make the mistake of seeing certain actions as ?irrational? when it is completely rational in the context of the overall big picture. In this case, even though an Israeli military strike on Iran is ?crazy? in our eyes, it may be perfectly rational in the context of national survival. The Israelis may see that since the Iranian nuclear issue is such a serious threat to their national survival, if the world economy has to be damned to eliminate this threat, so be it!

In conclusion, our advice is: Be prepared.

How the folks in the finance industry got the idea of ?risk? wrong!

Wednesday, January 17th, 2007

In our previous article, How do you define risk?, we put forth our criticism on the way risk is measured by many in the financial service industry. Today, we will look at the underlying theory behind their measurement of risk. The recommended reading for today will be How the Finance Gurus Get Risk All Wrong.

As you may have noticed, ?risk? is often expressed as a nice and simple number in the world of finance. For example, in many stock research publications, the ?risk? of a stock may be defined in terms of a number called the beta. You may see risk jargons like standard deviation, the Sharpe ratio, variance, correlation, alpha, value at risk and so on. All these mathematical definitions of ?risk? give it a scientific feel, which seem to give us the impression that ?risk? can be measured and controlled. Unfortunately, in reality, these definitions and measurements of ?risk? are pseudo-science. The reason is because the underlying theory behind all of them is flawed in the first place.

What are the assumptions behind these conventional measures of ?risk?? They are all based on the assumption that price follows a statistic device known as the normal distribution. If a stock price follows a normal distribution, it means that at any given day, there is a 50% chance that it will go up and a 50% chance that it will go down by the same amount on average. In the long run, the vast majority of stocks? price will hover around its average, with a smaller percentage deviating from it. In other words, the behaviour of stocks? price will follow a bell curve like this (horizontal axis?stock price, vertical axis?probability of the price being at that level):

Bell curve

Is this a valid assumption?We doubt so. As you can see for yourself in the real market, prices often do not follow such behaviour?frequently, they move in trends and at times, exhibit extreme behaviour. As the article in the suggested reading (How the Finance Gurus Get Risk All Wrong) said,

The inapplicability of the bell curve has long been established, yet close to 100,000 MBA students a year in the U.S. alone are taught to use it to understand financial markets.

Thus, as contrarians, this is not the way we define risk.