Archive for the ‘Book review’ Category.


I recently came across a book – How we decide ? This is a book about decision making and how humans make decisions under various circumstances. Although this book is not on some best seller list or by a very well known author, I found the book good and learned quite a bit from it.

Let me list some of my key learning’s from the book
–        The rational brain – prefrontal cortex is involved in rational decision making and can evaluate only a limited number of variables and data elements at a time. However our emotional brain, the amygdala and other parts are the hidden supercomputers of the brain. They are able to process more pieces of information and can do so much faster. The reason is evolution. When facing an immediate danger, such as a tiger, the emotional brain had to process the information quickly and cause a fight or flight response. There was no time to sit and think in such a situation.

–        The standard model of decision-making has been the rationality based model. Emotions are considered bad for decision making and corrupt our thinking process. That however is not true. Emotions can and do lead us astray, but they are crucial to decision making. The emotional brain and the rational brain are constantly communicating with each other and help us in arriving at our decisions.

–        The decision process is a not a smooth process involving the rational brain alone. It is actually an argument where the emotional brain and rational brain go back and forth and based on the situation a final decision is reached.

–        The learning process of the brain has a big emotional component. The dopamine system is involved in this process. Whenever we commit a mistake, the dopamine levels drop in the brain and we ‘feel’ bad about it. The emotional centers of the brain encode this memory and use it for later decision making.

–        Emotions mislead us several situations. For example, the normal response to price drops in the market is fear and panic. The typical response of most of the investors is to exit the market to avoid the pain and fear. However this is often an incorrect response. A rational and calm response would be to look at the individual stocks and evaluate the expected value at the given price. A decision should then been taken based on this number, than based on emotions.

Some key learning’s for investors (my conclusions)

–        Stock market investing is all about decision making under uncertainty. As investors, we can never have complete and full information. Perfect information is a myth. No one can ever know all there is to know about a company, much less an industry or the market.

–        A perfectly rational investor is an incorrect model. The above book and several other books I have been reading, point out that the best investors are able to combine rational thinking with their emotions.

–        Emotions are formed based on repeated experiences in a particular field. These emotions are referred to by several terms – intuition, gut feel etc. As one develops experience, the learning’s are encoded in the brain as emotions or intuitions. However one should not rely on emotions when starting out as an investor. At that time, one does not have enough experience and the emotions have not developed fully. However as one gains experience, one should learn to trust one’s instincts or at least be mindful of them.

I have personally faced this several times. When analyzing a company, all the numbers will look fine and the company looks undervalued. However some stray facts or a few points will keep troubling me. In most of the instance, where I have ignored such feelings, I have regretted later.

–        Smart investing is a mix of rational thinking combined with emotional learning. As one matures as an investor, one should learn to tune in to emotions and gut feel and try to at least understand what they are telling us. You will rarely see investors talk about gut feel or emotions. They are considered too soft or not macho enough!. That is however foolish. The human brain does not work that way. Decision making is a mix of rational thought and emotions. Ignoring emotions means using only a limited power of your brain.

–        Novel problems require thinking and should not be based on emotions. When analyzing a new company or business model, do not rely on emotions alone. One should think rationally and assemble all facts before making a decision.

–        Embrace uncertainty – It is amazing the level of confidence most people have on their investment. Analysts writing about a company, will provide you projections for the next 3-5 years. Sometimes these projections are not even round numbers (like sales would 1244 crs in FY2010). What crap !. Nothing is absolutely certain in the stock market. There are only varying levels of certainty. To simplify it, I look at low (20-30% probability), medium (around 50%) or high level of probability (around 70-80%) for any specific scenario. In addition, I always believe in developing multiple scenarios when trying to come up with an intrinsic value number. As a result you would have noticed that my estimates are generally in a range and not a fixed number

–        Entertain competing hypothesis – One should always be open to counter arguments to one’s investment idea. That allows one to accept contradictory information and weigh it properly. I try to constantly look for points, which go against my investment idea though i am not sure how successful I am at it.

–        Finally think about thinking. One should constantly analyze one’s decision making and thinking process. You should be able to look at your thought process objectively and look at ways of improving it ( read this process v/s outcome article by Michael J. Mauboussin ). This blog is my approach of doing it, though in a public fashion. In addition, I always write down my investment thesis when I am looking at an idea and also how I feel about it (though I don’t publish it as they are my private thoughts).

I would strongly recommend you to read this book. It is a very good book and has several crucial points on how the human mind works and how one can improve his or her decision making.


I have just finished this book. I wrote about this book earlier here. I have also read N N Taleb’s earlier book – fooled by randomness and liked it a lot.

I will not be doing a detailed review of the book as that can be found on amazon and a lot of other website. I will however highlight some of the points, which struck me as important and how they impact me as an investor.

One of the key points, which the author makes, is about the complexity of the real world and lack of predictability. For ex: No one predicted the rise and the importance of the internet. The Internet has become one of the major forces shaping our world. It can be termed as a positive black swan. As a result all complex systems such as the economy, financial markets, which get impacted by such black swans, cannot be predicted. But that does not stop analysts and all the talking heads on TV from making predictions (predictions for 2008 etc etc)

Now one can argue that some prediction do come through. Well, you don’t have to be a guru for that. Just take some events, toss a coin and make a prediction based on the toss. You will be right 50% of the time. Analysts and TV gurus are worse than that in terms of their success rate. There are numerous studies supporting it, so you don’t have to take my word for it. Try this on your own – write down some predictions you hear this year and check back a year later.

Why are we suckers for this? because we want to resolve uncertainity and anyone who can or claims to provide visibility to the future is sought out (we do have astrologers !) . The author terms this as the narrative fallacy.

Personally, I stopped looking at predictions, analyst estimates, top picks/ hot picks etc etc long time back. If I want to be entertained I would rather watch a movie or a cricket match!

A logical question is how to invest if you do not predict. Does developing a DCF not amount to forecasting a company’s cash flow? Well it does. The difference is between a macro and a micro forecast. Forecasting a company’s cash flow is much easier than forecasting the direction of the stock market. If you know the company well, it is in your circle of competence, and you can figure out the few key variables driving the cash flow of the company then it is possible to arrive at a reasonable estimate. Will it be accurate? I don’t think so. However if you are conservative in your assumptions (don’t assume 50% growth rates) then the impact of the negative surprises would be minimal. I would not worry about positive errors (cash flow more than forecast) as I will gain from it. In addition, if you buy at a discount to the estimate of the intrinsic value (margin of safety concept), then you are protected further from errors in the forecast.

Compare this approach with macro, top down forecast. If some one says – infrastructure stocks will do well because infrastructure spending is to increase by 50%. In addition to all the stock specific factors, you thesis is also dependent on the increase in the spending which in turn depends on multiple factors. The more variables in the investment idea, the more there is a chance of something going wrong. In addition, you will also pay more for such an optimistic scenario. So if the macro forecast or something else with the company goes wrong, the losses can be severe.


I am currently reading the book – The Black swan by N N Taleb. This is a great book on low probability, high impact events which are termed as black swans.

I am still in the middle of this book. One key point which I came across is ‘confirmation bias’ on which the author has devoted a complete chapter.

The basic idea behind confirmation bias is that once we make a decision, we tend to look for evidence to confirm it. As a result we tend to ignore any negative information which could refute our decision. As a corollary to this concept, any additional information is of no use as it would only re-inforce the decision and not add any more value to the decision making process.

Like others, I am equally susceptible to this bias. My approach to reduce its impact is to write a single page thesis on an investment idea and sometimes post it on my blog. I try to gather negative information and also prefer to get negative feedback on my idea. That helps me in wieghing all negative information and arrive at a better decision (hopefully).

I am not sure if I have been entirely successfull in it, but I have rejected a few ideas after selecting them, once I was pointed out some key information (which I had missed out). In a few other cases, the negative information, which I had missed earlier resulted in reducing my estimate of intrinsic value for the stock – for ex: I missed the impact of liabilities in the case of VST. As a result I ended up taking a smaller position