So, why do we need to diversify in the first place? We all know that all great wealth was created by concentrated holdings. Bill Gates has his whole networth in Microsoft. Ditto Dhirubhai Ambani. So, why not do the same thing? Well, the issue here is that we are not insiders or promoters of the companies we own stocks in. We don't have a handle on how the company is being run and don't "really" know the inner details that is required to have a great level of conviction.
There is also another factor. Although, concentration (in the right company) can bring huge rewards, it can also destroy great wealth. Think of the Modis and the Bangurs of India. They would probably have done better if they diversified their wealth in other ventures (maybe invested in the Reliance IPO!!!) than put all their money in their own companies.
So, diversification is important from a wealth-preservation perspective. And also because our level of conviction of a company's performance is never 100%. There are risks involved in investing. There are various types of risk involved, main ones being:-
- Individual business risk - the conpanu you invest in goes bankrupt (Enron, Satyam etc)
- Sector/industry risk - the industry declines (VCR, Walkman, Pager etc)
- Market risk - the stock market crashes (1929 US, 2008 Worldwide)
- Personal risk - you need money urgently for some unforeseen expenses
So, how much is enough. Charlie Munger, one of my gurus, had at one time only four stocks in his portfolio and was very comfortable with them. Others have somewhere between 10-25. Peter Lynch, also one my gurus, on the other hand had more than 1200 stocks in his Magellan fund!! But all of them, and other great investors, have said that having a portfolio of between 10-20 stocks is optimum for an individual investor. I prefer to have about 10 stocks in my core portfolio. And some more where I am either building up my positions or dwindling down. So, I personally try to stick to the 10-15 stock range. That is more so, because, I have seen beyond that I am not able to track the news flow in the companies I am invested in.
Another reason I try to stick to the range is that if I already have say 15 stocks and I get a great new idea, I would be forced to think about which one to replace. This, sort of, helps in moving out holdings where my conviction is lower than the new idea that I have.