If you asked Seeking Alpha readers why investors should own more than one stock, the overwhelming response would easily be diversification. The idea is simple: the more holdings you have, the less exposure you have to unsystematic risk (risk associated with a particular company or industry). Now, if you asked a follow-up question, "How many stock holdings you should have?", you would end up with a hotly debated topic.
On page 129 of my copy of The Intelligent Investor, legendary money manager Benjamin Graham advocates holding 10 to 30 positions. Modern portfolio theory supported this advice, and many continue to follow its preachings religiously. According to this theory, if you own 20 well-diversified companies, each held in equal amounts, you've eliminated 70% of risk (as measured by standard deviation) and reduced volatility. Can't argue with the math (or can you?), and diversification has been harped on by many as the foundation of any properly constructed portfolio. It is likely that anyone that has had a financial advisor or even discussed finances with a family friend has heard this advice before. Always spread your capital across multiple sectors and markets is in that person's best interest. Makes sense right? Who doesn't want less volatility and risk?
Warren Buffett apparently.
"Diversification is protection against ignorance. It makes very little sense for those who know what they're doing."
- The Oracle of Omaha Himself
So, Do You Know What You're Doing?
Of course, modern portfolio theory and its offshoots were theorized between the '50s and '70s. Volatility is up since then, and stocks have become increasingly uncorrelated with the underlying market. To more clearly illustrate this point, stocks increasingly don't follow a normal distribution pattern:
The results of the above image have been repeated over and over in recent market studies. The key takeaway for an individual investor is that the odds of a stock you own outperforming the stock market is actually worse than 50/50, contrary to what many investors might think off hand. The reason for this is because overall market returns have been boosted by just a handful of "superstar" stocks, like Apple (AAPL) or Microsoft (MSFT). If you don't own something like the next Apple or Microsoft in your portfolio (roughly 1 in 16 odds), then well, you're likely doomed to underperform. So if you have a portfolio of 16 stocks, what are the odds you have that one in sixteen superstar company included based on random chance? Just 38%.
Let us say you get lucky and manage to stumble upon a superstar. Now the question is whether you will continue to hold it as it multiplies. Enter the disposition effect. Retail investors have a tendency to sell winners (realizing gains too early) and hold onto losers, following the thought process that today's losers are tomorrow's winners. How many investors held on to Apple from $7.00/share in the early 2000s all the way up to more than $700.00/share (split-adjusted) today? The answer is likely very few. Retail investors took the profit from the double or triple (if they even held that long) and likely didn't reinvest back in because they had sold in the past.
None of this changes the fact that the more companies you own, the more you will inevitably track the index of the positions you hold. In order to generate alpha (abnormal return adjusted for risk), it is a fact that the more stocks you own, the less likely you will be able to generate that alpha. The more holdings you have, the more likely you will have just tracked the index that your holdings are a part of, but in an inefficient way. For all your trouble, you are out both your free time and likely higher trading costs. The question then is why bother with all the headaches of investing in numerous individual companies you buy individually, if you could simply just buy the index and take it easy?
If you take a look at major hedge fund and money manager holdings, it is clear that concentrated holdings are used to drive alpha. Visiting the Oracle of Omaha's portfolio, the man clearly practices what he says. The top five holdings of Berkshire Hathaway (BRK.A) (BRK.B) [Wells Fargo (WFC), Kraft Heinz (KHC), Coca-Cola (KO), IBM (IBM), and American Express (AXP)] constituted 67% of his portfolio as of September 30, 2015. 43 scattered holdings constituted the remaining 33%.
As for diversifying across sectors versus buying what you know and understand, 37% of Buffett's holdings fall in the Consumer Staples sector and 35% in Financials. The man clearly doesn't buy utilities just because portfolio theory tells him he should in order to reduce his risk.
Thousands of people will read this article. Are you smarter than two-thirds of them? If you don't believe that, buy ETFs, sit back, and be content with market returns.
If you think you're smarter than two-thirds of readers of this article (I suspect 95% of you believe that), then the takeaway is slightly different. Diversification, for the sake of diversification, is stupid. Buy what you know, can understand, and believe in the long-term potential of. Don't understand bank stocks? Reading their SEC filings even gives me headaches, and I work at one. If you don't understand the company, chances are you aren't going to pick a winner other than by dumb luck. You shouldn't lose sleep at night for not having exposure to an industry you can't adequately review, and it is likely your portfolio returns will thank you for it.
As far as how many positions to have, hold as few positions as you are comfortable with when it comes to risk and volatility in order to increase alpha on your high conviction positions. For most investors, that sweet spot still likely falls within modern portfolio theory guidance, around 15 to 25.
This article was written by
I have a decade of experience in both the investment advisory and investment banking spaces, with stints in portfolio management, residential mortgage-backed securities, derivatives, and internal audit at various firms. Today, I am a full-time investor and "independent analyst for hire" here on Seeking Alpha.
Disclosure: I am/we are long AAPL, AXP. I wrote this article myself, and it expresses my own opinions. I am not receiving compensation for it (other than from Seeking Alpha). I have no business relationship with any company whose stock is mentioned in this article.