Investing Lessons: Avoiding the Peter Lynch Bias

The single most important lesson I’ve learned about being a successful investor is the need to maintain emotional detachment.  Any feelings you may have towards a stock are unrequited.  If you love a stock, it will not love you back.  And if you hate a stock, it will not give you the satisfaction of responding in kind.  (As tragic as unanswered love may be, unanswered hate is often more damaging to your pride.)

A stock is like that unattainable cheerleader you had a crush on in high school.  She neither loved you nor hated you; she was completely unaware you existed.

No matter how much you love a stock (and write favorably about it in MarketWatch) it will not reward your loyalty by rising in price. And heaven help you if you allow your emotions to cloud your judgment in a short position.  I know of no surer way of losing your investment nest egg than to short a stock or other investment you hate.  Alas, I know from experience; I shorted the Nasdaq 100 in the fall of 2003.  In an outbreak of moral high-horsing that has (thankfully) now been purged out of me, I decided that tech stocks were overpriced and needed to fall further.  The Nasdaq had very different ideas, and I was forced to cover that short at a 20% loss with my tail tucked between my legs.

A closely-related investment mistake is succumbing to what I call the “Peter Lynch bias.”

Peter Lynch ran the Fidelity Magellan fund from 1977 to 1990 and had one of the best performance records in history for a mutual fund manager—an annualized return of over 29% per year.

Unfortunately, he also offered some of the worst advice in history when he recommended that investors “invest in what they know.”

On the surface, it seems like decent enough advice.  If you stumble across a product you like—say, a particular brand of mobile phone or a new restaurant chain—then it might be reasonable to assume that others will feel the same way.  If the stock is reasonably priced, it might make a good investment opportunity.

Unfortunately, “investing in what you know” tends to create muddled, emotionally baggaged thinking.  The fact that you like Chipotle (NYSE:$CMG) burritos and are intimately aware of every ingredient used in the red salsa does not automatically make Chipotle a good investment any more than your liking of Frappuccino makes Starbucks (Nasdaq:$SBUX) a good investment.   Rather than give you an insightful edge, liking the product causes you to lose perspective and see only what you want to see in the stock.

How do we mitigate our emotional impulses?

In a prior article, I noted that “brain damage can create superior investment results.”  But short of physically re-wiring our brains, what can we actually do?

I try to follow these basic guidelines and recommend them:

  • If you like a company’s products, try using one of their competitors before seriously considering purchasing the stock.  If I had really taken the time to learn how to use an Apple (Nasdaq:$AAPL) iPhone or Google (Nasdaq:$GOOG) Android device, I probably wouldn’t have gotten sucked into the Research in Motion (Nasdaq:$RIMM) value trap. Yes, RIMM was one of the cheapest stock in the world when I recommended it last year.  But I cannot deny that my decision to recommend it was biased by my ownership of a BlackBerry phone.  Likewise, many iPhone owners are probably buying Apple for similar reasons today.
  • To the best extent you can, try to follow trading rules and use stop losses.  What works for one investor will be very different than what works for another.  Perhaps you use a hard stop loss of, say, 10% below your purchase price.  Or perhaps you use a trailing stop or 20-25%.  If you are a value investor, perhaps you base your sell decision on valuation or fundamentals rather than market price.  But in any event, my point stands.  Lay out the conditions under which you intend to sell and stick to them.  Stock ownership is a marriage of convenience with quick, no-fault divorce if your situation changes.  Don’t make the mistake of falling in love.
  • Unleash your inner Spock.  For readers who are not Star Trek fans, Spock is an alien from the planet Vulcan who is incapable of feeling emotions.  When talking about a stock or watching its price fluctuate gets your heart racing, take a step back and try to look at the investment through Spock’s eyes.  Is it logical?  Do the numbers make sense?  Are the growth projections based on reasonable facts or on optimistic hope?  Would you buy a different company if it were trading at the same price multiple?

Admittedly, these are not precise guidelines.  But then, another lesson I learned is that it is a mistake to try to be too precise in this business.  Follow the lead of great value investors like Benjamin Graham and Warren Buffett by making sure you have a wide margin of safety in your assumptions.

Disclosures: Charles Sizemore has no positions in any securities mentioned. This article first appeared on MarketWatch.

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  • Bob

    read Peter lynch’s book and you’ll realize your article is filled with faulty logic.

  • Jca

    Charles Sizemore, you are a vulgar idiot. Your article is weak and poorly written. And where’s your track record? Mr Lynch has one of the best track record in the history of the industry, is a gifted writer and has done a lot to educate the public. Gee, you are a zero. Shame on you.

  • johnw121

    I agree with Bob; I think you may have misunderstood the message in Mr. Lynch’s book. He talks about investigating a stock if you like it’s product, for example, but also advocates never to invest on that sole basis. This piece of advice is also recommended by other well-known investors. If I remember correctly, “One Up on Wall Street” also gives examples of companies that made great products but whose stocks did not do so well.

  • http://twitter.com/winnieP12345 donnaelviira

    1) While Lynch was handed the Magellan fund in 1977, it was not open to the public before mid-1981. Before that it was the private investment vehicle for the Johnson family.

    2) The S&P 500 is an imperfect benchmark for the Magellan Fund, particularly when Lynch took a risk in the later years and moved approximately 25% of the holdings into the international market. Using a customized benchmark, the results do not appear as stellar.

    3) During his last four years, Lynch only outperformed the S&P 500 by 2% per year.

    As William J. Bernstein writes in “The Intelligent Asset Allocator,” and I quote, “As I’m writing this, more than a dozen domestic mutual funds have beaten the S&P 500 by more than 6% –Lynch’s margin–during the past 10 years. This is about what you would expect from chance alone.”

    that 29% return number — whose number is that? Is it Lynch’s, Fidelity’s or an actual investor who has really earned a 29% return on funds invested with Lynch. I had an account with Fidelity for years and every statement shouted out a fabulous earnings number, but when calculating the per share price times the number of shares, my investment never grew at all. I’ve always felt Lynch’s “genius” wasn’t so much in the wisdom of his investments but in the creative statements they sent out to investors.

  • Zevo Everton

    Very odd article. First it claims that knowing your investment is not important, then goes on to espouse as #1 rationale knowing your company’s products versus competition as part of your investing plan. Either knowing your investment is good or it is not, which is it? Lynch advocates deep understanding of a company’s balance sheet, profit potential, market potential, in addition to some grass roots knowledge of the products and company itself. He doesn’t advocate, “Hey I enjoyed that Taco Bell taco today, I think I will buy some shares in the company!”



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