Do you have difficulties knowing when to sell a stock? It's probably the single hardest action for an investor to do well. Sure, finding great companies with undervalued stocks is tough, but selling them is even tougher. You'll never achieve the 20- and 30-baggers of the next decade if you unload a great business at the wrong time.

Even great money managers get bit by the selling bug, sacrificing hundreds of millions in profit, even billions, in order to lock in gains. Selling a slow-growing mega cap such as Bank of America (NYSE: BAC) or Citigroup (NYSE: C) is one thing (and may have saved you some heavy losses during the financial crisis), but you could wipe out the next home run stock if you try that trick with a fast-growing small cap.

Do try this at home
In early March, one of the great small-cap fund managers, John Laporte, retired. Working for the T. Rowe Price New Horizons fund for 22 years, Laporte turned in an impressive performance. An investor who deposited money when Laporte took over, according to the Wall Street Journal, would now have a return of 7.8 times his money, net of fees. A similar investment in the Russell 2000, an index of small caps, would have grown to just 5.2 times the initial outlay.

A key component of Laporte's success was his ability to hold on to his winners, although admittedly even he sold some monster gainers way too early. Laporte held his stocks, on average, four years. But that figure understates the truth: New Horizons has held two-thirds of its top 20 largest investments for at least five years. On the other hand, the average small-cap fund flipped its portfolio every nine months.

The insanity of the average fund's actions is stark: How could you ever invest in the next household name if you hold a stock for just nine months? The renaissance of Apple (Nasdaq: AAPL) under Steve Jobs has taken years; the full flowering of Microsoft (Nasdaq: MSFT) under Bill Gates took a couple of decades. Can you imagine the millions you would have lost selling Microsoft just nine months after its IPO in March 1986?

And to get a sense of the capability and genius of managers such as Gates and Jobs takes time. Laporte confided to the Journal, "It often takes me years to get confident in the business strategy and the management team."

Two errors of commission
But despite its emphasis on buy-and hold investing, New Horizons has two notable sales that cost billions in total. It held a public stake in Starbucks (Nasdaq: SBUX) from 1992 until 1994, when Laporte was convinced that a short-term move in coffee prices would hit the brewer's earnings. The fund manager took a profit on the shares, and then watched as shares grew 10 times more. That move cost the fund $200 million.

Another sale was much more costly. Before Laporte's time, the New Horizons fund purchased shares of Wal-Mart (NYSE: WMT) during its IPO in 1970. As the company outgrew its status as a small cap, the fund sold in 1983. Today its stake would be valued at about $14 billion – twice what the fund as a whole is worth.

That's the power of buying and holding small caps. In fact, finance gurus Eugene Fama and Kenneth French discovered that one in eight small-cap growth stocks becomes large each year. According to the researchers, these soon-to-be large companies return up to 62% on average annually. Those are the types of gains that can turn you into an accidental millionaire if you hold on for the ride.

Where to begin
For those kinds of gains, focus on small caps that have high returns on capital and equity, such as the following:


Market Cap

P/E Ratio

Return on Capital (TTM)

Return on Equity (TTM)


$2.6 billion




Chipotle Mexican Grill

$3.6 billion




STEC (Nasdaq: STEC)

$602.2 million




Source: Capital IQ.

Fossil and Chipotle have had seriously good runs in the past year or so, and all three have had solid gains over the last few years or so. Their financials continue to look strong, even though one, STEC, has seen a massive price decline. But with such strong fundamentals, why should you sell any of these stocks now? Sure, Chipotle is up 70% over the last year, but "locking in your gains" in this case could mean you'll never score a two-bagger, five-bagger, or more.

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Jim Royal, Ph.D. , owns shares of Bank of America and Microsoft. Microsoft and Wal-Mart Stores are Motley Fool Inside Value picks. Chipotle Mexican Grill is a Motley Fool Rule Breakers choice. Apple and Starbucks are Motley Fool Stock Advisor selections. Chipotle Mexican Grill is a Motley Fool Hidden Gems selection. Motley Fool Options has recommended a diagonal call position on Microsoft. The Fool owns shares of Chipotle Mexican Grill. The Fool has a disclosure policy.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.