This fund may be overshadowed by its older siblings, but it's worth considering if you're willing to take a bit of risk. By Steven Goldberg, Contributing Columnist July 25, 2012 I'm nervous about the stock market. My allocations to stocks are below average, and most of the funds I own specialize in big, boring blue chips, the kind of stocks I expect to hold up best in a rocky market.SEE ALSO: Our Special Report on How to Be a Better Investor That said, my portfolio isn't entirely free of frisky funds, and one in particular is too appealing to overlook. The fund is Primecap Odyssey Aggressive Growth (symbol POAGX), which specializes in small-capitalization and mid-cap stocks -- almost three-quarters of them in biotech and computer-related tech names. What's to like about this fund? Most important is the Primecap pedigree. From its inception in late 1984 through July 23, Vanguard Primecap (VPMCX) returned an annualized 12.7% -- an average of 2.2 percentage points per year better than Standard & Poor’s 500-stock index. The fund is closed to new investors. But in the spring of 2011, I picked Primecap Odyssey Growth (POGRX), which is open and is a member of the Kiplinger 25, as my favorite fund for this market. Advertisement One of Primecap's founders, Howard Schow, died last April, but the other senior managers remain in place. In addition, Primecap has done a fine job of bringing along the next generation of managers and analysts. Like the managers at the gigantic American funds complex, from which Primecap's founders came, each manager of a team-run Primecap fund is responsible for running a slice of that fund's assets. The Primecap investment style is to buy growth companies when they're out of favor -- and patiently hold them. Vanguard Primecap's turnover typically runs less than 10% annually, meaning that each stock stays in a fund for more than ten years, on average. Low fees are another welcome part of the Primecap formula. The Vanguard fund charges just 0.45% annually; Aggressive Growth charges 0.68%. Primecap's managers have long favored the technology and health care sectors, which they consider the fastest-growing segments of the U.S. economy. Conversely, they view commodity-producing companies as long-term losers. Consequently, Vanguard Primecap currently has about half of its assets in tech and health care. Advertisement Primecap Odyssey Aggressive Growth is Primecap on steroids. About 43% of the fund’s $1.4 billion in assets are in health care (most of that biotech), and 30% is in technology. Aggressive Growth is also far riskier by other measures. The average market value of the stocks in Vanguard Primecap is more than $40 billion; Aggressive Growth's is $3.3 billion. The average price-earnings ratio of the Vanguard fund is about 15, according to Morningstar, based on analysts' profit estimates for the coming 12 months; Aggressive Growth's is 25. Aggressive Growth's dangers show in its volatility, too. The Vanguard fund is a shade more volatile than the S&P 500; Aggressive Growth is about one-third more volatile. But Aggressive Growth's returns have more than justified its risks. From its inception in late 2004 through July 23, the fund returned an annualized 9.3%, putting it in the top 2% among midsize growth funds. It beat the S&P by an average of 4.8 percentage points per year and the S&P MidCap 400 index by an average of 2.0 points a year. Surprisingly, Aggressive Growth did a tad better than the S&P 500 during 2007-09 bear market, falling 54.3% compared with the index’s 55.3% drop (the S&P 400 lost 54.8%). Advertisement Still, you shouldn't invest in Aggressive Growth thinking it'll beat the S&P 500 in future down markets. Biotech, which has been on a tear in recent years, provided a huge tailwind during the bear market. It's unreasonable to expect these risky stocks to perform well when the market is cratering. The fund's latest shareholder report, for the six-month period that ended April 30, lists Pharmacyclics as its largest holding, at almost 5% of assets, and Seattle Genetics as number two, with 4.5% of assets. Many of Aggressive Growth's holdings bounce around like jumping beans. The latest shareholder report listed InterMune as a 59% loser for the period and the aforementioned Pharmacyclics as a 109% gainer. The fund is still small enough to invest easily in stocks of smaller companies. One final note: Primecap doesn't do media interviews. Much of my information about the fund comes from Russel Kinnel, Morningstar's director of fund research, who has been a longtime fan of the fund, and other Morningstar analysts, who have been able to visit with Primecap's managers. In sum, Aggressive Growth is a risky fund, and although it boasts a fine long-term record, the managers hold their cards close to the vest. You don't want to bet the farm on Aggressive Growth, but if you want to add a little zip to your long-term portfolio, you'll be hard-pressed to find a better choice. Steven T. Goldberg is an investment adviser in the Washington, D.C. area. Kiplinger's Investing for Income will help you maximize your cash yield under any economic conditions. Download the premier issue for free.