(FORTUNE Magazine) – As his staff watched, Foster Friess, 50, recently approached a 400-pound pig on a golf course in Puerto Rico, only to be charged by the beast and forced to flee. He has had better luck with stocks, which is why 80 institutional clients and shareholders of the Brandywine Fund entrust more than $900 million to his money management firm, Friess Associates, in Greenville, Delaware. Some of his big winners include Compaq Computer, which he rode from $12 a share to about $90; Hasbro ($4 to $32); and Tandy ($6.50 to $34). According to CDA Technologies of Rockville, Maryland, Friess has scored a total return of 192.2% for the past five years, including reinvested dividends, and 28.4% for the past 12 months. Both figures beat Standard & Poor's 500-stock index, which returned 123.7% and 19.2%. In a recent interview with Fortune's Joshua Mendes, Friess told which stocks are in his viewfinder now.

So how do you pick the winners? Central to our strategy is the belief that you should never invest in the stock market as such, but in individual companies whose internal development outweighs the difficult-to-predict effects of interest rates, foreign currency values, commodity prices, and general market trends. That is why we stay away from big, mature companies and focus on dynamic, growing ones. We want companies with earnings momentum, meaning year-over-year gains of at least 25% to 30%. The current average for companies in our portfolio is about 44%. We also want a strong balance sheet, exceptional management that can motivate people, and a product that is well received and can be manufactured at a high rate of profitability. Relative to the market, the return on sales and equity is also very high for our companies.

What leads you to them? Partly just being tuned in to how our society is changing and to new ways of conducting business such as the distribution of goods through wholesale clubs or the transfer of information by fax machines. We also come across new companies through the ones we investigate. We'll ask a company to name some of its tough competitors.

Let's talk about two of your favorites: Nike and L.A. Gear. Do you really think they can keep on sprinting? In a word, yes. There is a lot of skepticism out there, but we don't see any signs of a slowdown. We've been to the malls, and their shoes are still selling very strongly. We think Nike's earnings will jump from $4.45 in the year ended last May to $6 this fiscal year and $7 in 1991. For L.A. Gear, which earned $3.01 for the fiscal year that ended in November, we're estimating $4.50 this year and $6 in 1991.

What about the industrial sector? We regard Stewart & Stevenson Services as an excellent play on two important trends: the increasing concern about pollution and the growing worldwide shortage of power. The Houston-based company combines General Electric gas turbines, which use a cleaner-burning fuel than coal, with electrical generators. The company currently has a backlog of $316 million in orders, equal to about a year's production, and we think its earnings will rise 20% or more for at least two years.

Do you go in for high-tech stocks? After we installed a personal computer network in our office, we came across SynOptics Communications, a Mountain View, California, company that found a less expensive way to hook up individual PCs into networks. Other companies were using coaxial cables to link PCs, but SynOptics found a way to do it with the telephone wire that's already in every office. Earnings per share have leaped from 92 cents in 1988 to $1.20 last year. We think they'll do $1.70 this year and $2.45 in 1991. Exabyte in Colorado is another interesting company. It is the only manufacturer of a special type of 8-mm cartridge tape used to store information from computer workstations.

Sounds like a product that could easily be superseded. That's what we get paid to watch. Digital audio tape is one potential competitor, which is why the price/earnings ratio of the stock has been running at only 11 times next year's earnings. But we believe that even when digital audio tape becomes more popular, its sales will be predominantly to the lower-end industrial and consumer markets. Exabyte's sales this year should be close to $170 million, up from $89 million in 1989, and earnings per share should reach $1.22 from 72 cents last year.

For conservative investors, would you describe a more down-to-earth stock? We like Toro, the Minnesota-based maker of lawn mowers and snow blowers. Many on Wall Street have stopped following the company because earnings have been uninspiring during the past couple of years. Both the winters and summers have been unusually dry. But we think Toro's earnings are going to get a big spurt from its purchase of Lawn Boy, an important competitor. There will be a lot of economies. Toro, which had been buying certain engines from a Japanese outfit, will get them from Lawn Boy. In addition, it will be able to shift some of its production in the North to Lawn Boy's lower- cost facilities in the South. We think this, along with new products, will boost earnings 50% to $3.10 a share in the fiscal year ending in July 1991.

I realize you largely ignore the overall market, but how do you size it up now? The least bit of bad news pulls a stock's price down fast, so we're being a little more cautious. But prices aren't exorbitant.