Business: Stock of the Month

With only 72 employees and revenues of about $17 million a year, Dallas-based Aztec Oil & Gas Co. seemed an unlikely candidate for widespread investor interest. But as far back as 1971, the company's stock began fluctuating sharply on the New York Stock Exchange. Activity became hectic last year, and in January Aztec became a full-fledged high flyer on the Big Board.On nine days it hit the most-active list: trading volume one day exceeded 400,000 shares, easily outpacing such giants as AT&T and General Motors. More than 3 million Aztec shares changed hands in January—57% of the total outstanding. The price...