When she took over the family business 20 years ago, Miuccia Prada came with an unusual pedigree. The dark-eyed Milanese was not only the scion to an 85-year-old family leather-goods business but also an active communist who dabbled in mime. An odd combination, perhaps, but evidently terrific preparation for the world of fashion, where Prada's mime-quiet minimalism has made her fashion house into the decade's most powerful design force.
Last week her firm announced its intention to become a powerful business force as well. Under the careful eyes of Prada's husband Patrizio Bertelli, its managing director, the firm grabbed 5% of...