COMMODITIES: The Great Potato Bust

Most Americans have never heard of Jack Richard Simplot. But they know of his product and doubtless have eaten it. As the "Idaho potato king," as well as the nation's largest supplier and processor of potatoes, Simplot funnels millions of ready-cut spuds to McDonald's, which turns them into millions of French fries to go with its quick-food goodies. But Simplot has a reputation as a wheeler-dealer in his favorite commodity, and last week he found himself entangled in the biggest potato-futures default in the 104 years of the New York Mercantile Exchange.

Even by the standards of the often rowdy commodities...