There was the balding trader whose wig was seen as a gauge of the market’s volatility; on the craziest days, the wig’s part ran ear to ear, Mr. Wilhelmi recalled. There was the analyst who died right there. “Bellies killed him,” Mr. Wilhelmi said. And there was the veteran trader who once told Mr. Wilhelmi — who was, at the time, trying to analyze a trading report on pork bellies — not to bother. “The bellies,” the trader told him, “are what we say they are.”

Pork bellies have long held a puzzling mystique to the public. Experts in the field offer a range of sometimes conflicting explanations: everybody likes bacon; the word “belly” sounds funny; no one actually knows what a pork belly is. Whatever the reason, pork bellies pop up in an inordinate number of references in magazines, popular culture and movies, like “Trading Places,” the 1983 film in which Eddie Murphy’s character used pork bellies to explain, in unforgettably bare terms, how a market works.

To hear many who frequented the Chicago Mercantile Exchange in the early 1960s tell it, the trading of pork belly futures seemed to open up a whole new set of possibilities — other livestock, for instance — for the exchange. “The bellies are gone,” said Gary Truitt, the president of Hoosier Ag Today. “But they really did make a contribution.”

Way back, pork belly futures made sense. The bellies were frozen and set aside, then used to make bacon during the summers when the demand for it (think bacon, lettuce and tomato sandwiches) rose. But the pork belly landscape has shifted, said Shane Ellis, a livestock economist at Iowa State University. With bacon accompanying salads, hamburgers, even chocolate, it is on call all year now, removing some of the demand for frozen bellies.

For many here, the announcement by the Chicago Mercantile Exchange in July that no further such trades would be made was merely acknowledging the inevitable. Some said it was high time. Past time, in the view of some, who had worried that the ups and downs of trading were too risky when almost no trades at all were being made. It was hard to imagine next to the memories of the old belly pit, where you had to really watch out, Mr. Truitt said, or you would “get your clock cleaned.”