Pity the pig farmer. Over the past seven months, since oil began its precipitous decline, lean hogs were the one major benchmark commodity to fall even further, according to the CME Group. The price of lean hogs—a term referring to butchered pigs regardless of paunch—has sunk 51.3% since the end of June. The drop follows record-high prices this past summer, after a disease called the porcine epidemic diarrhea virus whacked supplies. “The baby pigs were being wiped out at a rate that was never thought possible,” says Phil Flynn, senior market analyst at the Price Futures Group. But the virus subsided surprisingly quickly, and more little piggies started making it to market. The USDA recently revised its projections to show 5.5% growth in pork production this year. Meanwhile, less American pork is being shipped overseas because of slowing international demand, driving a glut. “It’s a perfect storm for pigs,” says Steve Wagner, a market analyst for CHS Hedging. Wagner expects that lean-hog prices will linger at decade lows for a while.

This story is from the March 1, 2015 issue of Fortune.