DOW JONES NEWSWIRES Smithfield Foods Inc.'s (SFD) swung to a fiscal fourth-quarter profit on a strong performance at its fresh pork and hog production businesses. The largest U.S. pork producer has posted improved earnings over the past year as it has been able to successfully pass on higher feed costs and take advantage of robust export demand. Adjusted profit beat analysts' expectations in the latest quarter, and the company unveiled a new $150 million stock buyback plan. For the period ended May 1, Smithfield reported a profit of $98.4 million, or 59 cents a share, from a year-earlier loss of $4.6 million, or 3 cents a share. Excluding debt-retirement charges and prior-year derivatives impacts and restructuring charges, earnings were up at 85 cents a share from 18 cents. Revenue increased 7.1% to $3.12 billion amid higher average selling prices and higher market prices for hogs. Analysts polled by Thomson Reuters most recently forecast earnings of 82 cents on revenue of $3.23 billion. Gross margin surged to 14.7% from 6.2%. The fresh pork business reported operating profit surged amid record margins and as sales grew 8.9%. The hog production unit swung to a profit as reduced supply supported higher prices, while margins improved amid robust export demand and favorable grain hedges. Smithfield's packaged-meats business, its largest top-line contributor, reported earnings declined 20% as a shift away from private label caused total volume to decline 2%, though sales revenue rose 12%. Shares closed Wednesday at $20.39 and were inactive premarket. -By Tess Stynes, Dow Jones Newswires; 212-416-2481; Tess.Stynes@dowjones.com