Oct. 30 (Bloomberg) -- Cotton futures fell to a nine-month low as the harvest accelerated in the U.S., the worldΆs largest shipper, adding to a global supply glut thatΆs helping to trim costs for the makers of Hanes underwear.

About 34 percent of the crop was collected as of Oct. 27, up from 21 percent a week earlier, U.S. Department of Agriculture data show. Cotton inventories at warehouses monitored by ICE Futures U.S. expanded for a 15th straight session yesterday to the highest since July 30. Stockpiles have surged more than 10-fold this month.

Global inventories will jump to a record this year as production outpaces use for a fourth straight season, and China, the biggest consumer, cuts imports by 46 percent, the USDA forecasts. Prices have tumbled 65 percent since reaching a record in March 2011. The fiber accounts for as much as 14 percent of the cost of goods sold for Winston Salem, North Carolina-based Hanesbrands Inc.

“WeΆre seeing seasonal harvest pressure” on prices, Phil Streible, a commodities broker at RJO Futures in Chicago, said in a telephone interview today. “The deliverable stocks are continuing to increase.”

Cotton futures for December delivery dropped 0.6 percent to settle at 77.84 cents a pound at 2:35 p.m. on ICE in New York, after reaching 77.68 cents, the lowest for a most-active contract since Jan. 18. Prices fell for a ninth session, the longest slide since May 31.

Prices slumped 11 percent this month, the most among the 24 raw materials in the Standard & PoorΆs GSCI Spot Index.

World production will total 25.6 million metric tons in the year that began Aug. 1, outpacing consumption estimated at 23.8 million tons, the USDA said in September. The harvest in the U.S. will reach 2.92 million tons, 31,000 tons bigger than estimated in September, Cotlook Ltd., the publisher of a benchmark cotton index, said Oct. 25.

Shares of North America-based apparel companies tracked by Bloomberg Industries advanced 79 percent since January 2012, as declining cotton prices helped boost margins.