Rio Tinto Group, the second-largest iron ore exporter, lowered its forecast on full-year sales from Australia as third-quarter shipments fell 5 percent, missing estimates, because of port and rail maintenance. Shipments declined to 80.9 million metric tons in the three months to Sept. 30, London-based Rio said Thursday in a statement. That compared with 85.6 million tons a year earlier and missed a 83.5 million ton median estimate of five analysts surveyed by Bloomberg. Rio cut its forecast for full-year exports to between 325 million and 330 million tons, from an earlier forecast of 330 million tons, joining rival producers in lowering guidance. Better supply discipline and cuts to Chinese output are among factors that’ve supported this year’s rebound in price, according to Liberum Capital Ltd. “It’s an oversupplied market, but each time the majors lower volumes it becomes less oversupplied, which is clearly at least a short-term positive for pricing,” Jeremy Sussman, a New York-based analyst at Clarksons Platou Securities Inc., said by phone. Rio’s shares advanced 0.4 percent to A$50.94 at 10:12 a.m. in Sydney trading, extending their gain this year to 14 percent. Iron ore may average $55 a ton this quarter and through the first half of 2017 even as more low-cost supply is added, according to Toronto-Dominion Bank, the top forecaster in a Bloomberg ranking. Ore with 62 percent content delivered to Qingdao closed at $58.37 a ton Wednesday, according to Metal Bulletin Ltd. data. It’s gained 34 percent this year. Rio held its forecast of shipments of between 330 million and 340 million tons in 2017. The company has been expanding sales at the slowest rate in years as it works to complete a $518 million program to install autonomous trains. Shipments in the last quarter declined as a result of maintenance on rail track and at the Cape Lambert ship loader, Rio said. Crude-steel output in China in the first nine months is higher than the same period a year ago, data published Wednesday showed. Production has increased as policy makers added stimulus, boosting demand, and as a price rebound improved profitability. Rio is becoming more optimistic on commodities demand in China, the top buyer, Chief Executive Officer Jean-Sebastien Jacques said in August. BHP Billiton Ltd., the largest miner, confirmed the buoyant industry outlook, saying Wednesday that it’s detecting early signs of commodity markets rebalancing, forecasting oil and natural gas will rebound faster than metals. Rio’s coking coal production surged 17 percent, while mined copper output jumped 16 percent. Copper volumes were boosted as Rio mined an area of higher grades at its Kennecott unit in the U.S. and on higher output at the Oyu Tolgoi mine in Mongolia, it said.