Sector movers: Rio leads miners lower

LONDON - Mining stocks headed lower today following the third quarter production report from Rio Tinto. The miner said mined copper production fell 6% in the third quarter mainly because of lower grades. Iron ore production dipped 2% from the record levels seen in the second quarter, due in part to two train derailments. Meanwhile, infrastructure challenges of congested ports and railways had a negative impact on hard coking and thermal coal production in Australia in the third quarter, down 10% and 24% respectively. The group added that margins in the Pilbara remain under pressure due to continuing increases in contractor and other mining input costs. Holders of shares in telecoms equipment testing group Spirent were cheered by news that the company has recommenced its share buy-back programme. During the third quarter the company spent ?6.8m buying back 27.4m shares, thereby reducing the company's shares in issue by just over 3%. The company said third quarter trading is in line with expectations and the board expects full year profits to meet its targets.