Boral of Australia reported a nine per cent decline in six-month net profit, but said it remains focused on expanding its US operations as earnings from its key domestic markets continue to struggle in the face of subdued housing activity. The construction-materials company said net profit for the six months ended Dec. 31 fell to A$172.4 million (US$127.5 million) from A$189.1 million, despite an eight per cent increase in sales, to A$2.34 billion. The company generates over half its sales from its domestic construction-materials division, which supplies concrete, cement and other heavy materials for both residential and nonresidential construction. The stock has climbed 55 per cent in the past nine months, with much credit going to the strength of the US market, which contributed 30 per cent of earnings.