The U.S. manufacturing sector expanded in December, following a month of contraction,a leading industry survey showed Wednesday. The U.S. Institute of Supply Management (ISM) said the manufacturing index, also known as the purchasing managers index ( PMI), rose from November\'s reading of 49.5 percent to 50.7 percent in December, indicating expansion in manufacturing for only the third time in the last seven months. A reading above 50 percent indicates that the manufacturing sector is generally expanding, while a reading below 50 percent indicates contraction. The new orders index remained at 50.3 percent for the month, the same rate as in November. The production index registered at 52.6 percent, a decrease of 1.1 percentage points. Of the 18 manufacturing industries, seven reported growth last month, including petroleum and coal products, as well as computer and electronic products. Nine other industries, such as chemical products and machinery, reported contraction, said the ISM. Manufacturing has been a bright spot by output and employment since the recession ended in June 2009. But the sector has shown signs of weakening in recent months.