1503 ET [Dow Jones]--Natural-gas futures finished trading down 6.1% to $3 per mmBtu. It's the largest decline in natural-gas futures since July, the second straight session that natural-gas futures sank, reversing big gains posted last week in response to a disruption of a pipeline in West Virginia. "Today's selling is attributed to profit-taking and several bearish factors in play," says NatGasWeather.com in a note. Mild temperatures in the U.S. are also affecting retail demand for natural gas.