Natural-gas stockpiles are 8% above last year’s levels and 6.2% above their five-year average for this time of year. Natural-gas prices fell Thursday, extending a recent November slide with moderate temperatures sweeping across the U.S. and limiting demand for the power-generation fuel. Most actively traded futures for January delivery dropped 4.2% to $2.720 a million British thermal units, bringing their tumble for the month to about 22%. Prices had surged to nearly two-year highs at the end of October as traders wagered that frigid weather late in the year would support demand, but forecasts in recent days have been milder than anticipated…