The natural-gas market is costing Todd Gross a lot of sleep. Mr. Gross, chief investment officer at Qeri LLC, a small commodity hedge fund in New York, used to wake up at 5 a.m. to look at the latest market data. Now he increasingly rises in the middle of the night to check the latest weather models and adjust his wagers. He doesn’t want to miss what he calls an “oh my God” move of 5% or more. Mr. Gross, 48 years old, says it has become common for those moves to start as early as midnight when electronic-trading programs react to weather updates hours before most human traders are awake. Natural gas and Mother Nature are […]