Group 1 - U.S. natural gas prices surged nearly 20% to around $3.70 per MMBtu, marking the largest one-day gain since October 2024 and the second biggest since September 2020 [1][6] - The surge in prices is attributed to an intensifying Arctic outbreak forecast to bring much colder temperatures across large parts of the U.S., significantly boosting heating demand [3][4] - More than 200 million people in the U.S. are expected to experience below-freezing temperatures, with wind chills dropping to 20 to 30 degrees below zero in parts of Minnesota, further increasing the demand for natural gas [5] Group 2 - Natural gas-linked stocks such as EQT Corp., Chesapeake Energy Corp., Antero Resources Corp., and Range Resources Corp. are expected to react positively when markets reopen [6]