The Texas Natural Gases stock index rose 2.9% to 3,500.30 at 4:03 a.m. on Friday, adding a second gain of more than 6%.
Texas Gas and Texas Electric also increased their market capitalization to more than $1.3 billion.
Texas Gas is the largest producer of natural gas in the U.S. and has the third largest natural gas storage capacity in the country.
Texas Natural has been expanding its natural gas production by expanding its storage facilities and expanding its production from underground to the surface.
The company reported fourth quarter profit of $5.2 billion.
The Texas Gas stock index has been up about 20% in the last year, rising above 5,000 points, and the S&P 500 index is up nearly 12% year-to-date.