The company advised Southwest Gas stockholders against taking any action until the board completes its offer evaluation. The offer expires Dec. 27 but could be extended an additional 60 days. On Oct. 5, Icahn shared an open letter to Southwest Gas noting that he was a "large shareholder" and criticizing the company for its pending efforts to buy Dominion Energy Questar Pipeline, LLC for more than $1.5 billion. Icahn accused Southwest Gas management of making "a number of egregious errors at the expense of shareholders" and that he was "extremely disappointed" with management over the past few years. "However, the purchase of Questar you are currently being rumored to make at the price you are willing to pay will make all past errors pale in comparison," he wrote in his letter. Questar Pipelines consists of 2,160 miles of interstate gas pipelines in the Rocky Mountains transporting and storing gas across Utah, Wyoming and Colorado, according to Southwest Gas.