Shares of companies in the energy sector gained due to uncertainty following increased hostilities in the Middle East threatening global oil supplies, particularly through the Strait of Hormuz.

Oil futures pull back from the overnight highs reached on the military escalation in the Middle East as Iran says it has received proposals from mediators for a return to negotiations.

Stepped up U.S. and Iranian strikes over the weekend pushed Brent and WTI to their highest levels in more than a month. The average price of a gallon of gasoline in the U.S. crossed $4 on Monday for the first time in weeks, according to AAA.

Magnolia Oil & Gas has agreed to buy WildFire Energy for about $4.06 billion in a deal that would increase its production by roughly 53,000 barrels of oil equivalent per day. Magnolia Chief Executive Chris Stavros said that the transaction would add more than 1.25 million net acres and upside development opportunities to the company's portfolio. It would also create a premier position in South Texas, he added, combining two high-quality and complementary assets near Gulf Coast markets that offer premium pricing for their products.

British energy company BP said it has agreed to sell its Austrian petrol station and electric vehicle charging businesses to Volenergy for an undisclosed sum, as it continues to slim down its portfolio and exit the retail space. BP said the deal includes 250 branded retail sites.