Energy stocks were slightly higher pre-bell Monday, with the Energy Select Sector SPDR Fund (XLE) up 0.1%.

The United States Oil Fund (USO) was up 0.2%, and the United States Natural Gas Fund (UNG) was 0.9% higher.

Front-month US West Texas Intermediate crude oil was up marginally at $61.00 per barrel at the New York Mercantile Exchange. Global benchmark North Sea Brent crude oil retreated 9.1% to $64.68 per barrel. Natural gas futures were up 0.1% at $4.13 per 1 million British Thermal Units.

SM Energy (SM) and Civitas Resources (CIVI) said they have signed a definitive merger agreement for an all-stock transaction. The deal values the combined entity at about $12.8 billion, inclusive of both companies' net debt, according to the companies. SM Energy shares fell more than 1%, while Civitas Resources shares were up more than 4% premarket.