North American drillers drove large-scale oil and gas M&A deal-making in May, according to S&P Global Market Intelligence data.

During the month, the sector announced 32 whole-company and minority-stake deals, compared to 22 in May 2020. The combined value of the deals soared year over year, from just under $625 million in May 2020 to $11.54 billion this year.

The aggregate value of announced asset transactions also rebounded significantly from roughly $774 million to $8.59 billion as the number of deals more than doubled from 22 to 46.

The biggest deal proposed during May was the $9.06 billion all-stock merger between Marcellus Shale gas driller Cabot Oil & Gas Corp. and Permian Basin shale oil producer Cimarex Energy Co. The deal, which surprised some observers, represents the second-largest industry transaction of 2021 so far.

Cimarex Chairman, President and CEO Tom Jorden, who will become CEO of the combined company, hinted that the Marcellus-Permian hookup might just be the start of deals.

"We're going to continue to be on the hunt," Joirdan said during a May 24 conference call.

Appalachian shale gas giant EQT Corp.'s nearly $3 billion acquisition of assets belonging to Blackstone Group Inc.-backed Alta Resources LLC was the second-biggest North American transaction announced during the month, followed by a $745 million sale of Diamondback Energy Inc.'s Williston Basin assets to Oasis Petroleum Inc.

Upstream and midstream consolidation in the U.S. and Canada has ramped up substantially in recent months, with some drillers forgoing intra-basin deals in favor of noncontiguous footprints.