Encana Corp., a big Canadian firm with substantial U.S. operations, said Thursday that it's buying Newfield Exploration in a $5.5 billion stock transaction.

Why it matters: The deal will make Encana one of the biggest shale producers in North America, according to Reuters. Newfield has a big position in Oklahoma's prolific Anadarko Basin, as well as acreage in Utah and North Dakota.

The big picture: It's the latest of several big deals in the U.S. sector this year.

• Earlier this week, Chesapeake Energy announced plans to buy WildHorse Resource Development in a $3 billion transaction.
• In August, the Permian basin player Diamondback Energy said that it's buying Energen via a $9.2 billion deal, while Concho Resources announced the $9.5 billion acquisition of RSP Permian in March.
• BP announced a $10.5 billion deal to acquire most of BHP Billiton's U.S. shale assets in July.