OZ shareholders today received $28.25 cash per share comprising $26.50 from BHP and a fully franked special dividend of $1.75 per share.

BHP has funded the deal via existing cash reserves and the proceeds of a debt facility.

The acquisition gives BHP ownership of the Prominent Hill and Carrapateena copper-gold mines in South Australia, the Pedra Branca copper-gold mine in Brazil, the large West Musgrave nickel-copper development project in Western Australia and a number of earlier stage development projects.

"This acquisition strengthens BHP's portfolio in copper and nickel and is in line with our strategy to meet increasing demand for the critical minerals needed for electric vehicles, wind turbines and solar panels to support the energy transition," BHP CEO Mike Henry said.

"Combining our two organisations will provide options for growth, bring new talent and innovation to unlock these resources in a sustainable way, and deliver value to shareholders and communities."

BHP chief operating officer Edgar Basto said the deal brought together two companies with shared values of safety, respect, innovation and performance.

"South Australia has the potential to be a major supplier of copper to meet the world's increasing demand for copper and we look forward to unlocking the potential of our people and their combined talent. This will require new thinking and new technology and we are excited to begin work on the opportunities ahead."

UBS noted that the universe of ASX-listed copper stocks was now smaller.

"While Sandfire Resources is the standout mid-cap copper play, BHP leads ASX listed large-caps on copper EBITDA, copper percentage of EBITDA, copper share of net present value, copper production and revenue share," it said.

UBS retained a sell rating for BHP and price target of $39. BHP closed 0.9% lower at $43.79.