(Anglo American/Supplied)

The board of Anglo American has unanimously rejected global mining giant BHP’s “opportunistic” proposed all-share takeover offer of the company valuing it at about R740 billion.

The board said in a statement on Friday morning that the proposal, which was conditional on Anglo first spinning off its South African platinum and iron ore assets, Anglo American Platinum and Kumba Iron Ore, “undervalues Anglo American and its future prospects”.

“Anglo American is well positioned to create significant value from its portfolio of high quality assets that are well aligned with the energy transition and other major demand trends,” Anglo chair Stuart Chambers said in the statement.

BHP’s play seems to be largely for Anglo’s copper assets. Chambers said in statement that copper represents 30% of Anglo’s total production. 

“With the benefit of well-sequenced and value-accretive growth options in copper and other structurally attractive products, the board believes that Anglo American’s shareholders stand to benefit from what we expect to be significant value appreciation as the full impact of those trends materialises.”

Chambers said the proposed structure is “highly unattractive” and creates uncertainty and risk that would be carried by Anglo, its shareholders and its other stakeholders. 

“The BHP proposal is opportunistic and fails to value Anglo American’s prospects, while significantly diluting the relative value upside participation of Anglo American’s shareholders relative to BHP’s shareholders,” Chambers said.

Some analysts had speculated that the offer may just be an opening one, and that another may follow.

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“Anglo American has defined clear strategic priorities – of operational excellence, portfolio, and growth – to deliver full value potential and is entirely focused on that delivery,” Anglo added.

Shares in the miner were only down about 0.7% on Friday morning, having rocketed by almost a fifth on Thursday. Shares in Kumba were up about 2.6% while Anglo American Platinum had gained about 3.9%.

Update: This article has been updated with share price information.