BHP Group’s bold bid to buy rival Anglo American in 2024 was supposed to set it up as the clear winner in a copper boom it had long predicted. Two years later, the copper market is indeed booming. And yet the world’s biggest miner is left sitting on the sidelines of an M&A frenzy it began.

People familiar with BHP’s thinking said the news that Rio Tinto Group and Glencore are closer than ever to a deal that would leapfrog BHP to become the world’s most valuable mining company has caused consternation within the Australian mining giant. However, some of the people played down the likelihood that it would respond with a move for Glencore, and said it’s watching from the sidelines for now.

Instead of cementing its clear lead over Rio and others, the failed attempt to buy Anglo helped create the conditions for two big tie-ups among its major rivals. Anglo itself agreed last year to merge with Canada’s Teck Resources, and now Rio’s prospective deal for Glencore threatens to create an even more powerful competitor at a time when BHP is also contending with a mounting dispute over iron-ore sales to its most important customer, China.

BHP surprised investors with a half-hearted last-minute bid to crash the Anglo-Teck deal late last year, fueling questions about its strategy after CEO Mike Henry earlier said the company had moved on from Anglo.

And a response to the Rio-Glencore talks would be even more complicated: BHP and Glencore are two of the largest miners of metallurgical coal, meaning any merger would certainly run into antitrust issues — although BHP could theoretically make an offer for the whole of Glencore and then decide to sell or spin off the coal assets to get regulatory approval for a deal.

Henry is also nearing the end of his tenure, potentially hindering the negotiation of a transformational deal.

The company is monitoring the Rio-Glencore talks and reviewing the situation and options with its advisers, the people said.

“If Rio combines with Glencore, and you’ve already got Anglo and Teck in play, BHP risks being left behind,” said Iain Pyle, senior investment director at Aberdeen Group, which holds shares in Rio and BHP. “There aren’t many other ways to gain copper scale.”

BHP declined to comment.

Henry has long preached a mantra of M&A discipline, gradually warming investors back up to dealmaking after a series of disastrous deals at the top of the last cycle. He walked away from his bid for Anglo in 2024 after demanding that the smaller miner spin off its South African businesses as a condition of any deal.

Today, thanks to a restructuring along the lines that BHP had proposed, a copper boom much like the one it had been predicting, and the deal with Teck, Anglo is worth about $52-billion — more than the offer that BHP walked away from.

“I think they’ve got to look very closely and think about it,” George Cheveley, a portfolio manager at asset manager Ninety One and former analyst at BHP, said of the prospect of a BHP bid for Glencore. However, BHP “may find it difficult emotionally after their failure to close a deal with Anglo American,” he said.

The combination of Glencore and Rio would likely exceed BHP in copper mining scale and could surpass Chile’s Codelco to be the world’s largest copper miner. Anglo Teck would also become one of the world’s largest copper miners, though still somewhat smaller than BHP, according to the two companies’ presentation announcing the deal.

“There are many in the market who feel BHP cannot afford to sit and watch all the other consolidation that is going on,” Mark Kelly, who runs merger arbitrage specialist MKI Global Partners in London, said in a note to clients. “BHP has obviously said repeatedly it doesn’t need to acquire, but there was talk in mining circles all last year about Glencore beautifying itself to attract both BHP and Rio, thus hopefully extracting the best price in any sale.”

Glencore has a market capitalisation of about $73-billion, compared with $158-billion for BHP, while Rio is valued at $138-billion.

A merger of Rio Tinto and Glencore would almost certainly put the combined company out of BHP’s reach for antitrust reasons. But Anglo-Teck could yet be an attractive target if and when the two companies’ merger is complete.

“It’s not obvious that this is the only thing they’ve got. There are other things that can happen,” said Cheveley. “To panic and pile in over the top of this one is not what you want to do.”