(Bloomberg) -- Rio Tinto Group has made an approach for Arcadium Lithium Plc, the two sides said on Monday, confirming the latest takeover proposal in a sector turning its attention back to growth, as major miners scramble to increase their exposure to energy-transition metals.

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The world’s second-largest miner did not provide the financial details of its preliminary move but, if it goes ahead, a swoop for the battery-metal producer could shape up to be its most significant acquisition in well over a decade.

Large miners have been returning to takeovers and landmark investments, but with caution, given poorly timed and ill-conceived deals during the last commodities boom that left the companies — and their shareholders — dealing with billions in writedowns. BHP Group’s bid for Anglo American Plc earlier this year gripped the sector until the world’s largest miner walked away in May.

Shares in Arcadium rose 38% in New York on Monday morning, giving it a market capitalization of about $4.6 billion. Rio Tinto traded little changed in London.

Arcadium — one of the world’s largest lithium producers, with operations in Argentina, China, Canada and Australia — also did not elaborate on the bid. Some of its investors, however, have expressed concern over the opportunism of Rio’s timing. With a market cap of $3.3 billion as of the end of last week, Arcadium was worth half what it was at the start of the year when it was formed through the merger of Allkem Ltd. and Livent Corp.

Lithium mining stocks have languished since the start of the year as oversupply and weaker demand from electric-vehicle makers drag down prices of the key battery material. The spot price for lithium carbonate in China is down more than 85% from its peak in 2022.

Arcadium has also underperformed many of its peers, fueling speculation that it could become a target for bargain-hunting majors.

“Arcadium offers Rio Tinto a mix of vital characteristics that is difficult to replicate with other lithium companies,” said YueJer Lee, Singapore-based fund manager at Arcane Capital VCC, which owns shares in Arcadium Lithium. “It may be unwilling to accept any offer below $5 billion, in my mind, given that they can self-fund their expansions through the decade, albeit at a slower pace.”