Shareholders at mining giant Rio Tinto have decisively voted down a proposal to examine dismantling the company’s dual-listed structure, which currently spans both London and Sydney.

The proposal, advanced by London-based activist investor Palliser Capital, sought to merge Rio Tinto’s operations under a single Australian holding company. Palliser has argued that such a move could unlock an estimated $28 billion in value for the holders of Rio Tinto’s London-listed shares.

Votes were cast by Australian shareholders on Thursday, following a separate vote at the London annual general meeting on April 3. Although around 77% of Rio Tinto’s investors are based in the UK, the company’s Australian shares trade at a roughly 25% premium, in part due to local tax benefits.

Despite support for the motion from major proxy advisers Institutional Shareholder Services (ISS) and Glass Lewis, as well as backing from more than 100 investors including Norway’s sovereign wealth fund, Norges Bank Investment Management, the proposal failed.

Rio Tinto reported that over 80% of shareholders opposed the motion, aligning with the board’s unanimous recommendation against it. Only 19.35% voted in favor, narrowly missing the 20% threshold that would have triggered a broader consultation process under UK rules.

The company defended its current structure, arguing that a unified listing is unnecessary to preserve strategic flexibility and noting potential tax complications.

Palliser’s campaign follows the example of mining rival BHP, which scrapped its own dual-listed setup in 2022, years after pressure from activist fund Elliott Management.

Rio Tinto, in a statement, said it remains committed to engaging with shareholders and will carefully consider the feedback provided.