The super-sizing of BHP within Australia’s flagship market indices will occur in a single trading session if the company’s structure is unified next week, despite index manager S&P Global conceding the change would create “material” turbulence on the local market.

BHP’s weighting in the benchmark S&P/ASX200 index will rise to about 10 per cent from about 6.2 per cent if shareholders approve a plan for the miner to consolidate its dual-listed company structure within a single Australian-listed company.