Mining behemoth BHP (BHP.L) is leaving the FTSE 100 index (^FTSE), as it plans to scrap a dual listing of its shares in Sydney and London. 

The move comes after two decades as part of the index. BHP will move its main listing to Australia following an announcement on Tuesday, with a secondary listing on UK markets. 

As a result of the move, many UK investors will be forced to sell their holdings. 

The industry giant is the world's biggest mining company and is a huge player in the market, regularly topping the charts in terms of market value.  

The company's chairman Ken MacKenzie said the move would serve to "unify BHP's corporate structure."

The company's stock was 5.2% lower by 1pm on Wednesday in London.

"Our plans announced today will better enable BHP to pursue opportunities in new and existing markets and create value and returns over generations," said MacKenzie. 

The delisting proposal comes just days after the company said it would be extracting itself from fossil fuels, merging its oil and gas assets with Australia's Woodside (WPL.AX). The company will shift towards commodities such as copper and nickel. Its thermal coal mine is also up for sale. 

Read more: European markets open higher after a day of selling

It is the second corporate giant to abandon a dual structure in London in the past five years — Unilever (UNA.AS) chose to simplify its own structure, opting for an Amsterdam listing, prompting speculation about Brexit flight.

BHP's move will make dealmaking easier for the company, as well as decarbonising and net-zeroing its output. 

Although it will also spark worry in UK investors, at a time when politicians and officials are looking to make London a more attractive place to list.

According to the Financial Times, BHP ended Tuesday as the second biggest company on the London Stock Exchange with an equity market value of more than £129bn ($177.5bn), just behind AstraZeneca (AZN.L) at £133bn.

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