Herbert Smith has won a role on what is set to be the world’s largest-ever initial public offering (IPO) as the Agricultural Bank of China (AgBank) goes public.

The UK top 10 firm is advising the underwriting banks on the landmark listing, which was initially valued at as much as $30bn (£20.2bn), although market estimates have since been tempered by a drop in China’s stock market, with a figure of $23bn (£15.5bn) now thought to be more likely.