Treasury Wine Estates, the maker of Penfolds and Wolf Blass, has built up a powerhouse business selling into China which analysts estimate is worth $4 billion alone after six years of robust growth.

While Treasury also operates large businesses in Australia and North America, it is the Asian operations, of which China makes up the lion's share, that drove the share price to beyond $19 in late 2019. Investors anticipated the thirst for luxury wine by affluent Chinese would keep expanding, but that has unravelled in a major way since August.