It is one of the many oddities related to investing in China-related equities that portfolio managers often draw on both atlas and alphabet when thinking about stocks.

Chinese companies are listed on exchanges all over the globe. But Beijing permits foreigners to trade the 1,620 stocks listed on its domestic exchanges in Shanghai or Shenzhen only if they hold special licences. Those licences give them access to quotas of individual stocks, worth on average $100m-$200m each - still too small to make a genuine difference to global fund managers.

Shares listed on domestic exchanges are classified into two types, A and B. The former, originally for local investors only, are the most common, although a few domestic companies continue to list B shares, previously the only kind that foreigners could trade.