Hang Seng Indexes has said it will launch a cross-market China index to measure the performance of shares of the country’s 50 biggest companies, whether they are listed in Hong Kong or on the stock exchanges of Shanghai or Shenzhen.

The index provider said it would start publishing the Hang Seng China 50 index in real time from June 30. It hopes to simplify the process of assessing Chinese companies, which has been complicated by the “one country, two systems” legacy of the 1997 Hong Kong handover.