The stock connect program between the Shenzhen and Hong Kong bourses, which has just celebrated its fifth anniversary on Sunday, is a role model for two-way opening-up in China's capital market, market insiders said.

The accumulated trading value of the stock connect mechanism reached 41.9 trillion yuan ($6.6 trillion) over the past five years, with the annual growth rate topping 94 percent, the Shenzhen Stock Exchange said on Sunday.

With the stock connect program, international investors are provided with access to invest in Chinese companies specializing in new materials, new energy, biomedicine and new-age information technology, the Shenzhen bourse said.

To date, international investors have held up to 1.3 trillion yuan worth of A shares through the stock connect program, equal to 4.2 percent of the entire A-share market value.

On the other hand, Chinese mainland investors have also held up to HK$1 trillion ($128 billion) worth of Hong Kong-listed stocks, injecting more vitality into the local market and consolidating Hong Kong's role as a world financial center, the Shenzhen bourse said.

With the connectivity mechanisms linking Chinese mainland and Hong Kong markets, such as the Shenzhen-Hong Kong stock connect program, the Hong Kong Special Administrative Region, as a world asset and wealth management center, has become an important hub where Chinese mainland investors can make overseas asset allocations, said Daniel Chan, head of the Greater Bay Area for HSBC.

Vibrant trading in both directions can be largely attributed to improving trading rules. Since May 2018, the daily limit for international investors to buy A shares via the stock connect program has been lifted to 52 billion yuan from 13 billion yuan. Likewise, the quota for Chinese mainland investors buying Hong Kong stocks has been quadrupled to 42 billion yuan.

The expanded daily trading quota has helped the A-share market in its inclusion into world benchmark indexes such as MSCI and FTSE Russell. It has also demonstrated China's confidence in further opening up its capital market, the Shenzhen bourse said.

Nicolas Aguzin, CEO of Hong Kong Exchange and Clearing, said in a letter released in June that cross-border capital flows between China and international markets will continue to grow. Perfectly placed through the stock connect programs and the close ties with Chinese mainland exchanges, HKEX can help support the exponential increase in cross-border capital inflows.

The trading targets under the stock connect program were enriched over time.

Companies with a weighted voting rights structure which are listed in Hong Kong were allowed to be included in the Shenzhen Hong Kong stock connect program in August 2019, with biomedicine companies included this September.

For companies listed on both the STAR Market at the Shanghai exchange as well as the Hong Kong bourse, Chinese mainland investors were allowed to buy the corresponding Hong Kong shares via the stock connect program. The measure took effect in February this year.

Yi Huiman, chairman of the China Securities Regulatory Commission, said at the annual meeting of the World Federation of Exchanges in September that efforts are being made to further expand targets under the stock connect programs. There are also many other opening-up measures in the pipeline to provide more efficient, convenient and fair services to overseas investors.

The Shanghai-Hong Kong stock connect program, which was the first of its kind launched in the country, kicked off in November 2014. The stock connect mechanism between the Shenzhen and Hong Kong exchanges started in 2016.