The Chinese mainland will likely announce the launch of the much-anticipated stock trading link between the Shenzhen and Hong Kong exchanges in the second quarter of the year, further opening the mainland's stock market to overseas investors, a senior analyst at UBS Securities said on Wednesday.

If the link is launched this year, it would mean that about 70 percent of market capitalization of the A shares will be available to overseas investors who already gained access to the mainland market through the existing Shanghai-Hong Kong Stock Connect, said Gao Ting, chief China equities strategist at UBS Securities.

The link will broaden investors' stock selection in the mainland as the Shenzhen market, unlike Shanghai, is home to many high-tech, innovative companies and private firms with high growth potential, Gao said.