Stock exchanges in Hong Kong and Shanghai kicked off trading Monday on a cross-border stock link that will allow foreign investors wider access to mainland China's tightly restricted equity market.

Officials in both cities banged gongs to mark the start of trading under the Shanghai-Hong Kong Stock Connect platform, which lets investors buy and sell shares through each other's exchanges.

"Today we are going to witness history," C.K. Chow, the chairman of stock exchange operator Hong Kong Exchanges and Clearing, told guests at an opening ceremony. "It is a breakthrough in the opening up of China's financial markets and an important milestone in the development of Hong Kong as a unique gateway between the mainland and international investors."

The stock connect will give all sorts of investors outside mainland China access to the stock market in the world's No. 2 economy for the first time.

Until now, access has been closely managed, mainly through a quota program for select fund managers representing a fraction of the overall market.

The trading link also gives wealthy Chinese investors access to a market outside of the mainland for the first time.

Investors will be permitted to buy and sell a total of up to 23.5 billion yuan ($3.8 billion) of stocks in a select list of companies each day. Up to 10.5 billion yuan of that daily quota goes to mainland Chinese investors, with the rest going to Hong Kong.

Hong Kong has officially been a part of China since Beijing took control of the former British colony in 1997 but the Asian financial hub retains its own separate legal and financial system and currency.