BEIJING (TheStreet) -- If China makes good on its latest market liberalization plan, Hong Kong investors next fall will be trading Shanghai-listed stock and vice versa -- more than seven years after regulators introduced a similar plan and promptly shelved it.

That's right: seven years. The so-called "through train" scheme for allowing and then streamlining cross-border stock trades announced Thursday in Beijing has been gathering dust on a government shelf since 2007.

And more dust will gather. Officials still "need six months of preparation time" before a formal launch, according to the China Securities Regulatory Commission, which announced the plan jointly with the Hong Kong Securities and Futures Commission.

Thus the program, dubbed Shanghai-Hong Kong Stock Connect, will probably start in October, although officials have not set a firm timetable.

Hong Kong's Hang Seng Index (^HSI) closed at 28,186.96 on Thursday, up 1.5% for the day. The Shanghai SSE Index (000001:Shanghai) closed at 2,134.30, up 1.4% for the day. 

The China Securities Regulatory Commission called the plan a "pilot" project to let mainland investors use their yuan currency to trade shares on the Hong Kong Stock Exchange, and to allow non-Chinese investors with Hong Kong brokers to trade on the Shanghai Stock Exchange. The scheme was first proposed in August 2007 and dropped the following month.

Back then, the government said regulators needed more time to write guidelines for controlling mainland investors' access to overseas markets, including Hong Kong. Since then, Chinese have been allowed to access foreign stock markets only through specially licensed funds.

Financial regulators at agencies such as CSRC, the China Banking Regulatory Commission and the People's Bank of China are famous for moving slowly. Market reforms in areas such as interest rate liberalization and foreign exchange rate controls, for example, started years ago and are still evolving.

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But the Hong Kong/Shanghai market-access "through train" -- an expression coined in 2007 and still used today -- has been particularly slow in coming.

The CSRC announcement coincided with a speech by Prime Minister Li Keqiang at an economics forum on southern China's Hainan Island, where he promised to ease barriers separating mainland and Hong Kong capital markets.

It also followed a scoop last week by the 21st Century Business Herald, a mainland newspaper, that said the long-awaited through train's arrival was imminent.

CSRC said the project is designed "to promote the common development of the mainland and Hong Kong capital markets." A research report by market analyst Z-Ben Advisors said the "implications will be wide-reaching for investors on both sides of the border."

Under the plan, the value of all trades targeting Hong Kong shares by mainland investors will not be allowed to exceed 10.5 billion yuan on a single day. Trades into the Shanghai market won't be allowed to top 13.5 billion yuan per day. CSRC said only shares indexed on the Hang Seng Composite Large Cap or Mid Cap or on the Shanghai SSE 180 or 380 would be eligible for trades.

According to Z-Ben, most brokers currently eligible to handle the kind of two-way stock trading to be allowed under the scheme are Chinese firms with Hong Kong affiliates. The only foreign brokers eligible at this time are subsidiaries of UBS Securities (UBS) - Get UBS Group AG Report and Goldman Sachs (GS) - Get Goldman Sachs Group, Inc. (GS) Report.

The original plan floated in 2007 called for letting any mainland resident buy Hong Kong stock only through an account set up at a single branch of the Bank of China in the city of Tianjin. That proposal prompted intense lobbying by officials in other cities around the country that wanted regulators to include their local banks, too. A few weeks later, the plan was shelved.

At the time of publication, the author held no positions in any of the stocks mentioned.

This article represents the opinion of a contributor and not necessarily that of TheStreet or its editorial staff.