BEIJING - Rules on start-ups exiting from the stock exchange take effect on Tuesday.

The Shenzhen Stock Exchange (SZSE) officially put into practice the de-listing system of the ChiNext Board, which started trading on October 30, 2009, to list hi-tech companies and those with high growth potential.

The amendments concerning stock de-listing have further clarified rules regarding trading suspension, trading termination, resumption of trading and other details.

An earlier statement from the SZSE said the amendments were aimed at enriching the ChiNext de-listing standard system and raising the standard for reviewing listing resumption.

A report of China National Radio said Tuesday that more than one fifth of the companies listed on ChiNext might be de-listed if they report losses for two consecutive years in line with the new regulations.

The amended rules would have zero tolerance on falsity when companies fail to make corrections after their financial reports evidently break accounting standards, the report said.

The ChiNext Index, together with the Shenzhen Component Index and the Shenzhen SME (small and medium-sized enterprises) Board Index, makes up the three core indices reflecting the performance of stocks listed on the SZSE.

Following announcement of the de-listing mechanism for ChiNext on April 20, the Shanghai Stock Exchange announced Sunday a draft proposal for improving its de-listing rules in a bid to protect investors and promote healthy development of the stock market.

Adjustments in the proposal include enriching de-listing criteria, simplifying de-listing procedures and creating a risk warning board and a board for equity sales before de-listing.

The current system for de-listing companies has drawbacks, including simple standards and a relatively long process.

The SZSE, the smaller of the country's two bourses, released a similar draft proposal for de-listing companies on its main board and its SME board.

Both bourses said they would solicit public opinions on the draft proposals till May 20.