Under the Z-category, the exchange -- which has been struggling to recover from the price rigging exercise last year -- has already put 300 companies in this segment, according to BSE president Anand Rathi. However, BSE would not delist the companies violating the listing norms from the exchange as this would not be in the interest of investors of these companies.

Currently, there are three major categories on the BSE. While major highly traded companies are in the A group, the others are categorised in B1 and B2 groups with all dud and thinly traded shares going in the B2 group.

Rathi said every month BSE would publish a list of 30 companies placed under the notorious Z-category. He said the category has been created to force these erring companies to correct their practices. Moreover, it will be asignal to the investors about companies involved in bad corporate practices like failure to finalise accounts, non-redressal of complaints.

"We have already received request from companies placed under the category for removing them from this segment saying they have resolved investor complaints and abide by listing norms," the BSE president said.

The exchange has also constituted three awards for companies adopting best corporate governance practices and creating value for its shareholders. These three awards include -- company with the best corporate governance, most investor-friendly company and firms maximising wealth for shareholders.

Meanwhile, in an attempt to punish erring companies, the BSE has decided to issue winding up notices to 163 companies. "We have already filed winding up petition against 163 companies which have not paid the listing fees and have large number of investor complaints against these companies," Rathi said.

In order to check price manipulation, the BSE has set-up anon-line surveillance system which would track the price movement of all the scrips traded on the exchange. He said the exchange has invested about Rs 6-7 crore in the sophisticated system which would be operational by the end of this month.