Sebi is expected to bring about changes in the three-tier margin system to a general margin system with another slab for volatile scrips.

"There has been a demand to simplify the margin system and the Sebi is inclined to make the margins more simpler," Sebi chairman DR Mehta said on the sidelines of a seminar here. A Sebi-panel on risk management comprising market experts from domestic and foreign brokerage houses are meeting on April 7 to decide on the issue, Mehta said.

Mehta said Sebi would soon put an end to the controversy over the appointment of Gujarat Ambuja Cement nominees on the board of Associated Cement Company (ACC). "We are consulting legal experts on the issue and would soon take a decision," Mehta said. The controversy arose after Gujarat Ambuja Cement appointed its nominees on the board of ACC immediately after the former bought 7.2 per cent stake held by Tatas in ACC. Mehta said that Sebi is looking into whether the appointment amounted to a change of management.

Currently, the stock exchanges attract various types of margins like mark-to-market, cross-exposure and volatility margins. Mehta said the total margins on scrips ranging between 35-45 per cent on an average, may come down after the rationalisation of margins.

Volatile scrips carry high margins and in some cases even 65-70 per cent and the committee would take a final view on this matter. Senior executive directors of Sebi, Pratip Kar and LK Singhvi are members of the risk management committee.

Mehta said that the stock exchanges had sought more time for a change-over from the eight per cent circuit breaker system to 12 per cent as the required software was not ready.

He said that Sebi would continue to add more scrips into the rolling settlement format, where share transactions are settled on a daily basis.

"We are going to add more scrips into the rolling format," the Sebi chairman said. Over 160 scrips would come into the rolling format from May 10. It is likely that more scrips would be added into the rolling settlement before may 10. Defending the claim that the volume of trades were coming down in scrips that have been put on the rolling system, Mehta said the volume of transactions have gone up over a period of time. "The volume of trades in speculative category have come down," he said adding that the delivery-based transactions have gone up in the scrips on the rolling format.