The Calcutta Stock Exchange, yet to recover from the Rs 120 crore (Rs 1.2 billion) payment default that hit the bourse in 2001, was facing another crisis with top officials, including its president Supriya Gupta, stepping down following a showcause notice served by Securities and Exchange Board of India on the governing committee.

The market regulator, in its notice served late on Tuesday, asked the board why the exchange governing committee should not be superseded by Sebi in view of its 'management deficiencies'.

With the resignations of Gupta and three public representatives on the Board -- Biswajit Choudhuri, B B Chakraborti and former Justice Prabir Mazumdar -- the exchange was now headless amidst apprehensions that Sebi might actually decide to supersede the CSE management, market sources said on Wednesday.

They said it would be a huge blow for CSE, which witnessed a sharp fall in turnover since March 2001, deepening the crisis for the beleaguered exchange.

After the resignations, which were accepted by the board on Tuesday, the exchange is left with a 10-member board comprising the officer-on-special-duty, seven brokers and two Sebi nominees.

Sebi's notice, served under Section 11(1) of the Securities Contract (Regulation) Act, 1956, came in view of the board's failure 'to conduct its meetings and deliberations in a proper and responsible manner' and apparent resistance of broker-directors to the demutualisation of the exchange.