Even as the deadline for decision on oil sector privatisation ends on Friday, the Securities & Exchange Board of India (Sebi) has come up with a disclosure that is likely to further complicate the issue of divestment. The capital market regulator has submitted to the Ministry of Finance and Company Affairs the list of top ten sellers of BPCL and HPCL scrips on the National Stock Exchange during the week preceding the meeting of Cabinet Committee on Disinvestment (CCD) on September 7.According to finance ministry officials, Sebi has informed the government that share prices of HPCL and BPCL fell sharply on September 9, after the CCD postponed decision on divestment in the two oil companies by three months. The deferment took place because of sharp differences between Disinvestment Minister Arun Shourie on the one hand and Petroleum Minister Ram Naik, Defence Minister George Fernandes and HRD Minister Murli Manohar Joshi on the other.The top ten net selling clients of BPCL scrips on NSE on the basis of net sell quantity for the period between August 23 and September 9 were: Sloane Robinson Investment Mgmt Ltd a/c (account) SR Global International Fund LP; Sloane Robinson Investment Management; Abu Dhabi Investment Authority; Stichting Pensionfonds ABP; Prudential ICICI Mutual Fund a/c Prudential ICICI Balanced Fund; Stichting Pension-KIA & IN-KU-FA-382-96; Government of Singapore Invst Corp; Prudential ICICI Trust Ltd a/c ICICI MF Balance; Alliance Mutual Fund; and HSBC Investment Bank (Netherlands) NV.The top ten net sellers of HPCL stock on NSE in the same period were: ORC Asia Ltd; Sloane Robinson Investment Management Ltd a/c SR Global (Mauritius) Ltd; Blackrock International Ltd; Baring Asset Management Ltd; Merrill Lynch Capital Market Espana SA SVB; Stichting Pension—KIA & IN KU-FA-382-96; OCBC Asset Mgmt; Prudential ICICI Trust Ltd a/c ICICI MF Balance; Morgan Stanley Dean Witter; and Government of Singapore Invst Corp.Sebi is enquiring the trading of BPCL and HPCL shares at NSE and BSE on the basis of information gathered from client level and exchanges. The stock watch system at exchanges generates prima facie alerts on securities based on significant deviations in price volume behaviour. The investigation departments of exchanges these alerts.In the cases where the investigation prima facie reveals the involvement of clients, promoters, etc, or where the activity spans more than one exchange, the exchange forwards the report to Sebi for necessary action. In the case of sharp fall in BPCL and HPCL shares, Sebi was informed by NSE as well as BSE. The Ministry of Disinvestment had also sought information on the transactions of these scripts in the said period.Sebi had sent the list of the top sellers of BPCL and HPCL. But MoD was not satisfied. It asked the market regulator to enquire into the matter and find out if any irregularity was involved.