MCS, the registrar to the recent Oil and Natural Gas Corporation public offer, failed to upload the revised allotment files with depositories till late Wednesday evening.

Securities and Exchange Board of India board member AK Batra had said on Monday the issue would be regularised by Tuesday.

As a result, investors kept waiting for the shares to be credited before they could plan their next course of action, a top broker said.

MCS Director B Narsiman told Business Standard: "The entire allotment file for the qualified institutional investors and retail investors has been completed. The allotment file for high net-worth investors is yet to be completed."

National Securities Depository Ltd managing director CB Bhave said NSDL was yet to receive full allotment files from MCS, though files covering 4,500,000 records had been received and updated.

Meanwhile, the markets were abuzz that some investors had already whisked away the wrongly credited shares from their accounts before the entries could be reversed on Monday. A questionnaire sent to MCS on Wednesday, asking the registrar how it was addressing the issue of credits already utilised, failed to elicit a reply.

In a faxed response to a questionnaire sent on Monday, MCS said it had initiated a "damage control exercise immediately on receipt of investor complaints". It added that the company had immediately informed the depositories and requested them to reverse the credits.

However, sources in the depositories said, "MCS only responded after we informed them that certain accounts had been credited in excess of their allotments."

The depositories had received the first set of ONGC allotment files from MCS on Saturday, which were duly credited to the beneficiaries' accounts by Monday morning. By the time the incorrect entries were reversed, some of the newly-allotted shares had already been transferred out of the accounts.