The Securities and Exchange Board of India (Sebi) has instructed the Bombay Stock Exchange (BSE) to pay a regulatory fee based on the annual turnover fee, taking into account the "notional value" in the case of options contracts. BSE, in response, disclosed that Sebi has also demanded payment of a differential regulatory fee for past periods, with 15% per annum interest on delayed payments. This move comes under Sebi's regulations, where exchanges must pay the fee within 30 days after the conclusion of a financial year.