New Delhi, March 10 -- The Securities and Exchange Board of India (Sebi) introduced curbs on options trading with the aim of cooling down market frenzy on expiry day. However, instead of merely slowing down trading excesses, these measures have triggered fresh rivalry between the NSE and the BSE.

Despite the regulatory crackdown, the overall impact on trading volumes has been minimal. Data from the two stock exchanges reveal that index and stock options' premium turnover declined by less than 3% in the six months leading up to March 7, compared to the corresponding period in the previous fiscal year.

A closer look at the numbers shows that this limited drop is largely due to a surge in options trading on the BSE, albeit on a significant...