The BSE will reportedly retain weekly derivative contracts linked to the benchmark Sensex after the Securities and Exchange Board of India (Sebi) tightened rules for trading in futures & options (F&O).

The market regulator rationalised weekly index derivatives when it mandated that exchanges can offer derivatives contracts for only one of its benchmark index with weekly expiry.

Weekly expiry index derivatives contracts are offered by stock exchanges apart from monthly contracts.

However, Sebi found there is expiry of such weekly contracts on all five trading days of the week across different indices or exchanges that led to speculation shifting from one expiry to another.

The rationalisation of weekly index derivatives products will be implemented from November 20.

BSE runs two contracts linked to indices — BSE Sensex and BSE Bankex.

A Reuters report said the Sensex contract has much larger volumes than Bankex and it made more sense to retain the more active contract.