mumbai, July 9 -- The stock market regulator may revise the weekly contract expiry schedule if its recent measures fail to cool the index options fever, a person aware of the matter said. Among the plans under consideration: Expiry every fortnight against the weekly system now, and only one expiry in a fortnight against twice a week now. "Certain additional measures on position limits and changes in the calculation of open interest on index futures and options took effect this month," the person cited above said on the condition of anonymity. Position limit refers to exposure a participant can take in index derivatives, while open interest refers to an outstanding buy or sell position. "Sebi will examine if the recent measures bring down the volumes meaningfully over the next few weeks. If the volumes don't dip or dip only marginally, more proposals, like doing away with weekly expiry in favour of, say, fortnightly expiry, and having just one benchmark index expiry per fortnight from two per week now could be discussed within the regulatory apparatus before a decision is taken. This could happen sooner than later through a consultative approach," the person said. The Securities and Exchange Board of India (Sebi), which had issued multiple measures in October to calm the exuberance in options, followed up with additional steps in May this year. Queries sent to a Sebi spokesperson remained unanswered. The plan for fresh measures comes against the backdrop of Sebi's interim order against Jane Street for alleged manipulation in index options on expiry day. The regulator has ordered the seizure of Rs.4,844 crore of allegedly unlawful gains by the US proprietary trader, which is expected to respond to the regulatory order soon....