New Delhi, July 31 -- Jane Street. When the name surfaced in the financial press, it looked like a new designer clothing label. I discovered it was a trading house which had come into focus at the Securities and Exchange Board of India (Sebi), the equity market watchdog, for alleged manipulation.

In focus was something called a Bank Nifty weekly options index (now closed), but there remain other weekly indices, run by the National Stock Exchange and Bombay Stock Exchange. Having never engaged with the stock market, either financially or academically, I had never peered at those instruments. But the compelling reason for not neglecting them now is that index options have entered the pages of the half-yearlyFinancial Stability Report (FSR)...