Mumbai: Trading in one of the country's most popular equity derivative contracts came to an end with the Nifty Bank's weekly futures and options expiring on Wednesday. With the Securities and Exchange Board of India requiring stock exchanges to offer weekly derivatives on only one index per exchange, NSE opted to scrap the Nifty Bank weekly contracts and chose to retain Nifty's.The cut-off date set by the regulator to discontinue weekly derivative contracts is November 20. "The move of Nifty Bank derivatives to the monthly contracts is a big step towards mitigating risk for the retail investors as the volatility is expected to go down and reflect the underlying fundamentals of the companies in a better way," said Vaibhav Sanghavi, chief executive officer at ASK Hedge Solutions. "While volume will shift to both Nifty and Sensex weekly contracts, the monthly Bank Nifty derivatives might also see more momentum.The Nifty Midcap Select contracts will be available till November 18, while Nifty Financial Services contracts will be discontinued from November 19.On the BSE, the weekly index derivatives contracts on Sensex 50 will be discontinued with effect from November 14. Weekly contracts of BSE's Bankex will also be discontinued from November 18.Both exchanges have retained the weekly derivatives contracts for their benchmarks, Nifty 50 and Sensex.