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Bank Nifty expiry change: Are regulators getting whiff of concentration risk?

A joint statement says that BSE requested NSE to consider shifting of the Bank Nifty expiry to any day other than Friday, as it would otherwise potentially impact the growth of Sensex or Bankex derivatives

September 26, 2023 / 12:46 IST
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A joint press release from BSE Ltd and the National Stock Exchange, announcing a change in the expiry day for Bank Nifty back to Thursday from Friday, has surprised the market. It was less than a month since the day was changed and it is now being reverted.

The first change by the NSE—from Thursday to Friday—had sparked chatter in the matter. BSE insiders alleged that the move was aimed at killing volumes in its (BSE) derivatives segment just when it had introduced weekly options contracts in the Sensex and Bankex. NSE insiders claimed the change was a response to feedback from market participants that the Nifty and Bank Nifty should have different expiries, as it would allow them to focus better.

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But the second change is intriguing, to say the least, and the press release makes for interesting reading. It says that the BSE requested the NSE to consider shifting of the Bank Nifty expiry to any day other than Friday, as it would otherwise potentially impact the growth of Sensex or Bankex derivatives. Obviously, the NSE would have known the effect of its decision to move Bank Nifty expiry to Friday would have on BSE’s derivatives segment. That’s because one of the unique selling propositions of BSE’s weekly index options was that its expiry was on a day when there were no other contracts expiring.

And this line too is puzzling: “Considering the need for balanced market development and avoidance of concentration risk in the market, BSE has requested NSE to consider shifting of the Bank Nifty expiry to any day other than Friday.” The NSE has agreed to the request and shifted the expiry of Bank Nifty back to Thursday.