"The shift of NSE’s expiry day from Thursday to Tuesday is expected to help the exchange claw back market share from rival BSE, which had seen a surge in its index derivatives volumes since its previous shift to Tuesday expiry earlier this year. BSE’s share in index options rose to 12.6 per cent from 3.1 per cent a year ago, with premium turnover climbing to around 22 per cent now from 16 per cent in December 2024.
However, Goldman Sachs expects BSE’s market share in premium turnover to drop by 3-4 percentage points with its return to Thursday expiries—down to 18.8 percent from the current 22.2 percent."