Revised lot sizes for index F&O contracts to kick in tomorrow. Here’s what you need to know

Traders in the futures and options (F&O) segment are advised to take note that the revised lot sizes for Nifty, Bank Nifty, and two other index derivatives, as per an earlier NSE circular, will come into effect starting January 2026 contracts.

While the National Stock Exchange (NSE) had announced the changes earlier, these will now be implemented from the expiry cycle following December 2025, impacting all contracts in the January 2026 series and beyond.

As per the revised framework:

• Nifty 50 lot size will be reduced from 75 to 65 units
  
• Bank Nifty will see a change from 35 to 30 units
  
• Nifty Financial Services will move from 65 to 60 units
  
• Nifty Midcap Select will be revised from 140 to 120 units
  

The lot sizes for other indices, including the Nifty Next 50, will remain unchanged.

This adjustment will not affect the weekly and monthly contracts expiring in December 2025, which will continue to be traded under the current lot sizes. The revised sizes will apply from the January 2026 weekly and monthly expiries, including longer-dated contracts such as quarterly and half-yearly derivatives.

For weekly derivatives, the final contract to follow the existing lot sizes will expire on 23 December 2025. The revised lot sizes will take effect from the next weekly expiry on 6 January 2026.

In the case of monthly contracts, the updated lot sizes will be applicable starting with the 27 January 2026 expiry, following the 30 December 2025 expiry, which will be the last to use the current structure.

Additionally, NSE confirmed that quarterly and half-yearly contracts will also adopt the revised lot sizes from end of day, 30 December 2025. The March 2026 contract, which was originally launched as a quarterly expiry, will be treated as a far-month contract under the new lot size regime starting from the end of the December 2025 monthly cycle.

These periodic revisions by the NSE are aimed at aligning notional contract values with prevailing index levels, maintaining efficient market functioning, and ensuring manageable position sizing for retail and institutional traders alike.

Market participants are advised to review their open positions and risk exposure as the transition approaches. Brokers are also expected to reflect the updated lot sizes on trading platforms and margin calculators in time for the January series.

Also read: Kotak Mahindra Bank fixes January 14 as record date for upcoming stock split

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