Fno-Segment - Stock Market Circularshttps://rhnvrm.github.io/stock-market-circulars/tags/fno-segment/Regulatory circulars from NSE, BSE, and SEBI with AI-powered summariesHugo -- gohugo.ioen-usTue, 21 Apr 2026 00:00:00 +0000NSE F&O Segment: Total Volume Field Size Expanded in Final Bhav Copy Formathttps://rhnvrm.github.io/stock-market-circulars/circulars/nse/2026/nse-2026-04-21-acf9565c3fb1e475-modification-to-consolidated-circular-part-d-annexure-9/Tue, 21 Apr 2026 00:00:00 +0530https://rhnvrm.github.io/stock-market-circulars/circulars/nse/2026/nse-2026-04-21-acf9565c3fb1e475-modification-to-consolidated-circular-part-d-annexure-9/NSE modifies Part D Annexure 9 of the F&O consolidated circular to expand the Total Volume field size from char(10) to char(17) in the Final Bhav Copy (DDMM0000.md) file, effective May 9, 2026.nsemarket-operationsmediumlowlowacf9565c3fb1e475https://nsearchives.nseindia.com/content/circulars/FAOP73824.pdffutures-optionsbhav-copyfile-formatdata-formatfno-segmenttechnical-changemarket-operationsSummary

NSE’s Futures & Options segment has issued a partial modification to Part D Annexure 9 of the F&O consolidated circular (NSE/FAOP/67775, dated April 30, 2025). The change expands the Total Volume field (field number 12) in the Final Bhav Copy file (DDMM0000.md) from char(10) to char(17). All other fields and the overall file structure remain unchanged. The effective date for live implementation is May 9, 2026, preceded by a mock run.

Key Points

  • Only one field is modified: Field 12 – Total Volume, size increased from char(10) to char(17)
  • File nomenclature (DDMM0000.md) and all other fields remain unchanged
  • Change is in Part D, Annexure 9 of the F&O consolidated circular
  • Reference base circular: NSE/FAOP/67775 dated April 30, 2025
  • Circular Ref. No: 48/2026; Download Ref: NSE/FAOP/73824

Regulatory Changes

Partial modification to Part D of the F&O Consolidated Circular:

Annexure File Field No. Field Name Current Size Revised Size
9 DDMM0000.md 12 Total Volume char(10) char(17)

No structural or format changes beyond the above field size expansion.

Compliance Requirements

  • All members and their technology vendors who parse or ingest the Final Bhav Copy (DDMM0000.md) file must update their systems to accommodate the expanded Total Volume field size (char(17)) before the effective date
  • Systems with fixed-width or strict-length parsing logic for field 12 are at risk of data truncation or processing errors if not updated
  • Members should test their updated systems during the mock run period prior to May 9, 2026

Important Dates

  • April 21, 2026 – Circular issued
  • May 9, 2026 – Effective date of implementation (mock run precedes live go-live)

Impact Assessment

This is a technical operational change with moderate impact on member back-office and data systems that consume NSE’s F&O Final Bhav Copy file. The field size expansion from 10 to 17 characters for Total Volume suggests increasing trade volumes in the F&O segment have exceeded the previous capacity of the field. Members using automated data pipelines, risk systems, or reporting tools that parse this file must update their field definitions before May 9, 2026 to avoid data integrity issues. There is no change to trading rules, margins, or compliance obligations.

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