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Material changes, corrections and additions, newest first.
A reference work earns trust by showing its scars. This page logs material changes: corrections to formulas or figures, new concepts added, and revisions that change the meaning of a page. Cosmetic edits and typo fixes are not logged.
18 July 2026 — NSE lot sizes and F&O expiry day corrected
Two NSE regulatory changes were applied across the library. Lot sizes: the NIFTY lot was revised from 75 to 65 (and Bank Nifty from 35 to 30) per NSE circular NSE/FAOP/70616 dated 3 October 2025, effective 28 October 2025; all worked examples and per-lot rupee figures were recomputed. Expiry day: NSE index and stock F&O now expire on Tuesday rather than Thursday — weekly on the Tuesday of the week, monthly on the last Tuesday — per NSE circular NSE/FAOP/68747 dated 25 June 2025, effective for contracts expiring on or after 1 September 2025. BSE/Sensex/Bankex keep their separate schedule and are unaffected. No arithmetic on this site depends on the lot size being current.
9 July 2026 — Launch
Initial publication: 67 concept pages across 8 sections, 10 client-side calculators, 6 reference sheets and 106 glossary terms. All 73 diagram types generated by the site's own Black–Scholes and statistics engine, from seeded deterministic series.
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Published 9 July 2026.