Methodology
Exactly how our explanations, curves and examples are produced — and their limitations.
Exchange conventions
Rules about expiry days, settlement type and settlement-price calculation follow the current NSE, BSE and SEBI circulars. Because these have been revised repeatedly (for example, the 2024 removal of Bank Nifty/FinNifty weeklies and the 2025 shift of NSE expiry to Tuesday and BSE to Thursday), every page presents the specific day-of-week as a current, verifiable convention and points you to the exchange for the live rule.
The pricing framework
Where we discuss option value, time decay and the Greeks near expiry, we use the standard Black-Scholes-Merton framework for European index options. Time-decay and gamma curves are generated from a numeric engine and rendered as inline SVG; shapes are qualitatively accurate, with relative y-axes because the shape (where a Greek peaks or decays) is what matters for learning.
The base scenario
Unless stated otherwise, examples use a Nifty spot of 25,000, a lot size of 75, and typical Indian volatility and rate levels. These are illustrative round numbers for clarity, not live quotes.
Limitations
All figures are educational approximations. Real settlement prices, STT on exercised options, brokerage and slippage will differ. Black-Scholes assumes constant volatility and no early exercise, so model values differ from live premiums. See our Sources.
Last updated 11 July 2026.