Use the source closest to the claim. Exchange specifications establish contract size, exercise, expiration and settlement terms. OCC notices establish U.S. listed-option adjustments. Regulator publications establish relevant rules and warnings.
Mathematical definitions
Expiration profit and loss is the sum of the signed stock and option leg values less the entry cashflow and stated fees. We evaluate stock-option losses down to a zero underlying price and inspect the high-price payoff slope. This avoids confusing a very large finite loss with unlimited risk.
Product-specific exceptions
Calendar spreads, portfolio hedges and futures cannot always use the same stock-option expiration model. We state the missing assumptions or valuation dependencies instead of assigning an unsupported exact result.
Dates and market data
Historical examples do not establish present prices or margin requirements. A source link is not a live data feed. Check a chart's own source, timestamp and delay label before treating it as current information.
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