Am I comparing the correct contract and a usable quote?
An option quote belongs to one underlying, expiration, strike, and option type. Verify that identity and the two-sided bid/ask before interpreting a premium, Greek, spread, or potential execution diagnostic.
A useful read order
- Verify identity
Check underlying, expiration, strike, and call or put. A neighboring contract is a different instrument.
- Inspect the market
Read bid and ask together, the observation time, and the spread rather than relying on last trade alone.
- Add the sensitivities
Compare Greeks, implied volatility, open interest, and volume within the same expiration and quote context.
Know the source
Massive is EFI's authoritative source for option expiration discovery, contract metadata, live snapshots, bid/ask, Greeks, open interest, and volume. Stock prices and history come from yfinance. Any permitted yfinance option-row quote fallback is labeled and only applies when Massive bid/ask is missing.
Later-expiration discovery uses contract-reference metadata. Browsing expiration dates is distinct from fetching the selected expiration's live chain.
A midpoint is a reference
The midpoint is halfway between a valid bid and ask. It is a reference mark, not a guaranteed fill. A naturally wide market remains wide; a clean-looking midpoint does not eliminate the cost of crossing the spread.
Volume measures trading activity and open interest measures outstanding contracts. Neither proves that a particular price is executable. Preserve contract identity, quantity, position side, and price basis when comparing paper receipts or research outcomes.
What this cannot establish
- A last trade can be old or outside the current two-sided market.
- Missing bid or ask should not be replaced with an invented clean spread.
- Greeks are sensitivities under a model, not fixed predictions of option returns.