How an option’s estimated value moves with spot, using FMV
Recorded in cvforge on May 31, 2026 by ConvexValue · Published July 25, 2026
A teaching tool that interpolates the live chain to show what a contract would be worth at different spot prices — the delta and gamma relationship, with real numbers.
Exact prompt
create an interactive visualization that lets me understand the effect of spot price on options price using real options prices. This should be an educational and teaching tool
Data cadence
Live U.S. option snapshots, refreshed through the session. Open interest is an end-of-previous-day figure and updates once daily.
Plan requirements
Runs on the free cvforge app and the free data tier (20 requests/hour). No card needed.
What the agent built
- Option price vs hypothetical spot using real same-expiration chain interpolation
- Current chain cross-section with selected/comparable strike markers
- Metrics for spot, estimated price change, intrinsic/extrinsic value, delta/gamma, volume, and OI
- Dynamic teaching notes explaining moneyness, price movement, convexity, and premium
Fields used
fair_market_value, implied_volatility, delta, gamma, theta, vega, strike_price, expiration_date
How to read it
Textbook explanations of delta use invented numbers. This build uses the actual chain and its Massive fair market value estimates: to show what a contract is worth if spot moves, it reads across same-expiration strikes and interpolates, so every point is anchored to an FMV estimate.
FMV is a proprietary estimate, not an executable quote. Moving along the strike axis is not the same as the underlying moving — implied volatility would change too, and the chain’s own shape is what supplies the curvature. It is the right tool for building intuition about the relationship and the wrong one for pricing a hypothetical move precisely.
Change it
The prompt is the interface. Ask for a different ticker, a different expiration window, or an extra column in the same sentence style and the agent edits the app in place — you do not start over, and you do not wait for anyone to build it.
Limitations
- Snapshot data, not a transaction tape: the build reads the chain as it stands, so it cannot attribute a trade to a buyer or a seller.
- Open interest updates once a day, so an intraday volume/OI comparison is always this session’s volume against yesterday’s open interest.
- Contract coverage is U.S. listed equities, ETFs and indices. Indices use the I: prefix, for example I:SPX.
- Current per-contract valuation is Massive fair market value (FMV), a proprietary estimate. cvforge does not provide option bids, asks, midpoint, quote sizes, NBBO or last trades, and FMV is not an executable quote.
- A teaching build simplifies on purpose. It shows how a mechanic behaves, not what a position would actually cost to run.
Related demos
Search focus: how option price changes with stock price. Related: interactive option pricing tool, delta gamma explained with real data. Originally posted on X.