SPX put skew across expirations, 25-delta against 10-delta

Recorded in cvforge on June 10, 2026 by ConvexValue · Published July 25, 2026

Implied volatility for 25-delta and 10-delta SPX puts at every expiration, with open interest alongside and a toggle for the difference between them.

What the agent built

• A chart showing IV of 25 delta puts and 10 delta puts, along with open interest, for each expiration. Also can toggle to display the difference instead of separate lines
• implied volatility smile vs absolute delta on the put side - you can select expiration
• put IV heatmap - very cool! - showing IV across not only delta but also expiration.
• expiration ladder giving me a table of all the relevant values for each expiration
• open cvforge
• enter the above prompt
• watch it come to live

Fields used

implied_volatility, delta, strike_price, expiration_date, contract_type

How to read it

Delta-referenced strikes are the professional convention because they stay in the same relative place as spot moves — the 25-delta put is always a comparable distance out, which a fixed strike is not.

The difference toggle is the panel to use. The two lines separately mostly show the general level of volatility; the gap between them is the steepness of the tail, and a steepening gap means the market is paying up specifically for far-downside protection rather than for volatility in general. Open interest alongside tells you whether the reading rests on liquid contracts.

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.
• Delta-referenced skew depends on the snapshot’s greeks; low-activity wing strikes can make the reading less reliable.
• This is the level and shape of implied volatility, not an implied-volatility rank or percentile against its own history.

Related demos

• MU IV term structure and skew in one view
• SPX skew for this week’s expirations

Search focus: spx put skew by expiration. Related: 25 delta vs 10 delta put skew, put skew term structure chart. Originally posted on X.