Implied probability and expected move · Demo

This week’s SPX expected move and its bounds

Recorded in cvforge on July 20, 2026 by ConvexValue · Published July 25, 2026

A stripped-back read of the current week: SPX spot, the expected move implied by this week’s expiration, and the upper and lower bounds it sets.

Exact prompt

Look at SPX options and give me a visualization of this week's expected move.

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

  • $SPX spot
  • Expected Move
  • Upper / Lower Bounds

Fields used

implied_volatility, delta, strike_price, expiration_date, underlying_price, fair_market_value

How to read it

The simplest build in the cluster and often the one you actually want: spot, the move, the two bounds. Nothing to configure.

The bounds are a one-standard-deviation range for this week’s expiration, which means roughly a one-in-three chance of finishing outside them. That is a much weaker claim than the clean lines suggest, and it is worth restating every time a range chart looks definitive.

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.
  • These are risk-neutral probabilities implied by option prices, not forecasts. They shift with volatility as much as with expectations.
  • Anything derived from implied volatility inherits the model behind it; treat the numbers as a market-implied range, not a measurement.

Related demos

Search focus: spx expected move this week. Related: weekly spx implied range, spx upper lower bound options. Originally posted on X.