Risk-Neutral Density · Advanced
Free to readDensity Alerts: When the Distribution Shifts
You don't watch a density curve all day. You get notified when the left tail inflates, when bimodality emerges, or when the implied probability of a key price zone crosses a threshold.
The risk-neutral density changes shape as the options market reprices. A tail that fattens overnight, a distribution that was unimodal this morning and bimodal by the close, an implied probability of finishing below a specific level that just crossed 20% — these are events worth knowing about. The Nations alert engine is built to watch for exactly this kind of threshold crossing on the density, so the chart watches itself.
What you can be alerted on
Density alerts are configured around three types of shape events. First, tail-inflation alerts: the left-tail probability mass — the area of the density below a defined downside strike — crosses a threshold you set. If the density assigns more than your threshold probability to a large decline, the alert fires. Second, skew-shift alerts: the asymmetry of the density changes materially, signaling that the market's fear of one tail has changed overnight. Third, bimodality alerts: the density develops a second local maximum — a new hump appears — signaling that a binary event has entered the pricing horizon.
Left-tail probability (density area below −15% strike) crossed above threshold. The market is assigning meaningfully more probability to a large decline than it was. Condition: CDF(spot × 0.85) > alert level.
A second local maximum has appeared in the risk-neutral density. A binary event may be entering the pricing horizon. Condition: second density peak detected above minimum height threshold.
The left-tail probability mass (area of the density below the alert strike) rises over time. When it crosses the threshold, the alert fires. The engine watches this continuously so you get the notification at the crossing, not a day later.
How it is delivered
Density alerts run on the same Nations alert engine that powers the index and vol-cone alerts — polling on a scheduled basis and dispatching by email or SMS when a condition is met. The density conditions are additive to that system: a new class of trigger computed from the Breeden–Litzenberger pipeline already running on-site. Alert configuration specifies the underlying, the expiration tenor, the alert type, and the threshold level.
An alert is a prompt to look, not an instruction to trade. A tail-inflation alert tells you the market has repriced a tail — it doesn't tell you whether the repricing is justified or excessive. Open the tool, read the full shape, then decide.
Understanding the alerts is free. Configuring them on your names rides the tier the underlying needs — ETFs with ETF Analytics, single stocks with ETF + Equities.
See plans →Educational content from Nations Indexes. VolDex® is a registered mark of Nations Indexes. Alert availability and delivery depend on plan and configuration. Nothing here is investment advice.