Thermal's Four Lenses: GEX, VEX, DEX & CHARM

Thermal computes dealer exposure from a single options-chain payload — one data pull covers all four views. A client-side toggle switches between four lenses, each showing a different Greek's exposure profile across strikes. Same data, four angles. Here is what each lens reveals and when to use it.

GEX lens — gamma exposure

The default lens. GEX maps where dealer gamma concentrates across strikes — the mechanical buying and selling pressure dealers must exert as price moves. It shows the gamma flip, call wall and put wall, max pain, and King node (the single largest gamma cell). Check it before the open to set the regime, and mid-session to catch wall migration. The fundamental question it answers: is dealer hedging working for you or against you today?

VEX lens — vanna exposure

Vanna measures how dealer delta shifts as implied volatility changes. The VEX lens maps that sensitivity by strike. It shows vanna walls (strikes most sensitive to an IV change) and the vanna flip (where the vanna profile crosses zero — above it, a VIX spike forces dealers to buy; below, it forces selling).

When to use it: VEX matters most when IV itself is moving — FOMC days, macro releases, earnings-heavy sessions. On a quiet day it adds little to GEX. On a day when VIX jumps 3 points, VEX shows where the second-order hedging pressure hits. Think of it as "what does the gamma map look like after a vol shock?"

DEX lens — delta exposure

Delta exposure shows dealers' net directional positioning across strikes. It reveals the delta-zero pivot (where aggregate dealer delta crosses zero — above it, bullish hedge bias; below, bearish) and posture (whether the overall tilt is positive, negative, or flat).

When to use it: DEX is the directional read. GEX tells you volatility regime; DEX tells you directional lean. When negative GEX meets short dealer delta, the setup favors downside. Negative GEX with positive DEX means long-delta hedges that can fuel a squeeze higher.

CHARM lens — charm exposure

Charm measures how delta changes purely from the passage of time — no price movement required. The CHARM lens maps this time-decay effect by strike, showing where delta is drifting as the session wears on.

What it shows you:

- Charm-zero pivot — the price where time-driven delta drift crosses zero. Above it, time decay is adding to dealer delta (supportive); below it, time decay is subtracting delta (pressuring). - Pinning pressure — charm concentrates at strikes with heavy open interest close to expiration. Dealers re-hedge as delta migrates, pulling price toward heavy strikes — the mechanical "expiration pin." See Max Pain Explained.

When to use it: CHARM matters most in the afternoon of an expiration day. On a Monday with a Friday expiry, charm is minor. On Friday at 2 PM with massive 0DTE open interest, charm is actively dragging price toward the heaviest strikes.

One payload, four views

All four lenses derive from the same underlying options chain data — open interest, strikes, expirations, and the Greeks at each point. Thermal computes all four exposures server-side and delivers them in a single payload. The client-side toggle simply selects which exposure to render on the profile and heatmap. There is no additional data fetch when you switch lenses, so toggling is instant.

Putting them together

A practical workflow: start with GEX to set the day's regime and mark the walls. If VIX is moving, switch to VEX to see which levels are most sensitive to the vol shift. Check DEX for the directional lean — does the hedging book favor bulls or bears? And late in the session on an expiry day, glance at CHARM to see whether time decay is pulling price toward a pin or letting it run.

No single lens is "the best" — each answers a different question about the same positioning data. GEX is the workhorse; the other three are context layers you reach for when the session demands them.

For how to read the heatmap and profile views themselves, see How to Read Thermal Heatmaps. For how to turn these levels into strike decisions, see Using Thermal for Strike Selection. Get access →

BlackOut provides educational tools and market analysis only and does not provide investment advice. Options trading involves substantial risk and is not suitable for every investor.