Hermēs DocumentationOptions & Dealer Mechanics
A 30-minute options primer for futures traders + dealer hedging mechanics
What You'll Learn
After this chapter you should be able to answer these three questions in your own words:
- Why must options market makers hedge — and why does that hedge feed back into spot price?
- What's the fundamental behavioural difference between Long Gamma and Short Gamma environments?
- What roles do the second-order Greeks Vanna and Charm play during a trading day?
If you can already answer these, skip to the 4-Layer Framework.
Section 1 — Greeks Primer (Futures-Trader Version)
We only need four Greeks. Dealers care about more (Theta, Rho, Vomma…); you don't.
Delta (Δ) — Option's "sensitivity to spot"
Definition: Delta measures "how many dollars does the option price change if spot moves $1". Range 0 → 1 (call) or −1 → 0 (put).
For a futures trader, the key use of Delta is figuring out how much spot an option represents:
| Option Delta | Meaning | Equivalent position |
|---|---|---|
| Call Δ = 0.50 | At-the-money call | ≈ 0.5 contracts long spot |
| Call Δ = 0.95 | Deep ITM call | ≈ 1 contract long spot |
| Put Δ = −0.50 | ATM put | ≈ 0.5 contracts short spot |
Key insight: when SPX rallies 1%, every ITM call's Delta increases (approaches 1) → dealer's net Delta automatically grows → they must sell a matching amount of futures to flatten.
That's where mechanical hedge flow comes from.
Gamma (Γ) — Rate of change of Delta
Definition: Gamma measures "how much does Delta change when spot moves $1". Mathematically, it's the first derivative of Delta with respect to spot.
Gamma is largest at ATM, near zero deep ITM / OTM.
So:
- Price near ATM → high Gamma → Delta swings violently → dealer hedges constantly, both directions
- Price far from ATM → low Gamma → Delta is stable → dealer barely re-hedges
The one sentence a futures trader must remember:
The closer price sits to large gamma concentrations (HVL / C1 / P1), the more violent dealer hedging becomes — and the more it shapes spot.
Vanna — Delta's sensitivity to volatility
Definition: How much Delta changes when implied volatility (IV) changes. Intuition: "VIX falling" makes deep OTM call Delta rise.
Vanna is the hidden engine behind US afternoon rallies (14:00–16:00 ET):
- VIX falls → call deltas collectively rise → dealers must buy more spot to hedge → "Vanna burn" drives price higher
- VIX rises → call deltas collectively fall → dealers cut hedges → pressures index lower
That's why SPX prints new highs while VIX collapses — it's not fundamentals, it's the Vanna hedge flow lifting the elevator.
Charm — Delta's time decay
Definition: How Delta changes as time passes. Charm intensifies as expiration approaches.
Charm is the fundamental reason 0DTE / 1DTE has reshaped market structure:
- Monday / Wednesday / Friday SPX expirations: near the close, ATM Delta collapses by the minute
- Dealers must rapidly unwind the spot they previously bought to hedge → End-of-Day magnet effect
- Hermēs's EOD Magnet card predicts exactly this close-period hedge flow
Section 2 — Why Dealers Must Hedge
Role definition: Market makers are risk porters, not gamblers
How dealers (Citadel Securities, Susquehanna, Jane Street, etc.) earn money:
Quote both sides
Post bid and ask on every strike, capture the spread. E.g. SPX 5950 call quoted 12.50 / 12.70, spread = 0.20 = $50 per contract.
Hedge immediately after a fill
When a customer buys the 5950 call, the dealer is short the call, exposed to:
- Delta risk: loses if spot rises
- Gamma risk: loses when realised vol exceeds implied
- Vega risk: loses if IV rises
Neutralise Delta with futures / spot
Immediately buy a matching number of ES contracts to cancel Delta. This step is mechanical, non-optional — not hedging means taking directional risk, which violates the business model.
Continuously re-hedge
As long as spot moves, IV moves, or time passes, Delta moves → dealers must re-hedge every second.
The crucial point: Dealer hedging is a mechanical reflex, not an opinion.
So their hedge size is computable and predictable — given open interest, IV, and time-to-expiry, you can estimate how much spot they need to buy or sell.
That's where the indicator GEX (Gamma Exposure) comes from.
Long vs Short Gamma — Two universes
The sign of dealer aggregate gamma exposure dictates the entire day's behaviour:
Condition: Spot > HVL (or 0Γ) → dealers net long gamma
Behavioural model:
- When price rises → dealer aggregate Delta auto-increases → must sell spot to hedge → selling caps the rally
- When price falls → dealer aggregate Delta auto-decreases → must buy spot to hedge → buying supports the dip
Result: volatility is absorbed → Mean-Reverting → IV compresses
| What you'll see | Why |
|---|---|
| Range trading, IV grinds lower | Dealers fade every move |
| Breakouts fail constantly | Hedge orders snap price back |
| Trend strategies underperform | No sustained momentum |
| ICT stop hunts work | Dealers "pin" price into the dominant range |
Key strategy: trade reversion, sell volatility, pin trading
Condition: Spot < HVL (or 0Γ) → dealers net short gamma
Behavioural model:
- When price rises → dealer aggregate Delta auto-decreases → must buy spot to hedge → buying accelerates the rally
- When price falls → dealer aggregate Delta auto-increases → must sell spot to hedge → selling accelerates the drop
Result: volatility is amplified → Trend-Following → IV expands
| What you'll see | Why |
|---|---|
| One-way days, fast moves | Dealers forced to chase |
| Support breaks → meltdown | Sell orders pile up |
| Powerful but fragile rebounds | Same mechanism in reverse |
| VIX spikes in sync | Dealers forced to buy vol |
Key strategy: trade trend, long volatility, breakouts, tight stops
This is Hermēs's core thesis:
The first decision every morning is: are we in Long Gamma or Short Gamma today?
- A wrong call here means your entire toolbox is mis-aligned (trend tools in Long Gamma → stops out repeatedly; mean-reversion tools in Short Gamma → catching falling knives)
- Hermēs's Market State card answers this directly
Gamma Flip — The moment of regime change
When price crosses HVL (peak gamma concentration) or 0Γ (Net GEX = 0 strike), aggregate dealer gamma flips sign → behaviour switches instantly.
This is the single most important event of the day, and the trigger for Hermēs's Gamma Flip Alert.
What should a futures trader do at a Gamma Flip?
- Immediately size down (the environment changed, your playbook may be obsolete)
- Check Hermēs's Confluence scores (the 4 layers are realigning)
- Wait 20–30 minutes for hedge flow to "recalibrate"
- Then swap toolboxes (Long → Short Gamma: shift from mean-revert to trend)
Section 3 — The Mechanical Chain from Options Flow to Spot
Connecting both sections, here's the full causal loop:
Client buys an SPX call
↓
Dealer is forced short the call (fills order)
↓
Dealer instantly carries Delta / Gamma risk
↓
Hedges in ES futures (buys or sells ES)
↓
Abnormal ES volume → SPX spot price moves
↓
Spot moves → Delta moves → re-hedge
↓
(Loop, thousands of times per second)The fact a futures trader needs to internalise: 30–60% of ES futures book liquidity is, in essence, SPX options hedge flow.
Once that clicks, your perspective changes:
- ES volume is no longer "market participants trading", it's "dealers re-hedging"
- SPX microstructure is no longer "retail vs institutional", it's "a reflection of hedge flow"
- Your stop is no longer "the level above resistance", it's "the next strike where dealers must re-hedge"
Section 4 — DEX (Delta Exposure): The Directional Cousin of Gamma
Gamma tells you reaction strength; it doesn't tell you direction. DEX fills that gap.
DEX = sum of Delta-weighted OI across all strikes
- DEX positive → dealers net long Delta → selling more spot if price drops → caps rebounds
- DEX negative → dealers net short Delta → buying spot if price drops → supports declines
The two key DEX anchors on Hermēs charts:
| Symbol | Meaning | Triggered behaviour |
|---|---|---|
D+ | Strike with max positive Net DEX | Crossing → hedge flow direction reverses, event-level trigger |
D− | Strike with max negative Net DEX | Crossing → hedge flow direction reverses, event-level trigger |
Real-world use:
- D+ usually sits above as resistance (dealers forced incrementally short there)
- D− usually sits below as support (dealers forced incrementally long there)
- Price crossing D+ → upside fuel sharply weakens → fade-prone
- Price crossing D− → downside fuel sharply weakens → bounce-prone
Hermēs elevates D+ / D− to ★★★★ top priority because they're the genuine trigger points for "hedge flow direction reversal".
Chapter Summary
Delta is hedge size, Gamma is hedge intensity
Every second dealers mechanically hedge from these two values; that hedge flow IS the spot book.
Vanna drives the afternoon, Charm drives the close
VIX dropping → Vanna fuels SPX higher; near the close → Charm triggers the EOD magnet.
Long Gamma pins, Short Gamma amplifies
First thing every morning — read Hermēs's Market State to know which universe you're in.
Gamma Flip is the day's most important event
Price crossing HVL / 0Γ → regime switch → swap your toolbox.
DEX (D+ / D−) marks hedge-flow direction reversal points
More "event-driven" than gamma walls; the key triggers for structural repositioning.
Now into the core: the GEX 4-Layer Framework that translates these mechanics into readable chart elements.