Delta Exposure (DEX)
Canonical definition, formula, interpretation rules, and live API reference for dealer delta exposure.
The net dealer delta exposure derived from option open interest weighted by per-strike delta. Measures the aggregate directional bias in dealer hedging — positive DEX means dealers are long delta (hedging puts), negative means short delta (hedging calls).
Where δᵢ is the option delta of contract i, OIᵢ is open interest, S is spot price, sign is +1 for calls and -1 for puts, and the sum is across the entire option chain.
- Large positive DEX: dealers long delta from put hedging. Bearish signal if dealers unwind — selling pressure as hedges are removed.
- Large negative DEX: dealers short delta from call hedging. Bullish pressure if they cover — buying pressure as short hedges are closed.
- DEX vs GEX: DEX is the directional sibling of GEX. GEX tells you how dealers re-hedge (mean-reversion vs amplification); DEX tells you where they are positioned directionally.
Live Example: SPY
Live SPY DEX data temporarily unavailable. See /stock/spy/gamma for current values.
Get DEX via API
symbol(path, required) — underlying ticker, e.g.SPYexpiration(query, optional) — filter to single expiry (yyyy-MM-dd)min_oi(query, optional) — minimum open interest threshold
{
"symbol": "SPY",
"underlying_price": number,
"net_dex": number,
"strikes": [
{ "strike", "call_dex", "put_dex", "net_dex",
"call_oi", "put_oi", "call_volume", "put_volume" }
]
}curl -H "X-Api-Key: YOUR_KEY" \
https://lab.flashalpha.com/v1/exposure/dex/SPYWhy DEX Matters for Trading
DEX tells you which way dealer hedging is biased. Positive DEX = dealers already long the underlying = supply overhead. Negative DEX = dealers short = latent bid.
- What it measures
- Net dealer delta exposure across the full option chain, in shares (or USD notional).
- What it signals
- The directional bias of dealer hedging flow — which way their book leans and which way they'll lean harder on moves.
- Why we measure it
- Unlike GEX (which tells you regime behaviour), DEX tells you the direction of the standing hedge. Pairs cleanly with GEX for a full picture.
- Who uses it
- Vol traders, systematic flow traders, and anyone using options positioning for directional bias confirmation.
How to read DEX
- Dealers must buy to stay hedged as price drifts
- Acts as latent bid on dips
- Often aligns with put-heavy OI below spot
- Bullish tailwind on squeezes
- Dealers must sell to stay hedged
- Acts as cap on rallies
- Common after large call-heavy retail inflows
- Bearish drag on upside attempts
- No directional hedging bias
- Price action set by spot flow, not dealer book
- Pair with GEX for regime
- Typical quiet-day reading
Rules of thumb
- Pair DEX with GEX. DEX gives direction, GEX gives regime. Using one without the other misreads dealer flow.
- Size relative to float. Raw DEX scales with notional. For single stocks, express as % of avg daily volume to compare across names.
- DEX shifts fast around OPEX. Charm moves delta through time — expiry weeks reshape DEX independent of price.
- Ignore DEX across catalysts. Earnings, CPI, FOMC overwhelm dealer flow. Don't trade the DEX signal into scheduled events.
- Combine with put/call OI skew. A negative-DEX signal with put-heavy OI is a stronger bullish setup than either alone.
How to Read DEX
Start with the sign. Positive net DEX means dealers are net long delta across the chain — they hold long shares or futures from hedging put open interest. This creates a latent selling overhang: when those puts are unwound, exercised, or expire, dealers must sell the hedge. Large positive DEX heading into monthly or quarterly expiration is a bearish setup because the de-hedging flow is directionally negative.
Negative net DEX means dealers are net short delta — they hold short shares or futures from hedging call open interest. This creates a latent buying underpinning: when those calls are unwound or exercised, dealers must buy to flatten. Large negative DEX heading into expiration is a bullish setup because the de-hedging flow is directionally positive.
Combine DEX with GEX for a complete picture. GEX tells you how dealers will re-hedge (dampening vs amplifying); DEX tells you where they are positioned. For example, negative GEX + large positive DEX means the market is in an amplifying regime and dealers have shares to sell — a setup that can accelerate selloffs. Positive GEX + moderate DEX means the market is range-bound and dealers are relatively balanced — the quietest conditions.
Related Concepts
Net dealer gamma exposure — determines whether dealer hedging dampens or amplifies price moves.
How dealer delta changes when implied volatility moves — the vol-coupling feedback layer.
The price level where net GEX crosses zero — the boundary between positive and negative gamma regimes.
The strike with the highest call gamma concentration — acts as intraday resistance in positive-gamma regimes.
The strike with the highest put gamma concentration — acts as intraday support in positive-gamma regimes.
Learn More
Complete guide to GEX, DEX, and options flow with dealer mechanics and trading applications.
Full endpoint reference with parameters, response schema, and tier limits.
Per-strike delta exposure visualisation for any US equity or ETF.
Live for 6,000+ US symbols. One API call, sub-200ms.
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