Dealer positioning
Also called long gamma, short gamma, gamma regime
Dealer positioning describes whether options market makers are modeled as net long or net short gamma, which determines whether their hedging dampens or amplifies price moves.
In more detail
In a long-gamma regime, dealers hedge against the move — selling strength, buying weakness — which compresses realized volatility and tends to produce rangebound sessions.
In a short-gamma regime, they hedge with the move, buying strength and selling weakness. That feedback tends to extend trends and widen ranges, and it is why short-gamma sessions are often described as fast.
The regime is inferred, not observed. It rests on assumptions about which side of open interest dealers are on, and those assumptions can be wrong.
How Hermes measures it
Hermes labels the modeled regime on each ticker page and, for SPX, tracks it intraday from same-session options flow rather than from open interest alone.
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Hermes puts dealer positioning next to price through the session. Free to use.