SPY Gamma Exposure - Dealer GEX Levels for S&P 500 ETF

Why SPY gamma behaves differently from the index

SPY options settle into shares, so dealers hedging SPY gamma buy and sell the ETF itself. That hedging flow lands in the same order book everyone else is trading, which is why SPY gamma tends to show up as intraday pinning around large open-interest strikes.

Early assignment changes the hedge

SPY options are American style. Short in-the-money calls can be assigned before expiration, particularly around ex-dividend dates, which forces dealers to manage a risk that cash-settled index options never carry.

SPY Dealer Gamma Exposure and Zero-Gamma Level

Why SPY gamma behaves differently from the index

Early assignment changes the hedge