The zero-gamma flip

One level, two different markets

Sum dealer gamma across every strike and you get a curve that depends on where the index is trading. At some price that curve crosses zero. That crossing is the zero-gamma flip — also called the gamma flip line, the gamma flip point or simply the zero-gamma level — and it separates two mechanically different markets.

Above the flip, dealers are net long gamma. Their hedging sells rallies and buys dips — a stabilising flow that tends to compress ranges and pin price near heavy strikes. Below the flip, dealers are net short gamma. Now the hedging buys rallies and sells dips, amplifying whatever momentum exists. Volatility clusters below the flip not by coincidence but by construction.

What the flip is not

The flip is not support, not resistance, and not a trade signal. Price crosses it freely — what changes is the feedback around every subsequent move. This site tested directional signals on years of this data and found nothing worth an arrow: the sign of net GEX alone carries no reliable edge. What the flip does tell you is which regime the tape is operating in, and how seriously to take a breakout or a fade.

Where it sits today

The flip moves through the day as flows accumulate — on the terminal it is the FLIP line, recomputed every second while the market trades. Every archived session shows where it was at the close and how price behaved around it; the summary on each session page states the close's distance from the flip in points. Related: what GEX is and the walls that anchor the gamma profile.