Positive-gamma days and negative-gamma days
Most index sessions fall into one of two shapes, and the shape is usually decided in the first hour. Traders who read positioning call them positive-gamma and negative-gamma days, after which side of the options book the dealers are on. The words describe what happens to a move after it starts.
Positive gamma
On a positive-gamma day price sits above the gamma flip, hedging flow leans against every push, and the index keeps returning to the strike with the heaviest open interest. Breakouts fail. Ranges hold. The temptation to chase is exactly wrong, and the trade that works is boring: fade the edges, respect the middle.
Negative gamma
On a negative-gamma day the flip has been lost, hedging now feeds moves, and each pullback finds the same side rather than the opposite one. Fading extremes is how accounts get hurt on these days. The trade that works is the one that waits for the move to confirm and then goes with it, sized for the fact that the range is open.
Telling them apart
Three early tells. Where price opened relative to the flip. Whether the first test of a wall was rejected or absorbed. And whether a dip found buyers quickly or slid. None of the three is decisive alone; together they usually are by 10:30.
This is the public vocabulary. Members get the numbers every morning, the read that goes with them, and the tools that show how the day is developing.
See plans