SPX gamma map — Oct 27: 7720 0DTE call wall caps a 0.35% coneS&P 500SP_DLY:SPXspxwevolutionSPX ~7702 (+0.3%) in a dampening regime (positive gamma), 1-day expected move about ±0.35%, VIX 17.9. FOMC decision tomorrow, and a macro release at 15:00 CET lands within 30 minutes of the open, so the first half hour is the riskiest window of the session. Key levels (index), lines on the chart: 0DTE call wall 7720 (red) — the one that matters today, less than 0.25% above spot; the all-expiries call resistance 8100 is far away. Put support 7650 (green) — gamma demand zone that cushions the downside. HVL / gamma flip 7630 (orange), same-day flip 7616 — price sits about 0.9% above it, which is what makes the regime readable. GEX magnet 7695 just under spot, the pole price tends to gravitate back to. Negative-gamma pockets 7715 and 7690 — moves through them get amplified for a few points before the next wall. 1-day cone 7671–7725 (grey). Scenarios. Range: price holds between the cone low 7671 and the 0DTE call wall 7720; positive gamma dampens, and the 7690 pocket can produce quick bursts inside the range. Upside: a 15-min close above 7725 leaves the cone and the same-day wall behind, with the open-interest magnets 7800 / 7825 / 7850 as the next references. Downside: a 15-min close below 7671 removes the cushion and puts 7650, then the 7630 flip, in play — below the flip the regime turns amplifying. Tuesday lesson — the 1-day cone. Half-width ≈ spot × IV × √(1/252), using the short-dated implied vol, not the 30-day VIX. With the 30-day VIX (17.9%) you would get about ±87 points, which is why that number is useless intraday; with the same-day implied move of 0.35% the cone is ±27 points, 7671–7725. Walls inside the cone (7720 wall, 7715 and 7690 pockets, 7695 magnet) are the ones that can actually be tested today; walls outside it (7650, 7630) only matter once the cone itself breaks. Levels are a map of dealer positioning, not a prediction. Not investment advice.