Strength Zones and Build-up

A thin line on a chart says “exactly here.” Options positioning doesn’t work that way. Gamma spreads across neighboring strikes, it shifts as price moves, and the estimate behind it rests on assumptions. So StratosHedge draws each key level — the Ceiling, Floor, Flip Line and Magnet — as a Strength Zone: a translucent band whose shape carries information. This lesson shows how to read that shape, and how to read the Build-up percentage beside it without reading too much into it.

Reading a zone’s shape

• Height: how spread out the gamma is. A zone starts at its anchor strike and reaches halfway to the next listed strike on each side — $0.50 either way for SPY’s $1 strikes. If nearly all the estimated gamma sits on that one strike, the band stays that narrow. If the strikes right next to it carry net gamma of the same sign and at least about half the anchor’s size, the band widens to cover them, up to two strikes on each side.
• Thickness through the day: how strong it is at each moment. Within that height, the band’s thickness at each moment shows its estimated strength relative to the largest zone on the chart. The zones share one scale, so the thickest band is the strongest zone at that moment. The Flip Line zone is the exception: it always spans the two strikes on either side of the crossing, and its shading is a separate confidence reading — how much gamma sits there — so don’t compare it with the other zones.
• Shading: a quick rank. Fills step through weak, medium and strong, and a thin center line marks the anchor strike. Each level also has its own icon and label, so you never have to tell zones apart by color alone.
• Wide isn’t the same as strong. A tall, faint zone means gamma is spread thinly over several strikes. A short, dense one means it’s concentrated on one strike. Height and thickness answer different questions.
• Shared zones. When the Magnet sits inside another zone — often the Ceiling — it’s shown as part of that zone rather than as a second band.

The Build-up percentage answers one question: how much has this zone’s estimated strength changed since a starting point? That starting point — the basis — is always printed. “Since open” compares with the zone’s strength at the first reading of the regular session. When StratosHedge has no opening reading for a zone — say it only formed later — Build-up compares with the zone’s first reading and says so, for example by naming the time of that reading. Strength here means the zone’s estimated gamma exposure: dollars of hedging per $1 move for the strikes inside the band. Build-up compares size, whichever side of zero that gamma sits on. If a zone’s net gamma changes sign during the day, Build-up shows no percentage, because growth across zero has no useful meaning.

Why a zone can build while open interest stands still. Open interest settles once a day, overnight, so during the session the contract counts behind a zone stay at last night’s figure. The estimate still moves, for three reasons. Price: gamma is highest at strikes near the current price, so as price walks toward a strike, the same contracts there carry more gamma. Time: gamma near the money sharpens as expiration approaches — fastest for 0DTE options in the last hours of the day — while gamma at distant strikes fades. Volatility: when implied volatility falls, gamma bunches up at strikes near price; when it rises, gamma spreads out to farther strikes. Run those forces in reverse and a zone melts: price drifts away, distant gamma decays, and the band thins. Flow is tracked separately: open interest won’t show new positions until the next morning, so StratosHedge keeps a separate volume-based estimate of today’s trading alongside the zone. So ▲150% doesn’t mean traders opened $180 million of new positions. The $180 million is extra estimated hedging per $1 move, and often most of it comes from the same contracts, repriced by distance and time.

When the anchor hops. Each zone is tied to an anchor strike. If another strike’s gamma grows past it — say price rallies and the $590 strike overtakes $585 as the largest positive strike — the Ceiling moves. To keep the map from flickering between two close strikes, StratosHedge keeps the current anchor until a challenger clearly beats it, smoothing over the last few readings. When the move happens, the new zone’s Build-up states its own basis — often its first reading as the anchor, such as “since 11:40” — so read the label instead of assuming “since open.” Zone history lets you see where the level used to be.