Around monthly options expiration (OPEX), charm and vanna flows intensify as enormous positioning decays and rolls off. That concentration produces drift, pinning, and the well-known post-OPEX unclench.

Why OPEX amplifies the flows

OPEX weeks carry the heaviest open interest, so the charm hedging (delta decay into expiration) and vanna hedging (vol-driven) are at their loudest. Charm tends to pin price to heavy strikes; the large positive-gamma positioning damps volatility, so OPEX weeks often feel oddly calm and range-bound — a low-vol drift toward big strikes.

The post-OPEX release

Then the expiring positioning rolls off, removing the damping gamma — and the following week often sees larger moves, the post-OPEX unclench. So OPEX has a two-part signature: pinned, calm drift into expiration, then a release afterward. The largest effects come at the quarterly quad-witching expirations.

OPEX is when the options market’s gravity is strongest — charm pins, gamma calms — and the week after is when that gravity lets go.

What it means for a scalper

Know where you are in the OPEX cycle: expect pinning and low conviction into monthly expiration, and more movement the week after. It reframes an otherwise-puzzling calm or sudden expansion. NoVo maps the live gamma and positioning so you can see the pin forming and the regime shift.